To crimp or not to crimp bottlenecks

[HNSB]

Are you guys crimping bottlenecks for magazine fed bolt action? (taper or Lee FCD)
The "universal wisdom" - which is far less universal than it used to be - was that crimps are for semiautos, not for bolts. But where did that come from in the first place? Is there a difference in the recoil or is it simply because of rounds getting smacked into the front of a magazine? (or more accurately, the front of the mag smacking into the rounds)

I've been reading about potential problems from crimping and a lot of people don't do it anymore, even for semiautos.

I guess tl:dr:
1. Is the reason for suggesting crimp for semiautos because of something different about the recoil or just because of the magazine?
2. If it's just the magazine, then does the same advice apply to magazine fed bolts?
3. Are you crimping your bottlenecks? In which applications?

[steveu]

I have never crimped a single round for use in any of my ar-15, m1 or m14 with j bullets. I have never shot a cast bullet in these rifles.

FWIW,
Steve

[Texas by God]

I don’t crimp any rifle rounds except 38-55.
It is a Winchester 94 with a tube magazine.
Bolt actions, single shots, and AR15s- never.


Sent from my iPhone using Tapatalk

[BK7saum]

I do not crimp any rifle rounds for bolt or semi-auto with jacketed bullets. I occasionally iron out the flare used with cast boolits and might give a very slight crimp at that time for semi-autos, For bolt action, I just remove the flare, no crimp.

[Hossfly]

I use the push method on custom boolits. Push with thumb pressure down on a scale to 50# and remeasure COAL if no difference then will not crimp. If COAL decreases then will address crimping.

[jdgabbard]

I don't shoot a lot of cast in rifles. Normally when loading for bolt guns with jacketed I'll just iron out any flare in the case mouth with a very light crimp. On semiautos such as the AR, AK, and my PSL, I typically use a factory crimp die. These can be rough in their feeding, so it does help prevent setback. When I do run cast, it really depends what I am shooting it in. In the 30-06, some bullets I'll put a slight crimp on the rounds. In the 7.62x39 I will put a very slight crimp. I don't currently shoot cast in my ARs. Others, I typically just make sure there isn't a bell on the case mouth.

[Der Gebirgsjager]

I don't crimp them for use in bolt actions. I do crimp them for tubular mags (lever actions) and semi-autos. I use the Lee Factory Crimp die.

DG

[MostlyLeverGuns]

I normally 'remove the flare' for ease of feeding in rotary and box magazines, and a very light crimp for cartridges used in tube feed rifles. Some/many rifles have chambers that lack enough chamfer to allow the sharp edge a cartridge to slide into the chamber, catching on the edge of the neck when chambering. I do chamfer these chambers when the need arises, to smooth the entry into the chamber, but a slight taper or rolled crimp does ease chambering. Many do not run into this problem because they shoot from a bench at a range and seldom 'run' their rifles. I use the Lee Factory Crimp die for most, but do have a taper crimp for the .308 and the auto pistol cartridges - 9mm, .40, and .45.

[Hick]

The only thing I crimp is rimmed revolver loads. The recoil of a revolver jerks the rim backwards which can cause the bullets to back out and jam the cylinder. I never crimp for tubular mags because the mag spring is the only thing that touches the cartridges so they don't feel the recoil to any significant degree. Similarly, my bolt actions hold the cartridges in a magazine that allows the bullets to move a little lengthwise if the recoil is really high, and I have never had a bullet back out on those so I don't crimp them either. It's a question of how comfortable you feel, but I've loaded over 100,000 rounds for my guns without a problem, so I'm pretty set in my ways.

[243winxb]

I never crimp bottle necks.
If there is a powder problem, not burning correctly, a crimp may help. Military test-


To avoid Delayed Ignition, use a mag primer, seat bullet deeper into the case, use a bulky powder that better fill the case. Increase bullet pull with a crimp, as a last resort. Crimps may hurt accuracy. Doing your own testing is the only way to know.

Lee Factory crimp die better then roll or taper .

Bullets need a cantalore to crimp into.

[45_Colt]

I guess tl:dr:
1. Is the reason for suggesting crimp for semiautos because of something different about the recoil or just because of the magazine?

The military auto ammo are all crimped. For what particular reason, I can't say, but the trip from the belt or magazine to the chamber can be quite rough. Or, maybe when ammo is bounced around and cans of it are dropped.

Keeps the bullets in place.

Since military semi & full auto ammo is crimped, my guess is that it is a carry over. Even Federal commercial American Eagle .223 is crimped into a cannelure.

2. If it's just the magazine, then does the same advice apply to magazine fed bolts?

It can. Heavy magnum rifles/rounds can set the bullets back due to recoil. They get slammed into the front of the magazine when a round is touched off.

I wouldn't do it for a .223, 220 swift or even a .308. But big magnums need it.

3. Are you crimping your bottlenecks? In which applications?

.223 and .308 in a semi, bullet has a crimp/cannelure groove and gets the Lee factory collet crimp die.

.223 in a single shot pistol, nope, no groove and no crimp.

On a side note, the .357 SIG (bottleneck pistol round), they get a cannelure and a crimp when loaded. Why? To prevent set-back from the bumpy ride into the chamber. This is an area that I think Federal & Sig goofed. No crimp groove or crimping of that ammo. Not even factory stuff is crimped.

The neck is too short to hold the bullet firmly. Although I did find that modifying the lips on GI 1911 mags and using them makes a difference. The tapered style versus wad cutter is better (then both .40 and 10mm mags). Just need to close them up a little (.424" body versus .476" body). Much smoother ride from the magazine into the chamber.

45_Colt

[redhawk0]

I crimp hunting loads for 30-06 in my bolt action. I was finding the bullets were getting pushed back into the cases due to recoil of bumping up against the front of the magazine. (obviously undesirable). I crimp for 30-30 and 35 Rem also since they are in a tube magazine. My only pistol cases that gets crimped are the 357Mag and the 44Mag. No crimp for any of my other calibers.

I use LFC dies.

redhawk

[HNSB]

Thanks to everyone for the replies. There's definitely some food for thought here. I'm surprised to find how many don't crimp. The chart showing better std dev with crimping is interesting too.
I guess I'll try both and see what my rifle likes best.

[Winger Ed.]

I put a light crimp on bottle neck rifle cases with cast, a slight taper crimp on .223*, and a noticeable one on .45-70.
What little bit of .30 jacketed I shoot, most doesn't have a groove anyway, so I never crimped them.

Years ago, I bought a .30 ammo can of 147gr-FMJ GI bullet pulls for 7.62 and one of .50BMG.
I put a slight crimp on the 147s because they look better that way,
but not the .50BMGs since I had a single shot for them.

*
I don't use cast in .223. I wait until I can find 55gr-FMJ '2nds' on the cheap and use them in the AR.

[AZ Pete]

I crimp cast bullets, and jacketed that are fed from a tubular magazine. I do not crimp jacketed that are fed from a magazine well or single fed.

[Slugster]

I crimp .444 Marlins and .45-70 for lever actions, heavy magnum revolver loads, & .50 A.E. in the Desert Eagle. Otherwise I only smooth out the flare at case mouth.

[Tedly]

I never crimped anything at all until I began casting ~2014 ? so ,I tried crimping some of my jacketed milsurp stuff and it shot better , tighter groups. Crimping is a way to even out all the differences and promote more uniform start pressure , per Richard Lee . To be sure though , these are all sporters or milsurps and I'm talking 100 top 200 yds rested off a bench

[JSnover]

I never crimp bottle necks.
If there is a powder problem, not burning correctly, a crimp may help. Military test-

I almost never crimp but the velocity and pressure deviations in the chart would give a lot of people something to think about.

[Cast10]

I use a slight crimp on all rifles. I shoot lots of autos and I want them firm. I also use the push methods to test to make sure they don’t move. A jam in a rifle with a non-crimped shell could result in driving it rearward upon chambering in certain situations. If I were benchrest shooting, well, I problem wouldn’t on any.

[Beast of Burden]

I tend to crimp everything, pistol and rifle, cast and j-word. It seems to ease my mind regarding set back, pressure spikes and proper chambering.