crimp or no crimp

[burntmuch]

Just started reloading? Im reloading for my nef 45/70. Should I crimp or not, & if I should how much of a crimp do I need?
                                                                                                                                                           Thanks JAY

[quickdtoo]

I use the Lee factory crimp die on every cartridge I load for if they make one for it! If you're gonna crimp, it's the way to go. Read the reviews at Midway on the 45-70 FCD...

Lee FCD Reviews

Tim

http://leeprecision.com/cgi/catalog/browse.cgi?1175378874.3426=/html/catalog/dies-crimp.html

[Tom W.]

Shouldn't need to in a single shot, unless you're not getting consistent ignition.

The Lee Factory crimp  is the way to go if you feel the need.

[PaulS]

I never crimp anything unless I have to. I crimp my magnum hand-loads so the bullets stay put but I don't see the need to crimp anything else. I have tried crimping and found it adds one more variable to the process of getting accuracy - Each crimp has to be exactly the same or it can throw your accuracy out the window. Its hard enough insuring that the case neck tension is the same. I get 1/2 MOA accuracy without the crimp and a bit over 1 MOA when I crimp - tested in my rifles in loads worked up without a crimp. Anyone who shoots an old 03A3 and gets better accuracy with the original barrel and chamber than 1/2 MOA can try to convince me that I need to crimp for accuracy. The old girl does OK without crimps.
The military crimps to keep bullets in place while the ammo is shipped all over the world - 30-30 loads are crimped to keep bullets in place, ammo manufacturers do it for the same reason. None of those manufacturers or loads is known for their accuracy. They certainly don't get 1/2 MOA accuracy in my guns.

[burntmuch]

So you dont need to crimp for a bolt action? Right now Im reloading for single shot 45/70, but soon I ll be reloading for my rem 700 7mag   Jay

[PaulS]

I can't tell you whether you will need to crimp your 7mm mag or not. Load a few rounds and fill your magazine after measuring the OAL. Fire two rounds and then check your OAL on the cases in the magazine. If the OAL hasn't changed then you don't need to crimp. If you ever find that the cases are affected by recoil then you may need to crimp. My 3006 and 358 don't need a crimp to hold the bullets so I don't crimp.

[Lloyd Smale]

9 times out of 10 ive gotten better accuracy with 4570s crimped. About the only time i dont crimp them is if im loading real light loads with fast burning powders.

[gypsyman]

I prefer the Redding Profile Crimp die. It's not a set crimp. You can adjust the amount of crimp, depending on what gives you the best accuracy. On most single shots, no crimp works the best. But there are times, like on a large capacity case like the 45-70, and a tapered case, just a small amount of crimp, will give you a more complete burn of powder. Plus, with a Profile crimp, you're not working the brass back and forth so much, so it lasts longer. My 2cents worth. We keep trying peace, it usually doesn't work!! Remember(12/7/41)(9/11/01) gypsyman

[burntmuch]

So crimping not only holds bullet in place ,it increases bullet pull . Im gunna reload 6 crimped & 6 uncrimped & shoot, see how they group. Right now uncrimped are grouping pretty good. ragged hole at 50yds, 2inch group at 100. Thats pretty good for me. & thats using the Lee classic loader. $15 at Midway  I can crimp with it , but I think uniformity might be tuff.

[beemanbeme]

I've shot a M700 in 7mag since Hector was a pup and never crimped my bullets.  And that includes most or all of the standard bullets as well as NP's and Grand Slams. 

[HEAD0001]

I reload alot of 45-70.  It is my favorite round.  I load for levers, and single shots, with smokeless and BP.

First-what type of bullets are you using?  I ask this for one simple reason, I have found that I need slightly more "belling", when I use soft cast, versus jacketed bullets.  The amount of "belling" you use is a factor.

Shorter(lighter) bullets normally need a little more crimping than longer(heavier) bullets.  There is less neck tension on the shorter bullets.  Some of this tension is due to "belling", and some is due to actual bullet length.   Check your run out.

When crimping, I prefer the taper crimp over the roll crimp.  IMO it does not work the brass as much. 

Your bullet selection and reloading technique will determine whether you should crimp or not.  Accuracy is also a factor.  What accuracy requirement are you after?  I you are using it as a hunting rifle, and limit your shots to 150 or so yards, then I see no difference between 1/2 inch or 1 inch at 100 yards.  I think you would be happy if you could achieve 1 inch at 100 yards.  I doubt if you achieve that goal. 

I suggest you try BP in that baby.  Just fill up the case with BP, lop off the excess with a butter knife, and seat a 405 that you cast yourself.  You can have alot of fun at the range.  And you can easily shoot 500 rounds for under $100.  I do not crimp my BP loads for my single shots.  And I find that I can get alot of loads out of a low pressure BP load, with very little working of the brass. 

The real beauty about the 45-70 is that you do not need hyper velocity to achieve "killing power".  Any load from 900 to 1600 fps will knock a deer off his feet.  hyper velocity is not necessary, and can be a detriment to bullet expansion depending on your bullet.  A soft cast at 1200 fps is devastating on deer.  If you want to bump up to 1600 fps then add a little linotype or tin.  I normally go to a jacketed bullet if I want to go over 1600(no real need) fps.  I will crimp those heavier loads.  Tom.

[218Bee]

I crimp only for the autoloader. I use the RCBS seater set up to crimp lightly.

The manuals only call for crimping in autoloaders, pumps and lever guns. I don't bother with the bolts and the singles.
I tried it with my Mauser and found I had better groups un-crimped.

The bullet must have a cannalure, as well.

Shoot 'em up.

Rick

[Black Jaque Janaviac]

I have seen .454 Casull bullets back out of the cases when they weren't crimped enough.  The cylinder locked up when the bullets pushed against the side of the forcing cone.

I've also heard of tube-fed lever actions pushing bullets deep into the case when not enough crimp is applied.

I've experienced straight cased cartridges hanging up on the case mouth when fed through a lever action.  Just enough roll crimp to prevent this works.

Beyond that, less crimp seems better.

[Wingman26]

Crimping isn't necessary on a single shot, but hard kicking loads in a rifle with a magazine usually need to be crimped.

[ihuntbucks]

I crimp everything I load.Lee crimp......Rick

[burntmuch]

I just loaded 10 crimped & 10 uncrimped. gunna see how they do

[PaulS]

I only crimp when it is necessary. It is necessary with certain powders in some cases. Straight wall magnums should be crimped when using H110 or W296. Other than that it is necessary to crimp only when a round changes dimensions while held in a magazine while shooting. It is common to crimp cartridges that feed from a tubular magazine and magnum rifle cartridges in box magazines sometimes need to be crimped or the bullets back out of the case due to recoil.
The best way to see if your cartridges need to be crimped is to try them both ways and see if the dimensions change under actual shooting conditions. I don't crimp bottle-neck cases for single shots but I do crimp my 357 maximum cartridges in my single shot. I also crimp my 357 magnums in my single shot guns. I use H110 powder in them and it needs a good crimp for consistent ignition. I don't crimp my 3006 or 358 loads. They have never shown any tendency to back out or get shorter in use. I don't crimp my 30-30 because it is used in a single shot. My accuracy is normally in the sub MOA with really good days having it in the sub-caliber group size.
It is this 35 year veteran reloader's opinion that crimping just adds another variable to the list of variables that affect accuracy. The fewer of those you have the easier it is to shoot smaller groups.