FMJ vs CMJ

[medic12]

Apologies if this has been asked before, searched without result. Is there a difference in accuracy using CMJ bullets? I am sure they are cleaner and the price difference is insignificant per case. Just wanted to put an order in with the tax refund burning a hole in my pocket. Thanks,

Bryan

 

[DukeInFlorida]

Copper plated jackets are not as thick as full metal jackets. FMJ's are made by deep drawing the copper/brass into a cup, and then installing a lead core, and then swaging the bullet into shape. Very rugged.

The copper plating, while a thick layer of copper, isn't as durable as a FMJ.

Most copper plated bullet manufacturers advise against having the plated bullet exceed a certain velocity (1200 fps). There's no such restriction on FMJ's.

If you're talking about shooting a pistol at 50 yards+, then yes, you might see some differences. If you're shooting at closer ranges, any reloads will be more accurate than the ability of most shooters to shoot them.

So, for plinking, copper plated are fine. When it's important, use the FMJ's.

 

[Supermoto]

CMJ is complete metal jacket not copper plated. There is no accuracy difference between CMJ and FMJ. JHP are inherent more accurate than either cmj or FMJ

 

[medic12]

CMJ is complete metal jacket not copper plated. There is no accuracy difference between CMJ and FMJ. JHP are inherent more accurate than either cmj or FMJ

Great thanks. Unfortunately I can't shoot JHP indoors at my club. I do the majority of my shooting indoors regardless of season.

 

[EddieCoyle]

CMJ is complete metal jacket not copper plated. There is no accuracy difference between CMJ and FMJ. JHP are inherent more accurate than either cmj or FMJ

This.

The only thing I can add is that I haven't seen any difference in 'cleanness' between FMJ or CMJ.

 

[Supermoto]

This.

The only thing I can add is that I haven't seen any difference in 'cleanness' between FMJ or CMJ.

I have notice when shooting a gun with a compensator, that there is more lead build up when you have an exposed base.

 

[medic12]

The only thing I can add is that I haven't seen any difference in 'cleanness' between FMJ or CMJ.

I thought I read it in a manual somewhere. Or i could have had a stroke, either way thanks for the help!

 

[EddieCoyle]

I have notice when shooting a gun with a compensator, that there is more lead build up when you have an exposed base.

Out of curiosity, is there any lead build up with a CMJ bullet? The only handguns with comps that I have are the X-frames, and I shoot mostly lead out of those.

 

[Supermoto]

no lead build up with cmjs

 

[38ExtraSpecial]

don't quote me on this

there are varying degrees of plated bullets. i think speer plates their bullets to as much as .030" thick and other brands like berry's and cheaper often plate as little a .002"

the .002" looks more like a copper washed .22 LR round than a FMJ. i haven't noticed any issue with the thinner CMJ plating breaking through, but i switched off to poly bullets recently, so i haven't spent much time loading the thin CMJ anymore

 

[Supermoto]

don't quote me on this

there are varying degrees of Plated bullets. i think speer plates their bullets to as much as .030" thick and other brands like berry's and cheaper often plate as little a .002"

Fixed it for you
True CMJ are jacketed, made like a FMJ with a cap on the back. Many companies call their products CMJ, but they are plated. Even the Speer, although as you said they are a lot thicker

 

[ShadeWPI]

I have some TMJ (Total Metal Jacket) bullets that are thick plated bullets. They seem to work very well in the .500 S&W Mag. I also have some of the same companies jacketed hollow points, which are the exact same bullet with the hollow formed after the plating process. This forms copper plating into the hollow point.

Plated Bullets and Capped FMJ (CMJ) are cleaner to shoot than FMJ since the soft lead is protected from the expanding gases.

The softer copper of plated bullets will lend them towards copper fouling, especially in rougher barrels. (Plated copper is basically annealled copper, so it's much softer than cold drawn & swagged jackets)

Very thin plated bullets offer none of the toughness of a FMJ, only the reduction in lead fouling, though thicker jackets can have some of toughness. FMJ bullets are almost always tougher due to the harder copper.

Some of the cheaper copper plated bullets suffer from cracking of the jackets - when I've seen these, I've set them aside and stopped buying those brands.

For target practice, most plated copper bullets are going to be fine, but if you're looking at plated bullets to offer the penetration of a FMJ, you'll likely be disappointed.

 

[38ExtraSpecial]

thanks mike.

what he said