Not a classic double issue but,
yesterday my old gamer Perazzi blew a choke tube out of the bottom barrel. It did not go gently. About two months ago I had a stuck choke and when it came out it was apparent there was a little rust in the threads. I cleaned everything up nicely and have keep things well lubricated etc. and have been changing chokes more frequently (sporting clays) but I guess it was weak. Anyway, the barrel is tweeked. A small irregular bulge right at the end and it looks slightly out of round. Of course, the chokes won't fit.
What to do? I really like the barrels and shoot them well for lots of things. Can Perazzi fix it? (I live in So. Cal.). Can Briley or some barrel guru put chokes in both barrels and away we go? Suggestions? Regards, Jake

Jakearoo,
I'm guessing they're Briley tubes? If so, Briley is best qualified to assess what to do. This is a very thin area and it may very well be damaged beyond repair. If so, cutting down the barrels and new choke tube installation may be the only economical option.

Chuck,
No, not Brileys. The gun is an old GrandAmerican combo. It came with Perazzi top thread screw in chokes in the single and the bottom barrel of the double. I don't shoot much ATA trap anymore but the barrel that blew was the bottom barrel on the double.
I think Briley is great for installing thier chokes on virgin barrels. I have heard mixed reviews for work that is out of the ordinary for them.
The barrel is not horribly blown. But there is a distinct slight bulge and distortion at the muzzle.
Indeed, the barrels can probably be cut. In fact, since I am shooting more and more sporting, chokes in both barrels could be good. I just hate to lose that 29.5" lenght I like. Jake

Check with Giacomo:315.336.1356.

Another good reason for fixed chokes. This tube thing is not all that it's made up to be.

Amen, Don. Another case of the Empiror's new clothes along with backbored barrels, ports, lengthened forcing cones, ventilated ribs, single triggers, 3-1/2" 12 bores, beavertail forends . . .
Just my old 2 cents worth. Maybe that's why I love vintage guns that are unmolested. Chops

Jake, I would suggest that you send it to Mike Orlen who is a member here and a bbl man. Let him evaluate it and tell you what your options are. He is diagonally across the country, but its not really an issue, that's what USPS is for. His work is highly regarded and he is an up front guy as many here can and will tell you. Call him first, take several good macro digital pics and email them to him.

Thanks TW. Do you have his contact information? Jake

Go to Google.com and type in Michael Orlen. He'll pop right up.

Well now I don't feel so bad. I had a choke tube blow out of a $400 Mossberg silver reserve and now your other end of the price spectrum Perazzi had it happen. On mine I shot a round of skeet and put he gun in the rack and saw the tube missing, I couldn't belive I forgot to put it in. So, I check my case and sure enough one was missing. I vaguely rememberd seeing something fly at station 3 so I looked out there but cuondn't find it in the weeds. I came back a few days later armed with a metal detector and sure enough there it was. It did'nt harm the bbl but the tube had a little dent on the back end I staightened it out and put it in. A few hundred rounds later it is still fine. I wish I knew why it happend

Here is Mike's info:

http://members.aol.com/sgunbore/brochure.gif

Pete

Any time a choke tube "blows out", it's likely it was either not screwed in tight or was a bad installation that left the tube protruding into the bore, so the wad and load caught it. That and pressure behind will do it. If the installation is correct and the tube is scewed tight against the shoulder in the barrel, there's no reason the above should happen. I would bet the Perazzi installation was correct(assuming it was from the factory). I would not be quick to bet on a correct installation from a Mossberg or their imports.

Jakearoo, a couple of years ago, one of the members at our club
had the bottom barrel choke tube portion of his high end German gun part company very quickly. He believed that the choke tube lossened, backed out partially, and caused the mishap.

He had the barrels shortened and retubed. After the work was done,he lost confidence in the gun and traded it off.

Gunny,
I explained that my choke had been neglected (briefly, I swear.) and left some rust in the threads which I cleaned and did all the right stuff to. (Great grammer there, eh?)
A very knowledgable friend suggested that the choke tube was damaged and not flush in the barrel. That it was ripped out by that edge getting caught on the wad.
I don't think so, but be VERY careful with your gun at this point. Make SURE that choke tube fits absolutely flush as it should. Make sure the threads are tight and good. I will continue to investigate. But, it is obvious that there is lots of downstream force when that shot and wad are thrown out.
Guns, ya just gotta keep workin' on em.
Jake

As a mechanical engineer, I am curious as to how choke tubes can blow out without, in some cases, at least, shearing off the threads of either the tube or the barrel.

It seems as if the barrel must expand outward enough to permit the tube to pass forward without thread shearing. One way that comes to mind might be substantial pressure leakage into the volume in-between the tube and the barrel around it. This pressure would cause the barrel to expand radially, while the tube would not expand, since it would experience approximately equal internal pressure (as usual) and external pressure due to the leakage. If the barrel expanded enough, radial clearance between the tube and barrel threads could occur. This would allow tube threads to slip past the barrel threads and the tube to blow out.

With information on the thickness of the barrel wall remaining after the threads were cut, tube and barrel thread dimensions, and an estimate of pressure, some simple calculations could determine if my guess as to how, and why, tubes sometimes blow out is reasonable.

If it is, keeping tubes tightly seated to prevent leakage would be particularly important. Without leakage, choke tubes are forced outward against the inner barrel wall, forcing tube and barrel threads firmly into contact and making slippage impossible.

In any of the cases observed, did shearing of the threads permit the blow out to occur? It certainly seems to have not been the case with the Mossberg in which the tube was re-installed and continued to function.

Unfortunately, as with many educated guesses, calculations using some typical dimensions do not seem to support mine. Anyone have any better ideas as to what might be physically happening?

If the tube became stuck as a result of rust, it is most likely that removing it required some considerable pressure and possible that the rust and force ever so slightly changed the tube enough to let gas behind. It may also be possible that the tube had been dropped at some time slightly damaging the sealing wall. It is recommemded by all choke tube manufacturers that if a tube is damaged in any way buy a new one and destroy the old tube, I suspect that this is what happened, next time let the moths out of your bill fold, it's much cheaper than a new set of Perazzi barrells. I have seen tghis happen before and the owner had been playing around with the gun, if i remember correctly the choke was origionally frozen in. he had the bottom barrell shortened and fitted an extended choke tude

Hotrack

On the Mossberg the tube had a dent on the leading edge, now I don't know if it happened when it hit the ground or thats what caused it to fly 20 yards out. It fits flush and tight now.
I can't envision how something like that happens except maybe the dent was there first.

Whether the choke tube is flush or not is not the important factor. What's important is that the rear of the tube is bottomed out, tight against the shoulder in the barrel at the back of the hole, so gas can not get between the tube and the barrel. The front of the tube may or may not be flush with the muzzle. Extended tubes will not be flush with anything but the important part is that they are tight against the barrel shoulder. I put mine in with a wrench and remove them with a wrench. Something waxy like bee's wax or Door Ease is much better than a light oily lube. You don't want to make it easy for them to become loose and back out a bit.

I use a good bearing grease and keep them tight. There is no reason for a tube to blow out if it and the barrel are undamaged and it is properly installed (that is, kept tight in its threads and in contact with the shoulder, as pointed out earlier).

Screw choke barrels are shot tens of thousands of times each week and this is a relatively uncommon (although not unheard of) occurance. Hardly the Emperor with no clothes, I should think.

Cheers

I have a three year old Beretta 687 Sporting Clays II with choke tubes that seem to loosen by themselves. I tighten them every so often when I am out on the course. The exterior smooth section of the choke tubes is about 2" long and is often dirty after shooting. I have been a bit concerned since I bought it but now I am real nervous that I am heading for trouble.

Builder, all my choke tube guns (both of them) get some gas stain and I've been shooting them for more than 20 years in competition and casual shooting. It is impossible to seal at the back end without hand fitting and some gas stain is part of the deal and harmless. My Beretta and "Briley for Beretta" tubes have been shot tens of thousands of rounds trouble free and are usually a little dirty when removed. The Lovely Linda's Krieghoff has Briley installed screw ins and it's the same situation.

Thanks. I feel better now. I guess I won't have to sell it before it blows out.

Best,
Milt

I know a fella that dropped an Briley choke tube. It looked fine and fit the threads perfectly. However it was just wenough out of round that the next time he shot it the barrel bulged at the choke. He replaced the tube and shot the gun with a bulged barrel for years and years. Then one day.....

He was on a chukar hunt and he shot a double (his first). One of the birds was torn to shreds, then he noticed that his choke tube was GONE. He thinks the tube hit the bird, and I think he is right about that. (Eightbore, you know the guy)

Jeff

Now that's centering your pattern!

Wuz shooting SC with a guy once who changed his choke, but didn't tighten. Choke was just inserted, not torqued at all... we walked out 25 yards or so, and picked it right up! No damage... other than to pride. B391, Angle Port.

A wrap or two of teflon tape on the threads seems to keep the optima choke from backing out of my 391 SC. Teflon tape used on pipe threads is cheap and easy to remove while cleaning the barrel.

Excellent idea. Thanks! Lots of it around. Probably eliminate rust problems noted above.

I have often noticed the tubes not tight on one or another of my guns while hunting, and I could see where there had been obvious gas leakage. I was thinking about using some Loctite on the threads, but concluded it must not be a big deal beacause nothing had ever been harmed, and I shoot the rompingest stompingest loads available when shooting at geese or pass shooting big ducks. I have even tightened the same tube more than once on a hunt using a quarter. Maybe I will use some Loctite - cheaper than a replacement tube.

I would not use Loctite since the thread area is very large and the adhesion would be pretty substantial regardless of which type of Loctite. You might try some plumber's teflon putty or the tape.