Is it okay to file/trim the inside diameter of a choke tube?

[Carmady]

While shooting slugs one of the choke tubes was ripped up a little. Only 6 slugs were fired through this 20 gauge Imp Cyl tube, three Winchester followed by three Federal. I stopped shooting after that in order to change to a Modified choke, but the IC choke was stuck so I decided to leave. I didn't notice the damage inside the tube until I was back home. Lucky thing I decided to leave. Here's a couple pics.

An easy-out removed the tube, and I fooled around with it and other tubes and think I found what may have caused it. Instead the barrel-to-tube mating surfaces forming a consistent step down into the tube (about 4-5 hours on a clock or 135 degrees), part of the choke steps the wrong direction INTO the bore causing a trip hazard for anything coming down the barrel...kind of like a revolver being out of time. I'm guessing that the IC tube protruded into the bore enough that the slugs snagged and pulled the tube further and further into the bore until it ripped. I guess the center line of the choke tube was not the same as the bore axis, and that's what caused the misalignment.

I was wondering if it would be okay trim the inside of the tube so it doesn't hang into the bore, or would thinning out the tube cause other problems? Looks like about .020" thick. Seems like a little less would be better than being a speed bump.

 

[44 AMP]

Recommended choke for slugs is Cylinder Bore.

Slugs are also hotter and faster than shot, "harder" too in a sense. You need a new choke tube, and to closely check the barrel to see if it got damaged.

With shot, that little "step in the wrong direction" might make a groove in the plastic wad column, but clearly when the slug got there, it was too much for it to take.

Foster slugs with their "rifling" are made that way so they can safely squeeze down and pass through any choke. This was a necessity when chokes were fixed part of the barrel. But with the old barrels, there was no "step" where the choke began. With choke tubes today, its possible and recommended to use cylinder bore choke.

I didn't see where you mentioned what gun this was in, you should check the replacement tube fit carefully to see if its got the same bad "step". Honing the tube might be the answer, if it does.

Unless there was no replacement tube made, I wouldn't screw around with the damaged one, its toast. Maybe you could fix it well enough to work, but what is it going to do down the line?? Perhaps a worse problem.

Get a new tube, move on....IF the barrel is good (threads, especially)

 

[Carmady]

Recommended choke for slugs is Cylinder Bore.

Three chokes were tested, Cyl, Skeet, and Imp Cyl. The Cyl with Fed had the tightest 3-shot group.

closely check the barrel to see if it got damaged.

After a thorough cleaning several other tubes screwed in and out with no problems, so I'm hoping the barrel is fine. Didn't see anything obvious.

I wouldn't screw around with the damaged one, its toast. Maybe you could fix it well enough to work, but what is it going to do down the line?? Perhaps a worse problem.

I agree 100%, I was talking about screwing around with good tubes...filing off the excess from the ID so it won't hang into the bore. I tested several tubes and just about all would extend into bore from 3 o'clock to about 7:30. The Cyl choke was the exception, but it's ID is about .635", and the others were around .620" to .630". That's what I was asking about fining/trimming...the ID of the tubes from 3 to 7:30 which would hang into the bore.

 

[44 AMP]

Ok, after seeing those pictures, there's no fixing that.

So, if I'm understanding correctly, your cyl bore tube's bottom end smoothly tapers to meet the barrel diameter, but the others do not. Instead of a chamfer tapering from bore diameter down to choke diameter, they have a square edge on the bottom, which creates a step, which acts as a protrusion into the bore, a sharp edge instead of a smooth tapering.

That should NOT be the case. If there is a warranty in place (as in they came with the gun and are covered under the warranty) you should seek a replacement set of tubes from the maker. And, if you get new tubes from the maker, check them for the same issue (before firing!). If this isn't possible, the fix is removal of a bit of metal, in effect chamfering the tube edge so it meets the barrel bore properly, neither above nor below the diameter of the bore.

Hand filing is possible, but I think it would be the worst way to go about it, simply for uniformity and precision. A hone or a reamer made for that kind of work would be a better way to go, I think. And, its quite possibly time for a professional to do the work.

Its not a lot of work, but if not done just right, you're not fixing anything and risk damaging the choke tube and/or the barrel.


IF you've got the right tools and the know how, go for it. Most people don't, and you might find paying a smith cheaper than buying the needed tools.

Good Luck!

 

[Carmady]

Thanks, I appreciate the input.

 

[timgd]

If all your choke tubes show the same alignment problem it might be your barrel is threaded off center, might need to be replaced.

 

[FITASC]

I was talking about screwing around with good tubes...filing off the excess from the ID so it won't hang into the bore

No, don't do that, it should come from the factory properly sized. Don't forget to use oil or grease on the threads. If it is a name brand choke and wasn't properly sized, call the manufacturer

 

[Carmady]

If all your choke tubes show the same alignment problem it might be your barrel is threaded off center, might need to be replaced.

I'm pretty sure that's the cause. I have a couple of chokes which look like they'll work.

No, don't do that, it should come from the factory properly sized. Don't forget to use oil or grease on the threads. If it is a name brand choke and wasn't properly sized, call the manufacturer

I was in touch with them last week and they offered to receive the barrel, remove the tube, etc, but I told them I'd try to remove it this weekend. I emailed them again today and hope to hear something by Wednesday. Don't eat that yellow snow.

 

[bamaranger]

gosh!

That is the dangedest thing I've seen in a while, and one I would not have thought possible. Makes an interesting case for the argument that a slug gun should have a fixed choke barrel.....period.

Quite a few years back, ..screw in chokes were still relatively new, ..I was given a rifle sighted, Rem 870- 20" slug barrel with Rem choke as a gift. The intention was to attach a turkey choke for a short and handy gobbler gun and that is exactly what I did. This was long before the advent of dedicated, stubby, heavily choked gobbler guns. My turkey carbine has served me well ever since.

The barrel came with two choke tubes; one IMP CYL, and a RIFLED tube, the latter presumably for sabot slugs. I have never shot the barrel with the rifled tube, nor have I shot slugs through the IC tube.

Inferring from the other posts on this thread, for a contemporary slug barrel with choke tubes, is it now customary for manufacturers to supply a slug barrel with a CYL tube instead of IC? I was not even aware that such a creature existed!

 

[JohnKSa]

Tube is toast. You're lucky if the barrel is still good. Whatever caused that, I wouldn't do it again. Typically, slugs should be fine through any choke up to full, so I'm not sure what the problem was in this case.

 

[Carmady]

Well, after sleeping on it I've decided to do the right thing and sell the barrel on ebay.

Not really, I'll shorten the barrel about 2" and go chokeless.

 

[stinkeypete]

You can also shoot it by shooting it without any choke threaded at all. Bare barrel threads.

I've never seen a choke torn up like that, thanks for posting!

As I understand you, there is a stair-step where the choke should be flush with the barrel at the 135 degree point.

If I understand what you're saying... you have other chokes and they all have this same stair step in the bore, at the choke?

This would indicate that the barrel was threaded eccentrically. It's not unheard of, esp. when a gunsmith without experience threads a barrel for chokes on a fixed-choke barrel.

The easiest solution is to take your chokes out and shoot the barrel with bare threads. Some skeet guys shoot no-chokes all the time and it's not an issue. That's a real 'open' choke.

If the barrel really is threaded eccentrically, rather than making custom eccentric chokes..
-who knows if that will alter the point of impact
-making custom chokes doesn't fix the problem, then it's a lurking danger if you ever forget or put an uncustomized choke in the barrel or put a customized choke in a proper barrel it might throw the point of impact?
-you can cut the barrel and install new post, have it threaded it properly if you wish, but cylinder choke is pretty nifty for bunnies and grouse, too. Problem fixed!

Please tell EBay purchasers that the thread is eccentric and barrel needs cut down!

 

[Carmady]

Please tell EBay purchasers that the thread is eccentric and barrel needs cut down!

I was kidding about that. I'll cut it back to about 18.5" and keep it.

 

[Carmady]

It came out to 18 11/16".