9 mm Major “Crimp” ?

[TANFARM]

I am loading 9 mm major reloads to 1.165.....is there an accepted crimp measurement that you all find satisfactory?

currently I’m returning the loaded brass to .380.... but wondering if this is effecting my case gauge tests?....I use a EGW U die which seems to be working fine on resizing the end of the brass.

Will increasing the crimp drastically effect the load specs?.....Thanks in advance.

[Hi-Power Jack]

Most are 3.78", just a little more than you are currently using.

 

BUT, if your 3.80" is working (chambers and no bullet set back), there isn't any problem.

 

Increasing the crimp "drastically" will probably affect accuracy, adversely.

 

 

[jcc7x7]

Crimp is not really a crimp on auto cartridges, it's more pushing the bell back straight.

The most I go is .002 under

So measure your loaded round just below where the bell was put in by the powder funnel and remember that number.

Then adjust the crimp die down about a 1/4 turn at a time until your at that measurement of .001-.002 below it.

I've found when I get .001-.002 it case gauges or better yet "plunk" tests much easier.

 

As a test I load a few round without crimp that I KNEW worked all the time in my gun.

W/O the crimp station none would case gauge or plunk.

At .000 about half plunked

At .001 under they all plunked

FWIW

[bigedp51]

Below a 9mm cartridge before applying a taper crimp, the case is wasp waisted that shows plenty of bullet grip.

 

 

Below the same cartridge after applying a taper crimp and streamlining the case mouth. Bullet grip is controlled by how small the case is sized and then expanded. Meaning  a taper crimp on a cartridge that headspaces on the case mouth has nothing to do with grip. Shooters who use range pickup brass sometimes use undersized dies that size the case .002 to .003 more than a standard die. This compensates for work hardening of the brass and brass spring back after sizing.

 

Below you can see the slight amount the case mouth is reduced in diameter and the wasp waisted case firmly gripping the bullet.

 

Edited December 13, 2018 by bigedp51

[slayer61]

^^ That right there is an outstanding demonstration! ^^

[hamiltonian]

That is a great photo!!  I have found that running an undersize resizing die from Lee is more important than crimp.  This way, I can just get the bell out, not deform the bullet and still eliminate setback.

[TANFARM]

Did a little experimenting last night....reduced “crimp” from .380 to .378........100 rounds mixed brass all dropped right in the Hondo....very interesting this minor adjustment makes such a difference.......still chasing the perfect 9mm Major Round !!,

Thanks to all...........

[36873687]

2 hours ago, TANFARM said:

Did a little experimenting last night....reduced “crimp” from .380 to .378........100 rounds mixed brass all dropped right in the Hondo....very interesting this minor adjustment makes such a difference.......still chasing the perfect 9mm Major Round !!,

Thanks to all...........

That’s about were I’m at maybe tad more