5.56 reload ?

never reloaded the 5.56, reading Patrick Sweeney, "it is usually necessary to crimp the bullet in place when loading for a semi auto", using a tapered crimp... is it necessary?

As far as I know, semi automatic rifles use a crimp unlike bolt guns. But for some reloaders who use more than enough neck tension of over .002 don't crimp at all for semi auto rifles. But its best to crimp bullets without the cannelure and lightly crimp the bullets with the cannelure so the bullet won't move in the case for semi auto rifles.

What Stan said. Smarter folks than me will eventually chime in but that works for me.

Neck tension can be sufficient. I still crimp mine just for peace of mind and it does not take me any more time.

Anyone ever done an experiment to see if bullets are pushed deeper into the neck during chambering? If so, what were the results?

Some of my 223 ammo I will not crimp. It just depends on the powder I'm using and how compressed the load is. The main worry on 223 ammo is the bullet moving deeper in the case during chambering in an AR rifle. This WILL increase your pressures, and could cause a problem. If you are running a compressed load with proper neck tension, the powder alone will keep the bullet from going deeper in the case. So no crimp is needed.

Also, adding a roll crimp or taper crimp can vary your neck tension on brass that has different case neck lengths (like when using mixed head stamp brass, or brass fired multiple times vs. other brass not fired multiple times). This will cause the rounds to not be the same effecting accuracy.

When I do crimp, I use a Lee crimping die, since it squeezes the neck, and does not matter on case neck lengths.

Friend of mine has a DPMS chambered in .260 Rem. Without a crimp, the first round chambered, the bullet would lurch forward. Exactly the opposite of what we expected. He applies a light taper crimp now.

That's the other worry, is the bullet moving forward at the sudden stop during chambering. If a round has adequate neck tension, it shouldn't move forward during chambering. But to give more tension, crimping is the answer.

Yes, as hard as ARs chamber, and the sudden stop, is what we figured.

One more reason I like my bolt actions better. ARs are a necessary tool for the tool box, and I have two. But I look at them like they're female rifles. They can be high maintenance.

I like females!

Evidently I do too. Wife, two daughters, both dogs are female, one outside cat that's female.

thanks

Exactly what I have at home except the kitty.

I always crimp on any type of service rifle or civilian semi auto; just in case. I love the Lee factory crimp dies for this.

As far as females; Wife, daughter mother, mother-in-law, grandmother-in law, sister, niece. I am drowning in the Estrogen Ocean.

I crimp everything.

I like many of you use the Lee crimp die. In most cases I adjust the die so it just kisses the neck then turn it in just a bit more, maybe 1/8 ~ 1/4 turn. That is unless there is a cannelure, then they get just a bit more.

I don't crimp my .223 ammo, have always found neck tension sufficient. My unscientific test was to take 5 rds, label and measure them, then cycle them through my AR ten times, then measure them again. All 5 were exactly the same length at the end, and I found with that particular load that my groups opened up to about 1 1/4" when crimped.

This is similar to my experience, albeit with 6.8 instead of 5.56.

When doing load development, I only add a significant crimp if neck tension isn't sufficient to hold the bullet in place during repeated chamberings. Just on a whim, I decided to crimp a few rounds from an established load, and found that the group went all over the place. This is probably because I'm essentially changing everything about how that powder load burns now and not specifically a problem with crimping, but it should serve as a reminder to everyone to work up your loads how you're going to shoot them.

If the bullets have a cannelure, I consider crimping, but not always. If they are slick, I rely on neck tension and I check my dies to make sure the tension is strong. Watch out for case lube entering the neck and clean it out if necessary. Inspect old cases for cracks in the neck because that will loosen the tension. If you can easily push your bullets deeper when placing the point of the bullets against a table top, you have problems in a self loader.

I had an issue with soft points in an older AR without the M4 Feed Ramps. I thought it was the mag but it happened with multiple mags too. Bullets would occasionally hang up and push the bullet almost completely into the case. Powder would spill into the action.
Lee collet crimp or factory crimp as they call it now solved the problem. I use one on all .223, .308. and 30-30. Especially the 30-30, with its very thin brass it removed the problem of rolling the shoulder when trying to put on too much crimp. Its very adjustable for amount of crimp. Most of the time its just a simple little kiss and provides peace of mind. Several thousand rounds and no issues.