Problem with CMMG rifle sights

My dad just got this CMMG made rifle, im only in this area because the upper and lower is engraved with CMMG

You can see the front gas block rail is lower then the rear sight rail. He had purchased a troy front sight. We are using a rear chopped carry handle type sight in the back. I use this same rear sight on my bushmaster.
Anyways the front sight is about 1/4 inch too low, and using laser bore we cannot raise the front post high enough. I now see because of the height difference of the gas block and rear sight rail thats the reason why.

So do I need a special front clamp on sight thats taller. I have no idea if such one is made.
The front sight cost my dad about $55
He doesnt want to take a chance and get another short one
We would appreciate any help given

So from searching many stores most sights I can find are flip up, which my dad doesnt want

and it seems the one he has must be made for handguard rails, which is why its lower in height
because I see some like that are sold for high profile gas blocks, and or handguard rails

Well as you have already figured out your Dad has a rail height site mounted on a low profile gasblock..So you could buy a reciever height clamp on gasblock and use the same sight..Or find a new front sight made for a low pro gasblock...I searched quite a while for sights to fit my Sons CMMG 22 upper that had a low gasblock and ended up using a Troy front flip..Easy to find flip fronts but it is a little harder to find fixed ones for the low gasblocks..

I know I found the fixed ones when searching for his rifle and will do some looking and see if I can remember where I found the fixed ones for the low block...If so i will let you know ASAP...

Replace the gas block. It's set screwed. CMMG has the receiver height gas blocks for the .22 with a nub in the gas tube hole to hold the hand guard caps.
Give them a call. I don't know why the low gas block even exist. No real purpose for it.
Dave N

does the flash hider need to come off then?
I noticed the barrel is way shorter then my m4 type bushmaster, and im wondering if the flash hided is pinned making it the legal length

I guess if he has to get a flip up then so be it, its just he will probably never fold it ever and im not a fan of the thin flip sights
is there a rail adapter to raise it to the height, like a clamp on piece of rail that has a rail on the top too just for this problem?

On the cmmg site this is the only gas block I found, looks like the one we have
http://cmmginc.secure-mall.com/item/CMMG-Railed-750-Gas-Block-1488

You will need to call. The .22 gas block has a nub in the gas tube hole.
Yes, the flash hider has toi come off.
The .22 barrel sits nearly 1.5" inside the receiver. Thats why it looks closer to a true M4
Dave N

thanks for the barrel tip
thats good news then if the flash hider spins off

my dad is taking the rifle to the store that sold him the sight, maybe they will have something in stock
they had told him that sight would work, as he also bought the rifle from that store but obviously they were wrong

Just ask for a receiver height or hand guard height sight.
The flash hider on some is real tight. I would use a barrel vice or put some leather (or a leather belt) around the barrel in the bench vice.
Dave N

Dave,I actually like the low profile gasblock and glad we have it...It allows the the Troy flip sight base part to not stick out like sore thumb and sit so high above the handguard,much better profile than the tall gasblock would provide I think..But then again maybe the Troy reciever height sights do not have such a big base to them either......

can you post a pic

I also like the lower gas block. The first one I had came with my Armalite a couple of years back. When I ordered my .22 parts I got the lower gas block so my sights I already had would fit either rifle. Some of us prefer the low block. Nothing wrong with the taller one, you just have to make sure you get the right sights to go with the block you have. Oh, and if you are buying sights, make sure you get the ones that go with the gas block, high or low, that you have.

This pic is actually my Sons CMMG AR22 upper but the same thing just in .22...I am not the best picture taker but here you go...

That is why we have choices. I got used to using flip up rail mounted sights on my department rifle. Just what I'm used to. My issue with the low gas block is the limited amount of sight options.
Dave N

I think this would work....I would email/call PA or YHM to make sure, it doesn't spell it out what gas block height it's for. In the picture it shows the shorter railed gas block...

https://www.primaryarms.com/Yankee_Hill_Machine_Gas_Block_Mounted_Front_F_p/yhm-9495.htm

I just like the solid type sights for strength
if the flip up types are as strong then no big deal
most of the ones I had in the past were pretty thin, really made to be used last

You know, I have never had a problem getting the right height sight for my AR's with the "low" gas block rail. But then it hit me tonight what the problem was. Most often the sights are refereed to as "gas block height"...this is for the lower height blocks like my rifles have. The shorter sights are often referred to as "rail mounted" sights. They are made to go up on the rail. Now, I have dealt with railed gas blocks for several years on several rifles so I don't think much about it. I have purchased several sets of sights and never gotten the wrong ones, BUT I always asked for the sight that mounts on the gas block NOT the rail.

So, what screwed people up was when someone decided they would make a gas block that was as tall as the rail. Now, you throw another combination into the mix and confuse everyone.

It use to be simple, gas block rails were LOW, rails were HIGH. Sorry they mixed it all up when some smart guy decided to make gas blocks that were as tall as the rail. Just remember, if you gas block lines up with the rail ask for a RAIL mounted sight. Otherwise, you have a "low" gas block and you want a normal gas block mounted sight.

Why do they have to make this stuff confusing?

Well my dad returned his $60 sight, and got a $140 one

Fits great and now is the correct height, has quick detach holes on it too, since his rifle didnt have a front sling mount

Not sure if I have it the correct direction it folds towards the rear

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