View Full Version : FMJ vs Non-jacketed
So I'm speaking specifically about 5.56/.223 - your typical AR-15 caliber(s). I had a discussion about american eagle black box ammo (i found some at a good price and wanted to know if it was any good) with a friend of mine who's an avid AR-15 user/owner and this is what he said regarding metal jackets AND (non brass) cases: "Steel casings and jackets are primed with paint because eventually they will rust. As the barrel starts to heat up, the paint begins to melt inside the barrel. Eventually the paint sticks to the inner diameter of the barrel causing the barrel diameter to "shrink". As the diameter shrinks eventually it won't allow a bullet to pass through. I (he) saw a guy the other day that had fired 2 shots and the lead never left his barrel. Usually if it's just one jammed in the barrel it can be hammered out. But this guy had 2 locked together and there was nothing they could do to save the barrel. He had to buy another one."
Is this true? I read somewhere else that THIS would happen if the bullet WASN'T coated. In other words, a non-jacketed bullet will leave lead deposits in the barrel eventually having the same effect.
Can someone please shed some light on this? Thank you.
"...I (he) saw a guy the other day that had fired 2 shots and the lead never left his barrel. Usually if it's just one jammed in the barrel it can be hammered out. But this guy had 2 locked together and there was nothing they could do to save the barrel. He had to buy another one."
I'm really doubting the guy's story here. If you had a bullet lodged in the barrel, regardless of why it was stuck there, and fired another live round, I'd be more worried about having to replace other stuff than the barrel: The bolt, carrier, upper receiver, and possibly parts of your face and hands. I can't imagine that NOT causing a catastrophic 'kaboom!'
As for the rest, I think he is talking about 'bi-metal' jackets, where there is a very thin layer of copper (and not paint) over a steel bullet. I've not personally heard of this supposed barrel-clogging problem, other than the usual steel case debate and how exactly it fouls the chamber, when it comes to such ammo use. (and that indoor ranges don't allow steel-core or bi-metal rounds, too damaging to the back stops.) As far as I know, most bi-metal bullets are from companies like Wolf, Tula, Brown Bear, and the like. The AE 'black box' stuff is good, I've never heard of it being bi-metal, if that was in question. As far as the more technical details of 'steel case pros and cons,' do a search here on 'steel case ammo' and you will find pretty much everything you could ask about it. Personally, I've not had a problem shooting a ton of Wolf ammo through my rifles when it's all I've got, but I always do a good cleaning afterwards.
Your buddy is retarded from the neck up.
There's too much wrong with his beliefs to even try to tackle it all. :rolleyes:
RearwardAssist
07-11-13, 09:18
Two different things here.
1 is the jacketed ammo you really shouldnt shoot lead projectiles at rifle velocities yes it well lead the barrel, I dont believe anyone sells un coated 223 it either has a jacket or is plated with copper so unless he had cast bullets and reloaded them I dont see that as happening but it is plausable.
2 yes steel cased ammo has a laquer or polymer coating the coating sticks to the chamber typically causing failures to extract I have never had this problem with my AK I dont shoot steel cased 223/556. I would have a hard time believing it entering the bore and causing a squib.
The other part of the story about having 2 rounds stuck in the barrel I would call bs on after the first squib the second shot would more than likely kaboom the rifle from all the pressure.
ETA: beat me to above but yeah same idea.
You know, I wanted to call him out on the BS story but black rifles are relatively new to me and I can't speak from experience on the topic so I left it alone to bring it here. But I've been an avid hunter/gun owner my whole life and this story didn't sit right with me.
On a side note, american eagle black box does sell a 5.56 NATO round that's MCBT (metal case boat tail) so it also got me wondering if all of their stuff was metal and not brass cased.
CrazyFingers
07-11-13, 09:42
steel cased ammo has a laquer or polymer coating the coating sticks to the chamber typically causing failures to extract
That is absolutely, utterly untrue, and has been confirmed as such many times on these forums.
If your friend hasn't had kids yet, sterilize him, then find a new friend. He is completely full of shit.
If your friend hasn't had kids yet, sterilize him, then find a new friend. He is completely full of shit.
:D
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On a side note, american eagle black box does sell a 5.56 NATO round that's MCBT (metal case boat tail) so it also got me wondering if all of their stuff was metal and not brass cased.
I've seen XM193 marked as MCBT, I can't imagine it's a copper coating like on the 'Bloc' import stuff. The thickness may be the difference between 'metal case' and 'coated,' but I don't readily see anything defining the specs on 'MCBT' right offhand. I was always under the impression that XM193 was a lead core, too.
I've seen XM193 marked as MCBT, I can't imagine it's a copper coating like on the 'Bloc' import stuff. The thickness may be the difference between 'metal case' and 'coated,' but I don't readily see anything defining the specs on 'MCBT' right offhand. I was always under the impression that XM193 was a lead core, too.
I'm talking CASE, you are talking JACKET.
While I'll admit to being new to the AR platform (Colt M4 Dec '12) I did do some serious reading on what ammo to use. From my reading I don't shoot steel in this rifle and to note, if I remember correctly (old timer's disease ya know) due to the expansion differences between brass and steel inside the chamber. I use steel (wolf primarily) for my SKS, it was made for that crap but I only do brass casings in the Colt.
As for the jacket, I believe I've only used FMJ and some Lake City and PMC green tip. I have not had any issues with this rifle.
I'm talking CASE, you are talking JACKET.
I'm pretty sure that (MCBT) is in reference to the bullet itself. At any rate, in the case of XM193, I know it is a brass case and I've yet to possess any 'black box' AE .223 that was non-reloadable steel case.
I'm pretty sure that (MCBT) is in reference to the bullet itself. At any rate, in the case of XM193, I know it is a brass case and I've yet to possess any 'black box' AE .223 that was non-reloadable steel case.
Cool. Thank you for the info. I just assumed that where it's called "metal case" ammo it was actually talking about THE CASE. Hahahaha. FMJ speaks to the jacket, so why wouldn't it be called MJBT (instead if MCBT) if it were actually referencing the jacket? I don't really expect you to be able to answer that question - that's really a question for the manufacturer. It doesn't make sense to have inconsistent naming nomenclature.
Yeah, I was scratching my head over it as well, and couldn't find anything (even on this forum) about what it meant exactly. I didn't see it mentioned on the Federal/American eagle site, either.
That is absolutely, utterly untrue, and has been confirmed as such many times on these forums.
It will be a cold day in hell when we finally stop hearing it.
That is absolutely, utterly untrue, and has been confirmed as such many times on these forums.It's true, but only if you're shooting left-hand ammo from a right-hand gun and vice-versa. (Reverse it if shooting below the equator.)
For all of you ambidextrous shooters out there ... well, you're hosed unless you reload.
Actually, I've shot my share of steel-cased ammo, and I do believe it's true that steel cases don't expand as much as brass, thus leaving room for crud to get in. I've never had a problem shooting steel after brass. But when I shot brass after steel (once), the brass came out with clumps of crud stuck to it. I even read a post by someone who claimed he always shot a round or two of brass after steel to help clean the chamber. Regardless, it makes me wonder whether it's the crud, not the lacquer or polymer, that builds up and causes problems.
I'm really doubting the guy's story here. If you had a bullet lodged in the barrel, regardless of why it was stuck there, and fired another live round, I'd be more worried about having to replace other stuff than the barrel: The bolt, carrier, upper receiver, and possibly parts of your face and hands. I can't imagine that NOT causing a catastrophic 'kaboom!'
As for the rest, I think he is talking about 'bi-metal' jackets, where there is a very thin layer of copper (and not paint) over a steel bullet. I've not personally heard of this supposed barrel-clogging problem, other than the usual steel case debate and how exactly it fouls the chamber, when it comes to such ammo use. (and that indoor ranges don't allow steel-core or bi-metal rounds, too damaging to the back stops.) As far as I know, most bi-metal bullets are from companies like Wolf, Tula, Brown Bear, and the like. The AE 'black box' stuff is good, I've never heard of it being bi-metal, if that was in question. As far as the more technical details of 'steel case pros and cons,' do a search here on 'steel case ammo' and you will find pretty much everything you could ask about it. Personally, I've not had a problem shooting a ton of Wolf ammo through my rifles when it's all I've got, but I always do a good cleaning afterwards.
i will say that this has happened to me personally, but only on a 22 semi auto rifle...
the first round lodged about halfway down the barrel, the second round joined it, and the third round expanded the barrel enough to allow all rounds to exit, not to mention that they were probably fragments by that time.
I think that he must have dreamed this, and then believed it really happened. Sounds like BS to me.
It's true, but only if you're shooting left-hand ammo from a right-hand gun and vice-versa. (Reverse it if shooting below the equator.)
For all of you ambidextrous shooters out there ... well, you're hosed unless you reload.
Actually, I've shot my share of steel-cased ammo, and I do believe it's true that steel cases don't expand as much as brass, thus leaving room for crud to get in. I've never had a problem shooting steel after brass. But when I shot brass after steel (once), the brass came out with clumps of crud stuck to it. I even read a post by someone who claimed he always shot a round or two of brass after steel to help clean the chamber. Regardless, it makes me wonder whether it's the crud, not the lacquer or polymer, that builds up and causes problems.
It is the crud.
i will say that this has happened to me personally, but only on a 22 semi auto rifle...
the first round lodged about halfway down the barrel, the second round joined it, and the third round expanded the barrel enough to allow all rounds to exit, not to mention that they were probably fragments by that time.
How did you come to the conclusion that this was happening?
anachronism
07-14-13, 19:47
MC-BT = Metal Case Boat Tail. We call them Full Metal Jacket Boat Tail (FMJ-BT). It is definitely the bullet of which they (Federal Cartridge) speak.
MC-BT = Metal Case Boat Tail. We call them Full Metal Jacket Boat Tail (FMJ-BT). It is definitely the bullet of which they (Federal Cartridge) speak.
Not to state the obvious, but the case and the jacket are not the same part of the bullet. On top of that, American Eagle sells both FMJBT and MCBT 5.56mm bullets, so why would they use 2 different naming schemes for the exact same bullet? Unless of course they are NOT the same.
So i just ordered Some American Eagle black box rounds and here's what I got:
ordered .223 Rem, 55gr FMJ - arrived as advertised
ordered .223 Rem, 50gr Polymer Varmint Tip - arrived as advertised
ordered 5.56mm 55gr FMJBT - arrived as Federal white box Metal Case Boat Tail (MCBT) - not what was ordered OR advertised
Maybe they advertise as FMJ because Federal missed-stamped the box as Metal Case? Who knows I guess.
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