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M1A/M14 brass sizing question

Discussion in 'Handloading and Reloading' started by Fatelvis, Aug 5, 2010.

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  1. Fatelvis

    Fatelvis Member

    Dec 25, 2002
    Lockport, IL
    I've been reading alot about measuring datum points on brass, and buying case guages, etc., for loading for the M1A. Do you really need a case guage? Please tell me if this method is wrong:
    Clean the chamber well, remove the Op rod spring and extractor, take about 6 cases that were fired in the same rifle and put them in the chamber and see if the bolt closes on them easily. They never do. Start by sizing one of the cases (using a FL die), so it barely bumps the shoulder. Chamber the sized brass, and try closing the bolt. If it doesnt easily close, size it again, after lowering the sizing die 1/16 of a turn (.0045"). Try chambering the brass again. If the bolt doesn't close, size the brass after lowering the die another 1/16 turn, and repeat until the bolt closes. At this time, try sizing at least three of the other fired cases, and chambering them. If they don't chamber easily, lower the die another 1/16 turn, and make sure they will chamber easily. After determining that the sizing die is bumping the shoulder enough to permit chambering, lower the sizing die another 1/16 turn, to giving at least .0045" shoulder clearance.
    I've done it this way for many years, and have never had a case sep, although I only loaded them 4 times after original firing, and only had 1 rifle. Thanks-
  2. Walkalong

    Walkalong Moderator

    Nov 20, 2006
    That method has been working fine since handloading began. Some like to size to fit the gauge for autos instead of just bumping the shoulder enough to chamber just for that little extra bit of reliability. If your reloads function 100%, you are good to go.
  3. loadedround

    loadedround Member

    Feb 18, 2006
    Valley Forge, Pa
    I've been firing my NM M1A for several years now and basically follow the same procedure you do w/o using a case gauge. I do full length resize all my cases and usually get four or five loadings if I don't end up losing them in the grass. BTW, I've been getting quite a few once fired LC cases and removing that military crimp was a royal PIA. Recently bought a Dillon Super Swage and what a pleasant change to that tedious task. Try one if you reload GI cases.
  4. Slamfire

    Slamfire Member

    Dec 29, 2006
    Without gages, that is the only way to do it, except it is crude and inexact. (How do you do that in a AR?)

    I used to size brass that way, for bolt action rifles. Then I got case gages. I can remember gaging my 270 brass, brass that the die was set up following your procedure. None of the brass gaged correctly. Either they were undersized or oversized. Same thing with 7.5 Swiss, though I had to use a Sinclair comparator.

    This small ledge is the difference between the Go and No Go on a 308 cartridge headspace gage. That .006” is awfully small.

    You will find that using the cocking cams of the action, often a 7:1 leverage advantage, hides an interference fit. Once I got gages, I observed differences in sized headspace in brass of different lots, different manufacturers, and brass fired in different rifles. There is no guarantee that each and every lot of brass with react similarly. I usually have my case gage on the bench to verify that I am not under sizing or over sizing. And if I need to, I adjust my dies real time.

    I took one set of 100 LC66 twenty two reloads in a M1a, always full length resizing, always setting the shoulder back about .003" or more and using lubricated cases. I never had a case head separation. My loads were full power: 168 Match with 41.5 grains IMR 4895/AA2495. Last I fired those cases was Rattle Battle at Camp Perry.

    Ignorance is bliss. There is always someone who can make a convincing case why they don't need calipers, a weight scale, or even why it is un necessary to know how to read and write. Except they won't be posting their opinion any time soon. :D

    Sizing rifle cases without gages is like driving a car without a speedometer.
    Last edited: Aug 5, 2010
  5. medalguy

    medalguy Member

    Mar 20, 2009
    New Mexico
    What he said.

    Case gauges are not absolutely mandatory if you do it the way fatelvis does it, but they sure do make things a lot easier and more accurate. Especially if you load for different guns of the same caliber as I do.
  6. ReloaderFred

    ReloaderFred Member

    Apr 28, 2005
    Oregon Coast
    I use the RCBS Precision Mic to set up my sizing dies for all of my rifles in .223, .243, .308 and .30-06. Two of those rifles are M1A's, a NM and a Standard.

    I like to set the shoulder back .003", as Slamfire1 does, and it's worked for me for over 20 years with the M1A's. I don't count the reloadings on my brass, but I've yet to have a case head separation with either rifle, and the brass just keeps on going.......

    Hope this helps.

  7. WNTFW

    WNTFW Member

    Jul 16, 2006
    I used to use the does the brass fit the chamber method. I recently picked up more cases gauge to fill the gaps on calibers I did not have. One was for .308 as it was easy fit the case to a bolt gun. I still had that to get the rifle out of the safe and bring it to my reloading area outside the house. Sometimes it was raining, you get the picture. Guess what? The cases that fit my chamber also fit the case gauge perfectly. Makes life easier. A lot quicker.
    You can also screw up on the feel of the bolt.

    I also have several instances that I reload for rifles that are not necessarily with me. I also reload some calibers that I want to insure are within SAAMI specs.

    Lacking a case gauge you have to do what you have to do. Having done it both way I'd rather have a case gauge.
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