Crimping bullets for AR

[Geezerbiker]

I'm thinking about loading up some .223 rounds in anticipation of finishing up my AR15 project. However none of the .224 bullets I have on hand have a cannelure to crimp into. Would it be ok to shoot uncrimped rounds in an AR15?

Tony

[Unclenick]

Most of us do shoot uncrimped. I don't know anyone who crimps match bullets, not even if they have moly or other lubricating coatings on them. The commercial match loads aren't crimped. I've never seen a problem result. You brass lasts better if you don't crimp. The only reasons for crimping are if the ammo is going to be subjected to extreme handling, as military use sometimes will, like running it through a SAW, or if you just absolutely have to use a powder that is normally on the slow side for your bullet weight and that needs extra starting pressure to ignite uniformly.

[T. O'Heir]

You really only need a crimp on heavy recoiling cartridges and ammo loaded for a lever action. Semi's don't require one.
No match grade ammo has a crimp. Bad for accuracy.

[lordmorgul]

I apply a Lee factory crimp die (FCD) on match ammo but so lightly I do not call it a crimped round, it’s purpose is merely to smooth the case mouth for loading.

Edit: based on later postings I felt necessary to clarify when I use this tool it is not according to the “touch plus 1/2 turn” instructions but MUCH less than that. I adjust by the amount of crimp actually applied not the thread, die, case length, and case holder tolerance stack up which is just a poor choice of way to specify how to position the FCD for use. It is basic and simple instructions but like many reloading tasks there is a better way by checking and adjusting results based on your actual tolerances. I set the due to where it just barely leaves a discernible marking on the case mouth where the 4 split die edges become visible, not where a clear and distinct smashing of the case occurred except for those gaps due to the split die.

Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!

[Geezerbiker]

Thanx guys. This is the first time I've reloaded for a semi-auto rifle and I'm straying into unfamiliar waters...

Tony

[chiefr]

There is a reason Mil Spec ammo is crimped.

Argued this point many times and seen a number of problems with uncrimped bullets in ARs. Some down right scary.

Two points:
The bolt slams forward with considerable force on the base of the case. The bullet resists forward motion. Newton 101

Not all mags are equal and not all ammo enters the case in perfectly horizontal movement. The bullet itself may touch parts of the chamber or the locking mechanism for the bolt when slammed into the chamber distorting or pushing the bullet further into the case creating a pressure situation.

All my reloads for AR 15s and 308s are crimped. Lee FCD or other means for non cannelured bullets.

[Charlie98]

Just like in a tubular magazine, rifle rounds in a box mag are subject to recoil and bullet setback. The key is neck tension.

My solution for ammo going into my AR's or my M1a is to use a light taper crimp... to just turn the case neck into the bullet without distorting the bullet like a roll crimp or FCD, or overworking the brass.

[Bart B.]

There is a reason some MILSPEC ammo doesn't have crimped in bullets.

Decades ago, Col. Hatcher had arsenals stop turning the crimping cannelure in their 173 grain FMJBT match bullet in M72 30-06 match ammo to do accuracy tests. Bullets were seated in case mouths smeared with asphalt sealant. None had case mouths crimped in. Bullets needed 20 to 30 pounds of force to pull them from the case. Spec for both service and match ammo bullet pull was 60 pounds minimum.

Uncrimped bullets without cannelure produced better accuracy and lower velocity spread. Bulleted uncrimped ammo was not altered in semiauto fire. Bullet pull spec for 30 caliber, and later 7.62, match ammo was set at 20 pounds minimum. USA military teams often pulled the 173 grain .3086" diameter arsenal match bullet then seated .3082" Sierra match bullets yet the reduced bullet pull force (10 to 15 pounds or less) still kept them in place during M1/M14 rifle recoil and reloading.

What bullet pull force is the minimum to keep consistent COAL on your ammo in the magazine and when chambered?

7.62 NATO match ammo from USA arsenals never had crimped in cannelured bullets. No USA commercial centerfire rifle match ammo I know of has crimped in bullets.

Bullet companies have proved that putting cannelures in bullets and/or crimping case mouths into bullets degrades accuracy. As have competitive shooters producing consistent best results.

In contrast, some folks believe the earth is flat and government forces block people from travelling past the earth's icy edge to go over the non-existant south pole. And the shortest distance from the Faulkland Islands to south Australia is over the north pole

[Jim Watson]

I ran into a single case of that.
I bought some bulk packed 50 gr Remington .224" hollowpoint bullets that appear plated overall, there is no lead showing, nor an open point target nose. They were inexpensive but quite accurate. So I ordered some of the same pattern 55 gr. But they have a cannelure and are not nearly as accurate.

[CarJunkieLS1]

Crimping ammo causes more problems than it solves. I do for a few rounds I load very lightly crimp them with a Lee FCD.

[FrankenMauser]

I crimp if there's a cannelure and it isn't a 'precision' load.
Otherwise... Nope.

[Charlie98]

Crimping ammo causes more problems than it solves.

Say what? Depends on the ammo, the bullet, and what you expect out of it.

I crimp if there's a cannelure and it isn't a 'precision' load.
Otherwise... Nope.

It's unlikely someone is loading SMK's for burn ammo (non-cannelure match bullet,) but not crimping just because it doesn't have a cannelure is a little silly. It just depends on the application.

[FrankenMauser]

It's unlikely someone is loading SMK's for burn ammo (non-cannelure match bullet,) but not crimping just because it doesn't have a cannelure is a little silly. It just depends on the application.

No, it's not silly at all.
I like my bullets to remain the shape that they were before seating, and don't let a load leave the reloading bench if it has inadequate neck tension.

What would be silly would be crushing and deforming the bullets by crimping with a Lee Factory Crimp die, simply because I was afraid of an uncrimped load.

[FrankenMauser]

Here's an interesting discussion on the Lee FCD: Range results with/without Lee crimp die

[lordmorgul]

Edited my earlier post after reading much of the linked previous thread on these. My post above has my process for setting the die at very minimal crimp. The LEE instructions may be in fact a very heavy crimp at the basic starting point, it depends on tolerance stacking of several machines parts and your own cases not just the die itself.


Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!

[Mobuck]

"You really only need a crimp on heavy recoiling cartridges and ammo loaded for a lever action. Semi's don't require one"
And how do you explain the crimps on most of the military ammo loaded since 1895?

[Charlie98]

No, it's not silly at all.
I like my bullets to remain the shape that they were before seating, and don't let a load leave the reloading bench if it has inadequate neck tension.

What would be silly would be crushing and deforming the bullets by crimping with a Lee Factory Crimp die, simply because I was afraid of an uncrimped load.

Well, you brought up what I said before... it largely depends on neck tension. Bumping the case mouth in with a taper crimp die isn't crushing and deforming the bullets... unless you are crushing and deforming the bullets with too much of it. I don't use LFC's because I think they cause more problems than they solve... And, again, it depends on what you are doing with the cartridge. I don't need to worry about crimping cartridges going into my bolt gun... I do need to use due diligence with my M1a. Granted, I'm not lining up at Camp Perry, either.

[Unclenick]

Originally Posted by Charlie 98

…but not crimping just because it doesn't have a cannelure is a little silly.

Man, you missed the big fuss between Sierra and Lee when Lee first came out with the FCD. Sierra was all about "don't be deforming our bullets; that's bad for their match accuracy" and Lee was all about it not mattering and being helpful to consistent ignition. This fuss was a big back-and-forth carried on in advertising in which Sierra said, "don't be crimping our bullets," and Lee finally said, "OK, maybe not your bullets, but everyone else's like what our tool does for them".

The whole thing was funny, a bit.

Here's what we know: A cannelure does allow for less bullet deformation by a crimp, but merely forming cannelures is very difficult to do without affecting precision (group size) because of the resulting imbalance described in the sententence after the next. Bullet deformation like the wasp waist the military put into M2 Ball causes extra shockwave formation due to there being more curves and corners on the bullet, so it does reduce ballistic coefficient some by that mechanism. But more importantly, since I've used some pulled M2 bullets (pulled to be replaced by 150-grain MatchKings for reduced range matches) for firelapping very rough bores, I have seen that when you roll them on the embedding plate, the pattern of embedded abrasive is uneven around the bullet. This means the crimp indentations were not symmetrical, so the bullet is unbalanced (center of gravity no longer coincident with the centerline of the bullet or the bore). That causes these bullets to drift off the mean trajectory in flight, plus they wobble in flight, further decreasing the net BC. This happens because even if the crimping force is applied perfectly uniformly, the case neck thickness and the bullet jacket both usually have nonuniformities that resist deformation to different degrees. The result is the dent in the bullet is not symmetrical, with the tip usually getting bent slightly to one side by it.

I suppose you could turn your case necks uniform and seat your bullets with minimum runout and then crimp them and look again for runout and eliminate all the rounds that had picked some up. Using lack of runout change as an indicator of probable accuracy problems, you could likely improve on the groups you get from crimped rounds. But man, that's a lot of extra bother. Why not just shoot the original straight rounds? I'd really have to have some strong justification for having accurate crimped rounds before I would even undertake the experiment to prove this was so.

The one place I think the LEE FCD has a legitimate role is in forming a crimp into the lube groove of a cast bullet. The end of the collet can be ground down to place the crimp in the desired location on the neck if you have a particular bullet you want to use it with.

[Bart B.]

People who have and do all the right stuff comparing crimped in bullets to non-crimped ones easily see which is best.

[BWM]

Yes I do crimp for my 223 and most rounds that I reload even my hand guns I like a little crimp on my reloads I use the Lee crimp er on all rifle loads and use the setting dies for hand gun loads it is up to you