Choke tube issue

Sonofagun · Oct 16, 2020

I swapped out a flush mount Invector DS choke tube today in my shotgun for a Carlsons extended Invector DS choke tube today to do some patterning. At the end of the day I cleaned the barrel real good, oiled it, and then unscrewed the Carlsons extended choke tube to lube the threads.

I was able to get the Carlsons extended choke tube off, put a dab of oil on the threads and choke body then proceeded to screw it back into the barrel.

It was easy to screw it in by hand but before the choke tube bottomed out in the barrel it was extremely hard to turn. So I get the choke wrench that Carlsons included with the choke tube and can get an additional 1/4 turn into the barrel but the extended choke tube still won't screw into the barrel completely. :mad54:

I took out the Carsons extended choke tube and tried to get the original flush mount Invector DS choke tube in the barrel and Viola! :thumbsup:

It screws into the barrel and bottoms out with no problems.

I'll get some pics this weekend to add to this thread but right now I'm at a loss as to what is going on.

My only guess is that there's some build up of carbon, etc. in the threads that got by the choke tube?

Maybe there's enough of a difference with the threads on the Carlsons choke as compared to the original choke?

Anyone run into a problem like this before?

Doco Overboard · Oct 17, 2020

Sometimes if you remove the choke tube before cleaning the barrel what will happen is the fouling from barrel cleaning can wind up in the internal threads. It's surprising how gritty the thread surfaces can become from what was thought to be a clean barrel if they were allowed to be pushed through. By accidentally doing so this can allow can allow tight threads when you re-assemble.
I would remove the choke tube, and carefully clean again the the internal threads of the barrel and the threads of the choke tube as well.

Something else you can to do to help determine if the replacement choke may have a thread problem is carefully inspect for threads to make sure they are straight to the choke itself, the same outside diameter or slightly less than the original one (measure with some calipers at more than one location) or do not have plastic wad residual or dings at the muzzle or internal side of the tube.

The other thing is if the new choke became slightly loose while shooting and then cleaning was done afterwards, when the tube was re-installed it could have pushed some fouling in ahead of the threads when it was re inserted.
Carefully cleaning just the barrel again should help to clear it up.

bigjohn · Oct 17, 2020

Clean the choke pocket with a bore brush and some air or bore cleaner to make sure all the barrel funk is out. You should be able to see if any is left in there. Choke needs to be fully seated before firing. Don’t force it tho. Light live in the threads when you get it fitting properly. I remove mine when I’m done shooting to prevent any issues too. On extended chokes, there is usually a very small gap between the choke and the barrel end to make sure the choke bottoms out and not the extended part

Harrys · Oct 18, 2020

What everyone else said, I have a Mossberg 12 gauge silver addition. I typically lube the chokes with high temp copper thread lubricant not the silver version. Never has an issue.

Sonofagun · Oct 21, 2020

Thanks for the reply. I was hoping to use the hi-tech camera to get some good close up pics of the choke tube(s) but when I turned the camera on the battery was dead. :mad54:

I looked around this weekend to see if I could find the charger. No such luck.

A new charger is on the way and I'll update this thread w/ some pics. I was also going to get some measurements w/ the calipers this weekend when I have some more time to address the issue.

Sonofagun · Oct 21, 2020

bigjohn said:
Clean the choke pocket with a bore brush and some air or bore cleaner to make sure all the barrel funk is out. You should be able to see if any is left in there. Choke needs to be fully seated before firing. Don’t force it tho. Light live in the threads when you get it fitting properly. I remove mine when I’m done shooting to prevent any issues too. On extended chokes, there is usually a very small gap between the choke and the barrel end to make sure the choke bottoms out and not the extended part

When I took out the flush mounted choke and installed the extended choke initially it screwed in w/o any problems. When the extended choke tube was fully seated the marking of the type choke (on the outside of tube) lined up w/ the front sight on the barrel.

This is how I knew that, after cleaning the barrel, removing the extended choke tube to clean it off and lube the threads that something was wrong. The front sight and the choke tube marking no longer lined up properly.

Sonofagun · Oct 21, 2020

Harrys said:
What everyone else said, I have a Mossberg 12 gauge silver addition. I typically lube the chokes with high temp copper thread lubricant not the silver version. Never has an issue.

Thanks for the info. On my other shotgun I've always used a little dab of high temp grease before reinstalling in a clean barrel.

Choke tube issue

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