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Joined: 28 Oct 2005 Posts: 126 Location: penna

Pardon if this has already been answered . What is the pressure in firing a sub ga chamber insert , such as a 20 ga 2 3/4 in a 16 2 1/2 chamber....less/same/more?
I would assume that the over bore would reduce pressure? Any one experience any problems?

First, does the 2 3/4" 20 gauge insert fit into the 2 1/2" chamber of the 16???? After that question is answered, look to see what the published chamber pressure is for your 16 gauge loads (assuming you reload them) and the same for the 20 gauge reloads. Don't reload either? You'll then have to rely on the manufacturer's stated PSI for those factory loads to try to determine the difference.

The longer I stay in the shooting world, the more new questions I see. Wow!

Joined: 28 Oct 2005 Posts: 126 Location: penna

Yes 20 ga insert fits into 16 ga 2 1/2 chamber. I just wondered if this was a safe practice. I was considering shooting 20 ga 7/8 oz loads in 16 ga 2 1/2 chamber.
I have a large supply of 20 ga low brass.
It would seem to me that the over bore would reduce pressure. I believe the mossberg 735 pump which shoots. 3 1/2 12 ga is actually over bored to 10 ga.

Member Joined: 06 Oct 2007 Posts: 2349 Location: West MI

Your interesting question might be best posed to the Cust Service at the insert MFG'er. Or if not still in buis, the description from one that is.

That said, as far as I understand it; peak pressure in a shotshell firing sequence occurs in the minuscule moment after the primer is activated and before the crimp opens up and bore size having little to do with it.

Assuming my understanding is correct, my best guess is the same of whatever the 20ga shell is listed as producing and the insert taking the brunt of the energy.

Pressures will be lower. the internal volumn of the barrel after the chamber will allow the pressure to lessen. This assumes the chamber insert is only about fired cartridge length.

Longer inserts like the Savage 410er have about the same pressure but it is mostly contained with in the insert.

Greg, Now a question, are you going to attempt to use a short chamber adapter to use a damascus or twist barreled gun? Or a nitro gun?
What 2 1/2 chambered gun will you use?

Mike

Joined: 28 Oct 2005 Posts: 126 Location: penna

Gauge mates. I own and operated many drillings, none Damascus, but all mostly
16 ga 2. 1/2 . Have previously been hand loading roll crimp 2 1/2 with 7625 at modest to reduced loads. Since I have a large supply of already factory loaded 20 ga
In 7/8 oz low brass I figured why not. I have fired 20 ga 3 inch a modern 311 16ga using gage mate which by the way extends beyond 3 inch plus open pie crimp.
And felt what I described as reduced recoil as compared to the same 3 in load in my 20. I also experienced a really good pattern. So figured there must be some pressure reduction and pattern improvement due to the over bore.

Hello greg
Thank you for the reply
Great use of GaugeMates.

Which GMs are you using? Gold or Silver?
And is the company through with all the divorce issues????

I might have to get a set for my Kreighoff 16x16x8x57IR

But I have sooo much ammo already made up for the gun Very Happy

Joined: 28 Oct 2005 Posts: 126 Location: penna

Using the silver, they extract and you remove empty. Wipe with light oil to prevent 20 ga from sticking in insert. I would like to know where I am at with pressure. And my chrono will not do shot velocity. Generally I find low pressure 16 ga 2. 1/2 hand loads burn dirty, and 20 ga factory burn clean. But what really interest me is the pattern, drillings generally shoot tight and over bore condition with insert changes the shot column I believe and effects the pattern for better upland applications. Why don't you give a pair of 28 ga a try, there has been some good sales of 28 ga at Walmart. And even more over bore. I only hope the wacko survivalists do not discover inserts ( these would allow any shot ammo avail to be used in one gun) and drive up the prices and supply like they did to 22 rim fire.
Ps on your 8x57 .318 bore I assume , buy a bullet sizer from ch and size down 170 gr
32 special bullets (.320) to .318 this ups the velocity and better performance on deer
Vs those 190 gr torpedoes.

Well I buy S&B ammo and it is cheaper than buying bullets Shocked

And I cast and have lots of 8mm moulds

And have skeeter inserts for most gauges Very Happy

Life is good when you are retired and have time to play

Mike

Joined: 25 Feb 2012 Posts: 40 Location: NE Kansas

Just go onto gaugemate's website and look up the FAQ's page. They answer both the question of pressure in you old guns ( though the question was in regards to damacus guns); Many Damascus barrels have been subject to modern nitro-proof testing. It is the users responsibility to insure that any gun used is safe for modern ammunition.

And the question of using tubes in a 2 1/2" gun; Yes, most GaugeMate adapters can be used in 2 ½” chambers. However, chamber dimensions weren’t standardized in Europe until the early 1900s – so, occasionally, fit may be a problem.

Hope this helps.

Member Joined: 17 Dec 2009 Posts: 155 Location: Vermont

I use 28 gauge Chamber Mates in my 2 1/2" 16 gauge guns .

Before doing so I called them and they said it will work fine and it does.

I hope these products come back on the market - they really work good.

Ernie