Why did 3 of the primer go concave


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HOWARD J
May 17, 2010, 03:04 PM
I loaded 357 mag--125 gr JHP with 17 gr of 2400 & 3 of the primers went partial concave--photo # 1--what caused this??????

http://img526.imageshack.us/img526/6222/photo1qr.th.jpg (http://img526.imageshack.us/i/photo1qr.jpg/)

Same load using 17.5 gr 2400---no concave

http://img52.imageshack.us/img52/9563/photo2ff.th.jpg (http://img52.imageshack.us/i/photo2ff.jpg/)

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Lee Roder
May 17, 2010, 03:10 PM
That's weird. What kind of primers? I'm thinking maybe just the primer cup was made a little too "thin" on the "dented" ones and it doesn't have anything to do with your load. Probably wrong though. Try it again and see.

HOWARD J
May 17, 2010, 03:11 PM
CCI small Pistol

Lee Roder
May 17, 2010, 03:40 PM
If you light off a primer all by itself in an empty case, is it "dented"? I'm now thinking all the primers get "dented" when they go off but are puffed back out by the force of the charge when the round ignites?

I just loaded a primer into a case and fired it. Once I got it out of my cylinder :D I see it's "concave" too. I think they just flatten out under full charge. 17gr of 2400 is "light" for that bullet.

Scrapperz
May 17, 2010, 03:52 PM
primers get "dented" when they go off but are puffed back out by the force of the charge when the round ignites?

I agree. I also think it's a sign of low pressure. Could also be from the primer/powder combo.

BTW, What kind of firearm was used?

ReloaderFred
May 17, 2010, 03:53 PM
When a primer is detonated, it backs out of the primer pocket and stops when it hits the backing plate of the revolver. Then the powder is ignited and the burning gases form pressure, which drives the case to the rear, where it also stops against the backing plate. This reseats the primer into the pocket. The resulting pressure will have an impact on the appearance of the primer, but isn't really a good indication of high or low pressure in and of itself.

I've never loaded .357 Magnum with 2400, prefering other powders for full loads. I also load heavier bullets for full loads. I like bullets in the 158 to 185 grain range for full power loads.

Hope this helps.

Fred

HOWARD J
May 17, 2010, 03:55 PM
That's what my oldest son says.....................
RE: Max load---If you check most reloading books published in the last 10 years--you will
find 17.5 gr is now a max load. Sierra goes to 19 gr I believe.
I have always used 17.5 gr--pretty flame & lots of noise...............
These days my hands tell me to go back to 16.5 gr..........................

GP-100 w/ 6" barrel

BTY--this powder is 30 some years old---maybe ????????

Tom S.
May 17, 2010, 06:36 PM
I ran this combination through Quickload and it comes back 7000 psi over the SAAMI 35000 maximum! Yet Speer #14 shows 17.5 grains of 2400 as max. Perhaps you might want to back down a bit...

ljnowell
May 17, 2010, 06:45 PM
I will load to 16.5, butr usually stop at 16 with a 125gr JHP and 2400.

243winxb
May 17, 2010, 07:31 PM
Load to Hot This is what your seeing in photo #1 . Each round will give different pressure with in a range. Get a case thats more heavy or has thick walls, and pressure may spike on a few rounds. Shame your not using magnum primers, we could blame it on that. :uhoh:

Presto
May 18, 2010, 12:11 PM
How old are your cases. I've seen this happen when primer pockets get a little loose and the primer backs out when fired. I can't tell if that is what is going on here, but it could be a possibility.

HOWARD J
May 18, 2010, 01:46 PM
Brass is about 30 years old--these fired twice..................

pockets were very tight

ranger335v
May 18, 2010, 03:16 PM
The "concave" loads were too light to form the primer cups fully flat against to the recoil plate.

Claude Clay
May 18, 2010, 03:31 PM
substitution of differing ingredients may result in unsettling
and/or dangerous results.

the receipt calls for magnum primers.

take some and call us in the morning

HOWARD J
May 18, 2010, 05:39 PM
Claude Clay
I see you don't have a copy of Speer Reloading Manual # 14--get one & read it !!!!!!!!!!!

243winxb
May 18, 2010, 07:26 PM
Why did 3 of the primers go concaveHammer Bounce. The primer is getting hit a 2nd time. :)

HOWARD J
May 18, 2010, 07:59 PM
why no hammer bounce on the heavier loads

I made up 3 test loads---5 cartridges--16.5 gr 2400-125 gr jhp
" ' --17 gr 2400-125 gr jhp
" " --17.5 gr 2400-125 gr jhp

The 16.5 & 17.5 worked fine
the 17 gr --I don't like 3 of the primers.

For many years I shot 17.5 gr 2400---I never had a problem using a
Ruger GP100 357 mag.
Now the reloading manuals are telling me that their old load are too hot
---must be talking about some other gun not a GP100...............

243winxb
May 18, 2010, 08:10 PM
why no hammer bounce on the heavier loads I thought all were the same load?? How the gun recoils may have an effect on hammer bounce. Compare a hard hold to loose, or free hand to benchrest. I know S&W M29 44 mags have there problems with it, plus the bolt can unlatch on older models letting the cylinder rotate backwards.

243winxb
May 18, 2010, 08:14 PM
Ok, i see 1/2gr difference, that means nothing IMO. Are you sure you dont have the data reversed or photos? Photo 1 shows the heaver loadings/pressure.

HOWARD J
May 18, 2010, 08:29 PM
I am correct---the bags were labeled & after shooting I put back in same bag...............

HOWARD J
May 18, 2010, 08:35 PM
I am going back to my good old load of 17.5 gr of 2400 & will forget this whole thing.

243winxb
May 18, 2010, 09:04 PM
& will forget this whole thing. Me too. :)

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