What's the diff ?

[joneb]

I have a new jug of AA#7 which is nothing like the old stuff For my .44spl loads I use it only with WLP primers and all is well now.
I had some good loads worked up for my .357 mag 4" using WSP and AA#7 but they all went to crap with the new powder lot( inconstant detonation) So now I'm using small magnum pistol primers with ok results but the accuracy is not as good, my question is what would the difference be between small pistol mag. primers, and small rifle primers in a .357 mag application with AA#7?or maybe #9 ??

 

[CMcDermott]

The difference is cup strength and the amount of energy produced when ignited, with the rifle primers having more of both compared to the magnum pistol primers. They need more cup strength as rifle cartridges are SAAMI spec'ed up to 65,000 psi, where few pistol cartridges go above 36,000 psi and those that do typically call for using rifle primers when reloading (454 Casull, 460 & 500 S&W Magnums). The extra energy when ignited is needed to help set off the slower powders used in rifle cartridges compared to the much faster powders used in pistol cartridges - the overlap is very small and centers on IMR 4227, one of the slowest powders used in pistol cartridges is also one of the fastest powders used for rifle cartridges.

 

[joneb]

Well this must be a stupid question to have received such a under whelming response. I doctored up the first post, I'm wondering how much hotter small rifle primers are than small pistol magnum primers and can they be used for .357 mag. pistol powders like AA#7 ? what would the load reduction be ? or should I just forget about it ?
Thanks CMc for your reply

 

[jvik]

I think that's a recipe you don't want to use. Rifle primers are for rifles, use pistol primers for pistols. The load data in manuals is based on the type of primer/powder specified for that cartridge. A hotter primer could give you unexpected pressures. If the new AA#7 isn't working for you it would be better to try a different powder.

 

[def4pos8]

I think you bumped into the right solution in using the WLP for the .44 Spcl. I do and have no problem with AA7.

I also use AA7 in .38 Spcl/.357 Magnum. I haven't had dificulty using the WSP primer. Of course, the powder lot could be fouled up but might there not also be a problem with the primers? Most folks are careful to store primers with care, but I did know one guy who kept hus in such a high-moisture environment that he suffered ignition troubles.

AND! --when in doubt ---- change the powder!! Good luck!

 

[Jim Watson]

Admittedly not with magnums, but in tests with small primer .45 NT, I found that a small pistol magnum gave higher velocity than a small rifle standard.

AA says standard primers, I believe.
But they get their powders from all over the world and there is a good chance that the present lot of AA7 is not really the same as the previous batch except in the overall "burn rate" to allow the same charge weights.

 

[joneb]

Here's a picture of the old and new AA #7 visually they appear quite different.
Thanks Jim, Does your .45acp NT brass have the standard or oversized flash hole ? Which primer type gave you the lowest SD ?

 

[koja48]

Old stuff, in addition to the color difference, appears to be a bit more coarse. I'm suggesting one or the other may not be quite right. I'd try a different lot of AA7 powder for comparison, then work-up the load again. Mag primers are a hotter flame & can create a pressure spike. I'm switching to CCI #41s for my AR loads when the shipment arrives & I'll drop the load I'm currently developing by a full grain or so and work up again.