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crimped vs uncrimped

rjv140
i have a marlin 336a 35 rem i was told that i should crimp the heads because on any gun that has a tube magizine because the recoil can affect the overall length of the cartridge. is this correct becuase i just crimped all of my rounds that i made for the 35.

Do bullets behave differently if they are crimped as opposed to uncrimped?

What are the benefits of crimping the heads?

Should I crimp all bullets that i make even if they are for a bolt action gun?

please advise
thanks
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4 comments

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  • heavyiron
    Hi,

    You will probably get a variety of answers on this one because there are a variety of facts and opinions on this subject.

    IMHO,

    1. Yes, the cartridges will have different properties if they are crimped versus uncrimped, although you may not be able observe any difference. Uncrimped bullet are alleged to be more accurate than their crimped counterparts because the internal ballistics are more consistent. Practically, unless you are a elite competitor, this difference is probably unnoticeable.

    2. Crimping can achieve several objectives. IMHO any tubular feed centerfire rifle or revolver cartridge should be crimped. This is not only to keep bullets from being pressed further into the cartridge casing upon loadng through the loading gate, but also to prevent pulling the bullets out of the casing under recoil. This is the same premise used for crimping revolver bullets. Crimping may also allow more complete powder combustion by increasing the burn time in the casing for certain slow burning powders.

    3. Whether or not to crimp all your bullets is a personal decision based upon the purpose of the loaded round. For example, any cartridge loaded into a tubular magazine for a centerfire rifle should have a crimped bullet to prevent dislodging the bullet under recoil. However, target practice with that same rifle loading only one round at a time may not require any crimping. Generally, hunting bullets should be crimped to ensure cartridge reliability and feeding of the firearm. Target ammo often times is loaded and shot one at a time. Often target ammo has no crimp. The cartridge case is only neck sized and the bullet is held in place by friction. Defensive rounds should all be crimped for reliablity and feeding.

    I will be curious to read the responses from other contributors.

    Regards,

    Heavyiron





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  • gotstolefrom
    What benefit do you get by not crimping ?

    Crimp, one or all of the above reasons are enough.
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  • ern98
    Crimping for the home loader is often very imprecise, with each crimp being either more or less then a given average, which can affect the accuracy somewhat. But in many cases it is a moot point as many brands of reloadable bullets come with no crimp groove in them. One of the big reasons to handload is so that you can build a cartridge either longer or shorter which ever your barrel lekes best and no factory crimp groove seems to ever be in the right place. So unless you are prepared to overcome this, the issue is moot. Still many bullets have the groove and the length is useable. So for me one of the better reasons to crimp is if the cartridge is for a heavy recoiling rifle. With a real heavy recoil the bullet is more likely to be shoved into or out of the case. The ammo for my 7x57 custom Mauser, that I am hunting deer with this year, is not crimped and gives me no problems. If I were using my 300Wby the ammo would be crimped. For a tube feed, as has been said above, always crimp.
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  • D.S.COLE
    Tubular magazine rifles can slam the cartridges back against each other in the tube at recoil. Crimping prevents their seating depth from changing.
    I crimp all my reloads for any type action as I have experimented a great deal with crimped vs. not crimped.
    Years ago when Lee came out with their Factory Crimp Die some of the other die mfgs. spent big bucks in negative ads in all the magazines putting it down. Richard Lee is a brilliant engineer and ballistician.
    His theory about starting pressure in the case being made more equal by the bullets being held under uniform tension in the neck is right on .
    At that time I was working with several 25 caliber rifles including a couple of wilcats in developing most accurate loads for each. I had several loadings for each rifle on hand together with notes on each loads average group size. After running all the already loaded rounds thru the factory crimp dies and more trips to the range ,all the groups ,in every case,in every rifle shrunk from their previous average size. Some by half.
    You can believe what you want about crimping but this proved all I need to know.
    I bought Factory crimp dies for all my calibers and crimp them all.Bullets without a cannelure or crimping groove react the same. The Lee crimper cant be over crimped or ruin a case as the standard dies can due to its design .
    You get a little circle around a non cannelured bullet ,Ive pulled them for exam but no harm is done and accuracy is better and no difference in performance on game can be found.

    <BR>
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