I would like to read some in-depth or at least practical discussion on this from those of you who know about this subject.

I'll start by asking a question or two. My focus is the 458WM, but of course getting the bullets to stay where they should, under recoil, applies to big bores in general.

What about the Lee factory crimp die? Is it really good and worthwhile, or is it crap like the rest of their stuff?

Can an adequate crimp be obtained by just using the roll crimp in the seating die, such as RCBS or Redding?

Does a crimp, such as that of the Lee factory crimp, affect accuracy in a bad way?

Is there another crimp method or tool that I haven't mentioned, and thus don't know about, that is better?

Thanks,
KB

I avoid Lee stuff also but thier Factory Crimp Die works well.

I have used the Lee Factory Crimp die on all my big bore 375s, 416s, 458 win. mags., 458 lott, 470N.E, and my soon to be finished 404 Jeffery.

I can tell you it does not seem to negatively impact accuracy, at least in my rifles...not sure if it improves accuracy as I always crimp my big bores. It is easy to use and works, it is the only crimp method I use...and would recommend it.

If someone knows something better, I am interested in hearing about it..

I have used the Lee Fact. Crimp die for 375HH, 458WM, 458Lott, and 45-70Gov't for some years now and it is a good tool. Easy to use and results are very near factory crimp appearance.
Very reasonable in price and they will custom make one as well.

quote:

Originally posted by jjs:
If someone knows something better, I am interested in hearing about it..

The LFCD basically allows you to put the same crimp on your handloads as the factories use on their ammo. For most applications a roll crimp is fine, but the LFCD does a better job.

If there were any real advantages to the roll crimp I would think that we would see it in use in some of the premium factory ammo.

The LFCD also allows you to crimp anywhere on the shank of the bullet, regardless of the location(or absence) of the crimping grove. This allows you to load to the optimum OAL for your rifle.

I don't crimp most of my big bores but that is personal choice and not something I'd recommend
to everyone.


One thing I do do is use a slightly undersize expander which makes the bullet to brass fit a bit tighter.


.

I have an RCBS 3 Die set in 458 Win Mag. I sent an E-mail to RCBS and asked if I need an additional Crimp Die for Full Power Loads and they said No you don't?

To my mind and experience there are a few things to consider when looking to crimp or not crimp and to get a good crimp if applying one.

Firstly I would be ensuring that the case neck provides the best bullet hold possible and annealing the necks will help as will matching the neck expander button to the bullet as 500N mentions above.

Some big bore (and smaller bore) bullets, such as RWS, Hornady, etc do not have a definite shoulder for crimping but rather a form of canneluring for crimping the bullet onto. A roll crimp is not so effective for these bullets unless done properly. Some factory RWS big bore ammo was known for pushing the bullets back into the case under recoil after being in the magazine for a period.

Kynoch, Norma, Woodleigh and others have a nice groove with a defined shoulder where with a good roll crimp applied it would be virtually impossible for the bullet to be driven back into the case under recoil (all other things such as neck tension etc being properly set).

To get a good roll crimp the bullet seating die (if using it for crimping) also needs to be made with close tolerance in the neck area.
My custom made RCBS 404J seating die very neatly swages back in the flair I apply to necks when seating cast bullets, I don't crimp these and they do not move in the magazine at all. The tolerance in the seating die is so close that 'as cast' bullets will not enter.

A good heavy roll crimp relies on the neck just behind the crimp being held tightly into spec by the die otherwise a bulge will be the result and the effect of the crimp lost.

I roll crimp with my standard Redding dies - works great.....the key is to not over do it.

Make sure all your cases are the same length (trim) and seat the bullet so the cripping groove on the bullet lines up with the case lip.....now un-screw the bullet seating stem....cam the cartridge back up into the die and hand tighten the die back down on the cartridge....you can usually feel the crimping process.....inspect a couple times until you just get enough crimp and you are good to go.....it is as easy as that.

quote:

Originally posted by MFD:
I have used the Lee Fact. Crimp die 458Lott for some years now and it is a good tool.

Was the Lott die a special order?

quote:

Originally posted by 500N:
One thing I do do is use a slightly undersize expander

Could you explain how you under-sized it?

I used to shoot Barnes X, when they switched everything to TSX I couldnt get good enough neck tension for my 338 & the bullets in the mag always seated deeper...I switched to NP and the problem went away.

I use and recomend the Lee Factory Crimp Die!

Mad Dog

I'm new to big bores, but I plan on getting a Lee factory crimp die to load for my new .375H&H. I own and use a Lee crimp die for every other rifle caliber that I load for, and have always had good luck with them.

Good Hunting!

If you load bullets which are designed to CIP standard for your particular cartridge, the crimp to nose length will be preset for you. Crimp into the first groove and carry on.

Have used the Lee FC Die on 375H&H, 458WM and smaller calibers. Works well.

I crimp my big bores with my factory RCBS dies. Lee doesn't offer their crimp die for the 416 Rigby. They wanted around $90 for a custom die for that caliber. Since I don't shoot these rounds that much, I just use my standard dies, but seat and crimp in two separate operations. Set your dies for seating without crimping then back out the seating stem and adjust the die body to crimp. Much better than trying to seat and crimp in one operation.

Well, I tried crimping with my Redding die, the one with the stamp "Pro CR", which I think is Pro Crimp, whatever that means. All the cases were Winchester 458WM, and trimmed to the same length. I adjusted the crimp die with a hard crimp, any more felt like it would buckle the brass. The bullets were seated the correct depth so that the crimp was in the cannelure grove.

I filled the magazine, three down, and I fired four rounds, loading each round singlely, on top, leaving the same three cartridges down. Upon inspection of the three rounds from the magazine, all the bullets had set back beyond the cannelure. Basically, the compression of the powder stopped the bullet from going further into the case.

Then, I shot a group with the three cartridges from the magazine, loaded on at a time in the chamber, and they shot a good group, only a slight shift in POA.

So, today I placed an order on line for the Lee die. Hopefully it works.

KB

Nobody has mentioned the Bayonet crimp. It was used in the past on most big bore Kynoch ammo and others. It was normally three deep "dents" pushing the case brass into the bullet. If you think we have heavy crimps today just look at a older big bore double rifle cartridge.

I really like the Lee factory crimp except on really expensive brass cases because I've had premature failures due to the sharp edge where the crimp is bent into the cannelure. Had a piece of the mouth rip loose and leave with the bullet.

But have not that problem with a roll crimp.

Also the Lee crimp works well where there isn't a cannelure on the bullet.

I looked through the .458 bullets carried by Midway, and in jacketed bullets the only ones without a cannelure are some Barnes original, and Rainier.

I think part of the issue is the Winchester brass seems annealed softer near the mouth than I've seen on brass for other cartridges. It work hardens a little with a few shots, but it feels butter soft going through the dies initially.

KB