I'm working some loads for my 7mm WSM built with a 26 1/2 barrel on a Montana Action. The bullet I've chosen is the Berger 140 gr. VLD and I've had some good success with IMR 4831. Right now my load gives me 3400 fps. with accuracy around .5 min at 200 yards but I'm plagued by the occasional flyer. All my brass have the necks turned and are weighed. Primers used are the Federal 215M. I'm looking to develop a load using Mag Pro or maybe H4831SC. My load with IMR 4831 is 66.5 gr. What I'm hoping to do is save a few bullets and powder in my search for a better load since both can be hard to come by at times. If anyone has experience with those two powders I would appreciate some input.
I'll give you a dollar for all of your 215M primers 3400 fps? Man... those are humming... no signs of pressure problems? I don't have any specific advice but I can say that I've had good luck in my 7mm Rem Mag (not SM) with 4831SC and RE15 (about to test H1000). The best groups (by a visible margin at 300 yards) were with RE-15. I've also had real good luck with ladder testing a range of velocities rather than load the fastest I can get. I'm not saying fastest is bad, just that sometimes it's not the most accurate. I ladder tested some rounds for a .308 recently and the max velocity (by the book) was the second best group. The best group was 100 fps slower than the max charge / velocity recommended in the Sierra manual. Actually... about 150 fps slower judging drop against the results from LoadBase (that's the last time I test rounds without a chronograph, too many questions come from not knowing the velocity of the round I'm testing)
Thank you Mike for the tips. I've tried other primers to include Remington, CCI and Winchester but those loads have consistently been twice the size of the groups shot with the Feds. I attribute the velocity to the 26 1/2 inch barrel. The same loads chronographed out of a 24 in. tube give me in the high 3200s. Of course, I'm at 6000 ft. too. I work all my loads from the bottom up but this rifle seems to like them hot. I'm just on the verge of a sticky bolt but don't see any expansion of the primer pockets. In my 7mm Mag with the 168 gr. Berger VLD, I had good luck with 4350 but the pressures got too high just about the time it was starting to shoot good. I've tried 3 or 4 powders including H1000 and the best I've found for that rifle is Retumbo which gives me good accuracy (1 in. at 200) at 3040 fps. It is the only accurate load I've found that will break the 3000 fps. barrier. Best part is, no signs of pressure and it shoots GREAT! This rifle has a 24 in. barrel. It is an old '98 Mauser that I have speed locked, squared the bolt, lapped the lugs and put a Timney trigger adjusted to 1 lb.gun)
I also have a Montana action with a 24 barrel. I shoot 140 gr. ttsx and 160 ab. both with mag pro 3436fps.with 140gr. 3223 with 160gr. both .5 moa or better at 200 yards.
Thanks again for the input. I think I learned something today and if anyone has any knowledge or experience with what I'm talking about, please let me know. I loaded 4 different charges of Magpro and the Berger 140 VLD. I started at 72 gr. and ended up at 73.5. I chronographed all loads and here are the results: Temp: 22, Elev: 6300:, adjusted barometric pressure: 23.9, humidity: 15%. All loads chronographed between 3288 and 3309 and accuracy was about the same with everything. They all shot 1.5 in. or better at 200 yds. My conclusions are: 1. This powder is sensitive to temperature and has a max. burn rate regardless of the charge when it's cold. I'll bet I don't get the same results when it's 80 and I don't see this with extruded powder. 2. I have reached the max that the barrel can burn and here again, regardless of the charge, everything that doesn't burn is simply thrown out on the snow. Now, I'm not a scientist and don't have any technical training but these are the only two scenarios that I can come up with that would explain the consistency of the velocities regardless of the amount of powder used. I laddered up a load with H4831SC and saw an increase in velocity with each increase in charge.... the same with IMR4831. Even though the charge weight was different, the best accuracy was attained between 3380 fps. and 3410 fps. At those velocities in the 26 1/2 in. barrel both produced groups of .75 or less at 200 yards. That, by the way, is probably as good as I can shoot at that range under those conditions. If any of you with some technical knowledge can add some light to what I have described it would be appreciated. Even though I've been doing this quite a while, I'm still learning..... especially when it comes to long range dynamics and I'm open to comment or suggestion. Hey everyone..... MERRY CHRISTMAS!!!!!!!!!!!!gun)
I have loaded for for 7mmwsm with 24" Hart barrel best accuracy was 66+gr 4831sc with Fed GM Magnum primers neck turned winchester cases, 140gr Nosler BT,3175fps very very accurate .2" at 100y. I wanted more speed for hunting as this gun only weighs 6.5lbs + scope etc. Loaded 75gr Magpro speed was 3290 to 3310fps. but had to give up accuracy .550" at 100y shot a buck at 420y with this load it was a instant kill. Friend noticed quite a muzzel flash with this load one evening late shooting at a wolf. Its quite noticble off bench in daylight. I have being using RL 17 in a 3006 and .280 rem for me that would be the ultimate powder for 7mwsm manitou
BradinCO, "Even though the charge weight was different, the best accuracy was attained between 3380 fps. and 3410 fps." I believe you have the essence of what you need to know right there. When loading for a new bullet I look at factory data. Most of the time there are loads that are listed as most accurate. I note the velocities of the accurate loads and base my test loads around those velocties. I normally try to get a load that is 95% capacity to slightly compressed as these seem to give a lower es. At your altitude temp stable powders would be a plus.
I have used IMR 4831, 4831sc and and Ramshot Magnum powders. These powders r very close in accuracy. My choice is 68gr. of Ramshot. I like the way the powder flows thru my 1500 loader. My second is 4831sc. Same powder charge. I can not find any Berger 140VLD's to save my life. So I use Nosler accu-bond 140's. The burn characteristics of the 3 powders is very close. I use the 215 primer, winchester cases. Start at 66gr and work up to 68gr. 1/2 gr increments. My 7mm WSM has a 29in. barrel. Reminton 721 action, sako extractor. I found the max. load by accuracy. When the rifle shot .5in 3 shot groups at 100, I quit adding powder. My rifle the bolt was not sticky. Depending on the make of rifle and the concentration of the shooter. accuracy can b obtained. LB Schertz TX.
Try the new LRX .284 140gr. from Barnes. Excellent bullet. I shoot these in my 7wsm,66.5grs 4831sc, 215m primers Winchester brass. These loads shoot bug holes at 100yrds. VLD bullets in 284 r very hard to come upon. I was tired of waiting on the VLD's and order a box of the MRX 140gr. barnes. very very satisfied. I am going to try these bullets in my 7rum. I ordered 2 more boxes before the news gets out. Does anybody shoot a 6.5 Rem. mag. I shoot Lapua bullets in this zinger. Lapua OTM Senar 108gr. bullets, 60grs Ramshot mag. 215M primers and Remington brass. .400 bug holes. The 6.5mag. is custom made. 5.5 contour Douglas barrel, 28.5in. long, varmit stock 5x20x44 Nikon.Very little recoil.The Lapua bullets r a work of art. The Berger VLD does not have anything over these Lapua bullets.gun) Thank u.
