.375 350gr SRA HPBTM in RUM

Ray B

Sierra has listed the .375 350gr Matchking but I haven't seen any load data for it yet. The only 350gr load data that I've found is for the Barnes TSX FB, max load using 87gr Hybrid 100V, 105% density with OAL 3.55" for 2580fps from 24" bbl. I fit the SRA bullet to my rifle, a M70 Classic SuperGrade rebarreled by CP Donnelly. Just off the rifling the OAL is 3.93", which puts the front of the boattail even with the juncture of shoulder/neck, so only the boattail is encroaching into the powder space. Since the OAL is too long for the magazine, it will operationally be a single-shot. With this seating, I measured the water capacity at 100+- gr. According to my Powley computer (slide-rule) 100 gr H2O results in 86gr powder, which calcs to a P/B ratio .245 and powder IMR 4831, which coincidentally has a burn rate similar to Hybrid 100V. The rifle has a 28" barrel. so the expansion ratio is 8.1 and the anticipated MV is 2460fps. Shooting at 1000 yards, the BC over that distance would fall mostly into the 1700-2200fps category, .780 after being at .805 for the first hundred yards or so.

Comparing the Powley results to Barnes data they appear to be quite similar, the main difference being that the Barnes cartridges are loaded with an OAL enabling them to operate through the magazine.

I'm looking forward to getting a supply of these bullets so that I can road test the rifle/cartridge/bullet and will provide the results to the forum. If anyone is involved with a similar project or has information regarding the SRA bullet, I'd greatly appreciate reading about it.

Ray

JustC

nononsense,..where ya at[?] This one has your name all over it.[;)]

nononsense

JustC,

quote:nononsense,..where ya at[?]

Actually, I'm still at work trying my best to get some projects finished up. Nothing like working on Father's Day! It's quiet since everyone is celebrating with their families as they should be.

Ray B,

Here is a little something I wrote for another member last year for the same cartridge, different bullets though.

http://forums.gunbroker.com/topic.asp?TOPIC_ID=539630

I've read your post through a couple of times and it seems like you're on the proper path to get some testing done safely. My hands are tied right now as I don't have the time to gather all the testing we did a while back to give you absolute data but I'm not sure that would be a good idea anyway. Our testing will be quite a bit different from yours because we were using some experimental rifling geometry for some solids then switching to cup/core bullets for comparison later. We were using a fairly stout single shot action also...

From what I remember, the 4831 family of powders will work correctly at full or nearly so case capacity. Being a devotee of Hybrid 100V, I was pleased when I tested it also. Be sure to throw some Re-25 into the mix along with Ramshot Magnum and V V N165.

Even the Chey-Tac performs better with that bullet seated way out which was the original choice for the testing. We brought along a couple of extra barrels for additional information. We even had a couple of suppressors to try to reduce some of the recoil. Cans get real expensive when they're that big though.

Best.

Ray B

I got a message from Paul @ Sierra. They haven't worked up data for the 350 gr 375RUM yet, but he agreed that 86 gr of IMR4831 would be a good starting load, given the circumstances that I provided. Now if the bullets will just get here[^][^]