To crimp or not?

hadjii

I'm loading my 375 ruger with 250 grain swift a-frames ahead of 81 grains of H100V. Recoil is substantial. Not painful, but more of a shock, LOL. Anyway, what's the consensus on crimping. Currently I'm not, and the rifle is shooting 3 shots inside an inch. I've been single loading rounds, mostly to get ready for the next sledgehammer hit, but thinking about putting on a slight crimp so I can load multiple rounds. Good idea, or not? Thanks

charliemeyer007

It doesn't help accuracy to crimp IMHO, and it may not hurt it either. Worth trying.

For the most part I don't crimp my 45-350 Rem Mag or 45-70 bolt guns. Ammo carried long term in bandoleers can benefit.

One of those big game hunters had an issue during a culling operation. He was shooting, keeping the magazine mostly full, by topping it off every shot. Anyway at some point he was down to the last round in the magazine (which had been there for many shots) and the rifle "blew up". IIRC it was suspected that recoil had set the bullet very far back into the case causing a pressure spike. I like full cases or even mildly compressed.

243winxb

Heavy recoiling dangerous game rifle ammo gets a Lee factory crimp (die.)

Test bullet movement. Load the magazine fully, fire all but the last round. Has the bullet moved forward? Longer OAL? If yes, a crimp is needed.

MIKE WISKEY

Test bullet movement. Load the magazine fully, fire all but the last round. Has the bullet moved forward?REARWARD Longer SHORTER OAL? If yes, a crimp is needed.
FIXED IT FOR YOU

hadjii

Thanks men. I'll try it tomorrow morning, and let ya know the results.

243winxb

Good catch above by Mike Wiskey.

Check bullet movement for both directions.

Some magazines, for bottle neck cartridges, have a bump or stop that contacts the shoulder . This keeps recoil from slamming the bullet nose into the magazine.

Bottom Gun

Unless your brass is extremely consistent, crimping will affect your accuracy to some degree. A few thousandths difference in case length, even if it's not enough to require trimming, will have an effect on your accuracy. Thickness of brass varies from one manufacturer to the next. This will also affect your crimp and your accuracy.
Granted, crimping is necessary for hard recoiling revolver ammo but otherwise I've found it best to avoid crimping altogether except when absolutely necessary.

hadjii

Went out and shot my 375 ruger today, and got the answer to my question. That answer is a resounding yes to whether I should crimp. Shot 2 times, and then measured the OAL of round 3. Not only was it .020 shorter, I was easily able to push the bullet in the case. I pulled the bullet back out and fired it to get rid of it, and it went right in the cluster with 3 other rounds for a 1" c to c shot group. Had 1 of 5 outside the group by 2", so I checked the cases and found a variance in length of about .020. Not sure if that was the reason for the flier, but I neck sized everything I had shot in the last few days and then trimmed them all to the same length.

I'll say this though. Since I put a McMillan stock on last week, after waiting for it for 8 months, the rifle shoots better. Of course I bedded the action and installed pillars first, but it sure feels better than the factory stock. For what I paid for it though, it certainly should shoot better.

Mobuck

I think you're going to need an extremely accurate rifle to tell the diff and this would be an unreasonable expectation for the type and caliber of rifle you describe.

hadjii

Mobuck, unreasonable expectations? Perhaps, but then again, that's why I shoot, and then shoot some more, and keep trying different things, and picking up tips and tricks from the people here on GunBroker that are waaay smarter than myself.

243winxb

Increase the neck tension by using a smaller expander. About .004" smaller then bullet diameter.
The brass should expand a minimum of .002" after bullet seating.

Neck Sizing- I hope your not using a Lee Collet neck sizing die. Lee claims only .001 to .002 neck tension.

But first, the sizing die must make the necks small enough to start with.

My hunting rifles get full length sized brass.

hadjii

243winxb, I'm using rcbs neck dies. The only Lee die I have is a flaring die I use when loading cast bullets. I've heard a lot about the Lee collect dies, but have no experience with them myself. I have shot 2 deer with this 375 using a 265 grain cast bullet, and it made em dead, that's for sure. Someday, I'll take it to Maine moose hunting if I can ever get drawn for a tag. This will be my 10th year applying. I would imagine I'd full length size whenever that opportunity comes around.