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Thread: Question on max loads for gas guns

  1. #1
    Member dkwarthog's Avatar
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    Default Question on max loads for gas guns

    I reloaded some 77 grain HPBT match bullets for my 223 (R-15 Rem) using MR2000 powder to see if my 1:9 twist would stabilize them. (It does). My stoutest load was 24.9 grains which is under listed max in the Alliant reloading info by a bit. These were loaded to max Mag length. There was still room for powder in the case.

    I ran the loads up from somewhat lower, but even at 24.9 grains, I didnt have any signs of pressure. No flatted primers anyway. I did notice that it "seemed" that the buffer spring was louder than usual when I fired.

    Anyway, the question I have is, how do I tell if a load is too hot for a semi-auto? Can I rely on pressure signs on the primer?... or if I get primers flattening have I already exceeded a safe pressure for my rifle. I not only want to prevent being over SAAMI pressures, but I want to not wear out my rifle prematurely for a few lousy FPS. Man, those 77 grains bullets shoot nice. I'll have to look and see if Sierra makes a gameking in a 77 grain. That would be a coyotes nightmare at 2700 FPS.

    So what is the limitation to max pressure in gas guns versus bolt guns?

  2. #2
    Member gunbugs's Avatar
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    The pressure limitations at the chamber are essentially the same. However, the pressure at the gas port can increase dramatically. That will cause premature wear on the components and springs. That is why some slower burning powders are not recommended for gas guns. It's just a 223. Stick to normal loads and enjoy the gun. If you want a faster bullet, try a 22-250 or some such. The gain in velocity by loading "hot" is not worth the considerable damage or increased wear it could cause.
    "A strong body makes the mind strong. As to the species of exercises, I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise, and independence to the mind."

  3. #3
    Member dkwarthog's Avatar
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    Thanks gun bugs. I have no desire to push velocities, I just want to be able to stabilize the heavier bullets without beating up my rifle too bad. I will chrono it and see where they are at..

  4. #4

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    Sierra made a 75 gr VLD SP that can substitute for the SMK

    23.8 Gr of RL15 is one of THE LOADS, gives good case life and shoots well. Works for 80 GR SMK as well.
    Groups well in the 20 In barells out to 600 yds

  5. #5
    Member dkwarthog's Avatar
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    Hey thanks Allen. I've got some RL15, I'll give that a shot as well. I see that Hornady makes a 75 grain A-Max as well, although I cant remember if that one is on the "non production list" for 2013 or not...

    For the record, these bullets I have are 77 grain Nosler competition bullets, but seem very similar to the SMK's..

  6. #6
    Member gunbugs's Avatar
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    At least in 30cal, I've found the Noslers to shoot as well as the Sierras.
    "A strong body makes the mind strong. As to the species of exercises, I advise the gun. While this gives moderate exercise to the body, it gives boldness, enterprise, and independence to the mind."

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