Does indixing in a push feed bolt action work?

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John Alexander posted this 2 weeks ago

I have tried indexing several times when I competed with a falling block rifle and could never find accuracy improvement. I have never read anything persuasive that showed that indexing improved accuracy. However, some pretty knowledgeable shooters use this technique so I would like to run an experiment.

Indexing swaged bullets that are near perfect seems unlikely to improve accuracy.  However, at present, I am not swaging my bullets and am shooting them in factory chambers and It seems theoretically more promising that indexing might help for these less than perfect bullets and chambers or when neck thickness varies. 

Indexing the bullet before the bolt starts chambering it is easy.  Knowing that it stays indexed after the bolt is closed and rotated to lock is isn't so certain.  The cartridge might be roading different amounts with each shot which would destroy the experiment. I am not sure the experiment is worth doing without having some technique for assuring that the cartridge is still oriented the same for each shot. Has anyone developed a method for indexing with certainty in a bolt action?

John

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Old Coot posted this 2 weeks ago

John,  would not the round you indexed be rotated the same with each use.  I mean, doesn't the bolt rotate the same amount each time it is locked up?  If so then the round and therefore the bullet will each be moved the same amount with each lock up.  Brodie

 

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John Alexander posted this 2 weeks ago

Brodie asked: " would not the round you indexed be rotated the same with each use."

You may be right but I'm not certain. Certainly the bolt rotates the same as you note.  But I don't know if the cartridge rotates with the bolt at all, same as the bolt, or sometimes part way.

Until the cartridge encounters enough resistance it is just being herded along ahead of the bolt.  I guess it wouldn't rotate until the extractor snapped over the rim I don't know when that is relative to the the bolt rotating or if it is the same from shot to shot.  

John

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David Reiss CBA Membership Director posted this 2 weeks ago

A little Dyekem on the cartridge may indicate if it rotates or not. With the help of some magnification it would be easy to see any rotation. 

David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
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OU812 posted this 2 weeks ago

Not with certainty, but I think indexing the bullet would work best with a hard alloy such as linotype. Harder alloy will help a bore rider align better in throat if loaded rounds are not concentric. I seat the bullet long in case then let bolt closing finish seating. If bullet is engraved well by rifling, the case neck will sometimes spin around bullet. Have you ever extracted a loaded round spilling powder inside barrels chamber? 

I have tried indexing in a bolt gun, but it was a little time consuming. The one piece scope base blocked view and made seeing a little difficult. I gave up.

My biggest problem when testing is loosing concentration and keeping the same hold on rifle every shot, especially when shooting 50 to 100 rounds. Using linotype and shooting at slightly higher velocities (1700-2000fps) has helped. Bullet leaves muzzle sooner.

I am tired

 

 

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RicinYakima posted this 2 weeks ago

John, I can not help with the "push feed" issue. On controlled feed, it will work if you hold the case with a finger until it pops up under the extractor. I used black felt marker on case head so know that there is some movement on some cases. My thought is that it is better than randomness. Ric

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Starmetal posted this 2 weeks ago

Almost all rifles leave marks on the primer inaddition to the firing often isn't dead center.  You can put a black marker pen index mark on your cartridge, then after you have fired you can look at the primer and tell what position the cartridge was in when you positioned it.  Then you can tell if it was rotated by the bolt closing. Example: Say your firing pin strike is off center closer to the 12 o'clock position on the case. With that in mind complare it to your index mark as to where it was when you chambered the round.  Works for and BTW I've not see cartridge rotation in the rifles I've tried this in. 

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Ken Campbell Iowa posted this 2 weeks ago

here is my best "" shot "" ...

assemble some catridges with no primer or powder ... push the catridge in the chamber with the bolt but don't lower the handle ...   ... now push your cleaning rod down the barrel from the front and mark the bullet with that off-center pip you ground into the end .... that will mark the bullet orientation ....  bring back the rod 1/4 inch and lower the handle and mark the bullet again .... now withdraw the catridge and see if the bullet got turned by the revolving bolt face .  repeat twenty times and draw a graph and do statistical analysis .  report back .

of course if you had a mid-bolt locking lug rifle the " breech block " forward bolt part wouldn't turn .  mas 36?? ... ruger77h ? ... remmy 788 ? ...i gotta look at my 788 in 223 ... forgot how it works ...  be glad to ship it out if you promise to keep it .. it is a nice one .  shoots .5 with mj .

old frankly liked orientation ... didn't he use a 788  often ?? ...

one small data dot wuz i tried indexing in my 722/222 with out of round bullets and had the same problems as above... too finicky and i couldn't see if the cases turned .  no verdad .

ken

oh... or swage-bump  the damm bullets ...

ken

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Old Coot posted this 2 weeks ago

You will probably shoot better scores if you spend the time practicing instead of this foolishness.  The whole thing sounds to me like some "old shooters tale" repeated over and over until it was taken as fact.  

"If you hold the  magic feather in your trunk Dumbo you will be able to fly."

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Starmetal posted this 2 weeks ago

old coot it definitely isn't an old shooters tale as it's been repeated many times over in modern times. In fact the tests were indexed around the clock and the groups on the target were in different positions accordingly. 

As a note I remember an old SAKO L579 action rifle I use to have that I necked sized only for and after a number of shots on the reloaded cases they needed to be brought back to specs with a full lenght resizing.  You all know how they start to give a snug bolt closing. Anyways the head of the case would show swirl rotations marks from the bolt, meaning the case didn't turn. It may have been because the case had a good purchase on the chamber walls.  Loose fitting cases may turn, but as previously stated I've not had it happen in my rifles, push feed or control feed. 

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John Alexander posted this 2 weeks ago

Starmetal; -- Very clever idea to take advantage of off center primer indentations.  I hadn't thought of that.  Won't work this time because all three rifles i want to test in make primer marks very close to center.  I have others that don't of course.  Something to remember.

Ken, Good thinking I don't see why that wouldn't work to find out if they rotate or not. Thanks for the generous offer of the 788 but unless it has a 9" twist it won't stabilize the long bullets I am interested in testing.

Old Coot -- You are probably right that practicing my trigger jerk would probably work better for raising scores, but I like to find out stuff.  You may also be right that improvement by indexing may be an old shooter's tale --or not.  As mentioned at the top,  I have tried to find improvement by indexing several time and have failed.  I also have never seen a report showing improvement that didn't fall into the category of an anecdote instead of a study -- save one.  That one reported such fantastic and regular improvements that it was simply unbelievable. However,  I am willing to listen and the motive for my planned test is to find if and when I can make indexing work.  Indexing may help with cases with uneven neck thickness but I have not been able to show it.  If  someone knows of a well planned study that shows indexing improved accuracy please let us know. 

John

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Old Coot posted this 2 weeks ago

John, I vaguely remember reading a discussion about indexing in which that report ( the study not one of the anecdotal ones) in this forum.  I agree trying to find out or questioning things and testing them is great fun.  Why don't you just put a mark on the case rim near the primer and see how that comes out?  It might be a good way to begin your study.  Brodie

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GWarden posted this 2 weeks ago

John

In "Cast Bullets" by Co. E.H. Harrison, NRA publication is a article by Frank Marshall on "Orientation and Selection: two keys to Accuracy". I don't know if this is the article being referred to? The rifle it shows that he is using is pre-war Win. 70 in 30.06.  Have a great day

Bob

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John Alexander posted this 2 weeks ago

Thanks Bob,

Yes, that is the article I was referring to. Frank did good shooting with that rifle.  Held some CBA records as I recall.  He also helped CBA by writing several year's worth of great tales about CB shooting in the old days for the Fouling Shot. He was a mainstay in the early years and we are all in his debt.  However, I don't believe the huge improvements he reported in that article for both indexing and sorting bullets by weight have ever been replicated nor anything even close and I don't expect they ever will be.

John

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Ken Campbell Iowa posted this 2 weeks ago

,,,, don't forget that about 20 years ago two very respected scientists created cold fusion with a glass of water and a flashlight battery ...    for a week or so ....

as per my mother's advice ::  " wishing doesn't always make it so " ...

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

i suspect that orienting does add some predictability ... but at our less-than-laboratory environment and systems that give one-inch groups from even the same case ... ... the noise/signal ratio is pretty small .

wish we had a well funded experimenter today to pursue Dr. Mann's interests .... what could he have done with a digital camera and a lap top ??  i sit by my phone waiting for a sponsor to call, but it has been pretty quiet ...

ken

 

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M3 Mitch posted this 6 days ago

The "acid test" would be to shoot several groups oriented with a push feed versus an equal number of groups without orientation.  Ideally you would have a co-conspirator load the rifle for you, keep records of the groups, so you don't inadvertently "help" the indexed rounds shoot better. 

If there is a statistical difference between the groups, indexing helps (or at least you will have a confidence interval saying something like "73% confidence it works".  The guy who runs Mountain Molds gets into this in the most recent FS - statistics can be a bit dry, but if you don't do it, you don't really know if what you did actually improved your "system" accuracy or not. 

As Ken Campbell notes, the rest of the "system" - bullets, rifles, mundane things like scope mounts being tight - all that has to be pretty "clean" to avoid drowning out the effect of indexing, which common sense indicates to me is going to be pretty small if you are using good brass, etc.

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TRKakaCatWhisperer posted this 6 days ago

You could also test it by orienting the index mark up with 10 rounds and down with 10 rounds and compare the mean point of aim (centers of the groups) for a shift in position.

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John Alexander posted this 5 days ago

Ken -- Yes it would be great to have some megabucks so we could do CB experiments full time like Dr. Mann but I think lack of money is a poor excuse for not doing lots of good experimental work that we could do with the rifle and equipment we have.  The cost would mostly be for powder, primers, wheel weights and a little exercise of our brains.

 

M3Mitch -- What you suggest is what I have done two or three times with the additional twist of alternating groups between indexed groups and random orientation to avoid the bias of changing  conditions, level of fatigue etc.  The results have always been no improvement.  So I no longer index.  What I wonder is have the shooters still indexing done similar experiments and found the opposite?  I have never seen any indication of it. If not -- why haven't they? Just wondering?

 

Catwhisperer -- Of course!  Why didn't I think of that?  Unless my reasoning is cockeyed that should be far more efficient and get believable results  with fewer shots.

 

John

 

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M3 Mitch posted this 5 days ago

As to why people who index have not done a good, scientific test to see if it works, that's easy.  Doing the test is too much like work, most don't want to bother. 

My understanding is if you are going to index, you first have to index the cast bullets to the case, which as far as I know means you have to mark the cavity on one side, most like me are reluctant to "deface" a mold.  You could orient on the parting seam, but you would have half the bullets 180 deg "out" of each other, since you don't know which side is "up". 

I think indexing is just so appealing to "common sense" that a lot of people go on and do it, without doing a real test to see if it is helping or not.  The same as individually weighed powder charges - it just makes so much sense that this should be better, but testing has shown that generally ammo loaded with a good powder measure shoots just as well.

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RicinYakima posted this 5 days ago

I'm one of the indexers. Mostly for a two groove 03A3 barrel for the seam to be in the grooves and the chamber is crooked. I only did five 10-shot groups, indexed and another set every other one turned 90 degrees. Indexed was better in the 03A3,by maybe a 1/16 inch, but not in my Savage .308 Model 10 SP6. I seat bullets in a Wilson hand die, so indexing doesn't take any more time than not.

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John Carlson posted this 5 days ago

I also orient bullets, particularly in the 2 groove.  My Lyman 314299 mold has a slight irregularity in one seam of each chamber so I can not only eliminate the "50/50" issue but segregate by cavity.  I have not done any testing on this, just accepted the results demonstrated by John Alexander when he "shot the donut".

I see a different issue in the orientation of the cases.  One school of thought seems to perceive a level of irregularity in the chamber and orienting the case so it duplicates that irregularity each time it is fired contributes to consistency.  Perhaps I've missed it but I haven't seen the issue of case uniformity addressed.  In my experience a variation of .002" in wall thickness from one side of an individual case to the other is not uncommon.  Perhaps we need to be orienting the cases so the "fat" wall is always in the same position rather than orienting according to the headstamp?  Of course the neck wall thickness can be eliminated by turning....................................

I wonder just how long and cold this winter is going to end up being?

Holding public office should be viewed as an obligation to serve, not an opportunity to rule.

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GP Idaho posted this 4 days ago

As a group, reloaders tend to obsess over small details in our craft. Some of the attempts work and some just make us think we are building a better round. Indexing in my mind is one of the many things that make use feel we are covering another variance. As mentioned above, what if the thickness of the case wall doesn't occur in the same place in relation to the headstamp or whatever mark we use to line up the case? While indexing MIGHT help ( I personally doubt it) only testing in your rifle will tell if there is any marked improvement.  Gp

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John Alexander posted this 4 days ago

Lots of interesting discussion. I can see the reasoning and "common sense" that leads to indexing and John's mold with slight flaws in the mold near the seam does seem like a natural situation for trying it. 

I was surprised by Ric's statement that it doesn't take any time.  My perception when I was indexing that it was a PITA and certainly took a bit of extra time for each round even though I was using a hand die similar to a Wilson and was loading for a falling block where the back of the case was clearly visible when seated. Of course it may have something to do with the patience/laziness/ size of bullet difference between Ric's and my situation. Nice to hear of an experiment where enough groups were fired to really have a chance of learning something.

A quick comment about that donut.  The flaws were huge compared to the bullet weight and I knew exactly where they were unlike the air voids we worry about. Indexing for cases with uneven neck thickness seems to me as maybe the most likely to get a positive answer.

John

Of course if a shooter believes in and likes to index by all means do it -- just don't tell a beginning CB shooter he should do it until we have better proof. 

 

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RicinYakima posted this 4 days ago

John,

Ready to load cases are neck down in tray, so I pick them up with the crack between my thumbnail and cuticle exactly at the first letter of the head stamp. Turn it over, and dump powder from measure. With off hand pickup bullet and rotate to marked seam aligned with thumbnail. Set gascheck into case neck, place chamber over case/bullet. Slide under arbor press and seat. If it take one second more than random, I would be surprised.

I would never tell anyone to do it. It seems to work for me, from my testing. You guys are on your own. Just look at the match results, and ask who does and who doesn't.

Ric

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John Alexander posted this 3 days ago

That sounds very efficient Ric. I never doubted that you could do it, only that it was one more thing that I would like to avoid unless it improved accuracy.

I like your suggestion to have it on the tech data sheet.  Maybe we could get it added.

John

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