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Thread: Crimping knowlage

  1. #1
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    Default Crimping knowlage

    I am a novice reloader. I shoot a 375 h&h and have never had to crimp a cartrige. I trimmed all my cases to the barns book 2.840 and loaded them with 71gr. rl15 and have seated 270gr barns x with a crimping groove. I understand that if seated to deep will cause exesive preasures. My rifle feeds them nice out of the magazine a post 70 classic. This is the question the lead isn't deep enough to crimp the end of brass is only a few thou. short to reach the groove I am using rcbs dies I don't exactly know should I set the round deeper then crimp, and if so how do I know if I go to deep?
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  2. #2

    Default Crimping

    If your dies are set properly, there really is little need to crimp a .375 like you would a straight-walled cartridge, such as a .44 Magnum. You need to snug the case to the bullet, but to try to force a crimp will only crush the case. Position the crimp in the seating die to be snug, but not balloon or crush your case at the bottom of the handle stroke once you have determined what overall length you want to load to.

    The crimp line on a centerfire rifle bullet is there just because the manufacturer put one there. It does not mean it has to be used by any means. I load and shoot Nosler Partitions in my .375, and there is no crimp line on them. Some of the practice ammo I load in this gun and others have crimp lines, but some of the loads are adjusted either above or below those crimp lines, depending what I am shooting.

    The MAIN thing you must be sure of is that your case is trimmed to the correct length and the loaded round is within the maximum overall length for that cartridge. Then you can play around with it a bit to make it fit your gun individually. Some chambers are shorter than others, and if you know how, you can match the round to your rifle for the optimum in accuracy. However, that same round either may be hard to chamber or may not chamber in a different gun of the same caliber.
    The only way to ensure that is to load them to the factory specs.
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  3. #3
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    If this bullet is the 270 grain XFB with the crimping groove I don't think it is at max length when seated to the groove. Max length for the cartridge is 3.600".

    First of all, you don't need to crimp the 375 H&H with any bullet. It offers no advantage. But you're correct about the trim length 2.840"

    Secondly Seat the bullet to where the mouth of the brass is in the center of that crimp groove. If this seating depth is .025" to .075" from rifling contact, you're good to go.


    I'm not following what you're saying in your last sentence. Are you saying lead as in the bullet material? It is copper. Are saying lead as in the part of the rifling that is tapered? This is what the bullet will contact. If you seat the round deeper or not it will have very little effect on pressure, this 71.0 of RL-15 is a mild load. If you seat the bullet out until it contacts the rifling lead (leeed) it will boost pressures alot.

    If you want to crimp, seat it in the center of the crimping groove, then readjust the die to crimp only. Back off the seating stem and screw down the die body to just contact the brass (crimping ridge in the die) then 1/4 turn more only. Any more will bulge the case mouth.
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  4. #4

    Default Seating depth

    Also, the only thing that will cause increased pressures is if the overall length is too long or the case is not trimmed and is jammed into the chamber when fired, That will cause a lot of grief. Properly trimming cases is one of the most important things you must do.

    You can seat bullets quite a ways into a case, but if the case and bullet are normal, that won't be an issue if you strictly follow the guidelines, as you should. For example, some folks load 250 to 275 grain bullets into a .308 case, which causes the bullet to be seated very deeply into the case. The .308 is most effective with a 150 to 180 grainer, and anything bigger is just a waste of gun. This is not recommended or necessary, as you need a bigger round than your gun is really capable of, you should get a bigger gun.
    The long bullets start taking powder space, which causes the larger bullets to be loaded to slower velocities than they were designed for. All this does is negate any advantage you were trying to gain by going to such a big bullet in such a small case. (This is possibly what you were referring to about increased pressures. If you don't reduce the powder load when going to a bullet that takes more cartridge space than it is designed for, this could be a problem).
    Now just why in the hell do I have to press "1" for English???

  5. #5

    Default Lee factory crimp

    For all the rifle cartriges I reload I use the Lee factory crimp. I used to wrinkel my 308 and 375 cases trying to achieve a good crimp. I press the bullet in the case and and have the die set to just before it crimps. I then use the Lee factory crimp. I have found that with any bullets I can crimp as tight as I would ever need. During the crimping process the die presses the brass into the bullet and creates it own crimp grove. I hope this was of some help.
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    Default

    .375H&H, RL-15 and a 270 X...nice combination. I've loaded it for many years.

    Like others have said, you really don't need to crimp the .375H&H. I used to crimp it, but I stopped a couple of years ago after reading a post from our Professor Murphy explaining why it wasn't necessary. Also, around the same time I started loading the new 270 TSX, and quickly found out that the concentric rings didn't line up well for the optimal OAL I needed for my newly rebarreled rifle. Anyway, Murphy was right, you don't need to crimp this bad boy.

    If you feel that you must crimp, then I think the only problem you may or may not have is accuracy. That is, your OAL will be dictated by the cannelure for crimping rather than the optimal distance off of the lands for the X bullet. I doubt you'll experience any pressure problems since you're trimming to the right length, the OAL is not beyond SAMI specs, and you're certainly not over packing the RL-15.

  7. #7
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    Default

    Quote Originally Posted by Murphy View Post
    If this bullet is the 270 grain XFB with the crimping groove I don't think it is at max length when seated to the groove. Max length for the cartridge is 3.600".

    First of all, you don't need to crimp the 375 H&H with any bullet. It offers no advantage. But you're correct about the trim length 2.840"

    Secondly Seat the bullet to where the mouth of the brass is in the center of that crimp groove. If this seating depth is .025" to .075" from rifling contact, you're good to go.


    I'm not following what you're saying in your last sentence. Are you saying lead as in the bullet material? It is copper. Are saying lead as in the part of the rifling that is tapered? This is what the bullet will contact. If you seat the round deeper or not it will have very little effect on pressure, this 71.0 of RL-15 is a mild load. If you seat the bullet out until it contacts the rifling lead (leeed) it will boost pressures alot.

    If you want to crimp, seat it in the center of the crimping groove, then readjust the die to crimp only. Back off the seating stem and screw down the die body to just contact the brass (crimping ridge in the die) then 1/4 turn more only. Any more will bulge the case mouth.
    Mr. Murphy SUH:

    Granted, I have not loaded/fired beeg bore rifles such as a .375 H&H, and I lack the wealth of experience that causes me to lean so heavily on yours, in many, perhaps even most, areas, but then perhaps, my brain hasn’t been scrambled by recoil either, and my logic hasn’t failed me.

    Then again, perhaps it has. You be the judge. I can take it. Not lying down though.

    If crimping offers no advantages, then why do the Factories crimp most, if not all cartridges they put together?

    If nothing else, I believe that crimping is good insurance, but there ARE, some something else’s.

    Number one advantage, would perhaps be durability, and the integrity of the round itself. A’ hem.

    Crimping can result in more uniform neck tension, and can aid accuracy. (That what Lee Precision tells us when they want us to buy their Factory Crimp dies.)

    It keeps the bullets seated where they belong as the rounds are banging around in the magazine while other rounds are being fired. (From deep in the Heart of Darkest Africa, where dwells the Constipated Ape.)

    And, let us not neglect the traditional aspects of this practice. Crimping can be very Spiritual.

    If your boolit has a crimping groove, and using it allows for seating off the lands, I see no DIS- advantage in crimping into it.

    I crimp my 30-30 loads, and my 338 loads if the above is applicable, and it always is, in my 30-30, and often is, with my 338. If it had been known, I would have been known, to crimp other loads in other cartridges too.

    As far as “max length” for a cartridge, it has been of little value to me. I think that factory loads are usually much shorter than that length. Handload data that IS at the max OAL, can be dangerous, since a rifle throat can be too short to accommodate that length.

    I will concede that you can conceivably get by without crimping a 375 round, if it is not a match for you choice of loading components, but I’d be more comfortable if the cartridges were crimped. Why wouldn’t you?

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  8. #8
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    Quote Originally Posted by Smitty of the North View Post
    Mr. Murphy SUH:

    Granted, I have not loaded/fired beeg bore rifles such as a .375 H&H, and I lack the wealth of experience that causes me to lean so heavily on yours, in many, perhaps even most, areas, but then perhaps, my brain hasn’t been scrambled by recoil either, and my logic hasn’t failed me.

    Then again, perhaps it has. You be the judge. I can take it. Not lying down though.

    If crimping offers no advantages, then why do the Factories crimp most, if not all cartridges they put together?

    If nothing else, I believe that crimping is good insurance, but there ARE, some something else’s.

    Number one advantage, would perhaps be durability, and the integrity of the round itself. A’ hem.

    Crimping can result in more uniform neck tension, and can aid accuracy. (That what Lee Precision tells us when they want us to buy their Factory Crimp dies.)

    It keeps the bullets seated where they belong as the rounds are banging around in the magazine while other rounds are being fired. (From deep in the Heart of Darkest Africa, where dwells the Constipated Ape.)

    And, let us not neglect the traditional aspects of this practice. Crimping can be very Spiritual.

    If your boolit has a crimping groove, and using it allows for seating off the lands, I see no DIS- advantage in crimping into it.

    I crimp my 30-30 loads, and my 338 loads if the above is applicable, and it always is, in my 30-30, and often is, with my 338. If it had been known, I would have been known, to crimp other loads in other cartridges too.

    As far as “max length” for a cartridge, it has been of little value to me. I think that factory loads are usually much shorter than that length. Handload data that IS at the max OAL, can be dangerous, since a rifle throat can be too short to accommodate that length.

    I will concede that you can conceivably get by without crimping a 375 round, if it is not a match for you choice of loading components, but I’d be more comfortable if the cartridges were crimped. Why wouldn’t you?

    Smitty of the North
    Smitty,

    Yeah, though you walk through the valley of the ape, you need not crimp the H&H.

    Crimping is OK but when crimping you introduce another variable to the long list of things that can change the load. If crimping, cases must be the same length, there must be a groove, the die must be properly adjusted, and of course the seating depth must be exactly right for the best accuracy and within the designs of the cartridge. It also requires a separate operation to do it correctly. There is no disadvantage if done correctly. A good way to keep the bullet from being pushed down into the case is to fill the case with the appropriate powder. The factory don't do this, they use faster cheaper powder, and they don't make very good ammo.

    Crimping 30-30 ammo that is stacked in a tube magazine is a different story than for a bolt gun which carrries rounds stacked on top one another in a box magazine.

    You may crimp but don't need to.

    As for the max OAL length, you're right if it fits the magazine then we make it best for the rifle. Not much else matters.

    I have walked in the dark jungles and open plains of the dark continent with and without a crimp and see no advantage of a crimp.
    Last edited by Murphy; 08-12-2007 at 14:33.
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    I agree with Smitty's "spiritual" aspect of crimping. When loading for my .454 Casull, the heavy crimp I put on it is one of the most important steps in the process, and I sure feel a sense of comfort as I look at the finished product...that's spiritual.

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    Spiritually speaking, crimping big bore revolver rounds, especially for heavy bear loads, is of utmost importance. But I have yet to hear a good reason for crimping any round for a bolt action rifle. And,'because the factory ammo is crimped' is not a reason. BTW not all factory ammo is crimped. What do we think will happen to the round if it isn't crimped? What is better if it is crimped?
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  11. #11
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    Default Yeah, OK, I guess.

    Thank You Mr. Murphy:

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    I'm with you professor...you made a believer out of me a couple of years ago, and I no longer crimp for bolt action ammunition.

    The reason that factory ammunition is crimped is not a mystery...factory ammunition is produced or all types of actions, e.g., bolt actions, pumps, lever actions, semi-autos, etc. I've never seen a box of factory ammunition with a warning label stating, "For bolt actions only."

    Factories load ammunition genericly, while we handloaders produce custom ammunition...and it sure is fun.

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