Bullet type - FMJ vs TMJ - SAME?

D

dpollard

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Is a Full Metal Jacket bullet the same as a TMJ (I assume Total Metal Jacket)?

I am getting ready to buy 1000 TMJ bullets for my .40S&W and want to know what load data to look at.

I have been loading using Ranier Ballistics hollow points. Having problems with over pressure. I am loading according to load data (minimum load) but still getting velocities WAY over what I should be - 1500 fps. I had to drop the powder charge well below minimum to get them to shoot like they should. Not sure what is causing this!?!?
 
Originally Posted By: dpollardIs a Full Metal Jacket bullet the same as a TMJ (I assume Total Metal Jacket)?

I am getting ready to buy 1000 TMJ bullets for my .40S&W and want to know what load data to look at.

I have been loading using Ranier Ballistics hollow points. Having problems with over pressure. I am loading according to load data (minimum load) but still getting velocities WAY over what I should be - 1500 fps. I had to drop the powder charge well below minimum to get them to shoot like they should. Not sure what is causing this!?!?


Not the same (kinda).

Total metal jacket is a full metal jacket, since it is a jacket and it is full.

But in common usage, the term full metal jacket is a bullet with a cupped jacket that is open in the back, and is made by forcing a lead core into a copper cup and shaping it after insertion.

With the total metal jacket, the core is shaped into the final bullet form, and about ~16 thou smaller. Then it is copper plated all over so there is no lead exposed.

Both are very good bullets, but the true FMJ can take more stress because the real jacket is stronger than the copper plating, so they are recommended for magnums.

Total metal jacket bullets will show more velocity than the same loads for a FMJ, because the copper plating is softer that the standard jacket, so there is less resistance to acceleration in the barrel.




 
Be sure that your definition of a TMJ is not standing for "Truncicated Metal Jacket"... This is a bullet with a fairly flat nose, compared to a normal FMJ Round Nose...

I use a lot of them in loading for my .40 and 10mm handgun rounds and other than working up my "safe" loads, have no problems with either function or accuracy...They do tend to import a little more kinetic energy on impact with steel plate targets...Takes them down with a little more authority...
 
Originally Posted By: dpollardso when looking at load data I would just use jacketed bullet data or should i reduce by "X" % with the cooper plating?

Use the jacketed data - don't EVER expect the velocities in your gun to match the velocities in the loading book - even when you use the same kind of gun, cases, primers, powder, and bullet - there are always differences.

Just load 'em up and be happy.
 
The plated bullets act more like lead bullets than jacketed ones. I use lead data to start with them and work up. You'll also want a nice bell on the case mouth and no crimp, just remove the bell. It's real easy to scrape through the plating and you'll get some strange results when that happens. I had them keyholing on me once, turned out I was shaving a bit of plating off while seating them, not enough bell. I've used a lot of Ranier and Berrys bullet, they are great just have personalities of their own.
 


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