Need Input On My New 300 "whatever" Rifle

[Retooferab]

I would call Mike Milli at Dedicated Technologies and ask him what size port he puts on his. I used his uppers on two that I built and they cycle everything that I stick in it. I am using a paladin gas block. I have a standard buffer spring and a Spikes buffer.

[Code_4]

Ok I just figured it out. I broke her all down and started really looking at it. Turns out TP's block was not lining up quite right with the gas port. The barrel shoulder to port hole is about .255. The block was about .300. So I took some material off the back of block and now it is lining up over the hole perfect. I a pretty sure that was giving me at least a .075 sized port if not smaller.

I wish I would have figured this out before I picked up all those powders...oh well.

Thanks for all the help and input. I will take her out on Wed and see what she does. I will report back then.

[rsilvers]

Originally Posted by Code_4

Ok I just figured it out. I broke her all down and started really looking at it. Turns out TP's block was not lining up quite right with the gas port. The barrel shoulder to port hole is about .255.

That is is not compatible with standard gas blocks.

[TCCrewchief76]

Well that's a first for me...I've never heard of a gas port being off that much. I've heard of M1A's being off a little when you shim up the gas system, but never an AR from the get-go. Weird. Kudos to you for figuring it out!

Kevin

[rsilvers]

It is actually not uncommon though the error is usually less than 0.015. Many makers do not know where the gas port hole is supposed to be. Some of them just measure an existing barrel the best they can, and go with that. The problem is worse for gas-blocks, with I would say most makers putting the hole in the wrong location - confused by copying the M16 front sight gas block, which expects the forearm-holding metal end to be there as a shim between the gas block and the barrel. But with rails, that does not apply. This is an example of something I have commented on before, about how few gunsmiths make proper use of drawings and why I like products that are designed by Engineers and made by actual machinists (who are best to *not* be gunsmiths).

[Code_4]

Originally Posted by rsilvers

That is is not compatible with standard gas blocks.

My measurements are probably not spot on. I did not have the right calipers to measure inside the block so I guesstimated it.

I have confidence in both machinists that did my work.

[Code_4]

So I have been looking at Barrel Specs this morning. Correct me if I am wrong. The gas port should be .295 back from the shoulder and the block should be the same? So it looks like the barrel got the port position drilled too short. I am going to let the guy that my barrel know and see what he thinks.

[ds762]

Originally Posted by rsilvers

It is actually not uncommon though the error is usually less than 0.015. Many makers do not know where the gas port hole is supposed to be. Some of them just measure an existing barrel the best they can, and go with that. The problem is worse for gas-blocks, with I would say most makers putting the hole in the wrong location - confused by copying the M16 front sight gas block, which expects the forearm-holding metal end to be there as a shim between the gas block and the barrel. But with rails, that does not apply. This is an example of something I have commented on before, about how few gunsmiths make proper use of drawings and why I like products that are designed by Engineers and made by actual machinists (who are best to *not* be gunsmiths).

[rsilvers]

Originally Posted by Code_4

I have confidence in both machinists that did my work.

They may have done a perfect job if their work matches the drawing. It could just be the drawing which is incorrect. Or there may be no drawing.

[Spook]

Originally Posted by rsilvers

It is actually not uncommon though the error is usually less than 0.015. Many makers do not know where the gas port hole is supposed to be. Some of them just measure an existing barrel the best they can, and go with that. The problem is worse for gas-blocks, with I would say most makers putting the hole in the wrong location - confused by copying the M16 front sight gas block, which expects the forearm-holding metal end to be there as a shim between the gas block and the barrel. But with rails, that does not apply. This is an example of something I have commented on before, about how few gunsmiths make proper use of drawings and why I like products that are designed by Engineers and made by actual machinists (who are best to *not* be gunsmiths).

Dude,Please,Pretty Please if that will help... if not for the sake of your own sanity, do it for the rest of us.