Crimp on semi-auto loads

An old argument. The US Military found out many years ago the importance of crimping ammunition used in semi or fully automatic rifles. That in itself should be enough said.
You will be hard pressed to find any factory ammo designed to shoot in semi autos that is not crimped.
 
I am going to agree with chiefr. Some of the semi-autos I have had were brutal with extraction and recoil. I am sure there is some movement involved. I have seen problems with milder lever guns over the years when it comes to reloads. I have used Herter's SPCE .308 in one of my semi-autos, and not really noticed a difference, but the brass around the neck seems pretty heavy. If it has a crimp, it is barely there. Even with that, I don't know that I would reload the brass and not crimp. Maybe if you stuck to reloading military brass, which usually has a heavier neck. I guess whatever works for you.
 
When I NEED a crimp, I use a factory crimp die.
Rolled or tapered crimp dies press STRIGHT DOWN on the mouth of the brass,
ALWAYS effecting the shoulder bends in the brass.

A factory crimp die presses 'IN' on the mouth from the sides, while supporting the shoulder, so you get a much more uniformed crimp pressure on the bullet.
Click to expand...

Worth noting that not all "factory crimp dies" work the same. The ones you are talking about are collet style like this.

fcdie.jpg
 
I am somewhat new to internet forum discussions, and absolutely did not realize crimping in the hand loading world was such a controversial topic.

I appreciate the thoughts and information. But in the end, I guess do whatever works for you since you are the one who has to live with the results.
 
I use the factory style crimp die from Lee also.
Supports the shoulder while crimping the neck.
MUCH more surface area on the shoulder than the mouth to get a good crimp.

I would like to see a 6 'Finger' collet crimp instead of 4,
But you get what's out there...

I don't recommend crimping a bullet that doesn't have a cannelure, deforms the bullet too much.
Since you can't order cannelure exactly where you want it, you are stuck with a cartridge over all length that works with the cannelure.

Not a huge issue with most range ammunition, but can be a pain in the butt when you are loading close tolerance ammo for a particular rifle.
 
Since you can't order cannelure exactly where you want it, you are stuck with a cartridge over all length that works with the cannelure.
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I have a cannelure tool from CH4D, with it you can put them anywhere you like.

canneluretool416rem.jpg
 
I would note that such a tool is best used on rifle & revolver bullets

Semi auto pistols do not use a mouth crimp since that's where they headspace.
Nor (IMHO:cool:) will a "factory (aka swage)" crimp do much to solve poor neck
tension since it swages the bullet smaller right along with the case
 
I'll be honest, I almost never use the tool, it was given to me.

About the only thing I have used it for is tube magazines or rather bullets used in them.

For the most part I use neck tension to keep the bullet where it should be.

It's pretty easy to test though, just load as normal, then chamber, eject and measure. Now fire a round, eject and measure. Repeat and measure, if they are not moving you are OK. If they are moving you cure the problem.
 
I have been loading .308 for my AR and have been using the Lee Factory Crimp die. However, after reading this thread, I want to try some rounds without the crimp.

So my question is, how does one go about testing neck tension?

BTW, I am using Hornady Match 168 gr HPBT
 
Two classic methods, both starting with using a Sharpie to draw a fine ring around the bullet right at the mouth after reloading:

- Using your hands only, firmly press the bullet into a hard surface like the side of your reloading bench. (Don't go crazy, just firmly press.)

........Has the Sharpie mark moved into the case?

- Load and cycle that bullet into the AR a few times.

........Has the Sharpie mark moved into the case?
 
Gunplummer
Never saw that before. I like the idea.

Reloadron
Pretty slick little tool.

Mississippi
That cannalure tool is slick..
Click to expand...

It reminds me of my mother's can opener in the 1950s.
 
the calipers you set the OAL with will work fine...
Click to expand...
Not necessarily -- especially when you have a deformable nose in ANY form (this includes SMKs if/when force is used -- ask me how I know.)

If you have a ogive comparator, fine.
But don't rely on OAL or you'll see changes that "aren't there."
 
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