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Thread: Crimping and velocity

  1. #1
    Member 8x57 Mauser's Avatar
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    Question Crimping and velocity

    I'm working up load #1 in the new 9.3x62.

    I'm shooting 286 gr. Hornadys over RL-15 and as I move up toward max published charges, I'm not seeing the velocities the published data dangled so tantalizingly before me. Part of that is the shorter barrel on my CZ 550 FS, I'm sure. And there's certainly nothing wrong with the speeds I'm getting. But I wonder:

    Could I eke out a few more fps with a heavier crimp?

    I've never fiddled around much with crimping. The cartridges I've loaded for in the past just didn't call for it. So when I started working up this load I put a little crimp into the cannelure on the Interlock, but didn't really lay it in there. Now that we're near listed max, the bullet is compressing the powder just a little, so I don't need a heavy crimp to prevent recoil from jamming bullets extra deep.

    What's been your experience? Would a really stiff crimp give the WLRs a better environment to do their job on the powder, or am I barking up the wrong dog?

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    Quote Originally Posted by 8x57 Mauser View Post
    I'm working up load #1 in the new 9.3x62.

    I'm shooting 286 gr. Hornadys over RL-15 and as I move up toward max published charges, I'm not seeing the velocities the published data dangled so tantalizingly before me. Part of that is the shorter barrel on my CZ 550 FS, I'm sure. And there's certainly nothing wrong with the speeds I'm getting. But I wonder:

    Could I eke out a few more fps with a heavier crimp?


    I've never fiddled around much with crimping. The cartridges I've loaded for in the past just didn't call for it. So when I started working up this load I put a little crimp into the cannelure on the Interlock, but didn't really lay it in there. Now that we're near listed max, the bullet is compressing the powder just a little, so I don't need a heavy crimp to prevent recoil from jamming bullets extra deep.

    What's been your experience? Would a really stiff crimp give the WLRs a better environment to do their job on the powder, or am I barking up the wrong dog?
    I think that crimping might have an effect, but it might not be noticable. It might result in a change in accuracy, but I doubt it would make for higher velocity.

    If it did, crimping would be much more popular.

    Smitty of the North
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    I would agree with Smitty but to take it a bit further, you can't really control how "deep" the crimp goes beyond a theoretical point and you might get a jump in pressure somewhere along that experimental track, I don't know how much pressure and I realize that pressure = velocity to a degree but my advice, and I'm sure Smitty's as well, would be to be happy with a good accurate load and don't waste time and barrel life striving for that "mythical" 50 fps

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    Member Float Pilot's Avatar
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    I played with a couple Lee factory crimp dies and managed to get some velocity change with crimps. Oddly enough the velocity started heading back down when I set the crimp deeper past a certain point.

    What barrel length do you have?
    What is your rifling twist rate?
    What is the load you are playing with?
    What velocity are you reading and how far away is the chronograph.???
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
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    Member GD Yankee's Avatar
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    One problem with crimping is that to ensure the loads (and hopefully pressure increases) are consistent, you'll need to trim all your cases to exactly the same length, other wise, the crimps won't be the same from case to case and therefore the neck tension will vary greatly compared to no crimp.

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    Float Pilot,

    The barrel is 20.5", with a 1:10 twist. I'm getting 2225 fps out of 57 grains of RL 15. The chronograph is right around 15 feet from the muzzle. That 2225 is a gain of 25 fps over 56 grains of powder (previous full-grain increases in the powder charge gave me 40-50 fps), so I'm probably approaching the point of diminishing returns. No pressure signs at this point. Standard deviations across 10-shot strings have been 14-20 at all charge weights so far.

    I'd like to find an accurate load that gets me up over 2300. It may not happen. I don't need it. I'd just like to. I imagine I've got some room to work up a little further on the charge weight alone.

    I'm curious Float Pilot: what kind of increases did you see? And with what cartridge(s)?

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    Yankee,

    I keep my cases very consistent. Because I'm a nerd.

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    Member GD Yankee's Avatar
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    Quote Originally Posted by 8x57 Mauser View Post
    Yankee,

    I keep my cases very consistent. Because I'm a nerd.
    Well there you have it! Quote from "She who must be obeyed": what another gun? That means you'll have to buy a new set of dies, and brass, and....." Uhh, yes, isn't that the point?

    Your load of 57gr of RL-15 is exactly what I use in my 9.3x62. Love that powder - meters great and I get awesome accuracy and consistency in everything from 223, 260 Rem, 30-06 Garand loads, and the 9.3. Interesting notes on the velocities; I haven't chronographed mine, yet, but my barrel is about 24 inches so perhaps your shorter barrel is stealing the last 50-100 FPS.

    Speaking of nerds, I joined the 9.3x62 loonies after looking at building a 35 Whelen and finding much better bullet selection and performance on the 9.3. I bought one of these from the guy on gunbroker and had the barrel turned down to a sporter contour. Very accurate barrel:

    http://www.gunbroker.com/Auction/Vie...Item=237854387

    Only problem with these barreled actions is that the rear scope base holes are not spaced correctly for any base I could find (including Warne).

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    Your load is actually not too bad for a 20.5 inch barrel. We experimented around with my buddy's CZ American which has a 23 inch barrel. We ended up using 58.2 grains of RL-15, a 286 grain Nosler partition, Lapua brass, a CCI-200 primer, loaded to a COL of 3.695. We only obtained 2,306 fps as an average. But is was very accurate.

    On the other hand, my 9.3 is a Carbine with a 20 inch barrel. It hates the above load, but likes the Norma 285 grain Oryx bullets and 59 grains of VARGET, with Norma brass and Federal primers. Loaded to a little shorter COL. It gives me over 2,350 fps. But is rough on brass. I think it is a little too hot actually. By about a grain.

    I have read that Ramshot Big Game powder works well in the 9.3x62, but I can never find a can of it when I have enough money to buy one...

    At your stage of the game, changing your COL, brass type and primers can make a difference of 50-75 fps.
    Floatplane,Tailwheel and Firearms Instructor- Dragonfly Aero
    Experimental Hand-Loader, NRA Life Member
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