357 Magnum Primer

[sjs]

My favorite load for my 686-6 is 158 gr Hornady XTP, over 13.5 grains of 2400, in Starline brass with CCI 500 standard small pistol primers. I estimate this gives me about 1175 fps out of my 6 inch barrel.

I am getting low on primers and went to my LGS and they were out of standard primers but had some CCI 550 magnum small pistol primers, so I got some.

I expect that substituting magnum primers will change the velocity and perhaps the accuracy, and I can adjust for that but I am concerned about the safety of it. None of my loading manuals show magnum primers for the .357 loads.

My load is well below maximum, which my manuals show as 14.8 grains. I would think that my load of 13.5 should still be safe with magnum primers but I don't know for sure.

Any comments will be appreciated.

 

[WR Moore]

Based on limited testing with faster powders and the 550, I'd expect limited change. That said, you might want to back down about a grain and work back up.

 

[august1410]

I use H110 in my .357 Magnum loads and it requires a magnum primer. I almost bought some 2400 on Saturday, but decided to stay with what I had been using. Had I known 2400 was good without magnum primers, I would have gotten some.

I once could only find magnum primers and loaded a batch of .38 Spl with them for use in a Model 10. Worked just fun with the standard load of Bullseye powder I had been using

 

[IAhunter]

SJS, I am loading 13.5 under the 158 XTP as well. I use this load in 4 different revolvers. I have used CCI 500, Win SP, and Remington 5 1/2 (magnum) primers after working back up to 13.5 grains. While all three provide similar results, the Remington 5 1/2 primers work the best accuracy wise for me.

 

[DWalt]

You will probably see no ballistic difference. BTW, small rifle primers work very well in .38 Special and .357 Magnum. In fact, that's all I use.

 

[Alk8944]

^^^^^^^^^^^What DWalt said

Can't say all I use is Small Rifle, but I have loaded a few hundred in .38/.357 and chronographed them against SP and SPM. I have chronographed several hundred making comparisons and can see no statistically significant difference! Small Rifle do usually give somewhat better extreme spreads and standard deviation compared to any SP or SPM primer I have compared them with in my experience.

 

[TAROMAN]

I have chronographed many loads with regular and magnum primers.
The statistical difference is usually quite small.
In a few cases, I have found magnum primers in light target loads to consistently give greater consistency and, possibly, improved accuracy.
Stocked up on Federal magnums during a recent panic.

 

[RGVshooter]

I've loaded thousands of .357's using Hornady's 158gr & 180gr XTP's using up to 12gr H110 and 9.5gr Blue Dot using both Winchester WSP and Winchester WSPM (magnum) primers and in all honesty, never noticed any difference i haven't chrono'd them, all I know is they went bang! And burned clean. From now on, I buy whatever's on sale, or cheaper

 

[BLUEDOT37]

None of my loading manuals show magnum primers for the .357 loads.

Apparently you don't have a Speer Reloading Manual?

Over 20 years ago they stopped testing/listing 2400 with Magnum primers & added a recommendation to "Do not use Magnum primers with 2400 or Viht N110 loads shown here or high pressures will result."

.

 

[rh73]

My Hornady 10th edition lists wspm primers for use in .357 magnum loads, 2400 included. Nosler also recommends wspm with .357 magnum loads.

Guess all "experts" don't agree.

 

[rockquarry]

I no longer shoot any magnum handgun cartridges, but used to use one load for all .357 Magnum revolvers: cast 160 grain #51 H&G SWC (the original .357 Magnum bullet) and 12 grains #2400. As I recall, the chronographed muzzle velocity was around 1,100 fps from a 6" Python.

I had been using standard CCI-500 primers for quite a while. With the same powder charge and bullet I tried all the various standard and magnum primers I could locate and fired many groups, benchrested at 25 yards.

I don't have the figures in front of me, but with the exception of Winchester, I got slightly better accuracy with Federal, Remington, and CCI magnum primers than I did with the CCI 500s I had used for so long. These results surprised me. While differences were small but measurable, they weren't enough for me to to start buying more than one small pistol primer. I stayed with the CCI 500 as a matter of convenience.

A more accurate gun and a shooter with better benchrest skills than I have might turn up something more definitive than my results.

 

[DWalt]

I started using SR primers in .38 Special back in the late 1960s. At that time I had a co-worker who was a top-level Bullseye competitor who used a .38 Colt OMT revolver in the CF stage. He mentioned to me that he used SR primers in his .38 Special WC competition loads as he found after considerable testing that they were more consistent, at least for him. I thought it was heresy at the time, as everyone knows that SR primers are for rifles only, not handguns, but he was right.

 

[Joe4d]

Lyman 49, fairly new manual, Uses CCI 550 in all 357 loads. and lists 14.9 of 2400 as a max load with a 158 JHP

 

[sjs]

Great info guys, thanks very much.

 

[ExRanger714]

My old logbook from the 1970s says I used to throw 15 grains of 2400 behind a 158 grain jacketed bullet to get a really hot load. That was before privately owned chronographs and I based that on muzzle flash, perceived recoil and ease of extraction. Notes further state that 13.5 of the same behind the same does the same job, whatever I meant by that. The 15 grain load I noted was for Colt E and I frames and S&W N frames only. Maybe 13.5 for K frames? I forget.

I quit reloading when my time became more valuable than the cost of factory ammo.

But I don't know how many times I've almost dusted off the equipment and bought components.

Regards JD

 

[BLUEDOT37]

Guess all "experts" don't agree.

Speer & Alliant are part of the same company, ATK. If you can't believe the company that makes the powder, who better?

.

 

[cowboy4evr]

A little side note about " Speer and Alliant " . Alliant says not to use Blue Dot in the 41 magnum yet Speer in their latest manual has load data for the 41 mag using blue dot powder . Guess one doesn't talk to the other ., Regards , Paul

 

[LoboGunLeather]

Any time you change components it is time to start all over in working up your loads. A change from standard to magnum primers usually calls for an initial reduction of about 10% in your powder charge, then you may carefully and judiciously work upward while monitoring for pressure signs.

About 30 years ago I helped a nephew get started in reloading. One of the issues he experienced was a perception that "magnum" primers were intended for "magnum" cartridges and loads, so he jumped right in with magnum primers for .357 mag loads. No major problems or damage, but still some lessons learned.

Magnum primers can be helpful in achieving proper ignition with heavy loads of slower-burning powders. That doesn't mean magnum primers are required for all such loads. Each combination must be worked up carefully, and any change in components (primers, cases, powders, bullets) must be treated as a "new critter" to be tamed.

Have fun, but do it carefully.

 

[loc n load]

My everyday load for the 357 since the 70’s has been 150-160 SWC over 13.5 @ 2400 lit off with a magnum primer. Have shot approx 300,000 of these in a variety of K,L & N frame 357’ over the years. Going shooting here in about an hour, got a couple hundred of them to run through an old M-65. This load will serve you well.

 

[Qc Pistolero]

A few years ago,I remember reading about an experiment using regular vs magnum primers.If I remember correctly,there was a slight increase in pressure but nothing to write home about.
The conclusion was something like if your load is near or at maximum,start a little lower and work up to it.
Now all you've got to do is determine if your load is near max in your gun.Like suggested above,maybe reduce your load a bit and check what's going on.