Tight Barrel Extnesion SS Barrel

[hjmpanzr]

I'm in process of finishing a build and the barrel extension of the 16" stainless steel barrel (great manufacturer/gunsmith) is tighter than anything I've experienced before. I've assembled about 10 uppers. The thing that caught my attention was that the barrel would not fit on the geissele reaction rod. Too tight. So I pieced the upper together to test whether the BCG would fit. (All new Colt parts except for the barrel, rail and gas block).

The BCG goes into battery if I pull the charging handle all the way back and release. However, if I let it slide forward more slowly it gets hung up as the bolt goes into the BE. The forward assist won't move the BCG at all. I manually cycled a couple of rounds and as the rounds eject I can see where the rifling of the barrel has scraped the bullets (but it is pretty light, not really an issue).

As I mentioned, I've never had a barrel that wouldn't fit on a reaction rod or had a BE this tight. Am I good to completely assemble and run it? I would like to think things will smooth out after a few rounds.

[vicious_cb]

I'm in process of finishing a build and the chamber of the 16" stainless steel barrel (great manufacturer/gunsmith) is tighter than anything I've experienced before. I've assembled about 10 uppers. The thing that caught my attention was that the barrel would not fit on the geissele reaction rod. Too tight. So I pieced the upper together to test whether the BCG would fit. (All new Colt parts except for the barrel, rail and gas block).

The BCG goes into battery if I pull the charging handle all the way back and release. However, if I let it slide forward more slowly it gets hung up as the bolt goes into the chamber. The forward assist won't move the BCG at all. I manually cycled a couple of rounds and as the rounds eject I can see where the rifling of the barrel has scraped the bullets (but it is pretty light, not really an issue).

As I mentioned, I've never had a barrel that wouldn't fit on a reaction rod or had a chamber this tight. Am I good to completely assemble and run it? I would like to think things will smooth out after a few rounds.

The barrel extension has nothing to do with the chamber. The barrel extension is where the locking lugs and feed ramps are. The chamber is where the round sits. Also manually cycling live rounds isnt a good idea. Those scrapes arent from the rifling either, its from the corners of the feed ramp as the round is being ejected. What you may be experiencing is an out of spec barrel extension.

Also, seriously you built 10 uppers without knowing any of this!?

[hjmpanzr]

The barrel extension has nothing to do with the chamber. The barrel extension is where the locking lugs and feed ramps are. The chamber is where the round sits. Also manually cycling live rounds isnt a good idea. Those scrapes arent from the rifling either, its from the corners of the feed ramp as the round is being ejected. What you may be experiencing is an out of spec barrel extension.

Also, seriously you built 10 uppers without knowing any of this!?

You're right on terminology. My bad and yes, I've assembled at least 10 and fine function.

I'd really prefer not to send this back. Want to see if anyone has experience with something like this.

[Reagans Rascals]

You have an out of spec extension. The teeth/lugs are oversized from what it sounds like. You need to replace it. The fact that a reaction rod wont fit it tells me that its a no-go... and I'm not sure of any way to physically fix it at this point since its already been machine finished and heat treated...

It sucks but I'd pull the barrel and either attempt to replace the extension yourself if you have the tools or send it back to the manufacturer.

[Robb Jensen]

I've seen lots of bbls have issues with Geissele Rod. Of those about 2/3s will fit but you have to press really hard to get them to seat. I believe whats going on with those is that the grooves of the bbl extension are milled as deep as other brands but they are deep enough for a bolt to fit through them just fine.

[hjmpanzr]

I've seen lots of bbls have issues with Geissele Rod. Of those about 2/3s will fit but you have to press really hard to get them to seat. I believe whats going on with those is that the grooves of the bbl extension are milled as deep as other brands but they are deep enough for a bolt to fit through them just fine.

Perfect, thanks Robb. That's what I was hoping would be the case. I will finish assembling today and take it out and give it run.
If I hadn't have moved across the country this upper would have been another one of those uppers you would have assembled that wouldn't have worked with the RR (and I would have left a couple boxes of mk262).