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Old December 22, 1999, 07:55 AM   #1
Bianchi
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I've been getting some head separation,(2 in 50 rnds) from my reloaded 308s shot in an M1A. I also noticed some of the primers slightly sticking out after firing. I use LC 92 brass, 40 gr 4895, and Hornady 150 FMJBT. I went by the instructions that came with the RCBS dies. Screw the die down until it touches the shell holder then turna another 1/8 of a turn so when you raise the ram their is resistence to bottom out the ram.
Am I over sizing? I don't have the RCBS mic yet or a case guage. I'll order them after the holiday's.
Thanks
Lou
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Old December 22, 1999, 11:18 AM   #2
Paul B.
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Bianchi. I think you just might be oversizing your brass.
Try this. Loosen your sizing dies lock ring, and back off about two turns. Take a fired case and blacken the neck and shoulder area with a Magic Marker. Don't forget to lubricate the casing. Size it. See where the die has marked the coating on the brass.
Turn the die down a quarter turn and size again. Continue adjusting the die downward until the marks just touch the shoulder. Refreshe the Magic Marker as needed. Lock the die ring.
Load up a few rounds to check for chambering when you go to the range. If they are a little snug, readjust the die about one sixteenth of a turn, and that should do it.
Hope this helps.
Paul B.
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Old December 22, 1999, 07:12 PM   #3
Bianchi
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Thanks Paul,
Thats a good idea.
Lou
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Old December 23, 1999, 09:59 PM   #4
HankL
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Lou, Paul is giving you good advise and I too think that you are just oversizing but...
Do take care of this "I don't have the RCBS mic yet or a case guage. I'll order them after the holiday's." Your load seems mild enough without being too mild so that should not be a problem. BTW don't shoot any more of those loads in your M1-A or anything else until you get a case gauge. Most new M14 barrels have pretty tight chambers so use some caution.
Hank
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Old December 24, 1999, 10:40 AM   #5
Bianchi
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Thanks Hankl
I have to check this out before firing any of these reloads. Someone suggested I disable the gas system, fire a round, then measure that fired round. can I do this without hurting the rifle?(M1A). Can I just turn the valve on the gas port?
Thanks Lou
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Old December 24, 1999, 02:32 PM   #6
HankL
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Lou, Why not measure one of the ones you have already fired? Or fire some factory ammo.
Those cases didn't have any traces of case lube left on them did they? Here is a link for more on the headspace thing.
http://fulton-armory.com/headspace.htm
Good luck and let us know what you find out.
Hank
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Old December 25, 1999, 12:31 AM   #7
alan
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Bianchi:

1. If you are using fired brass, how many times had the stuff been fired, and if it is ex-military fired cases, and thay had been fired in machineguns, the brass will not last long, due to having already been badly stretched.

2. Otherwise, it sounds likle you are pushing the shoulder back to far, when resizing. Back your sizing die out 1 full turn, resize a case. The following sounds complicated, but it isn't that bad. Strip the bolt, that means remove the plunger ejector and extractor. Remove the op rod, so that you can move the bolt by hand, without slaming. Insert a sized case in the chamber, and try to close the bolt, by hand. It most likely will not close. Screw your sizing die in, not more than 1/4 turn, resize case, and try to chamber it, closing the bolt by hand. You will reach a point when the bolt will just go home, that means the locking lugs will lie flat,with slight resistence. At this point, turn your sizing die in 1/8 turn, not more, and set the lock ring. Re-assemble the bolt and replace op rod.

3. Primers sticking out of their pockets, after fireing, could indicate long headspace, caused by either a worn chamber or over sized cases. The load you described should not be a problem.

4. There used to be a micrometer type gage around. It was a 2 piece set-up. You inserted a fired case into one part, screwed the thing together, just finger tight, and read the engraved calibrations, which read in .001". Then set your sizing die to move the shoulder back .002, which usually does the trick, with minimal working of the brass. Gas operated rifles can get a little finnicky sometimes.
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Old December 25, 1999, 01:01 AM   #8
HankL
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Alan post a world of wisdom in this one line!
"Gas operated rifles can get a little finnicky sometimes."
Hank
BTW after looking at my watch,MERRY CHRISTMAS!!!

[This message has been edited by HankL (edited December 25, 1999).]
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Old December 30, 1999, 07:31 AM   #9
Bud Helms
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Alan,

I'll bet the micrometer you refer to is made by RCBS. David Tubbs explained how he uses it to "shoulder bump", i.e., partial resize, his brass when reloading for high power matches. As I recall, it is a compromize between full-length resizing and neck-only resizing.

The neck gets almost completely resized and the body gets partially resized, but doesn't get "over-worked".

I used his method at our local club's varmint match for .223 in a 700V and got very good, accurate, safe loads ... and got a few more reloadings of the brass I was using (PMC).

I too would check headspace, if it's not been done, and make sure the loaded rounds are wiped dry before firing.

On second thought, I think the description of the problem makes a headspace check mandatory.

Sensop
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Old December 30, 1999, 04:54 PM   #10
alan
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Sensop:

The "micrometer" gage I mentioned used to be sold by Moe DiFina, a dealer/high power shooter from Conn, Middlefield as I recall. I have not run into him in a number of years, as I no longer shoot high power rifle competition. His "mike" measured only, and was used as I described.

Also, what you described sounds like "partial sizing", that would provice a "crush fit" when the round was chambered. This could work with bolt guns, though I wouldn't want to try it with a semi-automatic, which was the subject of the original post.

I have never seen the RCBS tool you mentioned, however Moe's case mike worked fine, I used one to set seating dies (full length) for 308 bolt rifles.
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Old December 30, 1999, 08:23 PM   #11
Bud Helms
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I wholeheartedly agree that partial resizing is not appropriate for autoloaders and probably some lever actions.

I got the instructions out and read them again. The RCBS Pecision Mic, as it's called, is designed for you to resize to just within an individual rifle's headspace dimensions.

It also includes a device to determine bullet seating depth.

Sensop
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Old January 19, 2000, 08:10 AM   #12
Bianchi
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Just wanted to give you guy's an update.
I ordered a Wilson case gage and an RCBS mic
to measure headspace and oal. What I found is that I was in fact oversizing the case. using both the case guage and the mic. I have resized cases now that are .002 under the fired case size.
Thanks again for all your help.
Lou
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Old January 19, 2000, 05:28 PM   #13
wildcat
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I came in alittle late on this one but here goes anyway.Your rifle was probably designed to fire .308 NATO.The NATO round is about .005 longer than the .308 winchester and is loaded to a somewhat lower pressure.I am sure some creative die adjustment will help.You may also want to keep your load near the starting load.This can really get critical with some of the weaker rifles chambered for this round like the Spanish Mausers and the rebarreled .303 british rifles. Try some .308 NATO surplus ammo and see what the cases look like.

[This message has been edited by wildcat (edited January 19, 2000).]
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Old January 21, 2000, 02:29 PM   #14
flatlander
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I use a RCBS PrecisionMic for all my 223 loads. If I had thought about it before ordering the RCBS tool, I'd have bought the Stoney Point Headspace Gauge instead. For about the same money(assuming you've already got a vernier or dial caliper), the SP tool will measure the cases for just about any centerfire caliber you can imagine. It measures the same dimension as the RCBS does, but with a set of inserts, it will fit any cartridge. Using one of these tools is a good way to avoid headspace problems with reloads, and will help make your cases last longer, and require less trimming.

As far as partial sizing in a FL die goes, you can make the shoulder move forward by doing this. As you run the case part way into the FL die, the die squeezes the case body down in diameter, and since the case head is held in the shell holder, there's only one way for the case to give to accomodate the reduction in diameter. If you don't run the case far enough into the die to set the shoulder back a little, it's possible that it will have grown enough to make it difficult or impossible to chamber. You can experiment with empty partially sized cases to see if this will be a problem.
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