.20 Cal Berger 55gr, any one using?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by strombeckj, Jan 19, 2011.

  1. strombeckj

    strombeckj Well-Known Member

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    I am looking at a .20 cal build. I want to shoot the 55gr Berger's but can't seem to find a 1:8 twist barrel.

    So my Q is this... What is really working? what cartridge are you using and what kind of accuracy and FPS are you getting?

    Thanks for your input. :)
     
  2. 65WSM

    65WSM Well-Known Member

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    Please note that Berger (Mr Litz) has redone the calculations and suggests a 7 twist barrel for this bullet. The only 7 I could find was Pac-Nor. I don't actually know if and what their timetable for delivery would be. I used an 8 twist McGowen 28 inch barrel. I had the barrel "nitrocarburized" so it will last a few rounds.

    So far my .20 BR is very fast. The Magnetospeed shows with CCI 450 and R-17:


    31.0 gr 3604 31.0 gr 3578 31.1 gr 3617 31.1 gr 3570 31.2 gr 3617 31.3 gr 3646 31.4 gr 3632 29.7 gr 3572 31.0 gr 3543
     

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  3. 65WSM

    65WSM Well-Known Member

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    I had actually started to build a 22 BR to shoot 80gr Nosler Berger and Sierra bullets at 550 yards (the back clay bank of my Club Range). When I ran into a supply of Berger 55 gr .204 bullets at Sinclair, I bought 2K and started to build a .20 BR. So far the 22 BR is more accurate than the 20 BR with Sierra and Nosler 80 gr bullets compared to the .20 Berger 55s. The .22 cal bullets go between 2800 and 2900 with R-17 or VV N-550. I think that a 7 twist barrel might be more accurate than the 8 twist that I own. Both rifles have Sightron 10-50X scopes and Richards Microfit stocks.
     
  4. 65WSM

    65WSM Well-Known Member

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    Because there is still case room. I am going to try VV N-550 at nearly case capacity with the 55s. That is my next project. At 29.7gr of N-550 I get just 3500 fps and the SD is not as good as the R-17. It is not up to max pressure.

    There are other IMR 4350 burn rate powders to try as well, the IMR 4451 interests me because it is built in that new ISO 9001 plant near Toronto that belongs to General Dynamics.

    I coat all of my bullets with HBN so copper fouling is present but probably a tenth as severe as most .20s suffer. I get a trace of blue on the first patch after letting Wipe-out Patch-out sit overnight.
     
  5. Garycrow

    Garycrow Well-Known Member

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    Mullerworks Barrel
     
  6. B23

    B23 Well-Known Member

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    Defensive Edge is building me what they call a 204 Terminator that'll be shooting the 55gr Bergers in. Considering the speed those 55's will be launching at a 1-8tw will be plenty and the barrel is coming from Krieger but the longest they'll do in a .20cal bore diameter is 26 inches.

    I think that 1-7tw recommendation is because they're assuming most with be shooting the 55's in things like a 204 Ruger and at those speeds you'd need more twist to stabilize them but at 4000+ FPS a 1-8tw puts you well into "stabilized" per Bergers twist rate calculator.
     
  7. 7mmShooter

    7mmShooter Well-Known Member

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    4k+ with the 55gr? Damn... Any more info you can share?
     
  8. B23

    B23 Well-Known Member

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    Just started the build about a month ago and we are still waiting for a barrel from Krieger. I talked to quite a few barrel makers and a lot of them don't make a .20 cal barrel and even some that do didn't offer one with a twist faster than 1-9. The barrel companies I talked to said since there isn't a great deal of demand for fast twist .20 Cal barrels the wait time will, likely, be longer than normal so I don't look for this build to be done nearly as fast as the others I've had built by Defensive Edge which is typically only around 3-4 months.

    The 204 Terminator is kind of a new creation from them and will have their proprietary +P throat design. In preliminary testing they were getting well over 4000FPS with the 55's. It has a pretty healthy amount of overbore so I'm fully aware barrel life will definitely suffer but I am certain it'll be a hell of a lot of fun along the way. Until it's done and we're shooting it I don't know much more than that.
     
  9. 7mmShooter

    7mmShooter Well-Known Member

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    Sweet, gonna be a fun laser while it lasts though :D gun)