6.8 SPC & Barrel Twist

Discussion in 'AR-15 Discussion' started by GunNut, Jan 19, 2011.

  1. GunNut

    GunNut New Member

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    OK, I have built a very nice lower and decided I wanted to venture into the caliber 6.8SPC. I did a little home work, or so I thought. I found out there are two chambers; the SAAMI (SPC I) and the DMR (SPC II) and that the better chamber is the SPC II so that is what I got. I did not want the current Fan Boy rage 16 inch barrel so I started looking around for at least an 18 inch unit. I settled on a Model 1 upper with an E.R. Shaw 18 inch medium contour stainless barrel with a SPC II Chamber. For those of you who do not know E.R. Shaw is made by Savage so it should be pretty good.

    Now here is where I started going off the trail a bit; the barrel has a 1 to 9.5 twist rate. I applied what I know about twist rate from other calibers that the tighter the twist the heavier the bullet you can load for and shoot. My thinking was I could go as high as 130 grains.

    Now today I get my American Rifleman magazine and there is a very well written article about the 6.8 SPC. Well in the article it reads that Randy Luth the former owner of DPMS did some research and determined the twist rate of 1 to 11 did the best.

    Anybody out there have any experience with the 9.5 twist barrel in 6.8 SPC. At this point I will be using the barrel I have so please don't send me negative information just looking for somebody who can help me salvage what I have. Recommending bullets or loads you have had good results with is what I am looking for. Wish me luck.
     
  2. mjkeat

    mjkeat New Member

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    A 16" barrel isnt the current rage. Its just the most common length for legality and function. If Im correct the 6.8 performs as such that the shorter barrels are actually better or at least there no significant gain by using longer barrels in conjunction w/ 6.8. As far as 1:11 being better, it may not be true. Im not a 6.8 guy but often chat with a guy who is. Hes has expressed dissapointment for jumping on the 1:11 bandwagon. Id venture to guess he's not the only one. And on top of that your talking about a guy who once ran the questionable business.

    You'll be fine w/ your 1:9.5
     

  3. jhog

    jhog New Member

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    I bought a M1S upper and then later found out about SPCI and II barrels. I called M1S and was told that it is marked 1-9.5 but it really is a 1-10 twist. I verified that with my own twist rate check and it is a 1-10. I have the SPCI so I can't shoot the SSA Tac. loads = too much pressure. The 1-11 twist is for less than 100 gr hot loads from what I can understand about the suject. Hope this helps. You can also go to 68forums and get really good info from those guys.
     
    Last edited: Jan 19, 2011
  4. GunNut

    GunNut New Member

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    Thanks guys,

    You both gave me good useful information. I have purchased several loads from three manufacturers;
    1. Remington 115 gr
    2. Hornady 110 gr V-Max
    3. Silver State Armory
    a. 85 gr Barnes TSX
    b. 115 gr OTM

    Since it is 20 degrees below zero in my part of the world and we do not have an indoor rifle range anyplace nearby I'll have to wait until early April to find out how they work.