doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 16/20 adapters for 2-1/2" gun- anyone using them?

Maybe this has come up before, but I have not seen a clear answer to my inquiry. I have a nice light german double hammer 16ga SxS that is not marked for chamber length, though am sure it is 2-1/2". It has done me well with RST, WR, and Polywads on pheasant and quail, but the shot variety is lacking.

I would like some input on a chamber reducer to shoot 2-3/4" 20ga shells in this gun. From what I have gleaned so far, only GaugeMate makes such a critter. NOT interested in 28ga (just as costly and bout as hard to find as short 16's around here). Any other quality makers? Pros and cons of silver-gold-or custom{guagemates}?

From what I have read, people have said that the chamber pressure is the same, but barrel pressure drops. The only testing I have seen by Sherman Bell was 16/28, and was measured in front of chambers which showed a considerable drop. Others say "chamber within a chamber" pressure at is constant. I have trouble grasping this concept, as you have a hard insert surrounding the shell and placed in the chamber. Wouldn't that lessen the pressure on the original barrel chambers?

BTW, I joined the 16ga loading group years back, and could not make heads or tails of the spreadsheet and soon after changed servers so lost track and interest. I have brass, paper, and plastic shells, fiber wads, roll closers etc for 16s, but easier loaders and components for 20ga. Also have better 20ga data for the bismuth I have left.

Any help appreciated.
Thanks
D

I suppose you have figured out that you pry open a factory shell, dump the shot, replce the shot with a like weight of the size of your choosing, and recrimp the shell. Not bad for hunting volumes of shells.

We consider chamber pressure because it translates into barrel chamber area force and into chamber wall stress. The liners will reinforce the chamber (I'd guess they will take full chamber pressure without support, but would check with the maker). The pressure is bound to drop as the wad skirt enters the 16 bore part of the barrel. But, from what to what? Basically, I'd not risk a it unless I had good, proven data from the chamber adaptor maker.

I think the GaugeMate 16/20 adapters have a machined 'split' the whole length of the adapter, so they are not rigid enough to completely contain pressure like one of the inserts w/o the split.

It seems that the total radial force from pressure inside the 20 gauge chamber part of the insert is contained by a larger surface at the 16 gauge chamber. If so, then the pressure at the larger surface would be lower than at the smaller to have the same total force. The insert is passive, and it could not add to the force being contained. Does this make any sense?

Guagemate Silvers do not have the split, so they would, in my mind, reduce pressure in the original chamber, atleast in my 12 to 20. It may be specific to the 16 to 20, I don't know. I was of the understanding the Golds had the split, Silvers didn't.

I measured my 12 to 20 and it is exactly 2 3/4' long. I believe, if you cut the Guagemate down to the 2 1/2" chamber size, it would be fine. You may not have to cut all the way to 2 1/2; the longer, the better. Might have to chamfer the outside of the skirt to get it in if it was cut to say 2 5/8. Still plenty of room for the 2 3/4" shell to unfold into the 16 bore.

However, the fired shell may not come out of the sleeve easy. If that's the case, might help to chamfer the inside of the sleeve skirt and polish.

When I fired my 20 sleeve in the 12, the fired AA shells would drop right out of the sleeve.

Dennis,
This is a bit OT, but I've been trying to reach you for a few weeks without success, so hope you'll check on this thread!
Please email me at (rsmith AT truepair DOT com). I finally have a pump gun (28" barrel) that should fit your Redhead case and I wish to purchase it!

The inserts won't have any effect on pressure. That will still be the same regardless of chamber wall thickness. Pressure may be a bit lower just ahead of the chamber because of the wider bore of the 16 gauge. However, the strain on the chamber walls will be considerably lower, after all you've just added the thickness of the insert wall to chamber wall. Not only that, you've also reduced chamber diameter which translates into less strain from any given pressure.
Nial

The gaugemate silvers have a split when they are only stepping down one gauge as 16>20 ... You will likely have to shorten them for a short chamber gun, I did. I have not shot a lot of shells thru them yet but they worked fine, they do put a little crease and possibly a split up the shell casing.

Hi Roger;
Just checked and found your emails. Will send pics and try to round up a 20ga 12 to check fit.
Regards,
D

Thanks all for the replies. Was really looking for someone with actual experience with such reducers. It appears that guagemates are the only ones actively marketing 16/20 reducers. I blew the pictures up, and it looks like both the gold and silver series are split full length. I don't know why, but probably to ease removal due to the thin construction?

Their info states that 2=3/4 shells can be used with their adapters in 2-1/2 chamber guns. I don't know if I should be concerned with excess chamber pressure in using a Win AA load in my gun or not. I will post some pics of barrel flats in another thread and see what the consensus is on proof(the more I read The Standard Directory of Proof Marks, the more confused I am).

Gun I am wanting to use these in is AOK as far as being on face. The barrels, (Friedr.Krupp Gewehr-Lauf-Stahl Primo Essen) are nickled, with no flaws.

I shoot this gun well. It is a wand for me, and am looking at 20's for cheap and EASILY obtainable off the shelf alternatives to exotic short 16's that must be ordered. I am at that point in life that when I feel good, I would rather be out shooting than loading.

Guess the next step is to contact the company, and also see if I can get any input from s Mr. Bell.

Thanks again for all replies.
D

Two years ago my i received a pair of Browning "Little skeeters" for Christmas, 20/16 gauge, I fired once, using my Merkel SxS both barrels on the skeet field. The empty shells are still in the "Little Skeeter " tubes, no matter how I try I can't get them out. I called the manufacturer and they told me it was because the German guns have a slightly different sized chamber.
Pete