Help wanted: 7MM WSM
I am a newbie to LRH and reloading. I received my custom 7MM WSM in September. It has a Krieger #5 barrel finished to 22Ē on a 700 frame. Initially, I was shooting Winchester Extreme 160 gn. XP-3 ammo. The XP-3 ammo was off the lands about .200. Although the box indicated a muzzle velocity of 3050 I was getting 3100 but not the accuracy I was looking for. I have finally accumulated reloading equipment and have tested several loads. Iím starting with 162 gn Hornaday A-Max bullets, New Winchester brass neck turned and trimmed, Primer pockets cleaned and deburred based on information from this site and others. Using WLR primers and setting the OAL (2.985) for .003 off the lands. I thought I would start with this length and after arriving at the best powder configuration start working to shorten the OAL and see the effect. The outside neck diameter is .311 before loading and is .3125 with the bullet seated. After firing the neck diameter is .3175. These load components were based on R. Horstís hunting load recommendations from the 6mmbr web site. With the 162 gn A-Max and 64.0 gn. Of H4831sc and WLR primers and a 1 in 9 barrel he was getting a muzzle velocity of 2950. I have no idea what his barrel length was. With 62 gn. I am getting a MV of 2650, 62.5 MV 2700, 63.0 MV 2740, 63.5 MV 2795 and 64 MV is similar to 63.5. Iím at a loss for why my rifle had higher velocities with the factory ammo and less than expected from the reloads. I had intended to find the combination for a MV of 2950. Where do I go from here?
Group sizes were slightly better and I was shooting under less than ideal conditions. My primary interest was MV and anything that stood out. After reading different post on load development, I am wondering if part of the problem is with 64 gn. of 4831 and the OAL set at 2.985", the case has to much air space.
Should I will try 64 gn. with an OAL of 2.850? Is the 4831 to slow for the 22" barrel? Also I was shooting at 100 yds and have since read that the long boattails don't stabilize untill about 300 yds. so I should be doing load development at that range? I have ordered QuickLoad software to help. This site has an enormous amount of information and will take time to search the different forum post for valuable information. Thanks to anyone that is willing to mentor/help a newbie.
Factory ammo generally has specially formulated "secret" powder recipes that are not available to the rest of us (patent pending, ... intellectual property etc). This gives them the additional velocity etc. Duplicating these results can take a lot of trial and error and many different powder/primer/brass combos etc, but the end result should fit "your" rifle better than any factory ammo. This is why we choose to "handload", and not reload (yes there is a difference).
I am a huge fan of H1000 in 7mm WSM w/ Fed magnum 215 match primers in this caliber. Dont get too hung up on MV. Focus on accuracy, repeatability, environment, scope alignment etc instead. Find your load with good ES/SD. Calculate ES/SD for the factory ammo. You might be surprised to find out that it can be pretty bad. Suddenly that "impressive" MV on factory ammo doesn't seem so important because it doesn't fit your rifle
I agree with the previous guys above. Sounds like you want a powder that will drive higher velocity. Try H1000 or Retumbo. Or, try Magpro. Just watch out for pressure spikes in hot weather - remember you're doing all your testing in winter temps. Don't toss out your H4831sc, you may end up going back to it in the end...
Don't worry about 300 yards during development, the Amax is not that severely shaped like a berger VLD.
I will tell you the berger 168 VLD in 7wsm kills like lightening, truly impressive results, even at longer ranges. My 542 yard antelope proved it for me last month.
I've not used the 162 Amax but my hunting partner has the 140 Amax in his 6.5-06imp and it was phenomenal on antelope and deer. Mostly no exit, quick drops and not a bunch of bloodshot meat. The extra energy of the 7wsm will probably change some of that...
We run RL22 and fed215m primers with the 162 A-max in my buddies 7wsm for a little over 3100fps and sub moa @ 1000yds. You should have no trouble reaching 3000fps+ with the H4831sc or other slow burners like H1000. Keep increasing the powder charge until you find the max in your rifle. WSM brass is pretty durable, most of my working loads in the 270, 7mm, and 300wsm flatten the primer somewhat and exhibit a little cratering around the primer strike.
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