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Thread: Crimped and Not Crimped.

  1. #1

    Crimped and Not Crimped.

    I took my .222 to the range this evening to try some "highly" recommended IMR 8202XBR powder. As is my practice, I loaded both crimped and uncrimped loads for the first test. (25 of each) Normally, I don't worry about the actual speeds I'm getting until I get some notable results, but today I had the chronograoh set up for my .308 loads so I clipped off ten shots of each .222 load: crimped and uncrimped. These are the strips from my Chrony. For those not used to reading Chrony, the arrow points to "Standard Deviation". The number above it is the Extreme Spread. Neither is good but the difference is noteworthy. The accuracy and speeds didn't live up to the 'recommendation' so I won't continue with this powder but the chrono data is telling.

    The bullet was a Hornady 52 grain HP Match. The primers were Rem 7.5 BR. All brass trimmed to same length, etc. Other than the crimp, all rounds were as close to identical as I could make them.~Muir




    Sorry this came out so small.....

  2. #2
    Quote Originally Posted by Muir View Post
    I took my .222 to the range this evening to try some "highly" recommended IMR 8202XBR powder. As is my practice, I loaded both crimped and uncrimped loads for the first test. (25 of each) Normally, I don't worry about the actual speeds I'm getting until I get some notable results, but today I had the chronograoh set up for my .308 loads so I clipped off ten shots of each .222 load: crimped and uncrimped. These are the strips from my Chrony. For those not used to reading Chrony, the arrow points to "Standard Deviation". The number above it is the Extreme Spread. Neither is good but the difference is noteworthy. The accuracy and speeds didn't live up to the 'recommendation' so I won't continue with this powder but the chrono data is telling.

    The bullet was a Hornady 52 grain HP Match. The primers were Rem 7.5 BR. All brass trimmed to same length, etc. Other than the crimp, all rounds were as close to identical as I could make them.~Muir




    Sorry this came out so small.....
    Hi Muir,
    Just looking at your results there, I notice that there's an average of 150 fps greater velocity with the crimped rounds, I'm thinking that all of the crimped and uncrimped rounds are of identical loadings. If so I asume that you will always see an increase in velocity with crimped rounds as opposed to uncrimped, do you think that the lower ES and SD figures are a result of the crimping or the increase in velocity. I'd be interested in your opinions.
    Kind regards
    ​dcg
    Last edited by DCG; 27-03-2013 at 11:41.

  3. #3
    man size



    interesting.
    ​I have some crimped versions of a load I already use that I have not tried yet

  4. #4
    Muir, I'm going to give crimping a go out of curiosity as I've not been reloading long (though have had excellent results thanks to help from friends met on here), and a mutual friend of ours swears by it... however another friend of mine who's taught me an awful lot asked a valid question - why is crimping any better than just having uncrimped rounds with consistent neck tension?

    Also, how lightly/heavily do you crimp? My lee .308 crimping die gives a barely noticeable crimp, and I've seen others with a visible dent in the bullet from crimping?

  5. #5
    Hi again Muir
    Thinking on a bit further, the last ammunition that I performed a crimp on, was back in my pistol shooting days, I'm not familiar with the lee die which I have read that you use in previous threads, does this impart a taper crimp or a roll crimp.
    dcg

  6. #6
    Quote Originally Posted by BunnyDoom View Post
    Muir, I'm going to give crimping a go out of curiosity as I've not been reloading long (though have had excellent results thanks to help from friends met on here), and a mutual friend of ours swears by it... however another friend of mine who's taught me an awful lot asked a valid question - why is crimping any better than just having uncrimped rounds with consistent neck tension?

    Also, how lightly/heavily do you crimp? My lee .308 crimping die gives a barely noticeable crimp, and I've seen others with a visible dent in the bullet from crimping?
    DCG: I attribute both to the crimping. Notice that if you toss the odd first round of the crimped loads (and i don't dismiss data) the Extreme spread would be around 30 fps, not 60. The brass was Remington, same lot, all trimmed to the same length and loaded in one session.

    BD: I would say that maybe it isn't any better than consistent neck tension but that isn't the only factor, and just because you have applied what you think is consistent neck tension, how do you know you truly do have it unless you've tested for pull weight? Brass varies in ductility. There are minute changes in case capacity. Minute changes in ignition and bullet diameter. Crimping levels these variables and is most appreciated in hunting rifles with standard chambers. I shot BR and never crimped; my dies were hand made for my gun, the brass hand sorted and weighed and tested for capacity.... Thinking back though, I doubt if a crimp would have hurt much.

    As to crimp pressure. I experiment. I am of the mind that a heavy crimp is OK. With my 308, the press handle makes a heavy thump as I reach the top. Try screwing the die down more. With the exception of light skinned varmint bullets, it does little to the bullet.

    I always use this as my argument for crimping: the best factory ammo is usually crimped. The best factory match ammo is crimped. I recently dug out a box of Lake City 30-06 MATCH and hey! it was crimped. It will deliver MOA from a good service rifle 98% of the time. Can't be too bad a practice.~Muir
    Last edited by Muir; 27-03-2013 at 12:06.

  7. #7
    Neither. It displaces the case mouth inward ala factory ammo. Quite different from handgun ammo or the roll crimp supplied on some rifle dies.~Muir

  8. #8
    So once you have decided that a crimp is thew way to go, the next question is how.......
    I have a standard Lee seating die, and a Lee factory crimp die, bullets have a cannelure, which do I use ?

    Neil.

  9. #9
    Quote Originally Posted by Hornet 6 View Post
    So once you have decided that a crimp is thew way to go, the next question is how.......
    I have a standard Lee seating die, and a Lee factory crimp die, bullets have a cannelure, which do I use ?

    Neil.
    use the seating die as usual then the crime die. set the crimp die up as per instructions then the more you turn the die in the heavier crimp you will get. doesn't matter if the bullet has a canellure or not

  10. #10
    only adds consistency if all the cases are exactly the same length

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