BCM gas block question

[Clyde777]

I had a quck question. How come bcm uses Knurled cup points instead of any other type of set screws? Is there a benefit with them?

[hickuleas]

They bite into the metal to prevent them from backing out or moving.

[Clyde777]

Okay so if I add one of thier LPGBs to another rifle should I still use red loctite?

[hickuleas]

I would but i am not a armorer and also pin the gas block to the barrel.

[Nightstalker865]

@Clyde777

Okay so if I add one of thier LPGBs to another rifle should I still use red loctite?

Dimple the barrel for the set screws and use thread locker. That’s how BCM does it from the factory. It makes for a rock solid setup.

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[hk_shootr]

Use Rockset not red thread locker

[Ryno12]

@Clyde777

Okay so if I add one of thier LPGBs to another rifle should I still use red loctite?

BCM used Red Loctite 272 on their GBs. The ones I’ve worked on were not going anywhere.

Knurled set screws, proper torque, and red Loctite and you’re good to go. I believe Sionics does the same thing.

[Iraqgunz]

When I was at BCM all blocks used those screws and red Loctite. When it is done correctly it will not go anywhere. This issue has been discussed numerous time. That set screw has micro teeth that help dig into the dimple.

If you do not dimple the barrel, there is no guarantee that it will be 100% correct.

[Cane55]

@Iraqgunz

When I was at BCM all blocks used those screws and red Loctite. When it is done correctly it will not go anywhere. This issue has been discussed numerous time. That set screw has micro teeth that help dig into the dimple.

If you do not dimple the barrel, there is no guarantee that it will be 100% correct.

Is there a reason BCM dimples only one set screw instead of both of them?

[joeg26er]

@Cane55

Is there a reason BCM dimples only one set screw instead of both of them?

tagged for interest…

[Clint]

@Cane55

Is there a reason BCM dimples only one set screw instead of both of them?

This is the recommended practice by just about everyone who knows what they’re doing.

ONE dimple is all that’s required to accurately locate the gas block over the gas port without the additional complications of tolerance stack ups between dimple location and gas block screw spacing.

ONE dimple will always work, regardless of the gas block used now or in the future.

[grizzman]

@Cane55

Is there a reason BCM dimples only one set screw instead of both of them?

There isn’t one standard for the spacing between the two set screws. If both were dimpled, and the user decided to change the gas block to one with different spacing, the 2nd set screw (not opposite the gas port) wouldn’t line up with the dimple.

[joeg26er]

@Clint

This is the recommended practice by just about everyone who knows what they’re doing.

ONE dimple is all that’s required to accurately locate the gas block over the gas port without the additional complications of tolerance stack ups between dimple location and gas block screw spacing.

ONE dimple will always work, regardless of the gas block used now or in the future.

This makes sense. Thanks for the info

[Iraqgunz]

Yeah, you pretty much nailed it.

@Clint

This is the recommended practice by just about everyone who knows what they’re doing.

ONE dimple is all that’s required to accurately locate the gas block over the gas port without the additional complications of tolerance stack ups between dimple location and gas block screw spacing.

ONE dimple will always work, regardless of the gas block used now or in the future.

[Cane55]

@grizzman

There isn’t one standard for the spacing between the two set screws. If both were dimpled, and the user decided to change the gas block to one with different spacing, the 2nd set screw (not opposite the gas port) wouldn’t line up with the dimple.

That makes alot of sense. Thanks for the answer.

[Cane55]

@Clint

This is the recommended practice by just about everyone who knows what they’re doing.

ONE dimple is all that’s required to accurately locate the gas block over the gas port without the additional complications of tolerance stack ups between dimple location and gas block screw spacing.

ONE dimple will always work, regardless of the gas block used now or in the future.

Thank you. Makes alot of sense. BCM makes incredible stuff.

[MQ105]

@grizzman

There isn’t one standard for the spacing between the two set screws. If both were dimpled, and the user decided to change the gas block to one with different spacing, the 2nd set screw (not opposite the gas port) wouldn’t line up with the dimple.

I dealt with this just yesterday. 0.400", 0.450", and 0.500" spacing on three different GBs. The advice to dimple only for the screw opposite the port is spot on.