Flash hole size advice needed

[ExPiney]

So,

I have several hundred 6.5 cm brass, lapua, small primer, small flash hole. I made the mistake of decapping with an oversize pin, and now about 1/3 of them have forcefully oversized flash holes, and the other 2/3 have the original .060. The lack of consistency is bugging me. The last thing I need is another variable to keep track of. I purchased a k&m flash hole tool that will give me a .080 deburred hole.

Question: How much of an affect on sd/es will upsizing the flash hole have? Should I size them all to .080 just so I have consistent brass? Or have 2 batches of brass, or lump them all together?

Thanks in advance.

jcs

 

[watercam]

I have shot Palma loads with .060", .0625" and .080" holes and have not seen any discernible difference in ES/SD between the three. If it were me I would just keep shooting what you have. FWIW I turned my .080" decapping pin down to .060"-ish and use it for both hole sizes with no issues.

 

[AlNyhus]

Take some that were decapped with the larger pin, open them to .080 with the large flash hole tool and back-to-back test them with the small ones. If there's no on-target difference, take 'em all out to .080.

I most definitely would not use a mish-mash of flash hole sizes. -Al

 

[Straightshooter1]

So,

I have several hundred 6.5 cm brass, lapua, small primer, small flash hole. I made the mistake of decapping with an oversize pin, and now about 1/3 of them have forcefully oversized flash holes, and the other 2/3 have the original .060. The lack of consistency is bugging me. The last thing I need is another variable to keep track of. I purchased a k&m flash hole tool that will give me a .080 deburred hole.

Question: How much of an affect on sd/es will upsizing the flash hole have? Should I size them all to .080 just so I have consistent brass? Or have 2 batches of brass, or lump them all together?

Thanks in advance.

jcs

In order to have cartridges as consistent as possible for precision shooting, one needs to have uniformity for as many things one can control as possible. But if precision shooting is not the objective, for example like for just hunting, then many things can be ignored. I'm in the reloading camp that says if there's anything you can control then uniform it. . . even if one can't determine a measurable effect. So, in your case, I'd make that batch of brass all the same and expand the flash holes to .080 and accept a lesson learned.

 

[243winxb]

Looks like the smaller flash (spit) hole increases pressure in the pocket. https://apps.dtic.mil/sti/citations/ADA606635

 

[cw308]

I use the #45 Drill bit on my 308 cases . I have found with different brands I would get different sizes the bit makes them all .080

 

[MagnumManiac]

I have large primer brass and small primer brass/flash hole in WW-Super and Lapua 22-250 reformed to 22-250AI.
I see a defined difference between the small primer/small flash hole (.062”) on both charge weight and ES/SD numbers.
The small primer is a little harder to tune with primer testing, but it has less ES/SD than my large primer brass.

I also think that you should segregate the brass that you have opened the flash holes on and NOT touch the remaining brass.
You can’t put it back if the one with the smaller flash hole shoots better.

Cheers.

 

[ExPiney]

Thanks all for the input. I’m going to load 10 rounds of each (.060, .mangled, and .080) and see what happens. I’ll post the results.

jcs

 

[D-4297]

Think the simplest solution would be to take the "over-sized batch , and add cases to round up to a group of say 50 , or 60 . And keep them segregated from the SRP cases . Develop a load for them , and when your SRP case primer pockets start to loosen , go to a slightly over-sized primer , with the larger hole . Kind of a recycling , without trashing a bunch of good cases . Unisys- Genix have a "rep" for being slightly over-sized , and they do make a SRP , but are hard to find in some areas . If at all , anymore .

 

[HPC]

Thanks all for the input. I’m going to load 10 rounds of each (.060, .mangled, and .080) and see what happens. I’ll post the results.

jcs

Were you able to determine anything definitive?

 

[cw308]

Would also like to know. Never liked a story with no ending.

 

[fkimble@charter.net]

I would have used a drill index set to measure the mangled holes. Then used the next larger size bit to uniform then all to that size.

Frank

 

[Old Navy]

Just how much did you open them up with the decaping pin? Couldn't have been much or the pin would have come out of the rod.

 

[R.Olds]

I have taken all my 6.5 CM small flash hole brass to .080. I also went to the 450 primer vs the BR4, the gun shoots very well with that combo.

 

[ExPiney]

I shot 15 @ .060 and 15 @ .080. I used a k&m uniformer to upsize the mangled holes (which were ~.070) to the .080. The ES & SD & accuracy were more erratic with the larger holes. I think I could re work the load though and get this back in line (CCI 450 & 41.9g H4350). As others have mentioned, consistency is crucial. All in all it was a pretty cheap way to learn a lesson. I still have 250 cases at the .060, and the 50 at .080 I'll use for hunting or experimenting.

Thanks for all your input.

 

[big john 5394]

I did the same thing that you did and found i had to put a 1/10 grain off powder more and it shot the same in a bra as the small primer hole.

 

[M-61]

Question: How much of an affect on sd/es will upsizing the flash hole have? Should I size them all to .080 just so I have consistent brass? Or have 2 batches of brass, or lump them all together?

A third option you left out. Keep the original ones together. Those with the oversize holes...well...fouling rounds?
I'm a firm believer is keeping everything the same that I know about. Those mystery ones can drive you nuts. You at least have a known variable.
1/3 of several hundred is a big number BUT it could be worse.
I also have had better results with small flash holes meaning better consistent groups.
Also I do next to nothing with flash holes. I check for a burr and trim it but I do not change the angle.
Surprised the pin didn't break or jam way before you did that many.