Anybody here have a 20 gauge chamber length guage?

[gregintenn]

I have a shotgun I suspected to have 2 1/2" chambers, but with a crude guage I made up, it's barrels seemed to measure the same as one I have that is known to be 2 3/4" chambers. I would like to measure the chambers definitively with a real guage.

[Guest SavageOne]

The correct chamber length for a 2 1/2" shot shell would be 2 3/4". Which is the length of the shot shell with the crimp unfolded. Firing a 2 1/2" shot shell in a 2 1/2" chamber would not allow the crimp to completely open on firing, resulting in severe overpressure, Shotgun chambers are always 1/4" longer than the designated shell length. Love the 20! My favorite skeet gauge.

[gregintenn]

Right. I understand that. This is the reason I would like to measure the chambers, as the information I've found says it could be either. I made a guage from a marker with the appropriate amount of electrical tape on the end to make it the correct diameter for a given point in the chamber. I stuck it in a shotgun chamber I know is 2 3/4", and marked it. Then I inserted it in the shotgun in question, and it went all the way to the mark, as if it would also be a 2 3/4"chamber. I guess I would like a more scientific and accurate measurement rather than taking a chance on blowing up a quality shotgun, and perhaps even me!

 

Would I be able to tell by inserting a 3" shell into the chamber?

Edited February 3, 2014 by gregintenn

[Oh Shoot]

Would I be able to tell by inserting a 3" shell into the chamber?

 

Wouldn't think so. I could put a 3.5" shell in my old 1902 vintage Remington 12 gauge, fit just as well as a 2 3/4" one, and never did find out if it was even 2 2/4 chamber, or 2.5.

 

- OS

Edited February 3, 2014 by Oh Shoot

[mikegideon]

Page 22...

 

http://www.saami.org/specifications_and_information/publications/download/209.pdf

[gregintenn]

I found the measurements. What I lack is a proper tool, or at least the knowledge, to accurately measure my chambers to tell what I have.

[mikegideon]

That 5 degree forcing cone makes it more difficult. You can have one made...

 

http://www.nevadashooters.com/showthread.php?t=18270

 

Or, you can make a chamber casting and drag it out where you can measure it...

 

http://www.midwayusa.com/product/462291/cerrosafe-chamber-casting-alloy-1-2-lb

 

Or, you can buy one from Brownell's

 

Or, you can start a thread on TGO :)

[gregintenn]

Yeah....I was kinda hoping to borrow one. :blush:  I guess I'll break out the old moth ridden wallet and either find a gunsmith with one, or else order one. Thanks.

[mikegideon]

Yeah....I was kinda hoping to borrow one. :blush:  I guess I'll break out the old moth ridden wallet and either find a gunsmith with one, or else order one. Thanks.

 

May be able to do it with a 3" shell, since you're not looking for exacts. Let me do some noodling. The shell will stop somewhere in the first half of the cone. I think I can get close enough to resolve a 1/4" difference. note that there's no SAAMI spec on a 2 1/5" chamber.

 

Anyway, I'll come up with a drawing. Just gimme a little while

[mikegideon]

OK, these are to SAAMI max specs. Drop a 3" shell into the gun, and it should almost chamber. If it sticks out by at least a 1/4". then you have a 2 1/2" chamber. I'll be intersted to see what real measurement you get.

 

[DaveTN]

You are a reloader so you must have a pair of calipers. Got anything in .684 diameter or anyone around you that can turn something down to that diameter?

[mikegideon]

You are a reloader so you must have a pair of calipers. Got anything in .684 diameter or anyone around you that can turn something down to that diameter?

 

A 20 gauge shotgun shell is .684.

[gregintenn]

LOL! Now all I have to do is come up with a 3" 20 gauge shell. My sister in law is right....I AM a bum. :rofl:

[mikegideon]

LOL! Now all I have to do is come up with a 3" 20 gauge shell. My sister in law is right....I AM a bum. :rofl:

 

Or... you know a 2 3/4" shell probably won't chamber all the way in a 2 1/2" gun. I KNOW a fired one won't, because it would be deep into the cone.

Edited February 4, 2014 by mikegideon

[gregintenn]

Or... you know a 2 3/4" shell probably won't chamber all the way in a 2 1/2" gun. I KNOW a fired one won't, because it would be deep into the cone.

A 2-3/4" shell will chamber and fire in this shotgun. It is my understanding that a 2 1/2" chambered shotgun will chamber and fire a 2 3/4" shell, and therein lies the danger.

[mikegideon]

A 2-3/4" shell will chamber and fire in this shotgun. It is my understanding that a 2 1/2" chambered shotgun will chamber and fire a 2 3/4" shell, and therein lies the danger.

 

If a FIRED 2 3/4 shell will chamber with no resistance, then it's a 2 3/4 chamber. I'm talking about one where the crimped portion is the same diameter as the shell. like one that's been fired from a known 2 3/4 chamber.

[gregintenn]

I can drop a fired 2 3/4" shell into the chamber and close the action with no pressure necessary. I also picked up a box of 3" shells today, and they will also chamber and close with no problems.

 

Would you be satisfied with that, or do you think I should go further in checking?

 

It sure is a dainty little double, and I would hate to break it by firing the wrong stuff in it.

 

From what I read, 2 3/4" was an option at the time it was produced, but not a popular option yet. Maybe it is, or perhaps someone opened up the chambers later.

 

I think I'll stick with light loads either way. I sure wish they would have marked them as they do today.

 

[url=http://s612.photobucket.com/user/gregintenn/media/IMG_2276_zpsd6bac1e6.jpg.html][/URL]

I don't have scales handy, but I don't think it would weigh in anywhere near five pounds. It's tiny, and feels more like a 28 or a 410.

Edited February 4, 2014 by gregintenn

[mikegideon]

I would be satisfied with that. Pretty gun, BTW.

[gregintenn]

Thanks for your help.