BR Shooters Moving to FL Sizing?

[Phil3]

Found this on another forum. Since it does speak to BR shooters, I thought I would BR shooters if they agree. It is mostly the last paragraph, but please read what comes before it. - Phil

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I've not seen any big difference in the accuracy new rimless bottleneck brass produces compared to what properly full length sized once fired cases produces. As long as the case neck's well centered on the case shoulder, they all center perfectly in the chamber when fired. Both new cases and full length sized ones. Doesn't matter how much clearance there is around the case body when the round's chamberd. And a good full length sizing die without an expander ball centers the case neck better on the case shoulder; the case body's held in place as its neck gets sized down.

Same for belted cases. Belted cases have one other issue; the ridge that appears right in front of the belt after firing a new case has to be sized down to the rest of the case body diameter else it'll interfere with the chamber at that point. Conventional full length sizing dies don't size it down; a special body die has to be used. Innovative Technologies - Reloading Equipment has a collet die that works fine. But full length size belted cases so they headspace in your chamber on their shoulder, not the belt and best accuracy will be at hand. Otherwise, new belted cases can shoot just as accurate.

The back end of a round's never centered in the chamber anyway; it's pushed against the chamber wall by the extractor in virtually all rifles. So it's a thousandth or so off center when fired. Up front on cases headspacing on their shoulder, they'll automatically center perfectly in the chamber (their shoulder's a good match for the chamber shoulder, isn't it?) as the firing pin drives them there; clearance around the body's not an issue.

If all this weren't reality, then the benchresters would not have switched over to full length sizing their fired cases a few years ago. The size of their smallest groups didn't get any better. But the size of their largest ones are now smaller. Overall accuracy improved quite a bit.

 

[BoydAllen]

One little detail about group benchrest competition my not be fully understood. The shooter that has the lowest combined average group size, not the one who shot the smallest group, wins the match, so factors that contribute to consistency of accuracy are very important. Also, on the short range group side, when Lapua brass came into common use, with the attendant rise in useful pressure and velocity, this advantage went hand in hand with the need to FL size. Another thing that may not be fully appreciated by many reloaders is how closely dies are matched to chambers, which invalidates many of the preconceptions that shooters may have about FL sizing. Typically, neither they, nor anyone that they know, uses a die that is that well fitted to a chamber, an lacking that experience, old information gets passed down even though it is out of date.

 

[CatShooter]

Benchrest shooters often shoot the whole string of shots in a short period of time because they were waiting for a dwell in the wind.

The FL die used for a bench rifle is not your off the rack RCBS FL die.

The benchrest FL die is custom made to match the exact chamber, and barely sizes the case - maybe 1 thou all around, while the regular RCBS die will take the body down 4 to 7 thou, and set the head space back as much as 14 thou.

The reason that the bench shooter uses a FL die is because if the case is tight, or the headspace is a thou long, the resistance to closing the bolt can disturb the settling of the rifle in the bags and require the shooter to stop shooting and re-set the rifle in the bags, which would destroy the group.

If time and wind conditions were of no consideration, I prefer neck sizing.

 

[BoydAllen]

The good thing about hobbies is that we get to do them the way that we want to. In past years I have seen a very good benchrest shooter neck size same set of brass all weekend, at a match, because he was getting his best accuracy with a lower pressure load. But for those who may plan on a "Ill neck size till they get tight, and then FL size." strategy, I will mention that even though they are fired in rotation, not all cases in a set will get tight at the same number of shots, and it has been my experience that if one has tighter and looser cases in the same group, it will be larger than if they were all tight or all looser.

 

[waltk]

CatShooter, good to see you back!
Where have you been?
Always enjoyed your comments.

 

[CatShooter]

Ha... you are in a crowd of one - most folks wanna take me out and hang me

I've been busy.... I tried to pull a failing ammunition company out of the ashes, but the owner was a child impersonating an adult. I got him a 1.5 million round order and he spent our powder money on a HUMVEE, and they went under for the last time.

I started my own company, and I was doing fine until Sandy Hook - now I can't get supplies

I'm working on some stuff I might want to patent.

Plus I still have a Rugrat at home

I haven't shot much for the past few years, but I just dug out some of my better riffles and I working up loads with some of the newer powders - I'm gonna kill some paper