The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Frequency of trimming casesGo | New | Find | Notify | Tools | Reply | |
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| One of Us |
okay, I just started reloading and purchased a bunch of brand new unprimed brass. how often should I expect to have to trim the case lengths down? After the rounds are fired and the brass is re-collected, do you always measure the case length after cleaning the brass, before reloading it? Thanks, Steve | ||
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You measure case length AFTER they are resized. Often times the expander button will stretch the case necks and that will sped up the trim frequency. Depending on the cartridge type, some are worse than others, the size of your chamber, how hot your load is and how much your dies resize will determine frequency. You may get 5-6 loadings on mild loads prior to trimming and 3-4 on others. Greg | |||
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Check the trim length suggested for each caliber. after I re-size I check the length and trim if necessary. I always full-size when I am using an AR rifle, prefer to neck-size when I am using a bolt action. If you have multiple rifles for the same caliber, its safer to full-size, for example, I have multiple 17 FB rifles and they each have different chamber sizes. Trim depends on a combination of the brass, caliber and load. For example. I have a 22 Squirrel rifle that I can reload the same case 65-70 times with Win brass and 40 times with Rem Brass, I seldom had to trim them. | |||
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If you only bump the shoulder .003 your brass will last much longer than FLR brass and less trimming to boot. Learn to measure your brass at the C/L datum of the shoulder to assure you are not under/over sizing your brass.  ________________________________________________ Maker of The Frankenstud Sling Keeper Proudly made in the USA Acepting all forms of payment | |||
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Fire form your brass. Resize it and trim it to match the shortest case you've got, or to the book valuse, whichever is shortest. Keep a sample to use when you're setting up your trimmer for the next go and then load 'em up and shoot 'em. When the length grows to approximate the book max, trim 'em again. Keep count of how many firings you get between trimmings and that will give you a guessimate with that rifle and that brass and that loading. There are too many variables to be able to say "You are gonna get xxx firings between trimmings." If you're going with some sort of red-line load, you'll be getting split necks and loose primer pockets before you have to trim more than a couple of times. Aim for the exit hole | |||
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This link from Varmint Al's Reloading Page will help you. The length from the datum line on the shoulder to the case head has nothing to do with when you need to trim. Varmint Al states that better accuracy will be had if you let your cases grow to approximate your actual chamber length...every chamber may be different, hence the gauges you can buy from Sinclair. The stated trim lengths in manuals leave a .050" to .070" gap between the end of the case and the actual length of the chamber.
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I trim every time I load... to keep a uniform length | |||
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Hmmm. Since the bullet's position would be constant relative to the lands, why would where the end of the case strikes the bullet affect the accuracy? Assuming, of course, that there is sufficient case neck to hold the bullet. And too, while I understand that until the case grows longer than the chamber, it is not a safety issue but if one wanted to keep this .005 distance, wouldn't one need to trim after every firing session? Which kinda defeats any idea of a +/- case length. I've never questioned the need to have your brass at a UNIFORM length to do your best work relative to accuracy but I've always felt that had to do with neck tension. Aim for the exit hole | |||
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Consistent lengths will generate a more consistent neck tension thanks to surface area of the bullet that is impacted. This would be in a pure state. In reality the + or - , within reasonable parameters, is not going to be noticed by the average or slightly above average shooter. If a guy determines MAX CHAMBER length with the Sinclair tools he can let the brass grow out to that length. It is usually a lot longer than we realize. It will cut down on trimming for the initial work. You could trim back to the minimum at that point and cut down the trimming until you get back to that much longer length. Greg | |||
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I have found that the cases for some of my rifles need to be trimmed more often than others. Regardless, though, you have to measure them every time you size them(after sizing them). To me, the most important reason for checking the size of the case is safety. If you load a case that is too long, when it is chambered it can pinch the neck and not allow it to expand properly to release the bullet when it is fired. This can result in dangerously high pressure build up in the chamber. Good luck, and safe reloading. Red C. Everything I say is fully substantiated by my own opinion. | |||
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And that happened to me early in my reloading life. I trimmed 30-06 brass to minimum and figured that was good enough for a couple of reloads. It was not. I blew primers. I have Gracey and Giraud trimmers in 308, 30-06 and .223. With these trimmers it takes 5 minutes to buzz through 88 rounds of match ammunition, start to finish. I have a RCBS trimmer for all the other cartridges. I trim each and every time, around 5 reloads the cases only need a thousandth's or two if they have been fired in the same rifle and sized with the same die. Changing rifles and sizing dies has changed the final length out of the sizing die. Don't know why. | |||
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