oversize gas checks

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  • Last Post 24 May 2019
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pondercat posted this 23 May 2019

In moving my reloading room a few weeks ago some things got misplaced, as they will sometimes do. In this case one of the things I lost was a box of .30 cal gas checks.  I wanted to seat some checks on my newly PC'd bullets but they are nowhere to be found.  Well I got to thinking I have a new box of .32 cal (8mm) checks that are not too far off in size so I tried checking with those.  I could not make it work till I got the idea that maybe if I run the .30 cal bullets with check thru the 8mm sizer first it would small up the check enough to work.  So I got a couple different results.  If I pushed thru the .30 cal die base first the check came out rounded.  If I pushed thru nose first it ends up with a dimple in the center.  If I tried to seat the check without running it thru the 8mm die first it came out somewhat deformed.

Now the question.  Will the rounded bottom check or the dimpled check work. without degrading bullet performance? I won't even try the deformed check.

Any thoughts? Anybody try this before?

 

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pisco posted this 23 May 2019

i have had similar experience it does not effect accuracy 

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45 2.1 posted this 23 May 2019

The bullet in no way leaves the rifles bore looking like your picture. You need to recover some fired gas checked bullets and see what they looked like after leaving the muzzle.

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pondercat posted this 23 May 2019

45 2.1.

What I was wondering is, since the check was oversized is it possible that it would end up slightly heavy on one side because of uneven metal displacement during sizing or unequal gas check deformation during firing affecting accuracy- particularly at longer ranges.  If you look closely at the deformed check in the third picture, you will see what I mean about unequal metal displacement during sizing. Even on the dimpled check (2nd pic) the dimple is slightly off center.

On the other hand, after re-examination of the rounded check after my initial posting I was thinking that the round bottom may create an even tighter seal in the bore as the check is flattening out and expanding the upper portion of the check, so using slightly oversized gas checks may turn out be a good thing in some instances.  Maybe?  

Hopefully the weather will be nice this weekend so I can re-cover some bullets.  I built a bullet trap last weekend to see how the PCing holds up, but the weather and work prevented me from doing anything.

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John Alexander posted this 23 May 2019

On the other hand, after re-examination of the rounded check after my initial posting I was thinking that the round bottom may create an even tighter seal in the bore as the check is flattening out and expanding the upper portion of the check, so using slightly oversized gas checks may turn out be a good thing in some instances.  Maybe?  

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Excellent thought.  Why not try a batch of the rounded ones and find out? Might be interesting.

John

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pondercat posted this 23 May 2019

Why not try a batch of the rounded ones and find out? Might be interesting.

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Gonna do just that! Hopefully this weekend. But I still have to find that box of .30 cal checks so I will have a fair comparison. I may just have to buy some more.

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pondercat posted this 23 May 2019

Pisco,

i have had similar experience it does not effect accuracy

What ranges did you shoot those at.  And what guns/caliber.  i am also wondering if smaller or larger calibers would make a difference - if there is any difference at all.

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45 2.1 posted this 23 May 2019

45 2.1.

What I was wondering is, since the check was oversized is it possible that it would end up slightly heavy on one side because of uneven metal displacement during sizing or unequal gas check deformation during firing affecting accuracy- particularly at longer ranges.  If you look closely at the deformed check in the third picture, you will see what I mean about unequal metal displacement during sizing. Even on the dimpled check (2nd pic) the dimple is slightly off center.

The only problem with uneven checks (based on how equal or not that they are on the gas check shank) is that the gas pressure seats the gas check the rest of the way (lead showing scooted up in front of engraved gas check). What you see before is what you'll see (flattened and deformed some) after recovering one. It took a lot of shots involving purposely ill seated checks to find that out...... the problem being one of finding one to recover (long range shooting involved). Unless you shoot ill filled out bullets, you'll probably not see too much difference. If you make sure your checks are seated all the way and flat, you should do fine.

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pisco posted this 24 May 2019

hi i shoot a 303 mostly at 100 y

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