Crimp Or No Crimp?

[Palmetto-Pride]

Just getting into "metallic" reloading mainly 300Blk and 308WIN. I bought the Hornady LNL single stage press and Hornady Dies I was reading the instructions that came with them on adjusting the seating die and crimping and not crimping the bullet. I realize for a bolt action its probably not as important as with a semi auto, but I was wanting to get the experts opinions on it.....

Thanks!

[Jbotto]

For my bolt action rifles, I do not crimp. It's just another step as I see it, and I'm happy with the results I currently get.

[Slamfire]

I only crimp for lever action rounds and for elephant gun loads. I hope I don't have to explain why for those loads.

I do not crimp for my 223, 308 or 30-06 rounds used in AR15's, M1a's/PTR91/FAL's and Garands.

Crimping damages bullets. You may not see it, but you are swaging the soft lead core. It is difficult enough to get good bullets, displacing the center of gravity from the axis of rotation will only create inaccurate.

Lee recommends creating a “cannulure” in the bullet with their crimp die. You can see the results on the 6.5 SMK bullets.

In my opinion, the "single most important thing ingredient to accuracy" is not "a uniform start pressure", but rather good bullets undamaged by a crimp die.


Crimp dies are un necessary if you control neck tension through your sizing die. You only need neck tension on your bullets if you are shooting a lever gun or an elephant gun, or a Vulcan 20mm chain gun.

[Palmetto-Pride]

Thanks! Gee I am glad you don't need to crimp because it does seem like a PITA step that I am glad is not necessary.

[eldermike]

In my experience the purpose of a crimp is to keep the bullet in place up until you cause it to move by pulling the trigger. With that in mind you can apply that thinking to the various action types and effects of recoil on rounds kepted in a magizine, tube or cylinder. I never crimp rifle unless its auto loading. I crimp all pistol stuff to keep bullets from moving on recoil. A pistol cartridge fired from a single shot pistol like a contender needs no crimp. And last: I learned a lot about picking the best powder for pistol by shooting zero crimp loads from a contender. Its my opinion that a crimp is the most un-repetable process in reloading and finding a powder, bullet and primer that works without the need for a crimp leads to better loads, less deviation and better accuracy.

[tmorone]

I crimp ammo that I load for my scary black guns. After loading and shooting thousands of rounds in 300 BLK and .223 I feel that it's cheap insurance. Plus, I've noticed no loss in accuracy.

[Hummer70]

The best way to ruin the accuracy potential of a match bullet with no cannelure is to crimp it.

The best way to ruin accuracy of any bullet is to apply a cannelure.

Think about it, Sierra nor Hornady nor Berger's have no cannelure.

Pistol ammo such as 38/357 needs to be crimped to develop higher pressures and burn more propellant immediately prior to bullet movement. Also with hotter loads in revolvers you will get rounds in adjacent cylinders creeping forward in recoil and if others are not crimped the bullet sticks it's nose out and your revolver is down.

In shoulder fired rifles with normal bullet grip everything will generally work fine.

Why does military crimp? A MG bolt as it comes to the rear keeps going far past the head of the case so the bolt has time for the spring action to get the bolt up to speed before it gets to the next round and it is really moving when next round is engaged. If bullet is not crimped the chances of the bullet setting back down inside the case is enhanced.

Rifles such as M14, Garand etc have much slower bolt velocity and the bolt has just started moving forward when the next round rises into strip position.

Then again if the load is not hot enough in a gas gun the bolt will come to the rear just enough to eject case out the side and not far enough to give the stack time to rise and you will get a BOB (bolt over base) or a FTS (failure to strip) stoppage for a FTR (fail to rear) which means on the last round the bolt stop does not engage and the bolt (COEC) closed on empty chamber.

Thus if you are not into belt guns you can get by just fine without crimping on rifles but revolvers you best do it and semi auto pistols may or may not need it.

[Bart B.]

Hummer70 commented on Sierra's and Berger's bullets not having a crimp cannelure. One other maker of match bullets finally took the cannelure out of them and stopped crimping them in match cases used at the National Matches and other levels of competition.

That was back in the 1930's(?) when either Townsend or Whelen did some accuracy tests with a given lot of 172-gr. FMJBT match bullets; some with cannelures and crimped case mouths into them, others with no cannelure nor mouth crimps in cases they were loaded in. One batch shot 30% more accurate than the other. Arsenals never crimped another case mouth nor cannelured another 172-gr bullet in match ammo thereafter.

But the black asphaltum sealant bonding the bullets in the case mouth still needs a 40+ pounds of release force to get them out and into the rifling.

[Black01Jeep]

I crimp ammo that I load for my scary black guns. After loading and shooting thousands of rounds in 300 BLK and .223 I feel that it's cheap insurance. Plus, I've noticed no loss in accuracy.

+1
FYI, I use the Lee FCD on .223, 308, and 300BLK

[Hummer70]

As Bart points out the mouth coating on military ammo can increase bullet pull but it can be far worse than that.

For instance the spec for the M118LR calls for a minimum bullet pull of 10 lbs and there is no max on the spec for some reason.

My last contact in the ammo industry tells me a bullet pull of 300 lbs is not excessive.

If you ever get the chance to pull some LC Match ammo you will be utterly amazed at how much difference there is in bullet pulls.High variations in bullet pull will give you vertical dispersion at long range that will drive you nuts.

The only way you know what to expect is chronograph your ammo. For long range you want a SD around 5. The Marine Corps ammo room wanted a SD of no more than 10 for their long range ammo in 14s.

Years ago I had a conversation with the owner of an ammo company in Fon Du Lac Wisconsin??? They loaded all pistol ammo and the name escapes me which is nothing new when you have CRS. As I remember their boxes were yellow and all of their cases were brass and not plated.

At any rate he told me the mouth sealant he used came from Olney paint company and they quit making it and he had to find something else.

The new stuff was a real pain. I was using it for qualification in Gov't Model 45 and I could get through one 60 round string fine. If I ran the course again about half way through I started to get FTLs (failure to lock) and the cases were gummy as was the chamber.

I called the manufacturer and talked with the owner and he explained he was trying to find something else as he had become aware of the problem. Never heard any more after that and apparently he went out of the business as I have not seen that ammo in over 20 years. He also told me there were like two previous owners and their QA was bad and there was lots of overpressure ammo loaded by previous owners.

So to keep shooting it I had to clean my 45 immediatley after shooting each string and the chamber was actually sticky.

[Slamfire]

My last contact in the ammo industry tells me a bullet pull of 300 lbs is not excessive.

Remember reading about the tin plated bullets (tin can ammunition) in Hatcher's Notebook? He said the stuff took 600 lbs to pull the bullet. An NCO found a fired bullet, at the National Matches, with the case neck attached. At least four M1903's are recorded in Hatcher's Notebook as blowing up with this ammunition.

Instead of acknowledging that the tin coating was welding the bullet to the case and creating a bore obstruction, the Army blamed it all on civilian shooters and greased bullets.

Somehow the Swiss were able to shoot greased bullets for over a century without any ill effects.

[Bart B.]

When I shot M118 7.62 match ammo a lot in competition, I oft times brough my Lyman 310 nutcracker tool with a .308 Win. seating die. It was set to push back the bullet about 10 thousandths to break the seal between case neck and bullet. Not-so-good lots of M118 could be made very nice indeed after "cracking" that seal for use at 600 yards and further. Elevation shot stringing due to big muzzle velocity spreads drop down to reasonable amounts.

[steve4102]

Every time there is a Crimp question Slamfire shows up with his Grossly Overcrimped bullets photo. The person that crimped these bullets was either Incompetent, ignorant or both. At any rate these bullets were destroyed by the handloader and not by the die itself.

The Lee factory Crimp die is an excellent way to help secure the bullet and increase accuracy.

Most of the naysayers concerning the Lee Factory Crimp die have either never used it or have Misused it as in the case of Slamfire's bullets.

I use it for all my Semi-Auto handloads, it works great and improves accuracy in all of My rifles. YMMV.

10 rounds each target.
100 yards
Colt AR-15.

[Bart B.]

Steve, folks not crimping their case mouths on bullets can shoot 'em into sub 1/3 inch all day long from properly rebuilt AR15 platforms. I think you're doing something wrong putting together your uncrimped rounds.

Nobody winning benchrest or high power matches with a bolt gun or semiauto service rifle does so with crimped in bullets. Neither Berger nor Sierra Bullets crimps their bullets in cases that will be used for quality control, do they?

Take your cause to www.accurateshooter.com and convice those folks to start crimping their bullets in place.

Most of the naysayers concerning the Lee Factory Crimp die have rifles and load ammo that shoots groups 1/4th the size of those you posted.

[Slamfire]

This weekend I pulled mid range targets at 600 yards. The shooters on my point were shooting F class 6mm PPC. They are excellent shooters, there is a lot more to shooting than the cartridge, but to go on, they shot out the three inch X ring with their last 40 rounds. I got showered with plastic when they shot through the spindles, the marking discs blown to heck, and there were so many pasters in the X ring you could not see the circle anymore.

They did not crimp any of their Berger bullets.

Now come out to a Mid range or Long range match and do that with your crimped bullets.

As for over crimping, just read Lee's crimp instructions. “you can seat your bullets to the best depth and the Lee Factory Crimper will form a cannelure in the bullet as it crimps the case".

Sure reads as though they are recommending cannelures.

Incidentally, I score 100 yard small bore targets with smaller groups than yours.

[steve4102]

Steve, folks not crimping their case mouths on bullets can shoot 'em into sub 1/3 inch all day long from properly rebuilt AR15 platforms. I think you're doing something wrong putting together your uncrimped rounds.

Nobody winning benchrest or high power matches with a bolt gun or semiauto service rifle does so with crimped in bullets.

No they are not, But they ain't winning these matches with an off the self totally stock $999 Colt either.

Whatever it takes, for me it's a Lee Factory Crimp die, apply the appropriate amount of crimp and I'm good to go with my off the shelf rifle shooting consistent sub MOA groups from cheap Midsouth bullets to Sierra Match bullets.

Here is more proof that the Lee Factory Crimp does what it claims and improves accuracy.

http://www.accuratereloading.com/crimping.html

[Bart B.]

Steve, how many of those pictured groups are no worse than 1 MOA? Never mind, I know what you're doing and why you do it.

Slamfire, note that all rimfire matches are won with and records set with crimped in bullets. Just an observation. . . . .but maybe they don't count.

[droptrd]

I crimp for my AR and semi auto handgun calibers. You dont need to sqeeze the hell out of them. If you are distorting bullets you are applying too much crimp. Less is more and a little goes a long way.

[Bart B.]

Some folks state Richard Lee says they need to be crimped in. According to his "Second Edition" a positive crimp affects the ignition, pressure, velocity, and accuracy of a round. He also says that there should be 100 pounds of "bullet pull" so the bullet starts to move as the chamber pressure passes 1338 PSI (for a .30 cal bullet). It's his opinion that this 100 pound bullet pull can't be reached without a crimp.

100 pounds of bullet pull or release force? Yikes. Why so much? I don't know of any rifle ammo's specs mentioning that amount of force.

Military 30 caliber M72 and M118 match ammo's spec'd at 40 pounds minimum of bullet release force. My own release force tests show it to be in the 50 pound range.

Most handloader's rifle bullets end up with release force somewhere between 20 and 50 pound range. Competitive shooters using shoulder fired rifles use about 10 to 20 pounds of bullet release force.

Benchresters typically use less than 10 pounds of release force on their bullets; many can be pulled from the case neck easily by hand.

[Slamfire]

Slamfire, note that all rimfire matches are won with and records set with crimped in bullets. Just an observation. . . . .but maybe they don't count.

Rimfire bullets are crimped and they are designed to be crimped with a deep crimp groove. They are also externally lubricated, proving again, that Hatcher's warnings about greased bullets blowing up your rifle are bogus.

Now you take a nice centerfire bullet without a crimp groove, and crimp it, you are going to deform the lead core.

But you knew that

[steve4102]

Steve, how many of those pictured groups are no worse than 1 MOA? Never mind, I know what you're doing and why you do it.

Don't give up, read this.

http://www.accuratereloading.com/crimping.html

[schmellba99]

I crimp for my AR and semi auto handgun calibers. You dont need to sqeeze the hell out of them. If you are distorting bullets you are applying too much crimp. Less is more and a little goes a long way.

Same here. I also run my bolt action (hunting) loads, Garand and even my .45-70 through a Lee FCD as well - just enough for the collets to smooth out any potential imperfections on the case neck, but I don't leave a cannelure or groove in the projectile.

It is an extra step, but on my Garand, AR and pistol rounds I'm loading on an progressive, so it's really not an extra step. On my hunting rounds, it is an extra step, but I only load 25-50 at a time, so it's really not anything that is excruciatingly painful to do either. My accuracy is more than acceptable, it makes me feel better about the round and it certainly doesn't hurt anything.

Overcrimping, which seems to be what several on here are describing as normal crimping, is bad and does nothing positive - pretty sure everybody would agree to that.

[Bart B.]

Some years ago, Sierra Bullets almost took Lee to court over their FCD' ads in shooting magazines. Sierra had run enough tests to prove that any crimping of case mouths on their non-cannelured bullets hurt accuracy. Lee finally agreed to put in their instructions for their FCD not to do so on Sierra's bullets. . . . .Or something like that.

To most folks, that was an admittance by Lee that with really good bullets shot in really good barrels from really good handloads, don't crimp case mouths on bullets.

PS:
I don't think Lee's facilities have the stuff to test accuracy good enough to tell the real difference.

[Striker1]

I use a LFCD on my hunting loads and for the AR. Two weeks ago I fired a 5 shot group @100 yds from the bench that measured .635.

Rifle - CZ550 in .270 Win

Load - Nosler 150 gr Partition.

I was pleasantly surprised to say the least. I make no claims it will do that for everyone, but it works good enough for me and FWIW, I have never had the issue depicted in the photos in this thread.

[Bart B.]

Striker1, is that .635 group the smallest your .270's shot? Or just one of the smallest?

If so, then all the others are definitely larger; how much larger is up to you to tell us about.