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Low profile gas block clearance.

Wisconsinner

Private
Full Member
Minuteman
Feb 24, 2013
156
67
Appleton, WI
I recently finished up my first build, and learned a whole bunch along the way. My concern is the clearance between the gas block and bottom of the inside of the handguard. There is about. .05 to .06 of clearance without pressing the barrel and handguard together, and it never touches unless I force them together. Will I run into any issues? Any insight would be appreciated!
 
It depends, I've seen some high speed footage and some barrels will have minimal whip, and seem will shake like a wet noodle. Shoot it, break in the barrel (whatever your preferred method, I just shoot and clean after the first range trip, but I also don't shoot super high precision) and if youre getting flyers that are hard to explain pull the handguard and see if you can make out a contact point, if not and you feel OK with the accuracy you're getting leave it until a problem shows up. If it is making contact then you can get a bigger id handguard, aero makes one thats massive on the inside, and there's a few others, pri is pretty big on the inside, but its $$$.
 
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I had Midwest hand guards that touched the bottom of the gas block. In my mind, I was missing due the flex of the hand guard. I’m only using Geissele rails now and my performance has gotten better. This is totally psychological!!
 
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I had Midwest hand guards that touched the bottom of the gas block. In my mind, I was missing due the flex of the hand guard. I’m only using Geissele rails now and my performance has gotten better. This is totally psychological!!
I had Midwest hand guards that touched the bottom of the gas block. In my mind, I was missing due the flex of the hand guard. I’m only using Geissele rails now and my performance has gotten better. This is totally psychological!!
This is the exact route I think I'm headed. This build has a MI handguard. I have another rifle that has the Geissele smr mk 2. I wish I would have just gone that route.
 
I had Midwest hand guards that touched the bottom of the gas block. In my mind, I was missing due the flex of the hand guard. I’m only using Geissele rails now and my performance has gotten better. This is totally psychological!!
Probably actual rather than psychological.
 
You can also try the lowest of low profile gas blocks . Badger Ordinance TDX.

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This is the exact route I think I'm headed. This build has a MI handguard. I have another rifle that has the Geissele smr mk 2. I wish I would have just gone that route.

If you mount the MI handguard well (i.e. use the green loctite, clean the nut and inside the handguard first, and tighten it really well) you won't have a problem with it. I have several myself and have installed others; only problems I've seen with them are people not doing a good job of installation. Blue #243 Loctite on the screws is always a good idea of course, same as any handguard.

The clearance you mentioned in the first post should be fine, if the handguard is mounted solidly and the barrel isn't a noodle.
 
If you mount the MI handguard well (i.e. use the green loctite, clean the nut and inside the handguard first, and tighten it really well) you won't have a problem with it. I have several myself and have installed others; only problems I've seen with them are people not doing a good job of installation. Blue #243 Loctite on the screws is always a good idea of course, same as any handguard.

The clearance you mentioned in the first post should be fine, if the handguard is mounted solidly and the barrel isn't a noodle.

Correction - I misread the OP to say 0.5"-0.6" of clearance (and thought that's a pretty fat handguard, but whatever). Yeah I'd want more clearance than that .05"-.06", by at least double.

I'm also not afraid to mill out a section of the handguard for clearance if it needs it, but that's usually around the top end, not the bottom.

Are the gas block set screws too long, or did you use one of those really cheap gas blocks that hangs down lower than most? Resolving either one should fix your problem; that's the only time I've seen that little clearance with a MI handguard. FWIW the $60 Seekins adjustable gas block fits pretty nicely inside these without any clearance issues, at least the .750" journal versions.
 
Correction - I misread the OP to say 0.5"-0.6" of clearance (and thought that's a pretty fat handguard, but whatever). Yeah I'd want more clearance than that .05"-.06", by at least double.

I'm also not afraid to mill out a section of the handguard for clearance if it needs it, but that's usually around the top end, not the bottom.

Are the gas block set screws too long, or did you use one of those really cheap gas blocks that hangs down lower than most? Resolving either one should fix your problem; that's the only time I've seen that little clearance with a MI handguard. FWIW the $60 Seekins adjustable gas block fits pretty nicely inside these without any clearance issues, at least the .750" journal
I went with the BCM gas block originally. I have the Badger ordnance tdx block coming right now. The way it looks from the pictures and specs it should offer a little more clearance.
 
I had a MI slim handguard over a superlative arms adjustable gas block that I had to replace. First tried to clearance the inside of the rail, but couldn't get enough room. Ended up going with a traditional 1.5" ID handguard and have plenty of room now.

If you have one of the slimmer MI rails, you'll probably have to find a really small gas block, or grind a bit of the inside of the rail out.
 
I recently finished up my first build, and learned a whole bunch along the way. My concern is the clearance between the gas block and bottom of the inside of the handguard. There is about. .05 to .06 of clearance without pressing the barrel and handguard together, and it never touches unless I force them together. Will I run into any issues? Any insight would be appreciated!
Like what what said: go shooting. After a couple hundred rounds, pull the handguard and look for rub marks. If there are, you can either replace the handguard, replace the gas block, or machine away the offending area of the handguard to make room.

No use in swapping parts right now unless you're *really* that concerned. Your money, your time, your piece of mind.
 
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I recently installed the new Aero adjustable block under my Centurion CMR rail. That thing is really tight inside for space. I had to shave the bottom of the block a little, but it clears with no issues on top. It's a pretty small block for being adjustable and has worked really well so far.