Shooting Cast after Jacketed Bullets

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John Alexander posted this 07 April 2019

First I have to apologize to any and all members who were following the thread of a similar name about the effect on cast bullet accuracy of jacketed bullet fouling.  I accidently deleted it and as far as I can determine that is irreversible.

I was responding to Joe's request to delete his previous posts of his tables and graphs  since all but the one he posted today were incomplete. i deleted the immediate past graph successfully. When the screen came back it was on joe's graph that he started the thread with and when I deleted this first post it took the whole thread.

All that I can do is apologize and ask Joe to repost his most recent table and graph. I will repost the data I posted yesterday because some may not have seen it yet. I hope others who posted recent comments will also repost.

John

 

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John Alexander posted this 31 May 2019

One of the advantages of shooting cast bullets is that the lower pressures cause less gas erosion and so barrels last longer. Only a few argue with that.  However, I don't think we know how much longer or even how to define it so a fixed number is justified. Interesting topic but probably should have it's own thread.

John

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shastaboat posted this 31 May 2019

I have no idea.  I think I'll be dead before that.  I use a lot of 2400 for bottle neck cases.  I'm sure I have 5000+ rounds through my Browning A-Bolt Medallion .223/5.56 and that is after at least 2500 jacketed rounds before I went to cast.

Because I said so!

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John Alexander posted this 29 May 2019

Sounds like you must have some high mileage on some of your rifles.  How many CB loads does it take to wear out a throat? 

John

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shastaboat posted this 29 May 2019

John,

I do not compete but would agree that cleaning between shots may be the ultimate procedure but obviously for my needs it just wouldn't work.  I've been known to shoot as many as 500 rounds a day at these squirrels but generally around 300 rounds per day.  I have cleaned after 100 rounds generally and then it is a trip back to the Toy Hauler for a lunch and beer break and cleaning break.  The cleaning break is much easier if I fire a couple of jacketed rounds first.  I figure 50% hits on squirrels out to 200 yards so the math is a bunch of squirrels to feed the crows, buzzards, hawks and an concessional eagle.  Even the coyotes might get fed.

 

Because I said so!

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John Alexander posted this 29 May 2019

Shastaboat,

I and others have observed some of the same things you mention.  It is quite common for some CBA competitors to bore clean after every target card to maintain best accuracy.  

On the other hand I, and others, sometimes find loads that produce a stable bore condition that never (as in whole match or even whole season) needs cleaning and maintains top accuracy.  I consider this the holy grail but can't always achieve it.

What is new to me in your post is the possibility that the hard powder fouling can be removed by firing full charge JB loads. if this is as effective as a quick bore cleaning (solvent - brush - dry patch) it might be the best procedure for match shooting and could even be done in the middle of a target card by a couple of quick shots JB into the backstop if wayward shots indicate fouling.  Of course the JBs and CBs would have to make clearly different holes in paper or others might object to shooting JBs during a CB match.

John

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shastaboat posted this 29 May 2019

I'm not into the scientific testing and mathematical posting of results as some of you.  I do know that when I'm out shooting Nevada Pot Gut Ground Squirrels (1/2 the size of a Prairie Dog) (Belding Ground Squirrel) out to over 200 yards with cast .223/5.56 that as powder fouling increases up to 100 rounds fired and accuracy decreases that if I fire  2-3 JB full power loads that accuracy increases until it degrades again with powder fouling.

Maybe it is the powder fouling that needs to be worried about.  Actual bore cleaning doesn't show any JB fouling and blue/green patches but the removal of the powder fouling with even Hoppes #9 sure allows a dry patch to run smoother through the bore.  And after powder fouling is removed accuracy certainly returns.

Because I said so!

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John Alexander posted this 25 May 2019

Test #11

The leftovers of another batch of gas checked bullets that were a bit too small to shoot well tempted me to run another test of before and after groups. I have a hangup about throwing bullets with three cent gas checks back in the pot. So i often find an excuse to add a three cent primer and a few more cents worth of power and shoot them. A good example of the lure of the sunk cost fallacy even on folks who know about it.

Procedure was the same as my earlier tests with the 223 Tikka. Conditions were a bit extreme a with nice sunny 65 F day but with a  mostly 12 o'clock wind gusting to maybe 30 mph busy blowing off targets, caps, and anything loose of low density off the benches.

Before CB groups: 1.04, 1,44, and 96 moa -- Average = 1.15 moa

Jacketed bullet groups: 1.14, 1.24, 1.28, and 1.08 moa -- Average = 1.18 moa.

After CB groups: .74, 1.84, and 1.02 moa -- Average = 1.20 moa.

This test  showed a 4% increase in group size in the cast bullet groups fired after the jacketed bullets instead of a small decrease like the heavy majority of the other ten tests so far.

Side note -- The jacketed bullets were bulk Remington 55 grain pointed soft points seated as far out as possible. The cannelure was about .2" beyond the case mouth.  This was still 0.112" short of touching the lands due to the "freebore" caused by 11,500 rounds fired.  Since these still grouped near 1 moa it shows how tolerant a JB can be to seating depth. 

John 

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John Alexander posted this 19 April 2019

There is an interesting set of remarks about jacketed bullet fouling and accuracy over in the 

Does The Amount Of Time In Between Firing And Cleaning Effect The Effort Required To Remove Lead?

What we need to extend our experiments is a prairie dog shooter who also shoots casts in the same rifles. Mashburn seems to know about serious JB fouling.

John

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John Alexander posted this 14 April 2019

I think Joe's remarks about what we know so far are about right.

I also think that it is pretty obvious that the dire warnings that a bit of JB fouling (up to at least 20 shots) degrades CB accuracy would be pretty hard to support in spite of the fact that we have been hearing them as absolute truth for at least 70 years.

John

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joeb33050 posted this 14 April 2019

Is it possible to get enough jacketed bullet fouling in a barrel to degrade cast bullet accuracy?

We don't know.

Will shooting cast bullets in a jacketed bullet fouled barrel remove that fouling?

Maybe-Probably

Will a slightly-moderately jacketed-bullet-fouled barrel degrade cast bullet accuracy?

Probably not, at cast bullet accuracy averages around 1 moa.

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joeb33050 posted this 14 April 2019

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RicinYakima posted this 13 April 2019

I am finding this very interesting. My memory of firing old military rifles with 50 years of fouling was that they shoot cast better after cleaning. BUT I never tested this hypnosis. Just cleaned down to bare metal with reverse electrolysis and then began shooting cast. Keep up the good work!

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John Alexander posted this 13 April 2019

TESt #10

Yesterday, 4-12-19 I fired another test of CB accuracy after fouling with JB loads.  It has been questioned if the CB fouling before the string of JBs might have prevented normal JB fouling because of the lube deposited in the bore preventing adhesion of the copper in the first eight tests.  Joe’s test #9 investigated this possibility. I followed Joe’s lead in shooting test #10 by firing the jacketed bullets starting with a clean dry bore to see if JB fouling deposited on clean steel had an effect on CB accuracy.  My test #10 follows.

Clean bore with Hoppe’s # 9 followed by the copper remover Sweets 7.62 until no trace of fouling can be detected.

4 5-shot groups with Sierra 69 gr MK and 18 grains of Reloader 7 - .98, 1.06, .82, .90 moa – Average = .94 moa.

One fouling shot.

4 5-shot groups with same CB load as before -.72, 1.14, .96, 1.24 moa. Average=1.03 moa

Clean bore with Sweets, 30 minute soak.

One fouling shot

4 5-shot groups with same CB load - .40, 1.34, .98, 1.68 moa. Average = 1.10 moa.

Summary

This test #10 again failed to show that JB fouling degraded CB accuracy.

John

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John Alexander posted this 11 April 2019

I missed what Joe was doing with his last test (#9)

This time the JB to lay down fouling was done on a clean bore where it may adhere better instead of a CB fouled bore which might avoid copper fouling by providing a dirty surface.

Because his average accuracy was worse than his previous "before" CB groups it may be telling us something.

I will try a similar test in a few days to see if I get similar results.

John

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John Alexander posted this 10 April 2019

Ken,

I sometimes during the CBA nationals we will drive the 40 miles or so to the Sierra and buy a few pounds of factory seconds. The bad news is that there isn't a major discount.  The good news is that they seem to almost always minor bleminish and seem to shoot as well as the ones in boxes.  Nosler is 15 miles down the road and the seconds are discounted even less but shoot fine.  I think the cheapest jacketed bullets are probably the bulk FMJ sold to the folks that like ARs, AKs and such.

I agree, heavier JB fouling is what we should test next.  Brodie is going to do a bit of that with his "new" Mauser.

John

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Ken Campbell Iowa posted this 10 April 2019

... joeb: ...

well, there goes my little billfold card that states 3 absolute rules for cast bullet success.  it was getting a little tear-stained anyway ...

**************

i wonder if sierra/hornady would have a bucket of reject bullets cheap so we could get a barrel real copper fouled .

if shooting cast removes copper fouling, is it the lead or is it the gunpowder ?? ...  or the graphite on the powder ?? 

thanks for your test .   ken

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joeb33050 posted this 10 April 2019

Shot Tuesday

6 PM Tue., 2 patches with odorless paint thinner, 3rd patch clean, nylon brush with #9, 2nd patch clean, overnight,

6 AM Wed.,-bore wet with #9, dry patch had some black stuff, another #9 wet patch and wait.

10 AM Wed.,black stuff on  patch, another #9 wet patch, wait

2 PM Wed., black stuff on  patch, another #9 wet patch, wait,

6 PM Wed., black stuff on  patch, another #9 wet patch, wait,

4 AM Thu., a little black stuff on  patch, another #9 wet patch, wait,

11 AM Thu., no black stuff on patch. The black stuff is probably Moly, from the cast bullets.

NO blue/green, no copper.

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Larry Gibson posted this 09 April 2019

joe

Interesting tests and I applaud you for posting.

Mike Venturino had an article published in Handloader magazine several years back where in he stated accuracy with his cast bullets (mostly in milsurp rifles) was just as good after shooting jacketed.  On the other forum I concurred with him as that was my was also my experience.  He responded to a couple posts about his article and received such a raft of criticism from self styled experts (my simple post was ignored......for once) that I don't believe he has posted there on that forum since.......

It's enlightening to see actual test results.

LMG

Concealment is not cover.........

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joeb33050 posted this 09 April 2019

 

TEST #9

 joe b. 4/9/19

 M10 Savage, M110 308 HV barrel, 5 shot groups, 100 yards, “

 Clean barrel

 Gray, windy, rain coming.

 Hornady 130 gr sp, 46/Varget. Fired 30.

 .875, 1.2, 1.4, 1, 1, Avg. = 1.095

 Then the wind started blowing hard, with light horizontal rain.

 314299, .3095, Lyman Super Moly, 15/A#9 Fired, 25 after.

 1.4, 2.125 with a stranger, .9, 1.725, 1.2; Avg. = 1.47

 Listed in the order that they were shot.

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joeb33050 posted this 07 April 2019

 

 

 

 

 

 

CAST AFTER JACKETED

 

From the Cast Bullet Association Forum

 

 

 

Will copper alloy jacketing in the barrel affect the accuracy of cast bullet loads?

 

 

 

Glenn R. Latham posted this 05 January 2019

 

I did a little test on this back in 1990.  I was shooting both jacketed and cast from my Shilen barreled .223 prairie dog gun.  I shot 5 rounds with the Hornady 50 gr. SX bullet and 28.0 grs. of T-2208.  I then fired two groups with the RCBS 22-055-FN bullet and 13.0 grs. of IMR4227 (2049 fps) which measured 1.58 & 1.51.  Cleaned the bore with Sweet's 7.62 Solvent.  This was all done at the range of course, and even with Sweet's I find it takes numerous patches over several days to get all the copper out of a barrel.  So running a handful of patches thru at the range isn't going to get all the copper out, even from just 5 rounds, but a lot of it came out on the blue patches.  Fired another group  that went 1.35".  Then I cleaned the bore with LBT bore lap, and fired a .78" group.  I don't have the patience to do a long, drawn out test, so this was good enough for me.  Remember, I did preface this by saying it was "a little test"....

 

Glenn

 

Test #1

 

John Alexander posted this 27 January 2019

 

I finally got around to loading and shooting a small test today to see if shooting 20 rounds of jacketed bullets degraded CB accuracy afterward and if so how much.

 

To minimize labor I scrounged around and found 37 left over sized and lubed bullets from a lot that didn't quite shoot up to snuff. Hate to throw things away that take labor to produce.  This was enough for three 5-shot groups before 4-5 shot groups of factory level JB and 4 5 shot groups of CBs after. CB load was 85 grain spitzer bullet of 25:1, Remington 71/2 SR primers, and 5 grains of TiteGroup.

 

For jacketed I found a box of Herter's 55 gr. Semi Pointed World Famous rifle bullets that were more accurate that any other rifle bullet or your money back. Additionally, these had been seasoning for about 60 years.

 

Resits:

 

CBs before: .90, .64, and 1.52 MOA -- Average 1.02 MOA

 

Jacketed : 1.82, 1.68, 1.64, 1.96 MOA -- Average 1,77 MOA

 

CBs after: 1.06, 0.78, 1.84, 1.86, MOA -- Average 1.38 MOA

 

This shows an enlargement in groups of 36%. Using Joe's statistical charts for dummies and extrapolating a bit, indicates a confidence level of maybe 75 -- 80 percent.  Not a sure thing but a pretty good chance that if we do more testing it will still show a loss of accuracy tending to confirming the conventional wisdom and remarks by Glenn, Brodie, and others.

 

John

 

 

 

John Alexander posted this 29 January 2019

 

Hold the conclusions. I'm afraid I have presented the results of a botched test. When I finally got around to cleaning the bore I found it badly leaded. After generous application of steel wool, lead out and elbow grease the bore was clean but what do you do with test reports partially obtained with a leaded bore?  Probably do the test again.

 

I now think that the bullets I dug out of that drawer were probably from a year ago last September when I was bore cleaning after every target card at the 2017 NT to avoiding loss of accuracy. Should have thrown the left over bullets away.

 

By looking at the group sizes with this new information the two good groups followed by much bigger ones, in both CB strings, take on a different light. Full charge JBs will clean out lead giving the CB string after the JBs a fresh start.

 

CBs before: .90, .64, and 1.52 MOA -- Average 1.02 MOA

 

Jacketed : 1.82, 1.68, 1.64, 1.96 MOA -- Average 1,77 MOA

 

CBs after: 1.06, 0.78, 1.84, 1.86, MOA -- Average 1.38 MOA 

 

If I had only fired two CB groups before the jBs and two CB groups after the results would have looked like this:

 

CBs before: .90, .64, -- Ave. =.77 MOA

 

CBs after JBs: 1.06, .78. -- Ave = .92 MOA

 

Still looks like the JBs didn't improve accuracy, but  only 20% worse and based only two 5-shot groups for each condition -- still, a strong hint that accuracy was degraded.

 

I will find some bullets that fit better and produce strings of groups that don't grow and try again.

 

John

 

TEST #2

 

dbarron posted this 08 February 2019

 

Well, you aroused my interest.  On 6 Feb, a test of whether metal fouling degrades cast bullet accuracy was attempted.  The details of the load are irrelevant except to say that before and after were identical.  The bullets were all from the same run, and were Accurate 31-215 LG, their version of 311284.  Alloy was COWW + 2% SN.   Velocity from a 24" barrelled Rem 700V .308 Win was 1600 to 1640 (1640 previously chronographed at about 28 degrees).   Range conditions were adequate.   It was cloudy, wind 5 MPH or so, blowing directly towards the target.   Range temperature was 13 degrees at the start of the test and didn't go up much, if any.  Two ten round groups were fired from a squeaky clean barrel, and two from the post-jacket fouled barrel.  Twenty rounds of home swaged 180 grain .308 dia bullets were fired between the test loads.   These were in commercial jackets of gilding metal.  Don’t know what the velocity was as I didn’t chronograph (hey, it was 13 degrees), but they were a near-maximum load of H 4895, so probably 2400 to 2500 FPS.  I did not measure the size of the jacketed groups, but just shot them as quickly as possible without over heating the barrel. (again, 13 degrees.)  I wazgonna attach a target, but one side of the target has disappeared from the pictures, and now I can't find the hard copy.   I am NOT a techie.  Nor, apparently, particularly organized.  Group sizes, as measured by On-Target were:

 

                                              Spread                                 Mean Radius

 

Before                                                                             

 

  Group 1                            1.654                                   0.641

 

  Group 2                            1.388                                   0.358

 

  Ave                                   1.521                                   0.489

 

After

 

  Group 3                            1.436                                   0.481

 

  Group 4                            1.189                                   0.371

 

  Ave                                   1.313                                   0.426

 

Difference (ave’s)               0.208                                   0.063

 

% (After/Before)                 86%                                     87%      

 

The “After” groups were slightly less than 15% smaller than the “Before” groups. Based on this, it would seem that there might be a slight edge to the “After” condition, but I suspect that it’s a non-result.   I don’t think the barrel was particularly fouled.  I cleaned the crud out with Ed’s Red and a dry patch, added accelerator and soaked with Wipe-Out for two hours.   The first patch came out only very faintly blue.  Nothing at all thereafter.  I’ll plead ignorance on this.  Of the heaven knows (I’ll not take the time to count) how many rounds have gone down this barrel in the last seven + years, these are the first jacketed rounds.   Apparently, it takes more than this to thoroughly foul the bore.   It looks as though this one is going to be time consuming to test, as it would seem that small amounts of fouling don’t have a major effect on accuracy, at least for 1 to 1.5 inch rifles, at frigid temps. Based on this and comments above, it's beginning to look like small amounts of jacket fouling don't really matter for most shooting.  The deer would be dead with either condition.  While these would not likely win Production class in a local match, it's as likely that they wouldn't finish last.

 

TEST #3

 

John Alexander posted this 2 weeks ago

 

This thread started with the question by max503 – does JB fouling degrade CB accuracy?  It has wandered a bit with detours for cleaning elixirs and target cameras but I think the original question is worth working on.  This warning of JB fouling is another conventional wisdom “we all know” that is supported by only anecdotal evidence as far as I can find – a very weak stick. In a 1-29-19 post I reported that my first try to test this old rule was questionable because of bore leading and said I would try again with bullets that fit better to avoid leading.

 

Our local range opened yesterday after a two-week closure by a 30” snow and today I shot another test. The CB load was a different lot of the 85 grain 25:1 spitzer bullets, Mag Tech SR primers, 6 grains of Blue Dot giving approximately the same MV as the earlier load with the same Tikka 223 rifle and no evidence of leading this time. The twenty rounds of jacket bullets were from the same box of Herter 55 grain wonders with the same load as before.

 

CB 5 round groups starting with a clean bore. -- .97, .84, 1.26, 1.08 moa  -- Average 1.04 moa

 

Jacketed 5 round groups – 2.20, 2.48, 1.34, 1.76 moa – Average = 1.95 moa

 

CB 5 round groups after JBs -- .46, .80, 1.50, .92 moa – Average = .91, moa

 

For a person who believes that small differences in even two groups prove things (Joeb’s statistics be damned) this “proves” that a bit of guilding metal fouling improves accuracy of cast bullet loads by 14%.

 

But usually such conclusions are jumping the gun.  It seems to me that these results give a hint, but not much more than a hint, that a bit of JB fouling may improve accuracy (in complete opposition to what most of us have been told). Consulting Joe’s tables this 14% improvement for eight 5 shot groups has a confidence level of much less than 70% -- far from certain. As usual, more groups need to be shot if we want to be more certain.

 

It would be interesting to see this experiment replicated with other calibers, alloys, muzzle velocities, increased JB fouling, etc.  I hope someone will jump in and try it.

 

John

 

 

 

TEST #4

 

tlkeizer posted this 5 days ago

 

Greetings,

 

Shot some before and after groups Saturday, interesting.  A couple comments first.  My Savage 99 shoots the cast left of the jacketed (yes, I do fire both in the rifle), and the first shot out of a cold barrel is quite a bit left, then subsequent bullets strike somewhat right of the first shot but left of the jacketed.  So, I have to either move sights or put up a siting target.  I elected to move the sights on the scope and re-zeroed for jacketed afterwards.  My rifle also shot first round left after sitting a bit while resetting targets.  I did not include first shots that were definite outliers into the measurements, if the subsequent shots were out a ways I did include them.  I cleaned the barrel a couple times before going to the range to let the solvent soak in for copper removal.  I had somewhat limited number of rounds, so did not get 3X5-round sets both before and after with the same load.  The best group was non-GC's after my comparison was done.  I will have to do a run with those sometime.  The mold used was a borrowed Lee 170 grain GC mold, and while I had it I cast about 500 bullets so I hope not to run out before the end of summer, batches are segregated.  The load was LC82 case, CCI 200 primer,  17 grains IMR 4227, cast and weighed 170 grain, Hornady gas check, SPG lube, .309 sizer.  Rifle Savage 99, .308.  Weather overcast, 38-43 degrees as day went along, no wind.  Shot off bench.

 

Before:   group 3.12 inch      mean radius 1.1 inch

 

              group  2.84 inch      mean radius 1.0 inch

 

              group  2.42 inch      mean radius 0.8 inch 

 

                        Average            MR  0.95 inch         

 

Jacket                                    mean radius 1.0 inch 

 

After      group 2.87               mean radius 0.9 inch

 

              group 1.76                mean radius 0.6 inch

 

                        Average            MR 0.77       

 

Values are rounded off.    Granted, a small population, but interesting and a starting point for me adding to the data base.

 

Just a couple random thoughts:  1.  Does copper provide a bearing surface for smoother flight of lead?  2.  Does copper microscopically fill in "potholes" allowing for better consistency?   I did not have a chance to use the Chronograph to see if before and after groups had varying velocities.

 

TK

 

TEST #5

 

tlkeizer posted this 4 days ago

 

Greetings,

 

My error in arithmetic, I used a different number off my working papers.  (Besides, I like your numbers better)  No, you did not misread;  I miscalculated off wrong data.

 

Now, on to today's results.  I shot 25 rounds cast, 12rounds jacketed, then 19 rounds cast (one case was cracked in the neck, so it went into the scrap pile while prepping cases). 5 rounds cast and 2  rounds jacketed were used to adjust scope. Load was LC82 case, Lee 170 grain GC weighed out as 170, CCI 200, 22 grains IMR 4227.  Note different charge.  Jacketed was 165 Speer BTSP,  ADI case, CCI 200, 48 grains H414.  Slightly different parameters, but if jacketed before cast improves cast groups, I think it would prove so generally across the board of variables; hence, some different round preparation.  Results in inches.  Groups for measurement were 5 round groups except for first group after jacketed, that was only 4 rounds.  Extra rounds were shot to bring groups near bullseye but not measured.  Some numbers rounded.

 

Results:                 Before                                                Jacketed                                  After

 

  Group :               3.30, 2.22, 3.49, 3.72  AVE 3.18         3.79, 3.35                            3.28, 3.34, 3.04, 2.68  AVE 3.05

 

  Mean Radius:     1.28, 0.79, 1.51, 1.35  AVE 1.23         1.18, 1.19                            1.28, 1.07, 1.12, 0.92   AVE 1.09           

 

  Results?  After the jacketed the cast did better again.  Difference in group size was 3.18-3.05=0.13.  .13/3.18=.041; 4%

 

                                                                                        Difference in MR was 1.23-1.09=0.14.  .14/1.23=.114; 11%

 

Hope I got it right this time John, otherwise I may have to stay after school and clean the blackboards.

 

I find it interesting looking at the group size averages  the mean radius averages; looking at the targets there were a couple outliers in the groups that enlarged them, and some after groups had most rounds much closer to each other than before groups.  What this seems to indicate to me is that using jacketed bullets just before cast bullets helps groups.  Long term, who knows, but in the short run firing 10-15 rounds jacketed before cast would help my scoring slightly.  I did not get the 14% mean radius difference, but at 11% that is still significant to me.  I think my new motto should be paralysis by analysis as seen in an earlier report in the forum.  I do like to work numbers in spite of my arithmetic.

 

John, hope your trip to the range was as good as mine, especially weather wise.

 

TK

 

TEST #6

 

John Alexander posted this yesterday

 

Finally got to the range today (March 29) for another try at the accuracy of CB after fouling bore with JB compared to accuracy from clean bore.

 

Load was the same as before except for a different lot of the same 80 grain spitzer bullets.

 

Accuracy of four 5-shot groups of CBs starting with a clean copper free bore .84', .70" .88", 1.50" -- Average 0.98"

 

Accuracy of four 5-shot groups of JBs 1.66, 1.70", 3.00", 1.64" -- Average = 2.0"

 

Accuracy of four 5-shot groups of CBs .78", 1.24", .42", .96" -- Average = 0.85"

 

Accuracy of the cast bullet loads were 13% better after fouling the bore with twenty rounds of jacketed bullets.

 

This result is similar to the previous four similar test results all showing improved accuracy after fouling the bore with 20 jacketed bullet . Groups shrunk by between 13 and 19 percent.

 

This is of course the exact opposite of what we thought we knew.  Every experienced CB shooter knows that jacketed bullet fouling ruins cast accuracy because that's what we have been told.  But when five series of groups by three different shooters using five or six different loads all show that 20 rounds of JB fouling improves accuracy an open minded shooter should begin to question the rule that you can't mix cast and jacketed bullets.

 

Of course these tests so far don't cover all the possibilities.  What about the fouling from 50 jacketed bullet loads, 100 loads, 200? Surely gross guilding metal fouling, the kind that we have been told degrades JB accuracy would also degrade CB accuracy. We can guess but at this point we don't know that either.

 

Anybody have a rifle not cleaned since the last prairie dog shoot that you have a cast bullet load for? Shoot a few groups before cleaning and a few more after cleaning and see what happens.

 

John

 

 

 

TEST #7

 

 

 

joeb, 4/3/19

 

M10 Savage, M110 308 HV barrel,

 

314299, .3095, Lyman Super Moly, 15/A#9 Fired 30 before, 25 after.

 

Hornady 130 gr sp, 43/IMR4895. Fired 30.

 

100 yard 5 shot group, inches, in order shot;

 

Clean barrel, 5 314299 sighters, then

 

1.625, .8, 1.3, .925, .85,AVG = 1.1 then

 

130 Hornady, 1.6, .85, .8, 1.4, 1.825 AVG = 1.283, then

 

314299, 2.9, 1.8, 1.65, 1.1, 1.15, AVG = 1.72

 

 

 

TEST #8

 

John Alexander posted this 4/6/19

 

I fired another string in the before and after jacketed fouling test yesterday (4-5-19).  The cast bullet load was the same as before but for the jacketed load I dug out some longer bullets (Sierra 69 grain HPBT Matchkings) in hope of reducing the jump short jacketed bullet must make in my Tikka with its eroded throat – same powder and primers. Procedure was the same starting with a clean bore (Sweet’s solvent until no blue green patches) and no cleaning during the test.  One fouling shot was fired before each of the 20 shot cast bullet strings. Tikka 223 rifle and no evidence of leading.

 

 

 

CB – 5-shot groups starting with a clean bore. -- .1.36, .88, .50, 1.64 moa -- Average 1.10  moa

 

Jacketed 5-shot groups – 1.20, .90, .76, 1.28 moa – Average = 1.04 moa

 

CB 5-shot groups after JBs -- .98, 1.10, .94, .84 moa – Average = .97, moa

 

Reduction in CB group size after jacketed fouling = 12%

 

The longer JBs which were seated just off the lands shot as accurately as the CBs.

 

Cleaning the bore afterwards with Sweets produced patches with a little blue green color.

 

John

 

 

 

 

 

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