Brief update 300-MP for .357

Infidel_319

Infidel_319

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Initially loaded my test rounds with a regular small pistol primer and everything worked fine, Alliant states you don't need magnum primers per their data.
Today at the range, I had several, probably 1/5 that did not ignite properly. Was using 125 grain xtp with 22.0 grains which is just under max and gave me the best accuracy and velocity was great at just under 1300 fps from my 2 1/9" model 640 pro.
I recommend using MAGNUM primers, I will be pulling all mine down (loaded 200 up) and working it back up with mag primers. Should have known better with a 22 grain charge, wish Alliant would give more data, but they don't and that's why I'm here today. Otherwise besides being somewhat dirty it's a great powder in .357. Muzzle flash is quite impressive, better than 296. Now just have to find myself a 586 pre lock with 4 or 6" barrel at a decent price. Good luck with that right.... Anyway, that's my experience for what it's worth. Enjoy. :mad:
 
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Is it possible you didn't seat the primers all the way? Did you try a second trigger pull on the ones that didn't fire? (if that's what you meant when you said, "I had several that did not ignite properly.")
 
They Fired, They Just Had Very Low Recoil Muzzle Blast Or Noise. Like Less Than Standard .38 Special.
 
What brand of primers? How much of a crimp? I use 18.0 gr under a 158 gr bullet with Winchester SPP and haven't noticed any problems. In fact performance is very consistent in both rifle and handgun.
 
With 22 grs of powder, I don't think a magnum primer would hurt................ you might even get better accuracy.

My test with imr 4227 and BlueDot showed that both regular and Mag primers would work, depending on fps and pressures.

Sorry about having to de-prime 200 loads......hope the new loads work out for you, after all your troubles.
 
I have been thinking about trying this powder for 357 magnum.
I have used one pound so far in a 44magnum and had great luck, I did not use magnum primers but did use Winchester LP and they say theirs work for both magnum and regular use.
I cannot see how it could be a problem if you work up from quite low charges.
I saw a chart somewhere recently that showed spread between magnum and regular small pistol primers.
Most were not as large a spread as the small pistol were , small pistol primers were almost double between the two.
Please do not take that as fact, but I do remember they were much more difference then large pistol or large or small rifle.
I have also had a similar experience with Accurate arms #9 in 45 Colt or 454 Casull, I can not remember which, but the point was magnum large pistols were not specified but sure seemed to be needed.
 
Hey Infidel

Sorry to hear you had a less than productive day shooting..

About primers.. In the last 40 years of doing this, I can't remember ever having a primer failure in handgun loads. But in the last year I have had a few. The last one was with my 686 and a CCI500. On the second punch, it went off.. I'm pretty sure these primers in question were purchased rather recently. I was quite puzzled by this, and now hear of your experience.. ?? Kinda weird..

I've been shooting 300MP for quite a while now and I can assure you that, in 4" and 6" barrels anyway, magnum primers are not necessary. It is counter-intuitive I know, but it's true. But.. maybe, in a short barrel, magnum primers will work better.

Of course I have not worked with 300MP in a 2" barrel so I can't say from experience,.. it may be that this powder might not be the ideal for a short barrel. It does seem like a lot of powder to burn in that short distance.

I have a 2½" Mod 66 that I worked up some loads for a few years back and found AA#7, Blue Dot and N-105 worked very well with 125gr bullets.

In any event, I'm looking forward to seeing how your next trip turns out. Hopefully the mag primers will do the trick.
 
Thanks for the reply. I have some True Blue that I will use in these pulled down loads so no need to de-prime them. I will prime some with cci 550s and let you know what happens. It was really strange, felt like half of the typical recoil, no muzzle flash, low volume. Could the crimp make a difference like that. The brass wasn't all trimmed EXACTLY the same, but within 3-4 thousandths so i suppose some of them didn't have as heavy a crimp as the rest. I don't use a heavy crimp, I would call it moderate.
 
Well, now that you mention you are putting a moderate crimp on these, that might well be a factor.
I would put a heavy crimp on this load because you want as much 'pull' as possible to get that powder to start burning. And in a short barrel, and a slower burning powder, you want that to happen quickly.

Just for kicks, I would give the load another try with a heavy crimp.. just to see.
And try some CCI 500's.. I know it doesn't sound right, but thats what Alliant tested with..
 
Not all brass and cannalures are the same..............

I take the extra time to seat the bullets at the correct OAL per the cannalure ,where ever it is..................
In most Jhp bullets you will notice a very slight difference
in your loads if set in a holder or laid on a cloth. ( non rolling) I then fine tune the loads that are a little off.

Then I crimp the loads in a final step, to try to get a load that
is of better quality than the powder, bullet, crimp, type reloads, that I normally do for my "Volume" loads.........

but you might not want to go through this much trouble and
just select the loads that look the best, when you are done with the normal way or reloading.

Tight groups
 
thanks For The Replies. Will Try HEAVY Crimp With Both Primers And See What Happens. Only Pulled Down Half Of Them So Far. I Will Say The Loads I Worked Up Were Just Under 1300 Fps With This Powder With Good Accuracy And A Very Impressive Fireball :)
 
I get a pretty impressive fireball from a 4" barrel.. I can imagine what a 2" would be like..:D

I expected good accuracy and velocity out of your gun from this powder. 300MP is an amazing product.

We just gotta get them shootin right..
 
300MP

I do have to agree with the other poster about this powder though, I only use Accurate #7 or even #5 for short barrel work in 357 magnum.
The other issue is bullet weight, I have always been told, lighter bullets per caliber , faster powder, now I do not go to Bullseye or anything, but a medium would be my choice.
Now , if your main objective is a fireball, you are on the right track, I would crimp as much as you can , switch to a magnum primer and let her rip.
Why not try a 158 grain bullet ?
I am going to start using 300MP in my 300 Maximum as 2400 is too fast and AA 1680 has been best so far.
But, I shoot it out of a 6" or 8" Dan Wesson or a 14" TC Contender.
I am thinking that a 180 grain bullet and 300MP are just made for each other !!!
 
Main reason for 125 grain bullet is that's what I carry at work and it's proven record for stopping power. Getting close to 1300 fps out of my 640 pro with 300-MP and Ramshot True Blue. I have a pound of 296 I'm playing with too. Also, in these times, you gotta use what you can get. Ideally, I'd just use 296 with 125 grain xtp and cci 550s.

I pulled down a bunch that were loaded with 300-MP, resized, loaded em back up and put a heavy crimp on em. Loaded up 10 more the same way with cci 550's. Hoping to get out and try them tomorrow. Also have some loaded with 296. I did go back and put a heavier crimp on all the .357 loads I had worked up. Wish me luck. Just need to find myself a nice 586 4 or 6" now for some real fun. Still kicking myself in the *** for selling mine YEARS ago, it was my first handgun.

Anyway, I'll keey ya posted, thanks for your input, you guys are great. Serously a bunch of really decent guys on here, glad I joined the forum.
 
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