COL. for reloading 120gr. SST's

Discussion in 'Reloading and ammunition' started by PRyan1877, Mar 29, 2018.

  1. PRyan1877

    PRyan1877 Roselle, Illinois SUS VENATOR CLUB LoneStarBoars Supporter

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    I am reloading spent brass with Alliance AA2200 powder, CCI 41 primers, and 270 caliber Hornady 120 grain SST's. From the factory the COL is 2.240", Alliance calls for a reload to be 2.260" and on the 6.8 Forum the consensus is 2.285". What repercussions would I experience from loading at 2.260" or perhaps the question should be, what is the advantage of not seating the bullet deeper into the shell?
     
  2. Six8

    Six8 New Member SUS VENATOR CLUB

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    Not seating deeper equals less jump for the projectiles ogive to reach the lands and grooves. Less jump = better accuracy. But not touching! That equals a dangerous pressure spike.

    I loaded mine long but I don't have the number on me. They are close to max PRI mag length. They shoot pretty good from 12" a SBR hunting rig, 1" groups.

    Nothing wrong with loading to 2.240 like Hornady does either. But the deeper seated might cost you needed case space.
     
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  3. PRyan1877

    PRyan1877 Roselle, Illinois SUS VENATOR CLUB LoneStarBoars Supporter

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    Thank you Six8, I pulled the 2.240's apart and when I dumped the powder to re-measure the load, the powder would not come out. I found that at 2.240 the powder was compressed, I had to dig it out. I loaded at 2.285 and it just fits my ASC mags 2.290 would be cutting it close. I had not considered the jump space that is left between the bullet and the lands when loaded short. I wonder if the Hornady 120 SST's are made for non SPCII rifles since the old 6.8's did not have as a deep chambering as the SPCII's. Thanks again for helping me out and giving me insight into how to better load my ammo.
     
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  4. Wildfowler

    Wildfowler Mis'sippi SUS VENATOR CLUB

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    It’s also possible you could discover even better accuracy? But you should load to the longest length that your magazine will reliably feed and test toward a shorter seating depth at small intervals on paper and see what your rifle likes best to know for sure.

    I don’t have a 6.8, but using that bullet in my 270 AR, I got best accuracy using standard mag length of 2.260”. I tested in .005” increments from 2.3” down to just below 2.26” when I started getting excessive pressure signs.
     
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  5. Six8

    Six8 New Member SUS VENATOR CLUB

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    Correct experiment in small increments to find the most accurate length. And yes Hornady probably did seat them that short for the old barrels out there. Me in my reloading room, we don't worry about no old SPC I barrels they are dead to me :D
    But that's probably something a manufacturer would want to take into consideration for more sales and less lawsuits because the dummy didn't read the box where it would of said DO NOT use in older SPC I barrels. But they did anyway and blew up their old SPC I rifle. lol

    * Not funny they blew up. But funny they didn't read then had the audacity to sue.
     
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