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Posted: 6/3/2008 5:26:36 PM EDT
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I am going to work up about 20rnds of 308 (These are my first rifle rounds, just finished up learning on 9mm) and am wondering about the crimp on the bullet ? I will start off with: LC 308 MG Brass sized and trimmed to 2.005 Fed 210 primers 41.5g of IMR 4895 147g BTSP I will be setting this up on my 550, Dillon suggests the crimp be approx .002" so I have to ask a stupid question, how do you measure the crimp I can only guess that around where the cannelure is on the bullet that it should measure approx .002" less than just below where the bullet ends in the neck, like I said it may be a stupid question but all I have are a few books and you guys to ask. Thanks |
Taken From........ www.chuckhawks.com/adjust_reloading_dies.htm Aloha, Mark |
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I crimp ALL my reloads. But I exclusively use a Lee FCD. For $8, it is an excellent addition to any caliber setup you have IMHO. Hell, I even shoot a cartridge that Lee doesn't make a production run FCD for (.35 Whelen). But for $29 I had them make me a custom FCD from a dummy round I sent them. In my book, FCD is the only way to go. - AG |
No. For slamfire and functional reasons, the brass must be slightly shorter at the shoulder than the chamber. You verify this with your case gage. If it won't chamber, and you measured with your case gage to make sure the resizing die is set properly, then you probably need to SB resize your MG brass. Basically, if the round drops into the case gage, then you're good to go. From a crimp perspective, if you chamber a round from the magazine and the bullet doesn't move a bunch, then you don't need to crimp it. |
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To crimp or not? www.scidetroit.com/bulletseating.htm www.speer-bullets.com/default.asp?s1=5&s2=30 Aloha, Mark PS.........since you're beginning. For your M1A (magazine fed rifle)......I suggest: If your bullet has a cannelure...........crimp it in the groove. IF your bullet doesn't...........then just use neck tension (or very little crimp), enough, so that the bullet won't telescope back into the case under recoil forces or when feeding into the chamber. Test by pushing (not too hard) the bullet end of a loaded cartridge against a block of wood. |
As for "checking" IF your re-loads will function.........may I suggest.
Note that this was my step #6. The main idea is to test, while you're producing ammo......so, there is no bad "surprise" when you reach the range. Aloha, Mark |
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I do not crimp my rifle reloads. If I were bound & determined to crimp despite good info that it is not needed, I have heard good things about the Lee Factory Crimp Die and would probably use it. ETA - There's no way I would crimp a rifle load unless the bullet had a cannelure, AKA a "crimp grove". Even then I don't crimp. |
I have a Dillon 308 case gage, I checked about 50pcs of the MG Brass from Top Brass randomly out of 1000 in the gage, the rear of the gage has a low cut in it and the base of the resized cases sat slightly above it and on the high part it drops down just abit acutally the base kind of sits in the middle of the two and on the bullet end the mouth is pretty close if not right at being flush on top so I can only assume they are sized correctly as they all measured 2.005" They do go right in the chamber with no problems and extract pretty easily, if they are sized correctly is there some way to use one to set my resizer die ? The bullets have a serrated line around then about 1/16" wide so I am assuming that I seat to the cannelure, check OAL then give it about a .02 of a crimp ? and see how they chamber And if they are sized correctly should I run them all thru again just in case one was not done correctly ? |
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They should be fine. If they don't cycle 100%, screw the die down a hair more till they drop into the min length step on the gage and try again. Ideally, you'd take your fired cases, measure and then set the die so that it pushes the shoulder back by 0.002-0.004". It can be difficult to get an accurate measurement on the type of gage you have, so I'd find something between min and max that works and run with it. It'd be pretty hard to get one of them longer than the others (the shoulder that is). I would recommend you trim or measure them all to make sure they don't exceed the max trim length. |
Assuming that you've re-sized all of the cases with consistency, that sounds GTG. BTW, I do things as a "lot." So, I always F/L size my fired brass. After re-sizing, I'll take a small test sample and IF one case needs a trim.......I'll run the whole lot though the trimmer. First Time: New, once fired (purchased and given) and range pick up brass are always trimmed (with few exceptions) for consistency sake. IF it's not done with your brand of trimmer..........don't forget to slightly chamfer and slightly de-burr the necks. I'll ease bullet seating. USE THIS STYLE OF TOOL.......... www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=364181&t=11082005 For ME........AT or BETWEEN the high and low cuts, is "good enough." Though, individuals will vary as to their own specs. for ammo (all at the high or all at the low cut). Whatever, "floats your boat." I've been told: You actually place the gauge (w/cartridge case) headstamp end down, on a flat surface. The case will sit on the flat surface. The neck end should be, at or between the two cuts, to be correct. Though, since you have a caliper.........measuring works too.
To "set the die"......use the lock ring to lock the position. That way IF you remove the die.....then you will just have to screw it back in (back down to the lock ring). Of course, you'll run a few test cases to check. That is the biggest reason why, I don't like the LEE brand of lock ring.
Yes, that band around the bullet is the "cannelure." You can seat it there or go longer or shorter, it's up to you. As for the .02 crimp. Well, it doesn't have to be "exact science." "Good enough" is what I look for. And, yes, testing throughout the process is always good.
You mean the re-sizer die? That is not needed, since you've been testing throughout the process. And, YOU HAVE FAITH, RIGHT? Besides, I've found that loaded cartridges won't fit the F/L sizer die (w/de-capper removed). Because, once the bullet is seated...........the case neck will be bigger due to expansion of the brass in the neck, when the bullet was seated. Perhaps, I should say, YMWV.............as there might be exceptions. Aloha, Mark |
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