CMJ vs FMJ [Archive] - Glock Talk

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CaptainXL
11-01-2012, 14:21
I have someone that wants to sell some MG CMJ 124 Gr 9mm pretty cheap.

I have never loaded any CMJ but assume that I can use my favorite 124 Gr FMJ load safely. Am I correct in assuming that I would reload just the same as if they were FMJ?

What is the difference between CMJ and FMJ? I think that I read somewhere a while back that the base is different. Is the base fully encapsulated?

What, if any, are the advantages of CMJ compared to FMJ?

Boxerglocker
11-01-2012, 14:45
CMJ just as you stated fully encapsulated, FMJ has an exposed lead base.

Advantage of CMJ loads is less smoke and chance of lead exposure.

SARDG
11-01-2012, 15:54
Right now I am using MG bullets exclusively; among them 147 CMJ and 230 CMJ. I have had great performance as for as accuracy, and (with my VV powder), no smoke. I've popped a few of the 230s out of the sandy berm and I think I can buff them out and re-use them. (Just kidding... but except for some minor serrations, they look pretty good.)

Colorado4Wheel
11-01-2012, 16:23
CMJ don't lead the compensator like FMJ can.

shotgunred
11-01-2012, 17:49
The indoor range I go to in the winter requires CMJ's.

CaptainXL
11-02-2012, 06:51
No one has answered my question regarding reloading CMJ.

Are they loaded the same as FMJ?

Should/can I use my favorite FMJ loading in CMJ?

I assume so but want to make sure.

F106 Fan
11-02-2012, 07:15
No one has answered my question regarding reloading CMJ.

Are they loaded the same as FMJ?

Should/can I use my favorite FMJ loading in CMJ?

I assume so but want to make sure.

Like everything else in reloading, the answer is probably 'maybe'.

I don't load anywhere near max so I would just use the same recipe. If I were truly concerned, I would back the load off a couple of tenths of a grain and work back up.

I have used some CMJ in 9mm and I don't recall doing anything special.

Richard

Hoser
11-02-2012, 07:27
No one has answered my question regarding reloading CMJ.

Are they loaded the same as FMJ?

Should/can I use my favorite FMJ loading in CMJ?

I assume so but want to make sure.

Same same.

You are good to go.

I load 230 and 115 CMJs with the same powder charge as normal. No difference.

CaptainXL
11-02-2012, 07:36
Like everything else in reloading, the answer is probably 'maybe'.

I don't load anywhere near max so I would just use the same recipe. If I were truly concerned, I would back the load off a couple of tenths of a grain and work back up.

I have used some CMJ in 9mm and I don't recall doing anything special.

Richard


I don't load near max either and therefore will use my normal favorite load and watch for any abnormal signs.

Thanks for the input.

Colorado4Wheel
11-02-2012, 08:54
Like Hoser, we have tested the difference between CMJ and FMJ in 9mm. They work the same.