Home Forums Reloading Big Game Rifles To crimp or not to crimp, that is the question

.45ACP, 9mm, and .40S&W, and .30 Carbine to name a few headspace on the mouth of the case. If you know what your doing a light crimp doesn'r deform the bullet and a lot of factory ammo is crimped even though the bullet has no cannelure. I trim .44 and .357 magnum once and forget about it. You need to find someone to help you. I've been reloading since 1965 and I'm 55 years old. Reading the info parts of a good reloading manual is a good place to start.

i did think of them but we're in the big game rifle section.


fine, your choice to, i never crimp .40- 38/357

tube fed yes!

dream on! I guess old habbits are truely hard to break?

shall i post all my first-second and third match winning stickers for you?

go ahead and keep crimping away LOL....i been loading for over 30yrs too

if you dont keep them trimmed, how in the hell can they be anywhere near consistant when you crimp them?

i think i'm better off talking to the wall.

Your responses make me think you were new in the hobby. If it's working for you then well enough. I shoot things other than paper so I need reliable guns, ammo, and accracy.

I don't even crimp the .460 Weatherby, it is not necessary unless you have a set of sloppy tolerance dies that do not fully size the necks.I also dump bad dies fast and rebuy a new set until they are right.

I do crimp some of the straight sided cases but that is for feeding purposes only.

again, you're so funny LOL

proof is on the paper

dont forget to click on the link of whitetails that didnt show up for some reason.

It's way beyond a hobby for me! I've crop damage shoot whitetails and have many many that aren't paper.



I think i am done arguing with someone who obviously has been figured out.

a few practice groups at 700yds and as exped to be the lower 3 shot group is 900yds (practice)


i hit groundhogs so far away i have to take a dog to find them, and i avg @ 100/year

A die doesn't have to be defective in order for a bullet to shift in the case from recoil. I regularly reload for 7-8 different calibers, and I crimp just about everything with Lee crimp dies. Let me be clear: I'm not suggesting that it's absolutely necessary, but I reject the notion that there's no value in it.

I've never understood why crimping generates such a viceral reaction from people. I'm not even going to make the consistent ignition pressure argument, but let me make a case that I can support with empirical data (and a set of calipers): Under heavy recoil, bullets can -- and DO -- contact the front wall of the magazine box due to the rearward inertial of the rifle, and they then can -- and sometimes DO -- push further into the case because of the resultant force. This changes OAL, and, if you've done any serious load development, you know that even 0.005" of OAL can have a dramatic effect on accuracy for a given load.

I defy anyone to prove to me that crimping REDUCES accuracy. So, if crimping simply guards against a shift in bullet depth from high-recoiling rifles, what's the problem?

Seems we need a very good consistent shooter to load 10 with a crimp and 10 without. Shoot each ten for a group and we'll get an idea whether accuracy is affected or not.

an AR would be another round worth crimping if you had any feeding issues.

but the original question to this topic, wich many opinions seem to forget as the post rolls on......
from Robc



i would not crimp it unless it is a tube feed.

you posted the same time i wat trying to type.



there ya go....let us know what you found out!

I have yet to hear one single 1k bench shooter say "i crimp my bullets"

I crimp for levers and handguns.

I have never crimped for my 30-378 378 416 and 460 Bee mags.

You wouldn't want to base anything on my shooting. I want to make kill shots on whatever I shoot at but to shoot 1000 yards, I'd have to shoot across 2 or 3 ridgetops or drive west.

Started loading in 1965 and you are 55yrs old? Started loading when you were two years old!!!! Wow, I am impressed. Most kids that age haven't learned to read.Rick.

what gun are you shooting? bullet? powder? brass? primer?
magazine fed? If it is factory gun, I would FL size your brass and fire once, measure your headspace of a fired round and "BUMP" the shoulder back .002-.003 to size your brass to your chamber. If you have a HS tool? If not, slowly FL size your brass slightly more each time until it just chambers easy enough that you dont have to work the bolt hard. AKA bumping back just enough to put less stress on the brass and fit your chamber.
follow me?
now your brass is sized just right, clean the lube off! or trim with it on like i do with my wilson
trim .010 from max length listed in manual (not necessary every time maybe 3-4th, square mouth is more important than length as long as it is not too long.
prime
I always from there select a reputible powder for the bullet shooting and work up with a crony to find max! then back off at least 1-2gr then play with seating depth for best accuracy.

neck tension is the next subject that i go for (the button that is pulled back through on the up stroke)

brass of different makes have different thicknesses! I select a brass that has .002-.003 of bullet release room!
measure a loaded round then a fired round. or you can controll that with neck turning. or a die like redding bushing dies.

i'll stop there for now

or maybe seampman700 with his hunting expertise can tell you the rest?

Benchrest guys shoot 12 lb rifles that don't recoil. They also don't feed their guns from a magazine. Next argument?

That would be good, assuming the test rifle was accurate enough to be considered a test rifle. And, the ammo was consistent enough for the resultant data to not be lost within the margin of error. What caliber would it be? How many rounds would we need to prove the point? It would have to generate sufficiently high recoil so that there was enough inertia to create the effect I'm talking about. Sounds like a lot of work. Who would shoot it? How would we know that they could shoot well enough to validate the results? Only the factory has the proper equipment and controls...but wait...they do crimp, don't they???

How about those of you who laugh at crimping just chew on this postulate: Changes in OAL can (and do) have a measurable effect on precision (this is beyond dispute). Blunt force, applied to the tip of a bullet from the magazine wall of a heavy recoiling rifle can drive the bullet into the case, thereby changing OAL. This is why your lead tips get smashed up, by the way; we can debate how much force this takes, but not that it does or does not occur. A crimp, if properly applied, can definitely retard the tendency of a bullet to shift in response to such a force. It's a mechanical lock. Seems like a reasonable control mechanism to me.

Thus, those of you who don't crimp, and have never needed to, likely wouldn't know if you would benefit from it or not. Being blissfully unaware does not disprove the efficacy of a procedure, no more than not wearing a lifejacket proves that they aren't necessary (because you haven't yet drowned).

I think I'll just leave my dies like they are for now. I put bullet in, aim at deer, pull trigger, gun goes bang and deer falls down. Yep, it's all OK.

sorry, friendly reply to richard (seriously, my typing may sound harsh but i don;t sugar coat it) it is NOT ment to be harsh it is just my reply and typing.



don"t recoil? DUH, complete BS! now we're defying the laws of physics

no magazine, exactly! so it is bullet in chamber

why don't they crimp it then if it gives better accuracy?
It dont! or the top shooters would be doing it, don't ya think?
maybe you should crimp a few and go to a santioned match?

I will go with tube fed and AR's and maybe some handguns but BS on the accuracy thing.

it would be there strictly to hold the bullet in place if needed.

I never said that crimping gave better accuracy (we're actually talking about "precision," not accuracy). My point was that crimping didn't degrade precision (in my experience), and it has other positive attributes in that it prevents bullets from slipping in the case neck under recoil and from their impact with the front of the magazine wall (in heavy recoiling rifles).

People tend to dismiss crimping as a fool's errand, but you're making my point that a lot of folks don't understand that it has purposes other than its effect on shot precision.

As to the benchrest thing, what I said was correct. Of course I didn't mean ZERO recoil, but there's no appreciable recoil in your typical benchrest rifle -- certainly not enough for the inertial effect of which I'm speaking to matter. Besides, you'd have to have rounds in the magazine (not the chamber) in order for the bullet to be pushed into the case by contact, and BR shooters load their rounds one at a time, directly into the chamber.

no problem, but to crimp a 308 winchester round still wouldn't make sense to me unless it is tube fed or in an AR semi platform

i have hammered 308 win bullets and case friction is plenty.

we still don't know what rifle or bullet rob is using ?

to really answer the first question,I think we can all agree on that?