Question about crimping

How do you determine that the crimp is sufficient? I’m an inexperienced reloader and am just not sure whether I’m applying it correctly or not. What should I be looking at? I’ve got Lee crimp die for my 375 and Redding taper crimp die for 223 and 308. Also I’ll be loading for 470NE which I’ll be crimping with my Redding seating die. How do you know you’ve setup the die correctly? The die instructions are a bit vague for me.

Crimping a case is a feel type of thing. The idea behind it is to keep bullets from moving out from the case while in the magazine of the rifle as you shoot other rounds. Start with a light one, with a taper crimp just set it so that it just does a small portion of the case. Then measure the over all length and go shoot some rounds with other rounds in the magazine/clip. Then measure the OAL of the rounds left in the rifle. If they are moving under recoil then set the taper crimp a little bit further down the case.

For a round that you use a round crimp on just set it to where it slightly rolls the case mouth into the bullet and do the same as was mentioned above.

For adjusting the crimping die get the bullet seated to the point that you want to seat it without crimping it. You may have to screw the seating stem down into the die a long ways until you get the depth that you want. Then back the seating stem out of the die. Run the cartridge back up into the die and then at the top of the stroke screw the crimping die down until you can not turn it in any further by hand. Lower the cartridge and then screw the crimping die in 1/8 of a turn and then run the cartridge back up. Pull the cartridge out and inspect it to see how much crimp you have on it. If you want more then continue turning the die in 1/8 of a turn at a time until you get the crimp that you want. It is a lot of trial and err to get it to the point that you want.

The largest caliber that I shoot is a .340 Weatherby and I have never bothered to crimp the cases into the bullet. I have enough neck tension to hold the rounds that I am shooting in place even under the heavy recoil of the rifle.

Agree with JimP....it's a trial and feel thing.

I have Lee Factory Crimp Dies for about a half-dozen cartridges and I have found that most of the time I am right around 3/4 of a turn past where the die hits the shellholder to get the crimp I am looking for. Never less than a half and never more than a full turn. This on cartridges ranging from 30 to 45 cal.

With the taper crimp on a standard sizing die, it is usually about the same...1/2 to 1 turn, with one turn equalling about 71 thousandths of an inch of crimp (14 threads per inch).

A lot depends on the crimp groove, amount of recoil, loading density and burning rate of powder (slower powder and lower loading density to me means more crimp in general).

375 and smaller require no crimp, subject to correct neck tension.
this can be adjusted if necessary by the size of the expander
with magazine rifles, bullets will tend to be forced back into the case.
doubles will try to pull bullets out of the case.
if you fire 1 barrel, it pays to use the unfired round from the other barrel next where possible.
where crimping is necessary, it pays to use the crimping groove as you will get more grip than just on the bearing surface.
not crimping in the groove, but on the bearing surface, can damage bullets.
if you can avoid crimping it is preferable if only for case life.
bruce.

Thanks for bringing this question up as I just got my Lee Crimping die for my 470NE

I don't crimp anything 375HH or under and have not had a problem. I have neck tension on my TSXs in 375 to hold bullets in place. I loaded some 404J and crimped them just enough to see it start to fold into the cannelure. Won't get the rifle til August but I am prepared. Will see what happens.

I crimp everything in lever guns!

I don't crimp even for my 416. But with lever actions with tubular mags it is quite often required. In recoil the base of one shell base bumps the bullet be hind it. Quite often never a problem if you take out the remaining shells after firing and insert your new rounds 1st. Then the same shells aren't always getting bumped.

Graham Hunter said:

I don't crimp even for my 416.

Click to expand...

Same here..

I don’t crimp either my 416 or my 375...

No problems to date...

Lee Factory Crimp Dies make it a breeze. I like crimping, but for some years didn’t bother with .416 Rigby or .375H&H, and it worked fine. I just didn’t like the looks of those bullets in the bottom of the magazine getting knocked in - still shootable, but I didn’t like it. I once had a problem with a double .500NE... either I forgot to crimp or did a lousy crimp job, and when I extracted a cartridge the bullet stayed lodged and obviously I had powder all through the action. I was in thick buffalo country with a lonely hike back to the ute (and adequate cleaning gear) with an expensive rifle that wouldn’t close. Cleaning with toothpicks was fun!

I never bothered to crimp for the single-shot .450/400 3” NE, of course.

yes tube mags can benefit from crimping to stop bullets being pushed into the case like can happen with box magazines.
another approach to this is to select a powder that requires a little compression with a working load.
no bullet will push back into the case then.
crimping will shorten case life seriously.
to some degree this can be minimized by partial annealing every shot.
interesting about bens experience with the double pulling a bullet fully.
just goes to show that a double is not always 2 single shot rifles.
for that to happen with 1 shot suggests very little neck tension.
0.003" tension should be considered minimum in any hunting ammo, and then partial annealing of the case must be correct as well, and no lube between the neck and the projectile.
bruce.

I crimp for lever guns, for obvious reasons......the recoil can push bullets deeper in the case, causing jams, inaccuracy etc. I also crimp any heavy recoiling handgun round......nothing worse that trying to cock the hammer on a DA .44 magnum and not having the cylinder turn.....because the bullet has advanced enough from recoil to come forward of the cylinder opening. I also crimp heavy recoiling rounds (for me, .338 Win. mag and .375 H&H mag).....recoil can slam the cartridges around in the magazine, damaging the nose and/or pushing the bullets deeper in the case; since I want accurate rounds, I want everything to be THE SAME as much as possible.....consistency is everything. Also, any semiauto rifle round gets a crimp as well (.308 and .223), for the same reasons.

I believe that the Lee manual contains the statement that crimping makes for accuracy as the slight pressure build helps to make each shot more uniform. I cant say I noticed any change when I was too lazy to crimp. But, I did make the Lee Factory Crimp die part of my routine. I dont think it hurts to put a slight crimp with it.

nose damage is totally unrelated to crimping.
minimize the effect by loading the worst nose damaged ones to come out of the mag first.
revolvers have the same issue as doubles - pulling bullets.
probably the most important ammo to crimp is that for dangerous game.
case life becomes a non issue there, and those rounds kick enough for crimping to be beneficial.
nose damage probably has less affect on accuracy than base damage, and reshaping the bullet by overenthusiastic crimping would fit closer to the latter.
I have fired hundreds of 375 h&h, 338wm, 9.3x64, with only neck tension, and never had a bullet move.
and thousands of 308 out of f.n, h&k, and sig, military semiautos neck tension only.
450 nitro 3 1/4 in a double I crimped.
black powder long range target ammo, and a lot of the ammo shot at bison in the great slaughter is/was slip fit in a fired case, but this is/was in single shots.
if you are not getting enough neck tension, you can either polish your expander ball down until neck tension is sufficient, or buy a bushing sizing die, and use no expander, changing bushings until all cases offer sufficient tension.
crimping can induce bullet runout in loaded rounds, reducing accuracy potential in otherwise good ammo.
bruce.

I've never bothered with special crimping dies, as when I've got the stem of the seating die exactly where I want it, usually an extra 1/4 turn is enough to neatly crimp the neck. After the lock nut is tightened, then I adjust the depth of the seating plug. Simple!

This pic is from a batch of 9.3x62, using this technique, that I loaded up last week.

I crimp pistol rounds, 375 H&H, and 416 Rigby. All other calibers and cartridges don't get a crimp. Couple of things about crimping:
1. Essential that brass length is consistent. Trim it to be sure. I use a Lee case length gauge in my battery powered electric drill. Fast, simple, no set up time and 100% consistent. Don't forget to "de burr" after trimming.
2. Don't over crimp. Case will bulge and either chambers with difficulty or won't chamber at all. Light crimp as pointed out by others is sufficient.
3. I do load for 25-35 and 30-30 in my lever guns but I don't crimp them. Never had a problem but I can see how I probably should give em a light crimp so that I don't develop a problem.

My first 40 years of handloading I only crimped magnum pistol, lever gun ammo, some 45/70 and 458 Win.

Since starting to shoot more of the bigger boys (ie over 40 rifle) in the past few years, I am re-thinking my non-crimping ways.

I learned from experience (with a chronograph) that crimping can have a profound impact on consistency, especially when loading certain powders in certain applications (magnum pistol with H-110/WW296 without a crimp can be a real circus!).

And while I will never admit that factory ammo is in any way better than the stuff I put together...you have to wonder why the factories, who are trying to maximize profit, would add any cost to their ammo by utilizing a crimp, if it did not add some quantifiable value to the finished product?

There is a reason (or two, or three) why essentially all factory ammo is crimped.

For ammo that does not need a crimp due to ignition issues or potentially rough handling or recoil-induced movement of the bullet, the crimp may only serve to reduce case life.

If any of the above mentioned issue might exist, I am crimping.

I am on loading number 4 on some of my 450 Dakota brass...going to see how long they last with a stout crimp on every round!

Both @Pancho and @tarbe raise some good points.

What a neat trick of putting a Lee trim die into a drill! I'm going to try that one out for sure!

I reload all my calibres well within max pressures, as it saves throats, barrel life and cases. I always crimp for my 458 and I'm now up to my 5th reloading on some - Winchester! - brass. (I'll hold my breath if they come up for a 6th time!!! )