Load Development 7mm Rem Mag Berger 195 Extreme Outer Limits (EOL)

[jdmecomber]

I found an issue and am not sure how far back through the process it happened, but my loctite busted free on my muzzle break! I hope I didn't just waste a bunch of time. Russ was over and mentioned that my ugly tank break didn't look level. I did't bother to check until the next day. Yep it had broken free. Bummer

 

[jdmecomber]

The brake was placed back on and leveled. I got it tightened down and put a decent amount of loctite on. I only had some blue loctite. Maybe I will have to put some of the red loctite???

I went out and shot another 4 shot group at least it was consistent .60 moa.

 

[jdmecomber]

Cold Ammunition Testing:

I left the gun and four rounds of ammunition outside this morning from around 1:00 am till around 7:30 am. The temperature dropped to around 32 degrees.

Last night, I cleaned the brass and went over all the brass techniques one more time. I uniformed primer pockets, once over on flash holes, trimmed everything to length, chamfer and deburred. I took my time with the powder.

Four rounds fired at 33 degrees:

Round 1: 2897
Round 2: 2879
Round 3: 2885
Round 4: 2878

It looks like the best I can do is a 19 feet per second spread.

I know this is not all that scientific but i have yet to find a powder that didn't have a drop in velocity when the gun and ammunition were cold.

60 degrees vs 33 degrees:

The average speed at 60 degrees was 2923 and the average speed at 33 degrees was 2884. It looks like a 39 FPS difference.

I will try this with my .243 Winchester with H4831SC in the morning if it's around freezing.

 

[curtiscd]

Your results are nearly a direct replica of my findings with Retumbo and this bullet. Charge wts very a touch due to HBN coating of course. One thing I did realize with the 195's and 175's was that I was bumping my shoulders back by about .020". I bought a headspace gauge and am now in the process of fireforming all of my brass accordingly. If you are not doing this, I believe that may be where your ES is coming from. Once I get this process done I will check results one more time. I expect spreads will be drastically reduced.

 

[jdmecomber]

I am bumping mine by .002. I think my spreads come from a 130$ Gempro and a mostly factory new rifle around 900$. I think its mostly powder. Which we will be able to test soon.

 

[jdmecomber]

The mountains got a little snow but we didn't hit freezing, so I didn't shoot the .243 Win to check the powder temperature. Maybe tomorrow

 

[midnightmalloy]

The brake was placed back on and leveled. I got it tightened down and put a decent amount of loctite on. I only had some blue loctite. Maybe I will have to put some of the red loctite???

I went out and shot another 4 shot group at least it was consistent .60 moa.

I would definitely not suggest red loctite as you will never get it off. Another good option is to use a crush washer as that works well if the brake was not professionally fitted by a gunsmith.

 

[jdmecomber]

I would definitely not suggest red loctite as you will never get it off. Another good option is to use a crush washer as that works well if the brake was not professionally fitted by a gunsmith.

It was fitted by a gun smith with a crush washer and loctite. I was pretty surprised it came loose. Maybe the gunsmith should have tried to get another revolution when be was putting it on.

 

[midnightmalloy]

It was fitted by a gun smith with a crush washer and loctite. I was pretty surprised it came loose. Maybe the gunsmith should have tried to get another revolution when be was putting it on.

I would definitely call that gunsmith back and let him know what the issue is. They should fix that.

 

[jdmecomber]

One last thing I need to check is that 39 fps difference from 60 to 33 degrees. I switched jugs of powder and need to verify the speed at 60 degrees again

 

[jdmecomber]

I just finished my cold ammunition and gun testing with the RPR .243 Win shooting H4831SC. My average speed at 60 degrees is 2918 fps.

Cold Ammunition Testing:
32 degrees 4 shots which is a small sample group as I have lots of data on this gun.

1- 2901
2 -2906
3- 2892
4- 2889

17 Extreme Spread
21 Feet per second slower on average at 32 degrees

60 Degrees: 2918 avg
32 degrees: 2897 avg

 

[dibbs]

Shot # 3 must be 2882 (typo?) Interesting thread, thanks for posting your results.

 

[jdmecomber]

Shot # 3 must be 2882 (typo?) Interesting thread, thanks for posting your results.

Oops. Thanks 2892

 

[jdmecomber]

Oops. Thanks 2892

I tested four more rounds at 60 degrees and they produced the same average 2923 fps. I need to get this load out in the mountains and see what it does.

Maybe at the end of the week

I was looking at the ballistics for this round at my speeds. It still had 1000 pounds of energy at almost 1400 yards.