Magnum Small Pistol Vs. Small Pistol Primers in 9mm Luger?

[Doug B.]

I have some magnum small pistol primers (which I would like to "burn up") and the reloading data I have found recommends small pistol primers for 9mm Luger. I will be using Accurate Arms AA-7 powder 115 gr. Rainier round nose bullets.

Here's my question: If using magnum small pistol primers verses small pistol primers, how much of a powder reduction would you recommend to keep me safe? I have heard from only one source to reduce the starting load .5 grain for starters.

I instinctively "start low and work up".

The magnum small pistol primers I would like to "burn up" are CCI no. 550's and the firearm is a Beretta PX-4 Type F semi-auto with a 4" barrel.

Suggestions would be appreciated!

 

[Walkalong]

Should work just fine. Stop a hair short of max. As you posted, start low and work up.

 

[greyling22]

I accidentaly loaded several hundred 9mm loads with magnum pirmers a couple years back. they were mild loads. I couldn't tell a difference. if you're not running a max load I wouldn't worry about using them at all.

 

[Doug B.]

Accurate Arms suggests starting at 5.7 grs. and maxing at 6.7 grs. with this bullet/powder combo. There is no "given" variable between these two primers and only one grain between minimum and maximum. I think using the magnum primers vs. the small pistol primers, I'll start at about 5.2 grs.

Should be safe as long as my powder drop is reasonably accurate. I'll weigh often to check.

Thanks for the reply.

 

[BeerSleeper]

What is the actual difference between standard and magnum primers? Someone told me once that the only difference was the physical strength of the primer cup, that magnums could resist the higher case pressure in a magnum loading, and that intensity of ignition had nothing to do with it. I was unsure if I believed that, but started to wonder if it had credibility when I noticed remington says to use their magnum primers with .40S&W (a well-known high pressure round), instead of standard ones, regardless of load data.

 

[Walkalong]

Start at 5.7, the suggested starting load. With AA #7 the primer difference might make .2 Grs difference, might. I would not download #7 that much, even with a mag primer.

 

[GLOOB]

+1. No need to go below the starting load, let alone .5 grains below the starting load.

BeerSleeper: some slow powders recommend use of magnum primers to ensure full ignition. It's not as simple as a stronger cup, else all CCI would be considered magnum compared to Federal or Winchester pistol primers.

 

[1SOW]

During the primer shortage period, a lot of reloaders could only get the Magnum primers.

Many said/wrote they seemed to make little difference in 9mm. Like all have said, start at the low end and work up to be safe.

 

[Hondo 60]

I definitely would NOT go as low as 5.2.
I too have used magnum primers when that's all I could find.

There really was no noticeable difference.

 

[gamestalker]

I've noticed a relevant difference as follows. Loading some .357 mag. with a healthy charge of H-110 I accidentally loaded some with CCI standard SP and had unburned powder and still burning powder blowing back on me. The same loads using the magnum primers worked flawlessly. Had the same experience with large rifle standard primers. I wanted to see if I could actually hear a difference as well so I primed only some cases with both and could easily hear the difference with magnums being louder.
Also, as another person or two mentioned, don't reduce that #7 below listed data or pressures could go up more than wanted.

 

[zeke]

I use fed small pistol magnums with AA 7 in 9mm and mid range 125 gn 357mag loads. While the mag primers may not be "needed", AA-7 seems to work much better with them.

Accurate may have newer loading data out, but their Number 2 version, lists Ranier 115 r rn with a 6.6 grain starting load of AA-7, and a 7.3 grain max load (31,100 psi), using wsp primer and fed case.


Well after checking Accurate's online data, they have updated their loads, and dropped the starting load for Rainer 115 rn considerable.

No 7 115 BRY RNDS 7.0 1,047 8.2 1,185 34,933 1.130
No 7 115 RAN RN 5.7 1,027 6.7 1,165 34,399 1.140
No 7 124 BRY RN 6.7 997 7.6 1,120 34,312 1.160
No 7 124 BRY HBFP 6.0 948 6.9 1,072 34,627 1.060
No 7 124 RAN HP 6.3 954 7.2 1,080 34,204 1.110
No 7 124 RAN RN 6.7 993 7.7 1,124 34,634 1.160
No 7 147 RAN TRN 5.7 867 6.6 984 34,748 1.160

Course it leads me to wonder why the Rainer 124 RN has a higher start and max charge, even with the extra .02 xtra length? Their new loads for the Ranier 115 rn look a little light compared to the rest of the bullets?

 

[Doug B.]

Yeh......and now look at this. NOTE: Highlighted red would be my load. My Beretta short-cycled until I tried 6.8 grs. of the AA-7.

RainierBallistics
Reloading Data

9mm Luger
Gun Obermeyer Max Length 0.754"
Barrel Length 4" Trim Length 0.744"
Primer WSP OAL Max 1.169"
Case FC OAL Min 1.095"

Start Loads Maximum Loads
Bullet Powder Grains Vel. Powder Grains Vel. C.U.P. Cartridge Length Comments
RAN 115 RN No.2 3.9 968 No.2 4.3 1100 33,300** 1.100"
No.5 5.2 967 No.5 5.8 1099 30,700** 1.100"
No.7 6.6 968 No.7 7.3 1100 31,100** 1.100"

Reloads with 6.9 grs.......

Factory......

I have no pressure concerns.