45ACP Large Flash Hole


May 12, 2013, 07:52 PM
A non-reloading buddy gave me some once fired brass, in the process of case prep I discovered some with large flash holes. An 1/8" drill bit drops thru, compared to ~5/64" for a normal sized flash hole. Any idea why these flash holes are so large? Are they OK to reload with standard WLP primers? I probably won't use them anyway as I have an ample supply of "normal" brass.

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ole farmerbuck
May 12, 2013, 08:15 PM
That large hole doesnt look very round.

May 12, 2013, 08:16 PM
I have at least 300 win .45s and none of them look like that. None of my other head stamps are that big either

May 12, 2013, 08:16 PM
Was that from "winclean" ammo? Betting so. I'd segregate it or recycle it.

May 12, 2013, 08:38 PM
Winchester increased the size of the flash hole when they went to their lead free primers. Seems like the primers were hotter and wanted to back out so the flash hole size was increased to compensate. I can see no difference in performance or accuracy when they are mixed into a batch of brass.
If you are dead set on getting rid of them, send them to me and I will "recycle" them for you. (After 15 loadings)

May 12, 2013, 08:58 PM
I found a few of these a few months ago. Out of curiosity I loaded them up with some with normal size flash holes and then chronoed them at the same time. I did see a slight increase in velocity with the larger flash hole. About 25 fps. This was with a mild load (172PF) so I can't say what might happen at a higher charge.

May 12, 2013, 10:03 PM
The hole is round, not the greatest pic. Went back & counted, only have 20, so based on the responses, I think I'll segregate and see if more show up and play around with them. Thanks for all the quick responses.

May 13, 2013, 12:30 AM
Those look modified and a hole that large will change the performance of the primer. I would put them aside and probably not load them.

As for them being WinClean rounds, I highly doubt it. That brass usually has a primer pocket that holds a SPP instead of a LPP and nothing to do with such a large flash hole.

May 13, 2013, 12:37 AM
There are rubber and plastic bullets sold for indoor target shooting that use a primer only as a propellant. The usual recommendation is to drill a larger flash hole in cases to be used with these bullets. This may be such a case.

I use Blazer aluminum cases for this so I don't get them mixed up.

Jesse Heywood
May 13, 2013, 12:52 AM
If the hole is .140 diameter it was probably used for blanks or dumdums as JRH6856 described. I have used many of these in 45 cal revolver rounds at reduced loads.

May 14, 2013, 05:06 PM
Kp321 has the correct answer.

The flash hole was increased in size when Diazodinitrophenol (DDNP) priming compound was first introduced. Due to the higher brisance of the DDNP mixture, the enlarged flash holes were tried in an effort to relieve the pressure faster in the primer pocket. The second attempt was crimping the primers in place, and the third, and hopefully final, solution was going to the small pistol primer in the .45 acp case.

Loading those rounds will cause no problems, and they will shoot just like the others. They worked once, and they'll work again. I don't bother to segregate them anymore.

Hope this helps.


May 14, 2013, 05:20 PM
I have some that I drilled out years ago, to use Speer plastic indoor practice rounds. They look just like these.

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