Chuck;
I have a 20ga O/U with .640 bores....nominally closer to a 16ga than a 20ga. It doesn't pattren any better or worse than any other I've shot.
As to backboring to reduce weight, excellent method! I had one of the first of a handful of 32" Beretta 680 barrels to come into the country nearly 15 years ago. At that time I was chasing all the fads in sporting clays and I came upon a set of custom extended and ported choke tubes that Larry Nailon had made for a backbored Beretta trap gun. Those tubes, and the pig-on-a-shovel handling of my new 32" barrels were all the reason I needed to have them backbored from .725 to .738. I had ProPort do it, the same outfit that was "pigeon porting" all my clays guns. The result was about 5 ounces of weight removed over the entire length of the barrels. I rebalanced by hollowing the butt and had a super sleek 32" O/U comp gun, way ahead of the crowd! Not only that, but it hammered targets with miraculous authority; must be magic in those big bores?
One day I was plinking at skeet with some serious skeeters, including a former world champion, and the smoke clouds I got when I connected led them to ask what chokes I had in. I told them they were cylinders and they didn't believe me. So I removed a tube and showed them the .738/Cyl etched on the tube. Everybody was suddenly a believer in backboring.
Some time later, I actually miked the bores and found that ProPort had left about 1/2" of the original .725 bore at the end, just behind the choke seat. That was their insurance against someone installing a factory choke and blowing it out. Trouble is, it added about .013 fixed choke so when I screwed in the Cyl tube I was shooting LMod!
I contacted them about having it removed and they said they didn't backbore anymore, but they recommended Tom Wilkinson in NC....
Tom Wilkinson
Oxford, NC
(919) 603-0167
twrayw@earthlink.net
I thought it would be a fairly trivial (inexpensive?) thing for him to backbore 1/2" of metal, but he actually backbored the entire lenghth, taking the .738 bores to .741 and it cost me about $400 as I recall.
I still think it was feasible and worthwhile at the time...a $750 set of barrels could become a lightweight set for $1150. Years later I paid $1200 for a virtually identical set of Beretta "Optima" barrels. I'd also considering backboring or jugging to restore choke to an open SxS, but I wouldn't backbore soley for any mythical ballistic efficiency.
Last edited by mike campbell; 06/28/07 12:08 PM.
