30 XCB, 2900 fps at 600 yards

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  • Last Post 19 March 2018
Larry Gibson posted this 11 March 2018

Got a chance to shoot 600 yards with my 30x60 XCB rifle using weight sorted 30 XCB bullet loaded to 2900 fps. I shot 46 rounds in 4 different groups.  The average group size was 1.3 moa. The results with pictures of the targets are at;

 

http://goodsteelforum.com/forums/topic/noe-30-xcb-30x60-xcb-600-yards/

LMG

 

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

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Ken Campbell Iowa posted this 11 March 2018

Great stuff, thank you.

Ken

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RicinYakima posted this 11 March 2018

Amazing!

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R. Dupraz posted this 11 March 2018

What Rick said! After  having competed in NRA high power and long range BPCR, I can appreciate your efforts and results. Thanks for the very detailed and documented report.

R. 

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nosee posted this 11 March 2018

That puts me to SHAME, I can,t shoot like that at 200. Thank You for showing us your shooting.---Nosee

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corerftech posted this 11 March 2018

Larry I believe that offers ME PERSONALLY some tangible confirmation that "your" visual and weight sorting can indeed generate improvements.

If you shot cast bullets out to 600 at MOA and Im not guaranteed that your the best man behind the gun that could have been there (take no offense, theres always a better wind reader, trigger man somewhere) then your small data mass provides me (Im dumb and gullible) some confirmation that you can keep a cast bullet stable and happy, just like a jacketed bullet, at HV and at serious distance.

There was a banter about sorting a while back and I have no input or opinion on the subject nor shall I speak about it at all except for the above statement.

You have indeed given jacketed bullet performance, repeatable (in my uneducated opinion).

I have always sorted by weight to .1 and visually and I believe Joe B when he says the data needs to prove it, I don't understand the data but I believe him whole heartedly. I do sort, makes me feel good like many do and, well, it can't hurt right? I don't mind wasting time doing something. Im richer with time than money.

Although this is not a proper data lot, my gut tells me when you shoot to 600 and 1000 yards, the data lot can get smaller as the measurement standard has increased exponentially. You went from measuring in say .001, to millionths, in machinists terms. 

But again Im poorly educated (truly) and that may not be true.

Here is the fact: It inspired me this morning to build a long range rifle of some kind. One that only shoots cast. I cheap and I am not rich, that makes for NO "I'm a sniper" rifles. I can't afford to shoot expensive bergers by the hundreds to punch paper, that the way it is. But I CAN shoot heat treated cast and many many thousands of them and I Can afford ONE good long range rifle.

Ive seen some scheutzen rifles make some really stupid small groups at 200, 1/2 MOA and SMALLER. Really stupid small, and repeatable. They are always cast and those guys don't shoot imperfect bullets, ever and they area always weight sorted. Ive been lured to begin to breach seat some rifles (walls/rollers) and this thread and report gives me some idea that maybe even your fixed performance could improve with breach seating a BR rifle, shooting cast. Or not.... 

Id like to hear your thoughts Larry (a different thread or by PM).

That was really good shooting too.

Appreciate you posting this.

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R. Dupraz posted this 11 March 2018

CBA Member

 

corerftech posted this 1 hour ago

 

"Larry I believe that offers ME PERSONALLY some tangible confirmation that "your" visual and weight sorting can indeed generate improvements"

 

I'm also moving in that direction. All I have ever done was visually inspect my castings and weight sorted only to the extent of trying to find the bullets that were way out of the majority weight wise and stopped there not being convinced that detailed weight sorting was worth the effort. But of late I have been paying more attention to the weights and sorting them into groups.

I have been shooting two Contender pistols, 30 Herret and a .218B, since the first of the year, when the weather cooperates, and have noticed a definite improvement in group size and the absence of those pesky wide flyers, at 5o and 100.

Now, I think that there may be some other factors involved here. Time will tell, But I intend  to continue the detailed inspection and weight sorting of my castings through the summer in my military rifles to see if I can find out.

I know where there is an 1885 Win. Highwall actioned schuetzen that will put five PB castings in .5" at 100 without any load development.  

 

 

 

 

 

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Scearcy posted this 11 March 2018

Larry

This is fascinating. Thank you for sharing your work. I picked up a nice used Savage F Class from an estate a while back. Perhaps this would be an application for that beast. Good stuff.  Jim

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John Alexander posted this 11 March 2018

Larry,

Excellent.  Thanks for your report. 

Keep up the good work and please remind us of the particulars once in a while -- loading details, bullet hardness, etc.

John

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Tooweels posted this 11 March 2018

Really enjoyed reading your write up Larry and bloody good shooting too very motivating

 

Steve

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Larry Gibson posted this 13 March 2018

R. Dupraz & corerftech

Appreciate your comments and notice both referenced the accuracy success many schuetzen shooter have at 100 and 200 yards.  Yes the schuetzen shooters I know only use the best quality bullets they cast.  They also shoot some amazingly small and accurate groups.  When comparing what schuetzen shooter accomplish and what is accomplished with high velocity cast bullet shooting we have to remember the difference between the two. 

The amount of diversion a bullet is forced away from the intended flight path by the action of centrifugal force is dependent on the intensity of the centrifugal force and distance.  The higher the RPM rate of a bullet the greater the affect centrifugal will have on a given imbalance of the bullet.  The longer the range the greater the distance the bullet will divert from the intended flight path.

Thus with a common schuetzen rifle with a 14" twist and a velocity of 1400 fps +/- the RPM is only 72,000 +/-.  If we used the same bullet but used it in a 10" twist the RPM increases to 100,000 +/-.  If we increase both the twist rate to 10" and the velocity to 2000 fps the RPM increases to 144,000 +/-.  There we see an increase of twice the RPM from the original.  Thus there will be a greater dispersion in group size more noticeable as the range increases because of the increased centrifugal force.. 

Basically the slower RPM rate of schuetzen rifles not generating near the centrifugal force on the imbalances that my be in the bullets.  The result is better accuracy with the same quality bullets.  If we look at the CBA match results we see much the same concept as many with faster 10" twists shoot relatively lower velocities than those who use slower twists (11 and 12") and a bit higher velocities.  I'm looking at actual chronographed not estimated velocities BTW. 

Pushing cast bullets to really high velocity requires controlling the quality of the bullets and the RPM. The 30 XCB bullet cast of #2 Alloy WQ's and weight sorted as reported in the other thread was pushed at 2900 fps out of a 16" twist barrel.  That generates 130,500 RPM.  That is very close to the same RPM a 10" twist barrel generates at only 1800 fps.  That is the same RPM rate as most CBA match shooters are using +/-.  The difference is with the 30x60 XCB rifle with the 16" twist I push the bullet at 2900 fps. 

 

LMG

 

 

 

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Larry Gibson posted this 13 March 2018

Anyone contemplating building a high velocity cast bullet rifle please don't hesitate to ask here or PM me.  I'll be glad to offer advise based on my last 10 years experience actually shooting cast bullets at high velocity with success.  It need not be expensive. If a high end BR type rifle with specialized action is your desire then that's ok.  However, My 2600 fps and my 2900 fps rifles are based on M98 Mauser actions and neither are BR rifles.  Thus building a HV cast bullet rifle can be as simple as rebarreling a rifle you already have.  The key to building a HV cast bullet rifle being a quality long barrel with a slow twist. Cartridges can be standard or a wildcat such as the 30x60 XCB that are simple to form with standard (not custom) dies. 

I can also give you straight information about shooting HV in standard twist rifle with 10, 11 and 12" twist.  However realize you just are not going to do 2600 fps or 2900 fps with those faster twist barrels and shoot sub 1 1/2 moa 10 shot groups at 500 and 600 yards. Of course using the right design cast bullet, a proper alloy and attention to loading details is also essential.  The proof is in the actual shooting. 

LMG

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R. Dupraz posted this 13 March 2018

Thanks Larry,  Interesting stuff.

R. 

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OU812 posted this 14 March 2018

Was this a test of sorted vs. unsorted. What if the unsorted shot just as well or better.

 

I think measuring as cast bullet diameter is important or maybe not. Nothing is cast in stone.

 

1.3" will not win a match @100 yards, but good shooting anyway

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Larry Gibson posted this 14 March 2018

OU812

No, this was not a test of sorted vs. unsorted to determine which shot better.  That question was answered for me in the earlier posted 300 yard test results in a couple threads addressing that question.  The bullets used in this test were the sorted bullets selected for match use as they had proven to be the most accurate.

I concur that as cast diameter may or may not be an important measurement.  You have some test results confirming that for us?

The end result of 1.3 moa average was for 4 different groups comprising 45 shots at 600 yards.  I am not aware of any CBA matches at 100 yards of that nature?  However, if we take the 2 actual 10 shot groups fired at 600 yards (1.2 moa and .98 moa) and convert them back to 100 yards subtracting normal group dispersion between 100 and 600 yards we see those two groups were more than like less than moa at 100 yards.  Then if we compare them to several 100 yard CBA match 10 shot group moa results we see those 2 groups may very well have won numerous CBA matches based just on probable group sizes.

Now if that was a NRA High Power match at 600 yards where the X ring is 1 moa and the 10 ring is 2 moa all 45 shots of all 4 groups, if centered on target, would have been well within the 10 ring.  That would have given a "possible" score with a very high X count.  Since I'm not aware of any 600 yard cast bullet matches I can't say whether or not that would be good enough to "win" but I'd sure enter the match to find out!

The rifle and loads used for my test were not made for CBA matches. The were made for high velocity cast bullet shooting.  The test  posted were simply a test to see how well the loads and accuracy held up at 600 yards.  It appears the 30 XCB at 2900 fps holds accuracy very well at 600 yards.

LMG

 

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

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Old Coot posted this 14 March 2018

If you didn't win Larry you would surely scare the dickens of whoever did.

 

B.E.Brickey

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OU812 posted this 15 March 2018

 

Larry, I understand and verygood job.

If I remember correctly, isn't that a three groove (5r type rifling) barrel you are shooting? Is fouling easier to remove from this type rifling? Does 5R style rifling work better with cast than say a standard six groove barrel?

Thanks, Keith

BTW I have lots of pictures of good groups, but I am trying to learn how to shoot 1/2" groups consistently when really needed or on demand. My favorite load is the shortened 80 grain Alexander bullet over 14.5 grains of older IMR 4198. These are cast in linotype (bumped round) and shot about 2100fps out of a 1/12 twist barrel...slower twist is better sometimes. Some believed this longer bullet would not shoot in the slower 1/12 barrel, but it will if you shorten the gas check shank.

Here is fouling test. Notice groups starting to open at group #4. I am still working with lubes.

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frnkeore posted this 15 March 2018

1. Something that needs to be considered in shooting HV cast bullets, is the diminishing returns if you do it with a bullet that is of low ballistic coefficient.

2. It also, will contribute to increased fatigue and uncalled or called error (flinch), do to recoil.

Note the increased LR wind drift, as compared to a 311299 @ 2200 fps. Wind drift, being the major foe that we have in LR matches. Even the short range drift isn't of much difference @ +700 fps increase.

The 311299 @ 2200 fps .377 BC:

XCB bullet @ 2900 .270 BC, I believe the actual BC is closer to ~.250:

Regarding RPM Vs accuracy. The PB class should shoot much smaller groups and higher scores than the Heavy or Unr classes, If it were true that RPM decreases accuracy. In truth, they are fairly close @ 100 yd but, the higher velocity Hvy & Unr have a edge @ 200. In good conditions, 200 yards, isn't to different though.

The 200 yard disadvantage, being because of the EXTREMELY bad velocity range that the PB class shoot in. Wind drift becomes less, as you decrease velocity, below 1400 to 1500 fps and not only that, wind drift becomes less as you increase velocity above that range. We try to over come the disadvantage, as much as possible, by shooting high BC bullets.

1450 fps .480 BC:

2200 fps .377 BC

The .480 BC is a little over optimistic, there are a handful that shoot BC's that high but, most bullets are in the .400 - .440 range.

Frank

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Larry Gibson posted this 15 March 2018

Frank

About 45 years ago I started shooting the 311299 and the 314299 (when it was introduced) because of the very BC you quote.  Thought, like many others, it would be just the ticket for LR (600 yard) shooting with the M1903s.  I shot if every way from Sunday with just about every load possible.  Found it would hold 2 to 3 moa 200 yards but more like 3 - 4 moa at 500 yards if started out at 2000 to 2100 fps.  The problem was that bullet did not hold up well transitioning sub-sonic.  I had my 1st Oehler chronograph in '73 so the velocities were known.  Lyman's chart, based on the .377 BC and 2100 fps, showed the 311299 bullet should have stayed sonic through 600 yards.  The problem was it wasn't.  It was dropping sub-sonic right around 500 yards.  Obviously the BC wasn't correct.   On the old 5V targets, if holding well, I could expect 60 - 70% hits in the black.  That was okay for practice but on the Decimal target scores sucked. 

Fast forward to 10 years ago when I got the Oehler M43 which actually measures the BC by measuring the TOF.  I found the published BCs, which were calculated, to be grossly over optimistic.  At 2000 fps the actual BCs of the 311299, 314299, the 311466 and the 311291 were actually .050 to .070 less than what Lyman says they are.  I have also found the BCs of newer designed cast bullets that are computed to be optimistic also.  An example being the 30 XCB.  It's actual measured BC is .250, not the .270 as quoted in the bullet specification drawing.  The 311299 out of a 10" twist is closer to .3000 and out of a 12" twist is closer to .315, both at 2000 fps.

 

Feel free to disregard RPM vs. accuracy but every single book on ballistics and even some reloading manuals tells us the facts; with a given bullet the higher the RPM the greater the dispersion (group size) will be.  Yes, you can sort through all the CBA match results you want and cherry pick results to verify your belief.  The problem there is all the other variables thrown in you're not considering. 

If you want to really see and understand pick one shooter with the same exact .308W cartridge/load at 2200 fps with a 311299, shooting under identical conditions with 2 otherwise identical rifles with the exception of one has a 10" twist and one has a 14" twist.  Oh heck, the rifles don't even have to be identical.  Have the shooter shoot 10 shot groups with each, alternating if you will and not knowing which rifle is which, at 100 and 200 yards with each rifle.  Measure the groups and you will quickly see the difference the increased RPM from the 10" twist made in group size.  On second thought, you won't even have to measure the groups....it will be very obvious visually. 

As to "shooter fatigue" that certainly is a consideration but after 46 rounds I wasn't fatigued.  Some may be though but even if we shot CBA military rules for score at 600 yards that would only be 20 shots plus sighters.  If that would fatigue someone is questionable.

LMG 

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Larry Gibson posted this 15 March 2018

OU812

The Broughton barrel is a 3 groove but with standard military style rifling.  It is not 5R style.  The barrel cleans up extremely easily.  A wet patch (Hoppe's #9), 10 strokes with a wet brush (Hoppe's #9),  2 dry pates, a wet patch (WD-40) and a dry patch and its spotless.

BTW; the Broughton barrel has 2800 HV rounds through it so far. 

Your testing is looking pretty good so far. What cartridge?

LMG

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Ken Campbell Iowa posted this 15 March 2018

slowest possible stabilizing twist benefits mj bullets also ... the benchrest score 30 cal guys mostly choose 16-18 twist for their 110-130 grain bullets.  ( fattest bullet to touch scoring rings with light enough recoil for their varmint class ) .

it would seem that even those perfect mj bullets aren't really perfect at muzzle exit ....  i believe their best jackets are about 0.0001 to 0.0002 out of round ; jacket wall thickness .  even with this " minute " error slower spin is better ... btw, a good swiss lathe can better that runout with solid bullets .

and of course... even a perfect bullet before ignition may not be so perfect by the time it is blown out the muzzle, especially a near-liquid one such as our castings .

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

precession from the spin .... can spin change precession for better or worse accuracy ?? ...

just some thoughts... ken

 

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