Head space question

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by BrentM, Feb 17, 2014.

  1. BrentM

    BrentM Well-Known Member

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    I recently installed a 26" barrel on one of my 204s and have some questions. This barrel does not allow me to shoot as high of pressure ie powder charge as my stock 22" rifle. As a result the velocity is also not as high.

    For example I can load 24.7 grains of h4198 in my 22 and get 3780. With the 26 I max out at 23.5 and 3700.

    I am using PTG hs guages and tried to set hs as close to same as the stock rifle as possible. Using the go Guage I run it to where I just get a little resistance, similar to the stock rifle. If run a piece of tape on the base if the Guage the bolt won't close.

    Ok so is this a problem with not enough hs? Should I set the barrel a little looser? I just don't get it. I expected 100 fps faster at same powder levels but can't get there. Another weird deal is factory Hornady ammo will in fact to about 100 faster. Accuracy is fine with my hand loads. Shooting around .25 or less moa.
     
  2. Bullet bumper

    Bullet bumper Well-Known Member

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    Don't muck about with the head space , you could make it too long and start stretching cases. It is most likely associated with bore tightness and maybe smaller chamber dimentions of the new barrel .
    Try using a tad slower powder and rework the load . It may make better use of the longer barrel .
     

  3. Mark611

    Mark611 Well-Known Member

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    I agree that's the same thing I was thinking:D
     
  4. Bullet bumper

    Bullet bumper Well-Known Member

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    They say that great minds think alike :rolleyes:
     
  5. 4bycamper

    4bycamper Well-Known Member

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    +2 on the headspace thing. Sounds right to me.

    Hmmm... less powder, almost as fast. Same 1/4 moa accuracy.
    A couple of thoughts if I may. Maybe it's the powder? Maybe 24 grains is not enough powder to use 26 inches of barrel?
    Could the old tube be one of those fabled fast barrels?
    Hodgdon starting load is 25.5, H335, 3665 fps. If you can't get this much powder in, how deep is your bullet seated? Have you tried a drop tube?
    Last thing, tell me about your chronometer. :D
     
  6. BrentM

    BrentM Well-Known Member

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    Almost as fast? 100 fps slower in a 4" longer barrel is not almost as fast IMO.
    24 grains maybe not enough, I agree, but I am at max with 23.5 w as mentioned.
    H335? Never tried it so I have no clue if that powder would fit in the case. I would imagine it would since I can get 28.5 H4895 and Varget in there. Bullet seating is .100 off the lands and fills 75% of the neck.
    Chrono is f1. However, I verify all my loads once a shooter is established. For the 204 I verify 500-700 yards. For my LR rifles I verify 500, 1000, 1500.
     
  7. 4bycamper

    4bycamper Well-Known Member

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    80-100 fps... OK I hear ya. 3700 is still pretty fast. What weight bullet?
    H 335 is a flaked powder. You can fit a bunch of it in a .223, I bet it will compact nicely in your 204. Might fix the velocity thing.

    Varget is small pellets, it doesn't pack quite as nice, but it works all season. It's our AR powder. We go through pounds of it every year. :D
     
  8. Canadian Bushman

    Canadian Bushman Well-Known Member

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    You mentioned youre .1 off the lands. Have you already tried seating depths closer to the lands? Maybe .01 or .02?
     
  9. BrentM

    BrentM Well-Known Member

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    It is not possible on this barrel to get that close. It has long throat and bullet to the lands means almost no bullet in the neck. My other 204 is not nearly as bad but it doesn't like shallow seating either. At .175 the old 204 shoots under .2 but that limits my case capacity. At .100 they both shoot much better than at .050 or less.
     
  10. BrentM

    BrentM Well-Known Member

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    40 grain Vmax and 39 grain Sierra BK.

    I tried to stick with temp stable powders and of course powders I could actually find on the shelf. LOL. I use this rifle during winter hunting in temps from 0 to 40 degrees so I guess it was just a peace of mind sort of thing.

    So far I have not really run out of room before I ran into pressure issues. Ejector marks and bolt lift.
     
  11. Canadian Bushman

    Canadian Bushman Well-Known Member

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    My thinking was to help reduce pressure by adding volume in the case.

    Assuming its a new barrel, i thought maybe the throat lead in could be causing more resistance than your 22" gun and a smaller jump could help increase volume and possibly allow more powder while smoothing the curve.

    Only other idea i have is to try a colder primer, or maybe a thinner case. If that isnt possible or doesn't work id revert back to bullet bumpers idea of different powder.

    I would find it difficult to start changing things with a load that shoots in the .2's
     
  12. BrentM

    BrentM Well-Known Member

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    Accuracy is not the issue for sure. I am fine with that. I do know something else is wrong though for a 26" barrel to be slower than a 22". So I am on a mission to increase my knowledge and experience. This is my first rifle build so I naturally figured I might have an issue with HS. Last night I was messing with my cases and checking necks, lengths etc. What I noticed is that some fired cases would hold a bullet tight and others would not, hmmmm, that is odd. I went to grab the cases used in the other 204 and noticed they were gone. Quizing my son it was discovered he cleaned them and unknowingly mixed all the brass together. DOH. So I have mixed brass.

    I am going to start over with annealing all of it, body size, shoulder bump, trim, etc.
     
  13. Canadian Bushman

    Canadian Bushman Well-Known Member

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    Ah yuck! Keep us posted. Id like to see what the resolution ends up being.
     
  14. BrentM

    BrentM Well-Known Member

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    Yuck for sure. It is OK, he thought he was helping and I didn't tell him what I was doing.

    I have some 1x fired Hornady brass from the new barrel that I will sort out and use for the next test. My hope is that my issue was with mixed brass and the chamber will handle more powder for a similar charge weight and get the increased speed and accuracy I expected. If this holds true I can fire a similar charge weight and get about 100 fps faster velocity via the barrel length.

    I have another 26" 204 varmint contour barrel I want to put on my original 204 with the 22". If all works out like I hope I will sell the new set up, rebarrel the old, and have gained the experience of building a savage.