Taper Crimp .376 ?

[2bfree]

I read this all the time on the net

Correct taper crimp should measure about .376" at the case mouth using .355" jacketed bullets.

.
I load 124 FMJ 9mm all the time at .377/.378. My bullets are .3555 and my brass is .0115 X2 = .378. I have shot many many 1000"s of rounds with out a problem. They all plunk in my 3 9mm, pass a cartridge gauge. I even let a .379 slip by once in a while.
Am I missing something ? I think SAMMI specs are .380.

 

[rcmodel]

I'm probably the one that keeps saying that.

I base it on a lot of years of measuring and recording factory loads of every brand you can imagine.

If .378" works for you?
That's what you should use.

rc

 

[gahunter12]

Also if you load different head stamps, you will get different measurements. Most of my loads are .377-.378" on average.

 

[LiveLife]

With jacketed bullets with.355" diameter, using .376" taper crimp is not an issue as thicker jacket won't be affected.

With .355" - .356" sized plated bullets, I will lean towards using less taper crimp (.377" - .378") to not cut into the thin plating which could range from .015" down to .0035" thick.

I seat and taper crimp in the same step for 9mm and for .356" sized lead bullets, I will use .378" taper crimp to not shave lead.

Will .379" and even .380" taper crimp work in SAAMI spec barrels? Sure but not if you want your reloads to work with a dirty barrel after shooting a few hundred rounds, especially lead reloads in a SAAMI minimum barrel.

 

[moxie]

And, it's not unusual to see .001-.002 or more variation between calipers.

 

[rcmodel]

I use a accuracy tested Starrett, or Brown & Sharp mic most of the time for important stuff.

Rc

 

[moxie]

Amen, but that ain't the norm. I had a caliper once that was dead bang accurate for many years. I discovered it had gone wonky by .002". Just loosened up over time. It wasn't a Starrett.