Crimping question

[JohnyFive3]

Been reloading .308 for a few years now. But i recently built a AR platform in 300 black out. Been starting to load it and am unsure on how to set my crimp or even tell if i'm getting any sort of crimp. I"m using Hornaday dies. Any help or advise is greatly appericated

thanks in advance

Jonathon

 

[ArmyJerry]

I have had issues in the past with consistent crimping, switched over to the lee collet die, no problems in AR's or the M1A which is the most brutal recoil.

 

[Facemelter]

To set the crimp.
Run a bullet down to your seating depth in the case.

Unscrew bullet seating stem from the top of the die at least a few turns if not more.

Loosen jam nut on die and move the jam nut up the die a few turns to give yourself work room.

Slowly turn die down about an 1/8th of a turn into press. After each 1/8th turn check your progress with a reload.

The crimp will be slight and hard to notice. Keep a non crimped reload near so you can see the very slight difference in the chamfer at the top of the neck. Use your fingers and finger nail to feel a difference. If its crimped to much,it wont chamber correctly and might even have a bulge or goofy looking neck.

Once you set the crimp and like it,lock the die in the press with the jam nut.

Put the reload back in the press,run the reload into the die and screw the seating stem back down so it touches the bullet.

 

[mtrmn]

I have found that it is better to NOT crimp and seat the bullet in the same operation. Here's why:

You must have all your brass trimmed to exactly the same length and the brass thickness needs to be about the same as well or your crimp will not be consistent from one round to the next. Some will be crimped lightly and others may be over-crimped using your seating die to crimp. Most regular seating dies use a roll crimp and a little too much crimp will collapse the shoulder of the case, causing the round to be difficult or impossible to chamber.

When I was using a roll crimp die to crimp my AR rounds, I was doing this on a single stage press and I had to develop a "feel" for the crimp and stop the press stroke when it felt right, kinda like using a torque wrench. I could NOT just "set it and forget it" and go full-stroke on the press without winding up with some collapsed shoulders. Later I aquired taper crimp dies and used them up until I got the Lee Factory crimp die that I use now.

YMMV, but in my experience all these factors must be considered when roll crimping bottleneck cartridges.

 

[JohnyFive3]

Thanks for the advice after much reading and thought I order a lee factory crimp die this afternoon thanks again!