Flash holes very big, a big problem?

[bobotech]

In my expermiments in converting berdan to boxer primed brass (7.5x55 swiss), I ended up with about 20 cases that have very large flash holes. About 7/64s in diameter. Quite a bit more than the standard flash hole diameter.

I haven't loaded them up or anything but I am wondering if I should just toss them or can they be salvaged/used?

I have converted another 100 or so and they are just about perfect with the proper flash hole size. The ones I screwed up on are my first batch of brass while I was learning and using a poor drilling jig with.

 

[Slamfire]

I don't know how much larger your drill holes are compared to standard holes.

A big hole do at least two things that I can think of:

The first thing is that more flame will get directly to the powder. This would be the equivalent of using a magnum primer: pressures should go up a bit.

The second is that pressure within the primer pocket will go up. Gas has to flow through the primer pocket hole, and that takes time. (Everything is in milliseconds) There is this lead/lag relationship between the pressure in the case and pressure in the primer pocket area.

By increasing the primer hole you are reducing a gas flow restriction and that will increase pressures in the primer pocket.

If the hole is too big, the primer will leak. Maybe blow out.

So, cut your loads and watch for early signs of primer piercing, primer blowout.

 

[Kernel]

Some guys will drill-out the primer holes in cases that will be used exclusively for shooting reduced velocity loads (under 2000 fps). The belief is the larger hole will result in the more consistent ignition of the tiny powder charges (like 4 or 5 grains) used with such loads.

Perhaps it's an "old wives' tale", but some swear by it. I've seen the merits debated and discussed, at length, on some other forums.

Due to a headspace phenomena that can arise from bottle-necked cases that are used repeatedly with reduced power loads, it's good to segregate such cases, anyway. Larger primer holes would help with the identification, even if it provided no other benefit.

 

[jim147]

I use large primer holes on reduced loads only if I'm not making enough pressure to slam the primer back int the hole upon firing. I would not use yours for full pressure loads. But some light cast bullet type loads would be a lot of fun.
Go slow and load safe.

jim

 

[bobotech]

Well then I'm not going to keep these cases. I'm going to end up with about 800 pieces of 7.5x55 Swiss brass so I won't be missing these 20 pieces.

I don't want to have to segregate certain brass because of a potential issue. I will just stick with my converted brass that has nice small factory sized flash holes and I will either give away my converted brass with large flash holes to someone who wants to experiment or just toss them.

 

[jmorris]

You are already off the map as you now have 3 flash holes correct (2 berdan and your boxer)? It's your experiment so you tell us.

FWIW there are different size flash holes in some pistol brass. I ran tests on standard and some large flash holes in 45 ACP a few years ago. The larger flash hole had a lower SD of the two.

 

[The Bushmaster]

Load'em. Shoot'em. Load'em again......................

In the years I have been reloading ammunition I have notice that flash holes range from "Damn. The decapping pin is stuck again." to "Man. I could drive a truck through that."

 

[ranger335v]

".. I am wondering if I should just toss them.."

I would toss them. Standard flash hole diameter is .081", yours are nearly .110", as a percentage of change that's quite a lot. It wouldn't matter much in light loads but it sure could if you ever got them mixed and "accidently" loaded them to full pressure.

 

[bobotech]

About the berdan flash holes, when I flattened the anvils, it squashes the berdan holes so that they don't nearly have the same opening before the squashing process. The berdan holes are MUCH smaller than the boxer primer hole anyways even before the swaging process.

 

[fireflyfather]

Due to a headspace phenomena that can arise from bottle-necked cases that are used repeatedly with reduced power loads, it's good to segregate such cases, anyway. Larger primer holes would help with the identification, even if it provided no other benefit.

Which is why people who do this a lot tend to use rimmed cartridges (.303 British, 7.62x54R, etc). Much less of an issue. Still want to separate out anything with an enlarged flash hole.