If you insert the lower handguard under the front trunnion, it is loose up and down. Not horrible but there is an obvious small gap. I cut a very precise block and slid it down the inside of the receiver and it goes all the way to the front of the receiver but stops about .3'' before the opening of the front of the receiver. When I measure the front of the receiver (heigth) from bottom to top of rail, it reads 1.29''. Anything not look right here?
Whew.....Let me tell you, drinking wine taking pictures and dimensions don't go together very well (it seemed like this took forever).
First, the lower hand guard. I had a rifle that the lower handguard was about 1/8" to short and was very sloppy in up and down movement. I used Brownell's Acra Glass Gel (some with stain and some without, you can tell). The gel that went into the receiver was hidden and tightened the movement completley. On the sides you could see it but it really didn't look that bad when up against the receiver. I used the gel to force the handguard against the forward retainer, that's why it's at the back of the handguard.
NOTE: I don't know how to separate the pictures (with text) so all the text will be up here and the pictures will be together.
Second, I took a reading of one of my ACE bends (haven't opened up the others) and the two K-VAR stubs I have. The Ace measured pretty close to perfect (both LH and RH)and it's OAL is more than 10.25" so I'm okay on the dimensions. Yours measured 1.29", make sure that your dial caliper is not level but follows the angle of the receiver. I put mine flat on the bottom and then raise the caliper to meet the upper rail as close to the side of the receiver without going into the curve. The dimensions for the AK receiver at the front should be 1.250" at the bottom and 1.200" at the rail with an OAL at 10.25". If your receiver block is 1.25" (bottom) by 1.200" (rail) (make sure it's in correctly) then measure the distance from the end of your block to the end of the (back) receiver. You should have an OAL of 10.25" or just a little bit longer.
Both the K-VAR (Bulgy) stubs measured weird. The bottom mesurement was 1.264" and the top rail measured right in at 1.200". Go figure.
I hope this helps. And now for the pictures.......