islandracing Posted September 5, 2009 Share Posted September 5, 2009 MONTANA GOLD OFFERS A FULL METAL JACKET (FMJ) AND A COMPLETE METAL JACKET (CMJ). ANYONE KNOW THE DIFFERENCE AND WHICH IS BETTER REGARDING THE ADVANTAGES OR DISADVANTAGES. I CURRENTLY USE MOLY BULLETS 180 BLACK BULLETS AND 185 PRECISION. THINKING ABOUT TRYING SOME JACKETED BULLETS. ANY ADVANTAGE TO THE JACETED HOLLOW POINT IN 180? Link to comment Share on other sites More sharing options...
yoshidaex Posted September 5, 2009 Share Posted September 5, 2009 CMJ will result in less smoke due to the non exposed base. You'll get some smoke with the FMJ due to the exposed base but less than your moly or lead variety. As for the jacketed bullets, some suggest better accuracy due to the slightly longer engagement surface (comparing bullet of the same weight but differing jacket construction). Link to comment Share on other sites More sharing options...
G-ManBart Posted September 5, 2009 Share Posted September 5, 2009 MONTANA GOLD OFFERS A FULL METAL JACKET (FMJ) AND A COMPLETE METAL JACKET (CMJ). ANYONE KNOW THE DIFFERENCE AND WHICH IS BETTER REGARDING THE ADVANTAGES OR DISADVANTAGES. I CURRENTLY USE MOLY BULLETS 180 BLACK BULLETS AND 185 PRECISION. THINKING ABOUT TRYING SOME JACKETED BULLETS. ANY ADVANTAGE TO THE JACETED HOLLOW POINT IN 180? The CMJ is really only "better" in that it won't give off the bit of smoke you get from FMJs (slight) and you get a bit less lead exposure. The vast majority of lead exposure comes from the primer, so the bullet isn't as big a factor from a health risk standpoint. For pure accuracy JHP's are better. Because of the way bullets are manufactured it's easier to make them consistently round and true with a hollow point design than an FMJ or CMJ/TMJ. It's not a huge difference in pistol accuracy, and not a big deal for what we do, but it is an advantage just the same. Since JHP's also have no lead exposed on the base you won't get the puff of lead smoke you will get with FMJ's, just like using a CMJ. P.S. typing in all caps is considered yelling Link to comment Share on other sites More sharing options...
Sarge Posted September 5, 2009 Share Posted September 5, 2009 (edited) YEAH! Edited September 5, 2009 by sandman Link to comment Share on other sites More sharing options...
islandracing Posted September 5, 2009 Author Share Posted September 5, 2009 Sorry on the caps and thanks for the tip. Just curious but why would you see less smoke with the full metal jacket over a moly bullet. Isn't the smoke caused by the interaction of the burning powder with the exposed lead? I am currently using 231 which smokes quite a bit. I used to shoot cast bullets and saw a reduction of smoke when I switched to moly. Link to comment Share on other sites More sharing options...
yoshidaex Posted September 5, 2009 Share Posted September 5, 2009 Good point. I'm thinking less smoke for FMJ compared to moly due to less exposed base but the moly does have that thin barrier. I'd have to do a test to confirm. Link to comment Share on other sites More sharing options...
barney88pdc Posted September 5, 2009 Share Posted September 5, 2009 I shoot the JHP out of an STI 5" and get great accuracy. I have never tired the FMJ/CMJ because I started with the JHP and see no reason to switch. IMO for a few dollars more $11/$6 respectively per 2500 I would just go with the JHP. I do not think you will be disappointed. Link to comment Share on other sites More sharing options...
Graham Smith Posted September 5, 2009 Share Posted September 5, 2009 (edited) I prefer the JHP because of the construction of the base, but I'm a bit skittish about hollow points because I shoot some in New Jersey and their laws could be a real pain in the ass to deal with if I were in an accident on the way too/from the range. It's just not worth the added bother it would create. I shoot the CMJ in preference to the FMJ because they have some cover on the base and it reduces my lead exposure. As to differences in accuracy, once I get to the point where I can put 10 shots in a 1" group I'll start thinking about it. If you are comfortable with what you are now shooting, then stick with them. I know a lot of people who shoot moly's and swear by them. Edited September 5, 2009 by Graham Smith Link to comment Share on other sites More sharing options...
CHA-LEE Posted September 28, 2009 Share Posted September 28, 2009 My buddy and I have been using the Montana Gold 180gr FMJ .40's for a while now and we got some 180gr CMJ's to try out. The main thought in switching was to reduce the smoke during the shot because the back of the bullet does not have exposed lead showing. The FMJ's are not bad with smoking but we do some indoor shooting and less smoke has to be better. In our chrono testing with the exact same load setup, the only difference being the FMJ vs CMJ bullet, the CMJ's were consistently 20fps slower than the FMJ's. I am not sure exactly why this is, other than maybe the lead exposed back end of the FMJ promotes the expansion of the back of the bullet once its fired to get a better seal against the barrel. We still have to do some back to back "Smoke level" testing, but for right now I think we are going to stick with the FMJ's due to their better velocity. Link to comment Share on other sites More sharing options...
al503 Posted September 28, 2009 Share Posted September 28, 2009 (edited) My buddy and I have been using the Montana Gold 180gr FMJ .40's for a while now and we got some 180gr CMJ's to try out. The main thought in switching was to reduce the smoke during the shot because the back of the bullet does not have exposed lead showing. The FMJ's are not bad with smoking but we do some indoor shooting and less smoke has to be better. In our chrono testing with the exact same load setup, the only difference being the FMJ vs CMJ bullet, the CMJ's were consistently 20fps slower than the FMJ's. I am not sure exactly why this is, other than maybe the lead exposed back end of the FMJ promotes the expansion of the back of the bullet once its fired to get a better seal against the barrel.We still have to do some back to back "Smoke level" testing, but for right now I think we are going to stick with the FMJ's due to their better velocity. I'd measure the diameter of the bullets. If one is slightly bigger, it'll probably seal a bit better for better velocity. The other thing I would check is the length of the bullet. If one is shorter than the other and you're seating that at the same OAL, you'll get a little less speed as there will be a slightly lower initial pressure spike. Edited September 28, 2009 by al503 Link to comment Share on other sites More sharing options...
CHA-LEE Posted September 28, 2009 Share Posted September 28, 2009 al503> I know that the OAL's between the rounds are exactly the same (1.225). But I will have to double check the bullet diamiter between the two. If one is slightly larger that the other it would make sense that it would seal better. I am currently using 4.7gr of Clays and know that I can get the velocity of the CMJ's back to to the FMJ's level by bumping the drop to 4.8gr but thats getting into my uncomfortable zone with the Clays powder. Clays can be evil if you use too much of it. Link to comment Share on other sites More sharing options...
al503 Posted September 28, 2009 Share Posted September 28, 2009 (edited) al503> I know that the OAL's between the rounds are exactly the same (1.225). Check the length of just the bullet (not the complete, loaded round). If the bullet is shorter or longer and you're seating it to the same overall length, then you're going to have a lower or higher initial pressure spike. Hope I made sense. If you're loading to 1.225" you should probably be OK with the clays. I think you have to worry more about it when the OAL is shorter. With that said, I don't load clays even though I load long like you. Edited September 28, 2009 by al503 Link to comment Share on other sites More sharing options...
Ray_Z Posted September 28, 2009 Share Posted September 28, 2009 The CMJ is really only "better" in that it won't give off the bit of smoke you get from FMJs (slight) and you get a bit less lead exposure. The vast majority of lead exposure comes from the primer, so the bullet isn't as big a factor from a health risk standpoint. I have never brought this question up because I was afraid that it might give those that read this forum for anti gun political ammunition. That said, has anyone ever seen a study on air born lead vs. ingested lead? Like a lot of other shooters, I wash up after shooting and before eating. Link to comment Share on other sites More sharing options...
GrumpyOne Posted September 29, 2009 Share Posted September 29, 2009 P.S. typing in all caps is considered yelling Maybe he's hard of hearing from all the shooting? Link to comment Share on other sites More sharing options...
CHA-LEE Posted September 29, 2009 Share Posted September 29, 2009 al503> The plot thickens..... Both the FMJ and CMJ bullets are the exact same diamiter (.3985 - .3990 variance between both of them). The length is different between them though. The FMJ's are .5915 - .5930 and the CMJ's are .5980 - .5985. So much to my surprise the CMJ's are a little longer which would make the inner volume of the case smaller when using the CMJ's, which should make the round "Hotter" than the FMJ's, but instead they are slower. With knowing this about the size of the bullets I am going back to my origional thought on this. I believe that the FMJ's are expanding slightly at the exposed lead base and creating a better seal in the barrel as it is fired. Link to comment Share on other sites More sharing options...
Aircooled6racer Posted September 29, 2009 Share Posted September 29, 2009 Hello: The Moly bullets take less powder to get the power factor I think you will find the bullet profile is a little different on the FMJ and the CMJ bullets. That may give the extra drag. I like the JHP and the CMJ bullets so far. The FMJ smoke just a little bit but not bad at all. You may try a different powder than 231 which I found smoked more than Tite Group. Thanks, Eric Link to comment Share on other sites More sharing options...
al503 Posted September 29, 2009 Share Posted September 29, 2009 al503> The plot thickens..... Both the FMJ and CMJ bullets are the exact same diamiter (.3985 - .3990 variance between both of them). The length is different between them though. The FMJ's are .5915 - .5930 and the CMJ's are .5980 - .5985. So much to my surprise the CMJ's are a little longer which would make the inner volume of the case smaller when using the CMJ's, which should make the round "Hotter" than the FMJ's, but instead they are slower. With knowing this about the size of the bullets I am going back to my origional thought on this. I believe that the FMJ's are expanding slightly at the exposed lead base and creating a better seal in the barrel as it is fired. Yup. Given all that, I'm gonna have to agree with you. Link to comment Share on other sites More sharing options...
SA Friday Posted September 29, 2009 Share Posted September 29, 2009 al503> The plot thickens..... Both the FMJ and CMJ bullets are the exact same diamiter (.3985 - .3990 variance between both of them). The length is different between them though. The FMJ's are .5915 - .5930 and the CMJ's are .5980 - .5985. So much to my surprise the CMJ's are a little longer which would make the inner volume of the case smaller when using the CMJ's, which should make the round "Hotter" than the FMJ's, but instead they are slower. With knowing this about the size of the bullets I am going back to my origional thought on this. I believe that the FMJ's are expanding slightly at the exposed lead base and creating a better seal in the barrel as it is fired. longer bullet=more friction between the jacket and the rifling. It makes is more accurate as the theory goes, but the friction is where you are losing the 20fps. Link to comment Share on other sites More sharing options...
38superman Posted September 29, 2009 Share Posted September 29, 2009 (edited) I used the MG 200 and 180 FMJ's for years but shoot hp's almost exclusively now. With lead bullets, a lot of the smoke produced is from bullet lube being burned, along with powder gases and residue. There is also a bit of lead that gets vaporized by the heat and erodes the base of the bullet during firing. Even when the bullet lube is removed from the equation, a jacketed bullet with an exposed base still can generate a lot of smoke. I wasn't too aware of the smoke when shooting because my attention was on other things (hopefully). I never noticed it until I watched video of a couple of my matches. I was really surprised by the quantitiy when I saw it on film, especially the Titegroup loads. I decided right then that I simply didn't want to continue breathing it. If and when you choose to avoide the exposed base bullets, you still have to decide the totally enclosed vs. hollow points issue. I generally go with the hollow points because testing has shown that they do tend to be more accurate in my guns. The draw back to the hollow points is that they do have exposed lead and it is easier to contaminate your hands, clothes, loading bench etc than with a fully enclosed jacket. Depending on the specific bullet, the exposed lead in a hollow point may be recessed into the cavity of the jacket and it may not. Its really a trade off, but with proper precautions in handling there should be little to worry about as far as lead contamination. I will wash my hands more often to squeeze a little extra accuracy. Tls Edited September 29, 2009 by 38superman Link to comment Share on other sites More sharing options...
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