Source for .7556 low-pro gas blocks?

[PatEgan]

I'm in the process of going from a DD Lite Rail on my BCM barreled upper to a Troy Alpha. My smith removed the original A2 front sight/gas block and attempted to install the .750 Troy low-pro gas block I provided. Winds up that the barrel is just a tad too big for it, as it mikes to .7556.

Anyone know a source for one that size, or does that require a clamping type gas block?
Thanks,
Pat

[Rayrevolver]

Like this?

http://www.rainierarms.com/?page=shop/detail&product_id=1872

[advntrjnky]

your gunsmith could just hone it out slightly. A gunsmith should be able to custom fit a part to a gun.

advntrjnky

[Col_Crocs]

Skip the low pro and just shave down the fsb.

[Todd.K]

Are you sure your gunsmith knows what he is doing with measuring instruments? Five and a half thou is not a little bit given the normal tolerance, it's more like not even close.

[PatEgan]

He does indeed know what he's doing. Multiple armorer certifications, and past assignments as an Armorer with the SO he works for. They also installed an identical rail on my 6.8 build, using the same diameter Troy lo-pro block. I guess it's also possible that the interior diameter of the gas block is out of spec.
Pat

[AKDoug]

Are you sure your gunsmith knows what he is doing with measuring instruments? Five and a half thou is not a little bit given the normal tolerance, it's more like not even close.

Todd- Back when you were with Noveske, your barrels were .750 on the stainless ones, right? It looks like someone is making match barrels at .755 because Rainier is make a gas block at .755 for match stainless barrels. What is the reason they are making barrels +.005 oversized?

[Todd.K]

I have no idea why some would make a non standard size. I've never seen it.

In general I am suspect of a gunsmith's machining and measuring skills until proven otherwise.

[AKDoug]

Measurement error was my first thought also until I saw Rainier offered an oversized gasblock.

[jaxman7]

Measurement error was my first thought also until I saw Rainier offered an oversized gasblock.

Saw that yesterday on their site while trying to locate a Vltor GB for a new project. From Rainier:

http://www.rainierarms.com/?page=shop/detail&product_id=1872

"Rainier Arms Low Profile Match Grade Gas Block was designed to fit the match grade barrels in the market place. Many of the LP gas blocks in the marketplace to day are designed to fit service grade barrels. If you have ever tried to install a VLTOR or Stag style gas block on a Match Grade Stainless Steel barrel, you know that many times, the gas blocks are just too tight and will either seriously mar the barrel or sometimes, you have to hone the gas block to a larger inner diameter .755.
Our new LP Match Grade block was purposely made .005 larger to fit better on match grade barrels."

-Jax

[PatEgan]

I have no idea why some would make a non standard size. I've never seen it.

In general I am suspect of a gunsmith's machining and measuring skills until proven otherwise.

It came straight from BCM that way. 16", 1/7 twist, HP MP tested barrel, not match grade strictly a combat config'd upper.

[AKDoug]

Pat- Is it a stainless barrel? I just checked my recently purchased BCM Standard CMV steel barrel and it measures dead nuts .7500

[PatEgan]

Nope, standard finish, definitely nothing fancy. The smith checked the measurement more than once, and the first indication was how tight the gas block was.
Pat

[horseman234]

I recently installed that Rainier gas block on a Rainier stainless match barrel. It was a tight fit.

[Crazy Chuckster]

I have always used a brake cylinder hone when having to open up a gas block a thousandth or two.

Something similar to this at sears http://www.sears.com/shc/s/p_10153_12605_00960638000P?sid=IDx01192011x000001&kispla=00960638000P&srccode=cii_17588969&cpncode=31-125864255-2

Go slow and check often to avoid oversizing.

[PatEgan]

All,
Thanks for sharing all of the info!
Pat