I have a HBAR 6600 with an ARMS mount with Burris Zee Rings with a Nikon Monarch 3x9x40 on it. I have shot this rifle since about 88 in IPSC with different scopes on it have have never had any problems with the A2 mount set up. Off the sand bags with Fed Match I get around an inch, with Fed 62 American Eagle it is good for just under 2" to 1.5", all at 100 yards. I have a Bushy AK Shorty A2 I just got and used the Smith Enterprise Tatical Mount with an Aimpoint that I now shoot in IPSC (had a Leupold M8 2.5x Compact on it for a while, now it is on the FAL). With the Aimpoint there is no paralex (spell check?) error at all so the whole check weld/scope height is also.....no issue. The Bushy will also get just under 2" @ 100 yds with the 62 gr Fed AmEagle. The other issue you need to consider is the trigger. I have a Jewel @ DCM 4.5 lbs in the HBAR and the Bushy has a JP @ 2.75 lbs, super crisp. I have used a Colt cheek piece and it worked fine, held my head in the exact spot again and again, don't know why it wouldn't work for you if you feel yu need it. I shoot off bags a lot and got rid of it because I started to shoot DCM/CMP with the HBAR. If you do get a flat top, you will need either a spacer or high enoough rings to get the scope high enough to see through, I have seen a few that are just too low to see through.
Good luck, my free 2¢
Bill
Happiness is a warm gun...
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