I just started reloading rounds for my 375, and was wondering if anyone applies a crimp to this caliber? I am used to reloading handgun ammo and have always crimped the case as the last step.

Thanks

Depending on the bullet, yes I have always crimped.

I haven't been crimping, but not for any good reason. Over the last three years or so I've been shooting a heck of a lot of H&H for practice and bench rest with heavy and light loads. I haven't had any issues with bullets creeping out of the case.

I thought it'd be neato to buy a crimping die for the H&H, but I haven't seen the real need.

I do. As long as there is a cannelure.

quote:

Originally posted by onefunzr2:
I do. As long as there is a cannelure.

Yep me too, but alway use a LEE Factory crimper if possible.

Yes Lee factory crimper

Ammunition in a revolver is held by the rims in the cylinder. Revolvers have relatively heavy recoil (due to the lightness of the gun) and the relatively heavy bullets have a lot of inertia that causes them to creep forward out of the case when the gun is fired. An additional reason for crimping handgun ammunition is that handguns have a very high expansion ratio, so the extra resistance added by the crimp assists in achieving uniform ignition and burning of the powder charge. A crimp in most rifle ammunition does not have significant effect on the initial burn of the powder.

The bullets in centerfire rifle ammunition sitting in a magazine do not tend to creep forward due to recoil because there is nothing to hold the cases to the rear. Bullets are actually battered slightly to the rear when they hit the forward magazine wall. However, with the proper neck tension, I've never seen the bullets in a .375 move due to recoil or nose battering.

Generally speaking, crimping rifle ammunition does nothing to improve its accuracy potential. If the bullet doesn't need crimping to stay in place, then don't crimp. In any event, don't EVER crimp in a single step with a conventional seating die. Pushing the bullet down while simultaneously folding the case mouth in cannot help but scar the bullet jacket and potentially deform the jacket wall. It may also deform the nose or ogive. If you must crimp, do it in a separate operation, either by resetting your conventional die, or with a Lee-type dedicated crimper.

I use the factory crimp die from Lee for my 375 H&H as my testing showed that it shot more accurately with the crimp applied.

I tested the 300 grain TSX, the 260 grain Partition and the 270 grain Hornady SP and the difference in three shot groups (15-20 groups per bullet) averaged over .3" smaller with the crimp and over .5" for the Partition bullet alone when crimped.

Thanks, I'll go ahead and get the crimp die ordered. Bullets are pretty snug but may apply a light crimp.
Thanks again for the info.

So what about the 375 flanged mag I'm building on a Ruger No 1? Any reason to crimp those? I probably will...just because I'm used to crimping everything over 338.

There's a study here on AR done by Saeed that proves crimping aids in accuracy. I crimp everything I can with a Lee factory crimp die, generally above 33 cal. jorge

I use the Lee crimp die on everything...even .243

quote:

Originally posted by ACRecurve:
So what about the 375 flanged mag I'm building on a Ruger No 1? Any reason to crimp those? I probably will...just because I'm used to crimping everything over 338.

Not much opportunity for bullets to move in a single shot, now is there?

As to crimping improving accuracy, I wonder why the benchrest boys have never discovered this?

quote:

Originally posted by Stonecreek:

quote:

Originally posted by ACRecurve:
So what about the 375 flanged mag I'm building on a Ruger No 1? Any reason to crimp those? I probably will...just because I'm used to crimping everything over 338.

Not much opportunity for bullets to move in a single shot, now is there?

As to crimping improving accuracy, I wonder why the benchrest boys have never discovered this?

I think it's because they sort their cases for exact weights, ream and then turn the necks for absolute consistency and set the neck diameters for an exact neck tension.

What I think that the crimp does is give each load more consistent neck tension. Because we don't mic and sort bullets by diameter and turn our necks for uniformity the neck tension varies greatly. I feel that by using the crimp die it insures that each cartridge has a more uniform tension and the pressure varies less per load.

In my 22.250 (no turn .250 neck) the standard deviation for my uncrimped loads was right at 22 fps. Taking those same loads and running them through the Lee factory crimp die resulted in a SD of 9 fps.

Yeah, not much chance for bullet movement in a single shot. Guess I'll hafta run a few batches of crimped and uncrimped through the chrony and compare SD's & look to see if accuracy is affected. Thanks.

Most of this "stuff" is apples to guava comparisons AND hardly ever any head to head comparisons.

The only way to know FOR SURE if YOUR rifle likes to be crimped or not is to test it. Work up the best uncrimped load then work up the best crimped load and compare the two final targets...


And...while you're at it be sure to turn the necks so inconsistencies in neck tension are reduced and not added into the mi...AND if you realy want to get down and dirty measure the belt depth while you're at it. Many peole don't know that belt depth is just as variable as necks, case weight, bullet weight and so forth.

I'm always amazed and have to shake my head EVERYTIME I read post on just about any forum. The way most people go about doing this reloading thing it's a wonder ANYONE gets any accuracy. Speaks well for the component makers.

I'm working with my just modified and painted 375H&H testing the 270 gr Hornady SP. Belt depth with R-P brass ran 0.206" to 0.215"... If you are swapping barrels around on a Savage action the difference can mean closing on a case or not closing on a case...and probably a lot of head scratching and looking for other reasons than the obvious. Very few people bother with belt depth on belted cases....pity because you can really improve function and accuracy with just a little bit of work. The necks ran 0.0010" to 0.0025" difference.

The best group I could get with 74 gr RL15 and mixed brass was 1 1/4"...not very bad indeed...but the best group with the same load by picking and weighing cases and turning the necks to 0.011" even, plus measuring the belt dept and using three at 0.208" and I got a bug hole group slightly larger then bullet dia.

And...something else most people haven't bothered to understand...the bullet impact shifted from +3.5"H/100M to 0.750"L and dead center elevation on the 2" bull at 100M.

I treat ALL my calibers and cases the same way by using benchrest techniques and ALL my rifles will shoot selected loads 0.500" or less or they get tuned so they will or traded off.

Most of the case prep only needs to be done once, takes about 3 hours for 100 cases, leaves about 20-30 almost perfect plus roughly another 30-40 very good ones using cheap R-P or W-W case or 95 plus Lapua. I also get at least 10 reloads with belted mag case before I toss the cases.

Almost forgot to add...I adjust my sizing die to headspace on the shoulder of the case NOT the belt...and push the shoulder back about 0.002"...by using a Redding Competition shell holder after I establish the best point through testing. It keeps trimming to a minimum...usually on the order of 0.003" per shot. The combination of finding the right belt depth for a slightly snug bolt closure and then adjusting the shoulder set back really protects the life of the brass and gives the bess accuracy...just like the benchrest folks. Hey...if you only want minute of elephant accuracy forget everything I just posted.

'Njoy

quote:

Originally posted by FOOBAR:
I'm working with my just modified and painted 375H&H testing the 270 gr Hornady SP. Belt depth with R-P brass ran 0.206" to 0.215"... Very few people bother with belt depth on belted cases....pity because you can really improve function and accuracy with just a little bit of work. . . .

Almost forgot to add...I adjust my sizing die to headspace on the shoulder of the case NOT the belt...and push the shoulder back about 0.002

Quite a sermon there, FOOB.

But in one paragraph you are obsessing over belt depth and in another paragraph you seem to have forgotten that already and are saying to forget the belts. Most readers tend to discount posts which make authoritative but contradictory statements. Take it easy and think about what you're writing and you'll enjoy your visits here on AR more and longer.

The only rifle I crimp on is my .375, but I'm going to most likely stop crimping them as well. I started crimping for it because the powder I was using at the time was resulting in a compressed load, and was pushing the bullets back out of the case. Other wise rather than crimping I would rather polish down the expander ball to increase neck tension, or get a set of bushing dies to accomplish the same thing.

To each his own, eh?

I crimp (using the Lee Factory die) wherever I can. I have no idea about the benchrest community, but it sure shrank my groups noticeably.