Barrell thickness for 20 ga
 

Can anyone point me to documentation that will provide the answer to what is the proper or acceptable thickness of the steel at the exit end of 20 ga. barrels. This is the 1929 V edition that I recently purchased. I went to the range today and put a box through it. Sweet handling and a clay buster, but when looking at the barrels when propped up in the rack I thought, "dang, they look pretty thin and dainty to me." I'd like to mic them and determine if they've been reamed for choking, shot out, or were just delicate to begin with when manufactured about a century ago. Thanks, gents.

There is no documented standard. The US does not have proof laws and never has. “Minimum and acceptable wall thicknesses is a topic that has been discussed at much length here and in nearly any other shotgun forum online. And it does have a lot to do with personal opinion and experience. Some searching of past discussions as well as review of British proof standards will likely enlighten you.

By the way. You shot the gun and it did not blow up. So that is a good thing. AND, if the gun has choke in it, which it likely does, the thickness at the muzzle means nothing. And it is no indication of the thickness farther back where it matters. You cannot measure wall thickness with a dial caliper. You need specialized gauges that cost at least a few hundred dollars.

Thank you. Appreciate the insight. I figured there was a mountain of discussion on this topic. Just was wondering if there were any published standards by Parker Bros. for barrels? And you’re correct, if it didn’t blow up or bulge somewhere I’m good. I wasn’t worried about the little Parker with the target loads, I was more concerned about the St. Etienne 16 that I was trying for the first time, shooting vintage Ted Williams shells we found on the back shelf at the range. All good.

The advice I generally see on here, coming from experienced shooters, collectors, and gunsmiths, is to have the barrel wall thickness of an old gun checked. Mirror bores could mean aggressively honed to remove pitting or frosting, but nevertheless dangerous.

Additionally, if an inner voice were speaking to me as yours was when you thought, “dang, they look pretty thin and dainty to me.", I would heed it and get a qualified person to measure the barrel walls for thickness, and as said above, search opinions on numerical safety limits on this Forum, and solicit them from qualified individuals elsewhere.

I would not be confident about the barrels merely because they had not bulged or blown up during one shooting session.

First, you need a PGCA letter in an attempt to find out what the factory choke is, or was. A Skeet In or Cylinder would be a very thin muzzle from the factory. Any other choke would indicate choke work has been done, and you should measure the bore, choke, and wall thickness to be sure everything is OK.

If your bore is at .615 (give or take) you are fine. It’s been shot innumerable times since it left the factory and if the bores have not been honed out you are good to go. IMO

Many parkers made prior to the 1920s do not measure to nominal dimensions for a given gauge. They are usually oversized. And that is now they were made.

Oversized bores in 1929?

I got a good answer from a member who pointed to me an article on this site that has what I want to follow up. I can't point at the link here because it was texted to me, but I believe it's located at the pages/faq/BarrelThickness posting from sometime back. In any event, it's great to hear and discuss this topic. As we all know, there are many variables involved here. For what it's worth, my 20 ga. shows no information available in the factory records. So I won't know from that. I will get the measurements now that I have a good idea of the standards based on the article mentioned above and then maintain the documentation for the next owner. Kind of like my old boats that I have a weakness for, we are only stewards of these treasures. I call my boats "floating furniture" - now I guess I'll call these fine old doubles "portable art." That's why we spend so much time and $$ on them. Thanks gents. Good discussion and insight. I think I have my answers.

nice words...shooting yesterday we had exactly that conversation about just being "stewards" of fine shotguns...and for me a particular boat. i'm sure both will still be in use long long after i'm gone.

Thank you for the note, Randall. Your art is stunning and delightful on all fronts.

thanks Loren...i never mentioned it here and i really appreciate that. good luck with your new shotgun.....i hope you enjoy it as much i am mine . the truth is the gun is better than i am....but i still hit a few. i just get a real kick out of shooting a 120 year old gun.

I've read it here in this forum by members that say they won't shoot a shotgun that has less than .025 MWT. Unless things have changed in the last 20 years, The London and Birmingham Proof Houses in England won't even mention MWT of a gun submitted for proof unless the MWT falls below .020 even though it may have passed proof below that thickness.

Yes, that number is being used by some knowledgeable gunsmiths, as well as the article in the FAQ/Pages section of this site. I think we are all in accord with the research and making sure we are doing right by these beautiful pieces. Thanks, again.