[gt3499a]

I have not really had a lot of experience with the jp gas block. But I did have one of the stainless ones and it was 7.25oz! Also the gas tube still had to be drilled and the hole then taped. As far as I can figure, if you were going to do all of that, you might as well have taken a regular gas block and made it adjustable.

Also the jp is tall, way taller than your tube is going to allow. It would look ridiculous at the 4" position without a handguard.

On the other hand I dont know of an adjustable 4" gas tube, but it seems like modifying an adjustable gas tube is going to be the way to go.

Dont know about your gas escaping troubles or questionable copper piece. Jb weld may be a lot easier.

luck,
Dan