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Curing bullet runout in your cartridges.

once a a BR shoot a group of shooters got together and had a discussion about run out a decided to compare each others loads and methods. Surprisingly the straightest ammo was loaded with old RBS partner press's and dies for each stage of reloading. Lookin at the equipment wasnt impressive, but results were effective.
 
James, well written. And I do believe your correct in pointing it out. I am biased when it comes to the runout thing. I dont mention it because I dont think its very humble when guys constantly remind everyone of wins or records, but I do hold 1000 yard agg records (Williamsport hg 6 and 10 match). So I can also shoot, and I have done a lot of testing. I dont form opinions on things without my own personal testing. I know personally I can get burnt out at the reloading bench, so I like to do what matters and not what doesnt. So I just want guys to test the runout thing in their rifles before spending the time and money to chase something that may not help them. My advise is always 100% uninfluenced and free, and its also free to ignore.
I agree totally. Everyone should do their own testing more shooting less typing.
I will say that we all shoot different disciplines and for me at 100-200 yards everything matters. When the LV100 yardage at this years nbrsa nationals was won with a .1504 five target agg. Everything matters
 
If the chambered round is forced into straight then you've introduced chambered tensions.

the term 'chambered tensions' does not sound like a good thing! can you discuss more?

i have this mental image that with a normal sized case (say, 0.002 headspace) the cartridge gets driven ahead before ignition and thus mostly centers itself on the chamber shoulder, aiding in bullet alignment (assuming runout has been controlled). if the brass is a tight fit this mechanism could be impeded, or at least would be inconsistent. if the brass is an interference fit it might actually be warped when forcing it into insufficient headspace.

so my question is, what are the effects on the target of chambered tension?
 
This has been my experience. You can shoot cases that are all tight in a group with good results. You can shoot cases that all chamber without resistance and shoot small, but if you mix them, the result will not be as good as either. You will get fliers. Here is a video of a very skilled shooter shooting a tiny knot of a group at 200 yd. in competition. If you pay close attention you should see that there is no way that his brass is tight in his chamber. It may fit well, but he could not handle the bolt as freely as he did with any binding.
 
i have this mental image that with a normal sized case (say, 0.002 headspace) the cartridge gets driven ahead before ignition and thus mostly centers itself on the chamber shoulder, aiding in bullet alignment (assuming runout has been controlled).
To begin, we have no idea about relative bullet centering of crooked ammo. It's an abstract. So jamming low angle shoulders into a center could be the very worst situation for centering of bullets -of 1 or 2 rounds in a group(while good for the others).
It's my contention that any amplitude of this affect would be tied to clearances/chambered tensions with it.
It passes tests logically, I know of nothing else that does.
But, I have not directly tested this, as it's not as easy to do so as it seems.

To test this theory means planning and acting to cause a broken condition. Producing and shooting high runout ammo in a chamber(entire chamber) tight enough to interfere with tension free chambering of that ammo. Then comparing results with normal straight ammo prior produced in that chamber. That's the only valid test.
Problem is, a tight chamber like that produces very very straight cases. How will I produce high runout ammo with that chamber?
Forcing seated bullets off center is only one runout type. To make realistic bananas for the test, takes heavy FL sizing of cases with thickness variance. Out of a tight chamber, this would take a good number of firing/sizing cycles.
It's hard to produce crooked ammo without clearances to do so. Efficiently doing it would mean testing with a cartridge so poorly designed that producing straight ammo with it is rare(like a 30-06). Then that same cartridge would have to shoot well enough to measure results in this narrow test.

Much of that goes into things I haven't and wouldn't ever do. Too much effort.
Would be interested in efforts/results from somebody else doing it.
 
I appreciate all of the input on this subject. Personally, I prefer my loaded rounds to measure .001 or less of runout. I do straighten rounds that are shot with the bullets seated to be jumped, but don't straighten those rounds that show small amounts of runout and are seated into the lands. Also, I use custom dies with bushings in the FL sizing die. For the 6 PPC, I use a custom bushing die built by the late Jerry Simison and a seating die from Jim Carstensen (JLC). For the Dasher, I use a FL bushing die from Hornady Custom shop and a Wilson seater. For the 6 BRA, I use a FL bushing die from Harrell's and a Wilson seater. I will admit that my tests may be anecdotal, but the above combinations work well for me. A large part of shooting well is one's mental attitude. Therefore, if a shooter has confidence in his procedures and equipment, he/she will be a better competitor. Good shooting....James Mock
PS- I turn my brass to give about .002-.003 of total clearance.
 
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