.358 Winchester and Magnum Pistol Powders 2400 and 300-MP

[KLR]

I'm new to the .358 Winchester and trying to work up some mild deer loads. It's been cold, snowy, and windy so my methodology is odd, but I would load one round, step out my basement door, shoot over the chronograph, and get back inside before I froze to death. Yes, I know I need an average of data from several shots, but I just wanted to get a general idea of what velocity I could get from the powder I have on hand. I also do not need full power loads because I intend to use this round on small deer and under 150 yards. Plus, it doesn't hurt that my pistol powder is $20 per lb vs $30 for rifle.

Details:

Winchester brass, Winchester standard Large rifle primer, NOE RCBS 200gr fngc clone with actual weight of 216gr, hornady gas check, tumble lubed in 45/45/10 lube, sized to .358.

I used the same piece of brass for the all of the testing. I fired 20 shots total. Brass length grew .004. Primer seats easily but is not loose. No cracks or signs of stress evident.

All loading was done in my basement where the temp was in the mid 50s. I don't see how outside temps would have any effect because I took the shot within 20 seconds of going outside and then returned as quickly.

Rifle is a Savage model 11 with a Shaw barrel cut to 20 inches. Bore slugged at .3565.

Chronograph is Competition Electronics ProChrono Pal model.

All charges were weighed.

I used load data from the Cast pics database for the 2400 and started below that for the 300-MP after

Day one:

IMR 3031, 30.2 gr = 1468 fps, slight flattening of primer
Alliant 2400 23 gr = 1718
Alliant 2400 24 gr = 1766
Alliant 2400 25 gr = 1867 Slight flattening of the primer. This was max load on the cast pics database.
Alliant 300-MP 22 gr = 1561
Alliant 300-MP 24 gr = 1760
Alliant 300-MP 25 gr = 1733 Don't understand how velocity could go down by adding one grain of powder?
Alliant 300-MP 26 gr = Too dark for chrono to read, but absolutely no pressure signs so I proceeded.

Day two:
Alliant 300-MP 26.5 gr = 1864
Alliant 300-MP 27 gr = 1863
Alliant 300-MP 27.5 gr = 1932
Alliant 300-MP 28 gr = 1799 What? How did it drop? I decided to shoot two more at 28 gr.
Alliant 300-MP 28 gr = 1836
Alliant 300-MP 28 gr = 1826
Alliant 300-MP 28.5 gr = 1902
Alliant 300-MP 29.0 gr = 1905
Alliant 300-MP 29.0 gr = 1926 slight flattening of primer
Alliant 300-MP 29.0 gr = 1910 very, very slight flattening of primer.

That's where I quit and decided to run this past those of you who are more experienced. The only pressure sign I've seen is the slight primer flattening. Extraction was always smooth and the brass doesn't show any signs of distress.

So what do you think? What accounts for those jumps in velocity? My three shot strings show good consistency. Is this safe? If so, I'll load up some ammo and test for accuracy once the weather breaks.

Thanks.

[Larry Gibson]

KLR

The velocity "going down" is simply from the ES over lapping with the different loads. That's a problem with 1 shot test strings; they really don't tell much except for the velocity of that one shot. Appears to me all are with in the ES spreads of the different loads. Nothing to be concerned about there.

I have not used 300-MP powder so I'm only speculating here. 300-MP appears to be fairly close to 2400 and your very minimal test somewhat indicates this also. Whether it burns efficiently as 2400 in this application we don't know. I suggest loading 10 shots each of 24 gr 2400 and 24 gr 300-MP and test them as 10 shot strings. That will give you a good ES and SD to proceed from. Right now it's just a cr*p shoot......need to have something solid to make any judgment on.

Larry Gibson

Stay warm BTW:-D

[KLR]

Thanks, Larry. I really appreciate your feedback. I'll load 10 of each at 24 gr and report back.

Today was our first day above freezing in a long time. Hopefully it will hold off long enough to shoot this weekend.

[Camba]

Have you tried the same loads with rifle primers?
Camba

[KLR]

Have you tried the same loads with rifle primers?
Camba

I was using rifle primers.

[Djones]

30.2 grains of 3031 is such a light load. Did you stop using that powder for a reason?

Any luck with the 2400?

[frnkeore]

300MP is about two steps slower burning than 2400 and one step slower than 296/H110. You can safely use start loads of 296 when selecting starting data in your application. In 357, 44 mag and 45 Colt, it produces more velocity with less pressure than 296/H110.

300MP needs magum primers, they do make a difference with this powder. It's being used in my disipline of shooting quite a bit now (Schuetzen), with excellent results, using mag primers.

Frank

[KLR]

Thanks for the tip on using a magnum primer with the 300 mp. I'll get some and see how they work. I didn't test any more 3031 because I'm out and can't find any around here.

It got above freezing recently and I did some more testing. I used surplus .308 brass I bought from a group buy here. Lube was two coats of 45/45/10 tumble lube. Here is what I did in order:

Cleaned bore.

10gr Bullseye with 158gr Lee TLSWC = 990 fps
24 gr 2400 with NOE RCBS clone 200gr = 1888
24 gr 300mp, NOE RCBS clone 200gr = 1720

All brass looked good so I proceeded. Shooting below was done several hours after the three test shots above.

24 gr 2400 with NOE RCBS clone 200gr
1 = No reading because chrono wasn't set exactly right.
2 = 1823
3 = 1828
4 = 1831
5 = 1836
6 = 1839
Avg = 1831

Little over 1/2" group at 50 yds

24 gr 300mp, NOE RCBS clone 200gr
1=no reading due to readjusting target
2=no reading didn't move the chrono quite enough
3=1672
4=1677
5=1660
group was erratic, bore was starting to lead so I brushed out the bore with a brush and let it sit for 30 minutes while my son shot his rifle
6=1731
7=1554
8=1546

I can understand the increase after brushing the bore, but what happened with the last two? I immediately proceeded with the next group:

24gr 300 mp with 250gr flat point, gas check
1=1692
2=1711
3=1693
4=1770
5=1705
Avg=1714

Group was about 1/2" wide and 3" tall. This included the last 3 bullets from the previous group using the 200 gr bullet.

Next step is to get rid of my leading problem. The barrel slugs at .3565 and I'm sizing my bullets to .358. I'm using Hornady gas checks. I mixed a batch of Ben's Red lube and will try that next. I think I'll also try upping the charge of 300mp and using a mag primer.

Thoughts?