Fitting gas block to barrel

[Scoots]

My AR project rifle is starting to come along, although it's going much more slowly than I'd like.

I just received my low profile adjustable gas block. I measured the bore diameter of the gas block and the diameter of my Oly barrel at the gas port. I either have to open the bore of the gas block .010" or turn down the barrel at the gas port .010" (hmmmm, I just thought of measuring the bore diameter of the old gas block ).

Anyway, what did you guys do to ensure a proper fit of gas block to barrel?

Thanks for your help.

[320pf]

I had to turn my barrel down to 0.750. The JP gas block has a nice snug fit.


320pf

[pug]

Like 320pf I also turn the barrel down. Great care must be excercised when turning the barrel because a loose fit will haunt you. Most would probably turn to within a couple of thousandths and then hand fit the block.

[Scoots]

Thanks for the replies and information.

Would it be easier to open up the bore of the block a little at a time & test for fit?

[sniperx]

No, not really. You will have to have it machined. .010 is too much to try and polish and would take a long time to try to hone it with a wheel cylinder hone.
Much easier to turn the barrel in a lathe.

[tp555]

You did not mention what size your barrel or gas block is.Go with the standard sizes like .750" ,.875" or .937". for your barrel. Gas blocks can be replaced a lot easier then your barrel. I would machine the gas block for that reason.I also make gas blocks for the ar in stainless. Sometimes they are undersized like .935"
or something.What ever the customer wants.regards.