View Full Version : Does YHM low pro gasblock fit under MI Rail?

Astig Boy
05-19-2010, 2:05 AM
Can someone please let me know if a YHM low profile gas block will fit underneath a Midwest Rail? TIA! :D

05-19-2010, 2:25 AM
yes- should fit fine.

05-19-2010, 8:13 AM
The MI and YHM rails are pretty large and all of the low-pro gas blocks should fit under them, but the main question you should be asking is if the rail you are buying is long enough to fit over the gas block you want. With the MI rail you are required to bolt the endcap onto the two rail halves in order to hold it together so make sure you rail is long enough to completely clear your gas block to allow the end cap to be mounted.

So for example, if you have a carbine gas system (7") and you have a long gas block that covers both taper pin holes (2") then you need a 10" rail to go over it. By contrast, if you have a micro gas block (1") then a 9" rail will be fine, but the front taper pin hole scar may be exposed (assuming you removed the front sight).

Conversely, if you have a mid-length gas sytem (9") and you want to cover a long gas block then you need to use a 12" MI rail.

With one piece free floats this usually isn't as much of a concern as the gas block can be even with the end of the rail, or partially, or completely exposed without affecting the function of the rail.

Astig Boy
05-19-2010, 10:00 AM
Thanks guys! :)

@Shark - I plan to use a carbine gas system (7"). I would like to use a 9" MI rail. I really don't know how long the YHM gas block is. Hope someone can help me there. Not to many stores stock this stuff, let alone help me in figuring this out. Thanks for your insight. I never bothered to think if the rail would clear the gasblock for the end caps. :)

05-19-2010, 10:13 AM
If you use a long gas block that covers both taper pin holes, then you need a 10" rail. This rail and gas block, for example:

MCTAR-24 10" rail: http://riflegear.com/p-44-midwest-industries-two-piece-free-float-10-carbine-length-mctar-24.aspx
std low-profile gas block: http://riflegear.com/p-111-midwest-industries-low-profile-gas-block.aspx

If using the 9" MI rail you need a short gas block like this:

MCTAR-21 9" rail: http://riflegear.com/p-42-midwest-industries-two-piece-free-float-mid-length-mctar-21.aspx
JD low-profile gas block:http://riflegear.com/p-558-jd-machine-low-profile-gas-block.aspx

Astig Boy
05-19-2010, 5:46 PM
Thanks Shark! That is exactly what I wanted to hear. :D Really appreciate your knowledge and time in posting!