No, it will not. This handguard is meant for AR-15 platform rifles. It will not fit an AK.
If you are referring to being similar to the Seekins SP3R, it is not flat like a pentagon. This handguard has 8 sides, so the bottom is flat, but then flares out to the sides and flares back in at the top.
It should be just fine as long as it is a standard low profile .750 gas block. If the gas block has a rail or some other protrusion it will most likely not fit properly.
Yes, the barrel nut is included.
This handguard is well made for a very low price and is similar in style to a few different much more expensive competitors. The manufacturer is sending us new stock regularly, so the best way to guarantee you get one would be to place an order for it to put it on backorder so you are guaranteed one when the next shipment comes in.
Yes, these handguards will come with a steel barrel nut.
The AIM Sports Inc AR/M4 MLOK Handguard will work with an AM15 if it has a low profile gas block.
The AIM Sports Inc AR/M4 MLOK Handguard is not compatible with gas piston operated rifles. So it will not work with the HK416 or MR556.
The AIM Sports Inc AR/M4 MLOK Handguard works with Mil-Spec AR15 upper receivers. So it might work on a Colt M16 .22LR but I recommend contacting Umarex to confirm. From what information I could find that rifle uses Mil-Spec dimensions for certain things and then has proprietary fitment for other aspects but there is not a lot of information regarding compatibility with after market parts.
Please email us at techsales@opticsplanet.com so we can better help you out.