What kind of gun are you shooting? Bolt action, or gas operated?

 

I have shot probably thousands of rounds of .308 through bolt guns over the years and never crimped. Never had a bullet come loose. On the other hand, it probably won't do any harm either. It's just another step to add to your reloading process, which may not be convenient with a Lee hand-held press. OK, after some thought, I remember crimping some rounds when I used a bullet with a cannalure. But now I mostly shoot my own cast bullets and I never crimp them. Unless you have some kind of issue dealing with loose bullets, I wouldn't do it.

 

I think you would need a better reason to crimp than the guy at work telling you so. Particularly so since you are having no trouble without crimping.

You could crimp only because you want to though(hand-loaders can do that). Your bullet seating may or may not have a crimp shoulder in it? Read up on that yourself. If not, here is one option.

Factory Crimp Die 308 - Lee Precision

Cheezywan

 

I do not crimp bullets when reloading ammunition for a bolt action but for a gas-operated or lever action rifle with tubular magazine, I do and for those I use a bullet with a crimp groove.

 

Thank you. I do shoot a bolt and I do not believe the bullets have the groove for crimps. I just wanted to get others opinions.

 

If your reloading your seating die has a crimp built into it. That should be all of the crimp you need.

If the bullet has a crimp groove I tend to put some crimp on it. If it doesn't it's optional. Depending on the gun you may need it for complete powder burn depending on what powder and load you are using but if you have loaded 100 rounds with it and you have had no troubles I'd forget what the "guy at work told me I needed to do". He is not loading and shooting your rifle, you are. The only gun I crimp every round for are my lever actions.

 

I crimp everything, but I also have single shot and bolt actions that really do not need a crimp, but I do it anyway. Proper neck tension alone should work just fine for you.

 

Crimp or not? (Not)

I never crimp centerfire rifle ammo unless they are extra heavy recoil magnum loads for magazine rifles (like 375 H&H or 416 Rigby). I do crimp revolver loads, such as my 44 magnum S&W Model 29. I have never had a problem with bullets moving out of neck and becoming too long to feed. I have loaded for about 30 years for about 15 rifles in a variety of calibers from 270 to 338 RCM to 35 Whelen to 375 H&H.

 

Have well over 3,000 rounds through my 308. Assuming I did a proper job of reloading, I've never had a bullet move. The reason I DO crimp some loads is because it lowers my ES/SD.
But that is really an application specific thing.
Also shot many thousands of rounds through various AR pattern rifles with no crimp, and no issues.


Unless you get into monster recoiling rifles, I wouldn't lose sleep over it.

 

You don't need to crimp them unless you want to, there is no reason to do so.

Magnum/heavy bullet revolvers? You must crimp those, and make sure you do so properly.

 

We can only assume that you are shooting a bolt gun so:

That Sierra Match King doesn't have a cannalure, so no don't crimp them. Like Cheezy said, Lee's factory crimp die is the one to use if you absolutely think you have to.

I shoot their 150 grain Game King in my 300RUM and if any bolt gun were to need crimped, that would be one. I only ever crimp my 44 mag, .357 and 45-70.

RJ

 

We can only assume that you are shooting a bolt gun so:

That Sierra Match King doesn't have a cannalure, so no don't crimp them. Like Cheezy said, Lee's factory crimp die is the one to use if you absolutely think you have to.

I shoot their 150 grain Game King in my 300RUM and if any bolt gun were to need crimped, that would be one. I only ever crimp my 44 mag, .357 and 45-70.RJ

Wow......A 150 Sierra in a .300 RUM. I hope the targets (if they are live and to be eaten) are downrange a ways!

RJunky is correct though, if you want to crimp get a bullet with a crimp grove (canneure). Like a 150 grain Hornady SST.

 

Do you have a kinetic bullet puller? If so, put one of your non-crimped loads in there and see how hard you have to whack it to get the bullet to move. I doubt your recoil or dropping a loose shell will ever get close enough to that energy to make the bullet move.

I only crimped a few samples when I was just starting reloading 20 years ago, and the crimped rounds were no better accuracy than the non-crimped, so I never crimped again. (Except for the few I reloaded for a 30-30 lever gun.)

 

I always crimp in the cannelure with jacketed bullets, and sometimes I use "Lee Factory Crimp Die" on my Nosler Ballistic Tips and Sierra Pro Hunters. Also, cast rifle bullets usually have a crimp groove, so I use it. I shoot many old military surplus rifles and accuracy is not quite as good as a CNC mfg'd gun, but they still fare pretty well. I haven't done many side by side comparisons (crimp/no crimp), but the ones I have done (which is not much), crimped shot better!

 

Some of the loads in my 308 bolt guns have shown slight improvement with a light crimp on a Lee Factory Crimp Die. I'm of the opinion that the extra step involved, and the extra working of the brass is usually not worth the small results gained.
For 100yd shooting at game, I get tight neck tension with Lee Collet dies and call it good.

 

The case neck tension holds your bullet in place, and crimping is rarely necessary on a bottleneck rifle cartridge execpt for a few semi-autos. You'll sometimes see a cannelure on bullets made for that purpose.

 

I agree with a lot of the guys here, saying that neck tension should be ok to hold your bullets in place. I don't crimp loads in a bolt action. I've got a question about your bullet. Will a Sierra Matchking reliably expand? I don't know.

 

No it will not.

 

I have been reloading a 223 for a number of years with Hornady 40gn V-Max and never crimped. I use it for prairie dog hunting and get a 1 1/2" group at 200 yds if I do my part. After I got a AR, I got the Lee FCD for the 55gn I was going to shoot.

Just for grins, I crimped a few rounds of my varmint load and ran some over the chronograph and some downrange to check the group. Very little difference in FPS but it did close up the group enough to be noticeable.

Lago

 

Some, maybe most long range and bench competition shooters crimp to try to make sure every round has the same neck tension, but they are working on minutia of accuracy that are irrelevant to most of us loading hunting and target shooting ammo. That is probably why most of us consider it unnecessary, we are not precise enough on the rest of the loading and shooting process to be able to notice any difference on most rounds.

If you do crimp, study carefully the proper techniques. As mentioned by several posters, crimping a bullet with no cannelure can deform the bullet and result in excessive pressure spikes so proceed with caution.

 

When I first started reloading for 7.62 nato, I didn't crimp. I was shooting rounds through an M14 and got good accuracy. I tried some crimped and got better accuracy, so now, for that rifle, I crimp.

You want to know wether to crimp or not? Load up 10 rounds without a crimp, load up 10 with a crimp and compare at the range. The difference, if any, and how much, will tell you wether to crimp or no.

As far as the bullet coming loose? If you've sized the neck like it supposed to, then forget about that unless your magazine feed system is particularly violent, or you've got an extremely heavy recoil round. The M14's gas system is pretty violent and I never had a non crimped round move, though I started crimping soon as I found an accuracy increase with crimping. Like someone said, try a kinetic puller and see how much force it takes to move one.

 

Expert Opinions on Crimping Differ

Published opinions on this differ. I use a Lee loading press and use their "Factory Crimp" die on every round. Why? Because they say it makes the grip of the casing mouth on the bullet more uniform and thus bullet performance will be more standardized and reliable. It is an easy, simple process, so I do it.

Necessary? No. Try and turn a loaded bullet in its casing. It should not turn with finger pressure alone, so it will not "fall out." Most experts seem to think that it is advisable to crimp where a cannelure is present, mostly found only on rifle bullets. The cannelure is the scored or striped portion ringing the bullet just above the base.

If you do crimp, pay attention to the directions. You can crimp too tightly, deforming the bullet. This will adversely affect accuracy and possibly even safety. Safety would become a factor if your crimping is so excessive that chamber pressure builds up too high because the bullet is delayed in escaping the casing.

 

If the rifle in question has a tubular magazine then crimp. It it doesn't have a tubular hag, I wouldn't bother. In my experience, for best accuracy you're better off not crimping.

However, as mentioned, if the rifle has a tubular magazine you must crimp for safety reasons.

 

I've used the Lee FCD off and on for various things over the years, but I have always marveled at the folks who used them on non-cannelure bullets and raved about the accuracy increases.

When you see what goes into bullet making, the lengths gone to in order to make them consistent, and then you see people willfully squeezing a bullet so that the core is loosened in the cup...makes me shake my head.

 

I recently started crimping all my rounds after experimenting with the lee factory crimp. It got rid of the Flyers and gives me single digit SD's . I think we got something for once out of Mr. lee besides hot air. Lol

 

If what you're doing now is producing acceptable groups and cycles reliably through your rifle, why change it based on advice from somebody who's probably never even seen you shoot your rifle? If you feel inclined to experiment, get yourself some bullets with a cannelure (fancy name for that knurled groove put there for the case mouth to crimp into), work up some loads and see how they shoot. Some loads and some rifles like them; some don't. As the Aussies say, "Suck it and see!" And no, I don't have a clue where they came up with that saying and probably don't want to.

 

I'm an Ausy and I can't say I have heard that one ,some one might of been pulling your leg.

 

With rifles, it's common practice to roll crimp with semi-autos, pump actions, or tube magazines. Also, bolt actions with heavy recoil and heavy bullets may need crimps, especially when hunting seriously dangerous stuff. In these situations, always use bullets with a crimping groove. All other rifle situations, decide with just whatever works best, recognizing that crimping can cause some negatives too. In handguns? Well, that's a whole nuther issue.

 

I use a lee factory crimp die.
I would measure the length of some rounds, put them in you magazine and cycle them through the cahamber.
Them measure them again.
I crimp because i think i get more consistent neck tension.
You can adjust the amount of crimp and if there is no crimp grove i do it very lightly...tj