• Watch Out for Scammers!

    We've now added a color code for all accounts. Orange accounts are new members, Blue are full members, and Green are Supporters. If you get a message about a sale from an orange account, make sure you pay attention before sending any money!

  • The site has been updated!

    If you notice any issues, please let us know below!

    VIEW THREAD

SBR Precision Expectations

mdmp5

Gunny Sergeant
Full Member
Minuteman
  • May 7, 2009
    5,087
    2,480
    This is my first time doing this, so I took my out my 9" MCX in 300 BLK to work up a load. Shot off a bipod at 100 for the first time and slapped a 3-18 scope on there (I shoot this thing in close with an aimpoint or irons). Using CFE BLK and 155 Palmas, the best 3 shot group was just over an inch. 2 of the groups on the hot side shot ascending, traveling up 4" from the first to last shot. It almost looks like a loose scope mount, but I think it was on tight enough. Shot suppressed, no endcap strikes or anything. The center group is the best, so is this about what to expect out of a 9" BLK, maybe fine tune it a bit? The loads were shot 20 gr - 18 gr descending in .5 increments, top left, low left, middle, top right, and low right
    IMG_3040.JPG
     
    Do you have a chrony , and I've always used .2 increments as per OCW method, .5 seems like a easy way to blow right past the node with such a small case capacity/charge weight
     
    If you have a chrony try .2 increments and find a spot where velocity flattens out , that will be your node then run a seating depth test
     
    I never had any problems making sub-moa out to 300 yards with a 12.5" 6.8 premium barrel and factory Hornady SST ammo. Given the small size, an SBR can be hard to shoot well. No idea what that particular gun is capable of.
     
    No chrony. I went in .5 increments as a coarse trial, and the plan was to narrow it after. I’m actually in the middle of muzzle device problems with 2 ARs right now, and I was hoping this isn’t number 3.
     
    My bolt action and semi-auto .300BO's have been very picky on ammo. Continue to dial in your recipes and you should be GTG.
     
    You ever see a powder charge difference cause a 4 moa group? Most I’ve seen is about half that
     
    True. Is it a sporter/pencil barrel? What is your twist rate?

    You may be heat stringing more than a wobbly load if you're not waiting for the barrel to cool between shots, or it could be a combination of the two.

    All that said, I have plenty of rifles that were a bear to try and get to shoot a minute. I think my record is a .220 Swift that I probably went through fifteen different bullets, and every powder there was a recipe for.
     
    It’s a sig barrel, 5 twist. Doesn’t get very hot unless you dump a mag. Can is warm to the touch but never scorching