Montana Gold CMJ accuracy issues?

[EmanP]

So today I tried that same load with 4.4gr of TG at 1.15 OAL out of another guys M&P. Same results. I tried his factory PMC rounds, not good but about 4.5" or so. Golddot's gave me a 3" group out of that M&P. Two witnesses.

Before that I sat down and did some extensive accuracy testing using my range bag to bench at 25yds. Gun was my Sig 226 that I've been using for comp and carry for the last few years with a new Barsto barrel that after today has 1074rds and 29,683 on the Sig. I shot groups in this order - 3.8gr, 4.0gr, 4.2gr, 4.4gr. I shot all the 1.12 OAL in a specific weight and then the 1.15 OAL in that weight to compare. I didn't see any change in group size from one OAL to the other. I did see some pretty bad groups, averaged 4" - 5.5". There was some potential but there were also a bunch of fliers that shouldn't have been there and just some loose groups. To compare I shot a group with my carry load, 124gr GD HP, a very good 1.5" with that.

Frankly, I don't know what to think. I just need to get another weight or style of bullet and see what happens.

[PLINK]

I am not sure if any of this can help you but I had a similar accuracy issue with MG 124 grain CMJ's and Win 231.

I was using 4.2 grains of 231 with a 1.160 OAL in a Glock 34 with a KKM barrel. I fired 10 shots over the CED chrono. The PF was at 123 PF low and 130 high with a 126 PF average (1018 fps average).

The gun felt great but the groups were not so good. To verify it was not me or the gun, I did try some Atlanta Arms 147 minor ammo a friend had and the Glock shot as it should. Had two different people try it with both types of ammo and the results were the same.

I went back home and pulled the barrel from the slide. Placed the loaded round and the chamber and noticed that the round would not spin freely in the chamber by hand. In my case the round must have been hitting the rifling or something. So I changed the OAL to 1.150 and bumped the charge .3 grains. I have read on BE that Win 231 likes a little more pressure to be accurate so I bumped the charge plus I was barely making minor. Repeated the test above an all is good. *I still need to officially chrono this load.*

Something I also noticed is the nose on the CMJ's are not all shaped the same. Some are a little pointier that others. So my actual OAL varies from 1.145 to 1.155 when measuring with calipers.

I am using a Dillon 550B with all Dillon dies. Crimp set to approx. .377 to .378.

Again I am not sure if any of this helps but maybe there is something in there for you to check or try. Please use load data at own risk. Keep us updated on your progress.

Edited April 21, 2009 by PLINK

[lugnut]

I am not sure if any of this can help you but I had a similar accuracy issue with MG 124 grain CMJ's and Win 231.

I was using 4.2 grains of 231 with a 1.160 OAL in a Glock 34 with a KKM barrel. I fired 10 shots over the CED chrono. The PF was at 123 PF low and 130 high with a 126 PF average (1018 fps average).

The gun felt great but the groups were not so good. To verify it was not me or the gun, I did try some Atlanta Arms 147 minor ammo a friend had and the Glock shot as it should. Had two different people try it with both types of ammo and the results were the same.

I went back home and pulled the barrel from the slide. Placed the loaded round and the chamber and noticed that the round would not spin freely in the chamber by hand. In my case the round must have been hitting the rifling or something. So I changed the OAL to 1.150 and bumped the charge .3 grains. I have read on BE that Win 231 likes a little more pressure to be accurate so I bumped the charge plus I was barely making minor. Repeated the test above an all is good. *I still need to officially chrono this load.*

Something I also noticed is the nose on the CMJ's are not all shaped the same. Some are a little pointier that others. So my actual OAL varies from 1.145 to 1.155 when measuring with calipers.

I am using a Dillon 550B with all Dillon dies. Crimp set to approx. .377 to .378.

Again I am not sure if any of this helps but maybe there is something in there for you to check or try. Please use load data at own risk. Keep us updated on your progress.

That is a great post Plink. FWIW I have some 124 CMJ loads that have a COL of 1.130" and 4.5gr W231 and I believe they grouped just fine out of my G34/stock barrel. Powerfactor was 135+ if I recall. Maybe I should double check my groups just to make sure!

[Jachin]

Greetings,

This is my story from another thread.

The advice I received centered around the crimp. I have since adjusted the crimp to 1.376 to 1.3765 which is the size the case comes out of the sizer. My original crimp was very tight, it left a dempled ring around the bullet. I also adjusted the OAL to 1.145.

Well tonight I went back to the outdoor range and at 100 yards nothing has changed.

During the week I went to a 20 yd. range and off a bench rest there was a difference but nothing like at 100 yards.

Everybody's telling me to bench rest at 10 and 20 yards, but 2 to 14 FEET is a killer difference. It's a lot better at close range but something is really strange here!!!

I just bought 2500 rounds of 180 in 40 cal. Same CMJ. And just loaded 3700 of these 124's. Guess I'll be doing a lot of practicing at 5 yards.

I hope ya'll pick this thread back up and maybe we can get to a cure.

Best Regards,

IT'S A PROUD DAY FOR THE NEW RELOADER

Well, I'm new to reloading. Also new to USPSA and my shooting habit brought me to purchase a Dillon 650 for reloading. I started out with 9mm, 124 CMJ Montana Gold, 4.5gr Winchester 231 powder and winchester primers in cleaned up one time shot brass. The OAL is 1.150 which I obtained from the Blazer Brass length of a 115 gr. round. At an indoor 10 yd range I shot the factory Blazer 115gr aside my 124 MG relaods to judge the recoil, accuracy and whatever. The recoil may have been a little different but no problem to control and no difference in grouping. Side by side, 70 rounds each, no difference in groups. Looking good and very proud of myself.

HERE COME THE BLUES

I go to a match last night to shoot my stuff and prematch I decide to shoot my goodies at a burm behind the 100 yd targets. It was dry and you could easily see the bullet impact on the burm. Looked like fun to me. Pick out a peice of paper about mid high on the burm and started shooting. First shot-6 ft. high, second shot-6 to 7 ft. high 10 o'clock, third-5 ft. 4 o'clock, forth-4 to 5 ft. 9 o'clock, 5th through 24th shots were all in about a fourteen foot group.

Ain't no way baby!!!

Pulled out a box of factory Blazer 115gr, loaded up and produced a two foot group with twelve rounds. How in the world can two bullets passing through a single four inch barrel go from a two to a fourteen foot group differential???

Question is: WT*?

Over.