Montana Gold CMJ accuracy issues?

[EmanP]

So I got a case of Montana Gold 124gr CMJ's since they were backordered on the HP's. I loaded up some with 3.8grs, 4.0, 4.2, and 4.4 grains of Titegroup. I can't seem to get any reasonable amount of accuracy in any of my pistols. A Barsto barrel can barely squeze out 5" and an M&P is something like 9"-14". OAL is at 1.120", Win primers and loading other bullets I haven't seen this issue before. Anyone see any accuracy degradation issues with CMJ's instead of open base bullets?

[DougCarden]

A couple of things come to mind.....

What distance are you shooting groups and what were the groups before with the jhps?

You might need to bump up the load some more to get the bullets to group better. You are not going to get the same groups with the CMJ that you do with the jhps, period. I have had one shot groups with jhps and then switch to fmj and the groups open up to 2-3inches.......it happens.

I would try bumping up the load until the group starts to become tighter and circular...that is probably the best you are doing to do.

Good luck,

DougC

[Sean Gaines]

are you sandbaging the gun, and is your target the same height as your shooting platform?

[lugnut]

Sorry about this... but do you folks really think that there is that much difference between a MG CMJ and FMJ? I've always used CMJ and not tried the JHPs.

EMan- what distances are you shooting at? Those numbers seem high for anything less than 25 yds and 9-14" seems really high even at 25yds. These aren't from the bench are they?

I shoot cheap plated bullets out of a regular Glock barrel and get groups < 3" without too much effort offhand.

Edited April 7, 2009 by lugnut

[mlmiller1]

What velocity range are these running in? What were the JHPs with these same loads? I bet it will take more powder to get the same speed. Not enough speed, no accuracy.

MLM

[Jman]

Eman,

First thing that jumps at me is your OAL. Seat some out to 1.150 or 1.155. That particular bullets ogive and Barsto's chamber may be a bit finicky with your cartridges OAL.

Jim

[RiggerJJ]

Load em longer...1.155 - 1.165 or so in a S_I.

I use MG 124 CMJ, and accuracy is fine. I can hit a 2inch circle at 15 yards off hand, plenty good enough... I don't understand the need for a HP bullet in action pistol games, 2 MOA, 1 MOA, or 1/2 MOA accuracy, who cares? reliability of feeding and consistency is more important...

jj

Edited April 7, 2009 by RiggerJJ

[P.E. Kelley]

Load em longer...1.155 - 1.165 or so in a S_I.

I use MG 124 CMJ, and accuracy is fine. I can hit a 2inch circle at 15 yards off hand, plenty good enough... I don't understand the need for a HP bullet in action pistol games, 2 MOA, 1 MOA, or 1/2 MOA accuracy, who cares? reliability of feeding and consistency is more important...

jj

DUDE!!!! Don't give away THE secret!

Patrick

[RiggerJJ]

oooops...

disregard everything I said, didn't mean it, JHPs are the only bullets to use...

jj

[edwin garcia]

Sorry about this... but do you folks really think that there is that much difference between a MG CMJ and FMJ?

No. It's personal preference.

[larry cazes]

Load em longer...1.155 - 1.165 or so in a S_I.

I use MG 124 CMJ, and accuracy is fine. I can hit a 2inch circle at 15 yards off hand, plenty good enough... I don't understand the need for a HP bullet in action pistol games, 2 MOA, 1 MOA, or 1/2 MOA accuracy, who cares? reliability of feeding and consistency is more important...

jj

This is my experience as well. I find the accuracy difference in my supers between the MG CMJ and JHPs to be neglible. Over four years of loading them for many different guns I find that feeding with the MG JHPs is 100% so I have stuck with them over the CMJs.

[Sean Gaines]

Sorry about this... but do you folks really think that there is that much difference between a MG CMJ and FMJ?

No. It's personal preference.

+1

[gino_aki]

Slight thread drift but I've had the strange experience of MG .40 cal 155 FMJ's shooting to a different point of impact than the same load with Hornady XTP's or Precision Moly's. Same group size but usually about 4" right and 5" high.

[Carlos]

Please check this:

-measure the diameter of the CMJs. Do not use a regular caliper. Instead, borrow a machinist's micrometer. While Montanas are GREAT bullets, they sometimes are sized too small for certain barrels; and if so, you might consider the .356 dia., waiting for the JHPs, or just try another brand.

[EmanP]

It is benched, tried by 4 different people, at 25 yards. The M&P was just down right aweful and unfortunetly I left it with a friend somewhere else so I can't try that one again for a while. The OAL is at 1.120 as meantioned. I was going to load some 3.9's just to chrono with the 3.8's so I'll try to load a few more in each weight again with a longer OAL. I thought I would get feeding issues if I loaded them that long.

I haven't chronoed the CMJ but when we did the Montana Gold HP's 2 weeks ago this is what we got. I don't know about accuracy since we were just chronoing.

For the 4.0's velocity in the M&P is averaging 1066fps (132.2PF). 4.1 - 1082fps (134.2PF), 4.2 - 1101 (136.5), 4.3 - 1125 (139.5), 4.4 - 1134 (140.6). Interestingly enough we found that a G19, an HKP30 & the M&P all matched pretty damn closely.

The Barsto is out of a Sig 226 and was 1081fps (134.0PF) at 4.0gr of Titegroup. 4.1 - 1113 (138.0), 4.2 - 1121 (139.0), 4.3 - 1148 (142.4), 4.4 - 1174 (145.6). For comparisons sake 124gr Gold Dot HP +P is 1211 (150.2)

[Aristotle]

Hey E,

I shoot MG .355 124cmj's, but in a Govt 1911. I load to 1.145 oal with 4.4 of Titegroup. I don't try to shoot for groups to often, but when I was developing that load I recall getting 3" 5 shot groups free hand at 10 yards or so. I'm sure it would be better benched or with a better shooter.

Load up 20 rounds and try hand cycling them in your gun. I don't know if it's a 1911 thing, but my bullets feed best when loaded to as long as I can get away with that will cycle reliably.

[EmanP]

Hey E,

I shoot MG .355 124cmj's, but in a Govt 1911. I load to 1.145 oal with 4.4 of Titegroup. I don't try to shoot for groups to often, but when I was developing that load I recall getting 3" 5 shot groups free hand at 10 yards or so. I'm sure it would be better benched or with a better shooter.

Load up 20 rounds and try hand cycling them in your gun. I don't know if it's a 1911 thing, but my bullets feed best when loaded to as long as I can get away with that will cycle reliably.

Thanks Ari, I'll give that a try.

[Strick]

I load the MG 124 CMJ on top of 4.0 grns of TG and get ver good results out of a Witness, XDm, and G34. I load them at about 1.15.

Edited April 10, 2009 by Strick

[EmanP]

Well I did some testing yesterday and it seems it's just my load for whatever reason. Aweful groups even loaded out to 1.15 OAL. Largest group for the 1.12 load was an 11.5" 10 shot group and best was 5.25" 5 shot group. The 1.15 OAL worst group was 14.5" 10 shot group and the best was 5.25" 5 shot group. The 124gr Golddots turned in a 2 3/8" 5 shot group. I even tried my load in another M&PL and that resulted in a 9.5" 5 shot group. I tried a buddys 115gr MG CMJ in my pistol and it turned in 3.5" for 5 shots. The lighter grained rounds (3.8 & 4.0 gr of Titegroup) seemd to move the rounds to the right where the heavier grained loads (4.2 & 4.4) centered them. I just don't know what to think.

[lugnut]

I just don't know what to think.

Me either. I just bought another 6000 MG CMJs though.

[Carlos]

What diameter did your MGs turn out to be? What about the Gold Dots you tried?

Well I did some testing yesterday and it seems it's just my load for whatever reason. Aweful groups even loaded out to 1.15 OAL. Largest group for the 1.12 load was an 11.5" 10 shot group and best was 5.25" 5 shot group. The 1.15 OAL worst group was 14.5" 10 shot group and the best was 5.25" 5 shot group. The 124gr Golddots turned in a 2 3/8" 5 shot group. I even tried my load in another M&PL and that resulted in a 9.5" 5 shot group. I tried a buddys 115gr MG CMJ in my pistol and it turned in 3.5" for 5 shots. The lighter grained rounds (3.8 & 4.0 gr of Titegroup) seemd to move the rounds to the right where the heavier grained loads (4.2 & 4.4) centered them. I just don't know what to think.

[EmanP]

What diameter did your MGs turn out to be? What about the Gold Dots you tried?

The MG's are the stated .355. The Golddot's measure a .354 right in front of the crimp on a loaded bullet. I don't want to pull one apart to see how accurate that measurement is but it seems to be right there.

[mpeltier]

I had a similar experiance when I changed presses in the middle of a case of MG 124CMJ. Turned out I had a slight bit to much crimp. When I backed off the die a whisker my groups whent back to bieng nice and tight.

[EmanP]

I had a similar experiance when I changed presses in the middle of a case of MG 124CMJ. Turned out I had a slight bit to much crimp. When I backed off the die a whisker my groups whent back to bieng nice and tight.

Thanks for the suggestion mpeltier. I've pulled some rounds thinking that might be the case and can hardly detect where the crimp line is. If I had an indentation on the bullet I might have thought it to be more of the issue but as it is I can barely discern where the crimp line is at on the bullet. Can't really feel it with the finger nail either.

[lugnut]

I had a similar experiance when I changed presses in the middle of a case of MG 124CMJ. Turned out I had a slight bit to much crimp. When I backed off the die a whisker my groups whent back to bieng nice and tight.

Thanks for the suggestion mpeltier. I've pulled some rounds thinking that might be the case and can hardly detect where the crimp line is. If I had an indentation on the bullet I might have thought it to be more of the issue but as it is I can barely discern where the crimp line is at on the bullet. Can't really feel it with the finger nail either.

Hmmm sounds like you certainly aren't crimping too much. My bullets rarely have any marks on them when they've been pulled.

Have you tried those loads in a Glock or different brand of gun?