What rounds to crimp ?

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  • TexMex247

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    Ok, so it's probably been beat to death all over the internet and maybe even here before. I guess I'm too lazy to search for and old thread to confirm. However, I can't help myself and still gotta ask... which rounds do you crimp, how much and why ?

    In the 13 plus calibers that I reload, they all get finished off with the Lee FCD. Always heavy on a mag round or a big bore lead round. Probably more medium on my 9mm loads since I'm loading mostly plated. Even my hunting ammo for a 280 Remington gets the treatment.

    Lately I'm chasing better groups in a AR10 platform .308. Instinctively I crimped like I would have for the AR15. Light w/o cannelure, medium with one. Recently I read about some competition shooters who claimed better groups without a crimp.

    For most everything I load for I feel pretty confident in the ammo I'm making with just about everything on par or better than factory ammo. Since the 308 is not there yet, I'll call upon the collective here at TGT for some sound advice. Do you crimp ? What for and how much ? Not looking for exact measurements just your experience.
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    Tactical Panda

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    The advice I've always heard was, crimp for autoloaders for better reliability, don't crimp for bolt actions for better accuracy, or rather, better consistency . But I'm like you, I use the Lee factory crimp for everything, mainly my M1. I doubt I shoot well enough to notice that level of difference anyways.
     

    Maverick44

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    What rounds do I crimp? If the gun has significantly heavy recoil that might cause the bullet to move in the case neck, or if the round is going into an auto loader, they get a crimp. How heavy that crimp is depends on the gun and the round. Some guns are very rough on the ammo and require ammo that has a decently heavy crimp. Others, not so much.

    If you're loading for something like 30-06 in a bolt action, a crimp is not necessary. For precision shooting, I am getting very tight groups with 6.5 Creedmoor in a bolt action with no crimp.
     

    lbbf

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    I don't crimp any of my rounds. 9mm, 40s&w, 380, 223, 22-250, 270, and 458SOCOM. All no crimp and never had a problem.
     

    robertc1024

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    Only .357's, .44 mag & .38 spl wadcutters. On autoloader rounds, when I'm seating the bullet, I just make sure the seating die is low enough to make sure the diameter of the rim is correct. I learned my lesson on .44 mags though. At one reunion I had some .44 mags that Orbitup shot that walked the bullets out and tied up his lightweight birdshead revolver. The bullets were cheapo Berry's or something and had no cannelure. I was afraid to crimp them too much and cut through the plating. Ever since, only cannelured bullets for magnum pistol rounds for me.
     

    LinuxAssailant

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    Only .357's, .44 mag & .38 spl wadcutters. On autoloader rounds, when I'm seating the bullet, I just make sure the seating die is low enough to make sure the diameter of the rim is correct. I learned my lesson on .44 mags though. At one reunion I had some .44 mags that Orbitup shot that walked the bullets out and tied up his lightweight birdshead revolver. The bullets were cheapo Berry's or something and had no cannelure. I was afraid to crimp them too much and cut through the plating. Ever since, only cannelured bullets for magnum pistol rounds for me.
    I didn't want to chance the full-house .357 Mag reloads locking up the cylinder, so I only do 158gr Jacketed, or Semi-jackets in .357 Mag for this reason... WELL, that AND I got the motherload of 158gr Semi-Jacketed HPs on clearance for about $0.1393/each... :D

    I haven't had 9mm, or .38 SPL walk yet, but I crimp everything, as I don't own anything bolt action, as of yet... but it's on the wish-list.

    Roll crimps I go medium-heavy,
    Taper I go firm.
     
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    AgedWarrior

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    For the AR 10, if you are going to crimp, do so only when you have a cannelure, and then a medium crimp. The problem that will arise with crimping .308, or any bottleneck rifle cartridge, is when the case lengths are not consistent. This will cause a small variance in crimps from round to round and can reduce accuracy. Keep case length trimmed consistent for best accuracy. Keeping your brass sorted into batches fired the same number of times is helpful too if you are going to crimp them. Crimping induces a variable that you need to minimize for accuracy. I never crimp rounds for my bolt guns.
    Be very careful with crimping on some straight walled cases because some headspace on the case mouth; .450 Bushmaster for example.
    Regarding handgun ammo, I taper crimp for semis and roll for revolvers unless shooting semi ammo like .45 ACP out of a revolver. Heavy roll crimp on big bore magnums and such.
     
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    Dawico

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    Most handgun rounds get just enough crimp to remove the bell on the case.

    Most rifle rounds don't get any crimp.

    Crimp Magnum handgun rounds and tube fed rifles.

    Neck tension should be plenty to hold the bullet in everything else. If not a crimp is a bandaid not a real fix.
     

    Txhillbilly

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    I only use a crimp on straight walled cases - handgun or rifle.
    There's no need in crimping bottlenecked rifle cases unless your shooting a tube fed magazine firearm.
     

    TexMex247

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    I had a chance to chronograph some rounds yesterday. I have been toying around with BLC2 in the 308. Since the Hornady black amax rounds shot well in the AR10 I was focused on duplicating those. I picked 45gr as my starting point with the amax based on other loads with the SST. It turns out I was loading just a touch hotter than Hornady with my rounds clocking in at 2592 fps while the factory load was 2540.

    After considering some input here I decided not to crimp these rounds. I was pleasantly surprised to get an extreme spread of 11 and an SD of 4. The grouping was a little loose(1.5") but it was the last 5 shot group I shot through a pretty warm gun on a fairly hot day. Based on this session I think I'm going to move away from crimping my rifle rounds. In the end I had 10, 5 shot groups with every loading under 20 sd except the Hornady black factory load. 4 of 10 were under 10 sd.

    In the next few weeks I might even alter a proven 223 load(by not crimping) to see if I can further shrink down some already great grouping bullets. Always chasing the dream !
     

    TEXAS "All or nothing"

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    If you shoot 357sig then you will want to crimp, especially the 147gr! Not much neck on those cases! Any full auto would most likely need crimped ammo? The headspacing comment holds true! I only have bolt guns in 264wm, 300wm and 338lm, but haven't reloaded any of the later 2. Been loading the 264wm for 37 years and never crimped any of them. Tube feed guns in 44mag and 45/70 (no lead bullets) I do crimp. Crimping on auto handguns (even though it's headspaced on mouth) just feeds smoother due to no edge (or as sharp/blunt edge) that works for me. Accuracy hasn't been an issue, but haven't checked velocity vs deviation. I've thought about getting a Barrett or Nemo (just rebarrel) with the quick/caliber change barrel in 300wm and have a 264wm barrel for it for an auto loader? It's more about what works for your gun!
     

    TexMex247

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    I'll keep crimping my auto pistols but lightly at that. Mostly for the reason you mentioned regarding feeding. The 45 Colt,357 and 38 will probably still get my heaviest crimp with the Lee FCD. Otherwise I'm going to move away from crimping all my rifle rounds except maybe the 7.62x39 and 30-06 if I'm making some garand ammo. Hard to say if my 7mm WSM should get one. I might have to take a handful of uncrimped rounds to the range with a dial caliper to see if I get any setback.
     

    BrianMDTX

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    For rifles, none except for the .30-30 Win. That gets a LFC. I’ve never seen a need to crimp any cartridges for bolt guns from a 7mm Rem Mag up to .338 Win Mag. I even marked a 250 grain Nosler Partition spitzer and left it in the magazine over 20 shots and the bullet never moved.

    But I crimp the .30-30 just to be safe in a tube magazine.
     

    Texasjack

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    Taper crimp on pistol rounds for semiautos (e.g., 9 mm, 40 S&W, 45 ACP) because the feed ramp can move bullets.

    Roll crimp for magnum pistol rounds because the recoil can cause bullets to move in the cases. I also roll crimp .38 specials and 45 LC because I don't see any difference in performance with or without crimp and I'd rather keep the bullets from moving. Also, I sometimes use the 45 LCs in a lever action rifle.

    Roll crimp for all semiauto or lever action rifle rounds, and for any magnum rifle rounds (again, recoil can move the bullets while in the magazine.) I also roll crimp .30-06 because, like with .38 spl, I don't see any performance differences with or without crimp.

    All crimping should be done to the minimum amount necessary to keep the bullet from moving. Take some time to get it set right.

    Yes, I know there are always people posting that they never crimp and they never have a problem. I think they probably just never noticed the problem yet. And, yes, there are people convinced that crimping does terrible things to performance. It should be pointed out that all factory loads are crimped, and unless you crimp tight enough to crush the bullet, you'll never see a measurable change in performance.
     
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