Do You Crimp 300BLK Rounds?

[Get Off My Lawn]

I use the Lee Factory Crimp as extra insurance in case a 300BLK round finds its way into a 223 magazine/rifle. Additionally the crimp is supposed to increase accuracy by delivering a more consistent pressure curve as the bullet enters the rifling, whether the bullet has a cannelure or not.
I recently picked up some 300BLK range brass and there happened to be a loaded round with them. I'm guessing they weren't reloads, or they would have picked up that tidy shiny pile. The loaded bullet pulled VERY EASILY out of the brass with a hammer style puller. I have to really smack my reloads to get them to move out of the brass. That round would have been a definite KaBoom in a 223/5.56.
I finally got around to removing the firing pin and trying to chamber 300BLK rounds into a 223 chamber.
It pushed the round into the cartridge 0.02"-0.0037", but they wouldn't chamber.
Before attempt:


Bolt didn't seat:

After attempt:

I wasn't able to locate the info/articles I started with ~8+ years ago. Here's a few things I dug up.



From the article link below, "The only problem I ran into while handloading the .300 Blackout was with bullet set-out when the cartridge was chambered. With some loads—particularly those using the 125-grain Nosler AccuBond and 150-grain Nosler Ballistic Tip—the bullet would migrate forward in the case when the cartridge entered the chamber. This had a horrible effect on accuracy."
https://www.shootingillustrated.com/articles/2014/6/17/handloading-the-300-aac-blackout/

*edit* My 300BLK are ARs, not bolt Guns.

 

[Jerzsubbie]

I do a light crimp with a Lee FCD. Can’t tell you exactly why other than based on what I read over the years it seemed like a safe bet with little to no downside.

 

[WildBill]

I have the RCBS AR series dies that puts a taper crimp on it. I don't do much for my subsonic rounds, even less for my supersonic.

 

[Catfish]

My limited testing was with H110 under 203gn polymer coated bullets at subsonic velocities, range pickup brass.
With a crimp I found more consistent velocity and no change in accuracy, so I choose to crimp. It does work the brass more, but I've found splits start at the shoulder way more often than at the mouth.

Also - and I'm not sure if this was your problem - I think that if your rounds have poor neck tension you should fix that separately before working out the crimp/no crimp issue.

 

[steelciocc]

Light taper crimp here.

 

[JBoyette]

Great post.

CRIMP LIKE A BEAST!!!!!

On 300blkout

One day you will thank me.

 

[Goofyfoot2001]

I only crimp when the bullet is tapering. I bought some seconds and they were quite long and pointy and needed a crimp.

 

[BBD280]

@Michael458 What say you?

 

[Jerzsubbie]

@Michael458 What say you?

I was waiting for him to chime in too.

 

[Michael458]

@Michael458 What say you?

I have never crimped a 300 BLK. I use RCBS Small Base dies for all rifle cartridges that are based on Semi Rifles, this gives those cartridges a little more squeeze than normal to assure feed and function in proper rifles. In addition I use mostly MilSpec brass, which most of the time is a bit heavier/thicker than some factory brass. Since 300 BLK is a cut down and formed 223, then the brass is thicker at the point of the cut. With small base dies, and the thicker Milspec brass, it has plenty of neck tension to hold everything together tight without issues. The vast majority of my 300 BLK brass is Milspec from Everglades. They do a great job with the brass, but it is not sized and formed in a Small Base die. Unfortunately for me, I have enough OCD that I have to run all of those thru my small base size die. The last batch I did was 4000 of them. I was sick and tired of that crap.

I very rarely use any crimps on any rifle cartridges, unless it is a rimmed case based on double rifles, or lever guns. Bolt gun cartridges I always prefer neck tension to hold the bullet. In a bolt gun the bullet moves back in the case, in the magazine during heavy recoil. I also much prefer compressed loads and neck tension to solve that issue. Lever guns you need the crimp so they don't get beat back in the tube, but a good compressed load can help with that as well. Double rifles the bullet wants to "jump forward" during recoil, so they require a crimp to stop that.

Pink's purpose in crimping does not deal with normal operation of the 300 BLK. Seems he is crimping for the sole purpose of keeping the 300 BLK from diving too deep in a 223 chambered firearm. Nothing wrong with that, and I can see where that would give some peace of mind.

 

[Ikarus1]

Let's just say I do it because the ONLY round that has exploded one of my rifles was a Remington factory round whick experienced setback by being chambered multiple times in a 5.56 chamber. With enough crimp I don't think it would have happened.

 

[Get Off My Lawn]

Let's just say I do it because the ONLY round that has exploded one of my rifles was a Remington factory round whick experienced setback by being chambered multiple times in a 5.56 chamber. With enough crimp I don't think it would have happened.

I shot my 223 the other day for the first time in years, the 7th round jammed the bullet completely into the case and jammed the rifle. Thankfully the bolt didn’t close. I had to slam the rifle butt several times to clear it. These were loaded with RCBS Small Base dies.
I need to add a Lee Factory crimp die to the tool head.

 

[Meckmeister]

I just found this thread last night. What a great dive into reloading, again.

 

[Slacker]

I shot my 223 the other day for the first time in years, the 7th round jammed the bullet completely into the case and jammed the rifle. Thankfully the bolt didn’t close. I had to slam the rifle butt several times to clear it. These were loaded with RCBS Small Base dies.
View attachment 202563

Howza. Yer' doing it wrong! 😉

 

[Get Off My Lawn]

Howza. Yer' doing it wrong! 😉

Don’t know what happened, it was in a Knight’s Armament SR-15 & the rounds were loaded ~15 years ago.

 

[Slacker]

Don’t know what happened, it was in a Knight’s Armament SR-15 & the rounds were loaded ~15 years ago.

The shoulder looks janky.
I'm betting a case gauge would have culled that resize job. I can see the Lee factory clamp marks on the case mouth.

 

[Get Off My Lawn]

The shoulder looks janky.
I'm betting a case gauge would have culled that resize job. I can see the Lee factory clamp marks on the case mouth.

I first tried the forward assist, then had to mortar the rifle a couple times to clear the chamber. The crimp is from factory ammo. I need to get a LFC die.

 

[Slacker]

I first tried the forward assist, then had to mortar the rifle a couple times to clear the chamber. The crimp is from factory ammo. I need to get a LFC die.

In my experience, the LFCD Isn't ideal for semi auto rifles.
I like it for 30-30 / 35 Rem / 300 Savage type cases where the neck is paper thin. that's about all the use I have for it.

Just for reference, I have a Sabre defense AR15 rifle that has an insane tight chamber.
Anything less than perfect headspace, the bolt won't close. It really woke me up to resizing mixed HS 556.

 

[clay_fv]

Old topic brought back to life. I only load 300blk for subs. For the 220gr berry's plated bullets, I use a light taper crimp. For the 190gr Horn Sub-x, I roll crimp on the cannelure. In everything I ever load, I only ever use a "light crimp".