Montana Gold FMJ vs. CMJ, difference?

[midvalleyshooter]

I am planning to order some Montana Gold 124 grain 9mm bullets. Do any of you BE forum members use the FMJ or CMJ bullets? If so whats the difference and which do you prefer and why?

Thanks in advance,

Keith

[MstngLX50]

I am planning to order some Montana Gold 124 grain 9mm bullets. Do any of you BE forum members use the FMJ or CMJ bullets? If so whats the difference and which do you prefer and why?

Thanks in advance,

Keith

I use the CMJ (Complete Metal Jacket) because as the name implies it's completely jacketed. The FMJ has exposed lead on the bottom.

[Maksim]

+1

I use either JHP or cmj. jhp in 124 9mm, cmj in 230 gr 45 acp. no exposed lead here.

Shoot quite well.

[ktm300]

Another vote for 124 CMJ's Just got another case yesterday. The cost is very close and no exposed lead is nice.

[HS101]

I use the CMJ's for the exact same reasons listed above. Less potential exposure to lead, price is virtually the same....

I use the MG CMJs in both 9 and 40.

[gng4life]

Same here, usually CMJ or JHP only. Here are few posts about the same thing:

http://www.brianenos.com/forums/index.php?showtopic=121361&st=0&p=1372167&hl=+cmj%20+vs%20+fmj%20+mg&fromsearch=1entry1372167

http://www.brianenos.com/forums/index.php?showtopic=118666&st=0&p=1343221&hl=+cmj%20+vs%20+fmj%20+mg&fromsearch=1entry1343221

http://www.brianenos.com/forums/index.php?showtopic=114046&st=0&p=1302461&hl=+cmj%20+vs%20+fmj%20+mg&fromsearch=1entry1302461

[Tul9033]

MG JHP's will have a more cocentric/consistent base. Take a close look at the CMJ's and you might notice the small gaps in the copper disc. JHP for me

[noylj]

I have always wondered about those that claim that they get leading in their compensators using FMJ bullets.

I shoot lead bullets in my compensated guns and have no lead issues.

Re: the exposed lead on a FMJ.

The time of exposure is so short and the heat capacity of lead is so high, that there simply isn't time for the lead on the bullet base to "melt." Many FMJ bullets have been examined after firing and the base is not affected by the flame front.

There is, however, melted lead if the bullet doesn't seal the bore and the hot gases blast past the bullet.

I prefer JHPs as they have always seemed to hold the edge in accuracy.

The question is, have any of those using the CMJs found that the FMJs actually did lead?

For me, it is FMJ from Precision Delta or JHP from Montana Gold or Zero.

[kbrview]

115s and 124s CMJ here also.

[MstngLX50]

The question is, have any of those using the CMJs found that the FMJs actually did lead?

I didn't see leading in the barrel with the FMJs, just more smoke. Especially when I was using Tite Group.

I use the CMJ and JHP/IFP without preference really. I use the different profiles to differentiate loads at a glance. For me CMJ is Production Minor, IFP is Open Major, and JHP is Open Minor.

I loaded up some production JHP's a while back when Montana Gold was temporarily out of CMJ and it seemed that the JHP is a little more accurate for me, but not enough to consider dumping the CMJ. Like an inch or two at 25 better. That said, I'm not really into bullseye load development. Once it runs and provides acceptable accuracy I'm done. It could be the JHP accidentally hit a OAL-Velocity-Astrological sweet spot.

[gng4life]

The question is, have any of those using the CMJs found that the FMJs actually did lead?

I didn't see leading in the barrel with the FMJs, just more smoke. Especially when I was using Tite Group.

I use the CMJ and JHP/IFP without preference really. I use the different profiles to differentiate loads at a glance. For me CMJ is Production Minor, IFP is Open Major, and JHP is Open Minor.

I loaded up some production JHP's a while back when Montana Gold was temporarily out of CMJ and it seemed that the JHP is a little more accurate for me, but not enough to consider dumping the CMJ. Like an inch or two at 25 better. That said, I'm not really into bullseye load development. Once it runs and provides acceptable accuracy I'm done. It could be the JHP accidentally hit a OAL-Velocity-Astrological sweet spot.

I'm with you here. I don't see lead but definitely can see the smoke and it bothers me. I usually use the CMJ for most loads since I have a few pistols that are sensitive to JHP. I just the JHP for my 9Major. I agree about the accuracy statement too but my tests show even less than that, maybe 1/2 inch at 25 so reliability in my other guns is more important that the accuracy tradeoff.

[shred]

Put enough rounds through an open gun with FMJs and you'll get more comp leading than JHP or CMJ. That extra smoke has vaporized lead in it that deposits out. Run your scope close to the front of the gun (like, say the one in my current avatar) and you can see the difference on the lens in fifty rounds. The difference in barrel leading isn't worth worrying about.

[Rambo]

As some of the above posters mentioned...I also use the CMJ with zero exposed lead to theoretically minimize leading in the comp of my open gun. Therefore I also use them in my 9mm minor loads so that I don't have to buy two different bullets.