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Range Report for MK107P

Went to out a local outdoor range with a friend of mine, we did some pistol drills and some rifle stuff.  I wanted to see how my PWS MK107P performed out to 100 yards.  

It has changed configuration since the last time I posted it.  I swapped the SIG SBX for the standard SB15 brace because the SBX wobbled due to the diameter of the pistol buffer tube being slightly smaller.  The SB15, however, fits just fine and is snug.  I also added a thorntail for my TLR-1S to be offset above the PWS CQB muzzle device.  I shot out from 100 yards, then 75 yards then 50 yards with Independence "IMI" 5.56 55gr XM193I to see what the grounds would look like.  I had originally zero'd the Aimpoint H1 at 25 yards using F2S's 100M zero.  At 25 yards the bullets were touching (same ammo).  I made slight modifications to it as I went closer, nothing over 2 MOA each way.

At 100 yards:

At least it hit the pie plate, right?  I did not really expect to see sub MOA groups at this distance from the MK107P with the IMI ammunition.  I do not know the rate of burn and it may have not gotten enough velocity coming out of the front end.  Is it still effective at 100 yards?  Pie plate hits say yes.  Of course it does not help that I have a 4 MOA RDS and should really be using a 1-4X minimum for this (my opinion).

At 75 yards:

Groups got a little tighter, I adjusted the Aimpoint a little and got the center of the bulls-eye.  

At 50 yards:

After a very slight adjustment, POA was center of bulls-eye, POI was in the 9 ring.  Which is what I wanted.  Like I said, this is a little bit of a work in progress as the 4 MOA H1 may not be suited for the short barrel, I may need a 2 MOA or a 1 MOA on a 1-4X or a 1-6X.  I guess to really test out the accuracy of the MK107P i'll need to get out and put a higher power optic and try different factory loads to see what works.  Maybe this will be a job for the SR8c, a bipod and a bunch of different ammunition.  As for now, it looks like 100 yards, with IMI, may be the top of the combat effective accuracy spectrum.

Just to add, I understand the 1:8 twist of the 7.75 barrel may need a heavier bullet, I will test that out next time.