As I write this, I assume that everyone reading this knows about "dime drills".

So I was doing some dime drills with my AK (a SA-M7 A1R) and found something unusual happening.

I began by balancing the dime on the portion of the barrel between the gas block and the front sight block.  Nearly every time I pulled the trigger, the dime slid off the barrel.

But then I moved the dime and balanced it on the flashhider and found that the dime stayed put every time I pulled the trigger.

I then did the dime drill on my .30-06 and SAR-1.  I tried both rifles with the dime balanced at different points along the barrels of both and the dime almost never fell off of either.

Any ideas what's going on?  All I can think is that because the SA-M7 A1R barrel is very smooth as compared to the .30-06 (matte finish) or the SAR-1 (small ribs on barrel), the dime is less stable there and is more prone to falling off.  Either that or my SA-M7 A1R action is somehow much more violent than that on either of the other rifles.

Again, any ideas what might be happening?

Thanks for your input.

try it with a cleaning rod inserted in the barrel, and the coin on the rod. takes some finesse. good training though.

I've not heard of that before, but I'll keep it in mind and see what results it yields.  A better measure than putting the dime on the barrel?  Maybe, but it sounds really tough.

Edit: I cannot even get a dime to balance on the cleaning rod.

You're supposed to stand the dime on it's edge, you willow-shaking pussy.

Ok I'll ask, whats a dime drill?

It's where you balance a dime on the barrel of your rifle and dry fire the rifle without knocking the dime off.  If the dime falls off, it indicates a problem with your trigger pull.