Crimping

[houdni]

Hi,

Im about to step into the water and start reloading...i hear so many different opinions...is crimping necessary on the 308 AR's?

[imschur]

Well this will probably spark some dialog. Its mostly personal preference in an AR. I suspect many AR shooters perform a light crimp. I believe its only mandatory in tube fed guns and guns with decent recoil. Some folks also let the bullet dicatate. If it has a canalure they crimp it.

[imschur]

I just found this which mostly goes with what I said only its explained better :)

[survivalshop]

I light taper crimp all rifle ammo I load .

Crimp grove or not ,you only need a light crimp .

[SWshooter]

My experience with my LR-308, and my HK-91 is that if you don't crimp you will get flyers caused by bullets being driven back into the case during the rather violent loading process. Perhaps polishing the feed ramp or adjusting the magazine feed lips might eliminate the problem, I simply crimp my ammo in a lee factory crimp die, canelure or not, and problem solved. If you occasionally notice missing primers from what is usually normal pressure rounds, that is also probably the cause.

[Dusty44]

I have been aware that the neck resizing of the 308 Win rounds I am loading is really not all that tight.  It does very well when single loading my bolts but the LR-308 loading sequence and recoil is stiff.  The scope is rotating inside the rings on the LR-308 from recoil. Other than obtaining new and better rings,  there are a lot of forces there.  I am waiting for the mailman to deliver a 308 Win Lee Factory Crimp die,  $10 + shipping from MidwayUSA.

[survivalshop]

Are you neck sizing only for your AR 308 ? Semi auto reloads should be full length sized, at least.

Just be careful with any type crimping die ,if you over do it ,they will set the case back & bulge the case shoulder.( especially 223 )

I personally use small base die's ,but most will not need them .

[houdni]

i will be starting off with some small base dies....RCBS that is....i believe the bullet die puts a crimp into the process...

[SWshooter]

The advantage to the Lee die is that it puts no strain on the shoulder of the casing. You can put a very heavy crimp, even on a bullet with no canelure, without damaging the case in any way. I would not use a a small base die unless I had to, it puts a lot of strain on the brass and may prematurely work harden the cases, especially in the head area. I've loaded for dozens of autoloaders and never found it necessary to use small base dies. I do however  full length resize for my autoloaders. The RCBS dies will be fine for crimping with a canelured bullet. Use care when adjusting them, and be aware that overall length is critical with that type of die. Another reason I like the Lee dies, case length has no effect on the crimp.

[CraigOK]

a buddy loads for an m1 and he doesn't crimp b/c his loads are compressed enough that the bullet can't be set back by recoil- so if that's the case w/ what you've got I'm sure it's slightly easier on the brass to have none.  I use a Lee fcd and put a light one on there- I subscribe to the idea that it might help to even out my velocity SD. Haven't got a chrono to test that theory though

[seasprite]

I use a light crimp or my col would change when chambering a round.

[NoFail]

I use a Forster FL die and it leaves .002" of neck tension. At least it did until I polished the sizer ball down to leave .0035" neck tension. I haven't made a dummy round to check if it works yet. Should get on that.

[Pappy1600]

Light taper crimp here...

[survivalshop]

Since this subject started , I purchased a Lee factory crimp die for both .223 & .308 & I kinda like them , testing as far as velocity & grouping is on going .

[Ben Diss]

If you're loading a boat tail bullet and prepping the neck correctly, you don't bell the mouth, right?  If that's the case then you've set the proper neck tension in the sizing step.  Neck tension is what holds the bullet from set back.  Changing neck tension AFTER seating could compress the bullet.

I don't see why you'd ever crimp a .308 round.

[98Z5V]

I don't see why you'd ever crimp a .308 round.

Wouldn't really be necessary on a bolt gun, but on a semi, autoloader, just the feeding process can cause setback.

[Pappy1600]

Wouldn't really be necessary on a bolt gun, but on a semi, autoloader, just the feeding process can cause setback.

Agreed..

[seasprite]

Wouldn't really be necessary on a bolt gun, but on a semi, autoloader, just the feeding process can cause setback.

I had the opposite problem when the bolt slammed the round in the chamber the bullet slid out a little. Kinda like using a kinetic puller.

[98Z5V]

That just means you're running that bolt like you mean it!  <laughs> <thumbsup>

[Hitman]

I just purchased a POF and this info has me thinking. I've loaded my own ammo for bolt guns for over 40yrs. Also some Rem 742s. My out of box accuracy was not as good as I hoped. I've only got 200rnds through it and am going to start trying to brew up some better ammo. I got 260rnds of Winchester 147gr FMJ white box with it and am averaging a little less than 2" @ 100yds. I'm using a Leupold VX III 6.5-20X40 EFR mounted in Nikon P Series rings. My bullet is going to be the Sierra 168gr MK. I haven't made a powder choice yet but have a few jugs of W748. I found a deal on a few hundred Federal Gold Medal Match brass 1x fired in a Mod 70 Win. I've never tried a roll crimp on a non canellured bullet, don't know the effects of attempting it. I've adjusted neck tension before by modifying the expander ball but I'm not sure it would work on this platform. I have this stuff all prepped and ready to go, I just need to get some feedback on your experiences. I believe this rifle is capable of more than I'm getting right now. I've always been an RCBS man and have never tried the Lee taper crimp. I barely bump the crimp on ammo for my 5.56 but this is an entirely different beast.

[Skiffjockey]

Another happy lee factory crimp die user here. I never had problems with bullets moving (that I noticed) but I no longer need to uniform my case length. As long as the case length is in spec the crimp die does the rest and you get uniform neck tension and a sturdy round for for the violent action of the 308. I also use a small base die because the loaded round/chamber tolerances are greater therefor giving you greater reliability. I have tried regular dies with no difference in accuracy.