doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Target-gun bbls - what's the latest thinking?

You'd think as long as Gunmakers have been reducing the kick & turning it into useful work that guns would be pulling away from us by now, instead of setting Back. All this still brings to mind the words of the late Julian S Hatcher when he said there are a lot of things which sound good if you say them "Real Fast" which just don't stand up to scrutiny. Last I heard Recoil was still determined by 3 factors.
Total weight of the ejecta, total velocity of same & total weight of the gun.

Conservation of momentum requires that the gun have a rearward velocity proportional by the ejecta weight vs the gun weight to the forward velocity of the ejecta. That requires that the gun experience an acceleration proportional to any experienced by the ejecta. Total recoil of the gun is easy to determine for both momentum and kinetic energy. The fly in the ointment is that we have, so far, no way to know what the shooter actually senses. It could be peak momentum, peak energy, displacement, acceleration, etc. It is based on pressure only in that pressure is causing acceleration, not pushing back on the gun.

All involved in this discussion need to read "Sporting Shotgun Performance" by Dr. Andrew Jones. Constriction was about it for choke effect. The gem of his book is, however, a computerized method for pattern reading and analysis, statistically valid analysis. To my knowledge, this is a real first. Anyone taking the time and effort to shoot patterns owes it to himself to read this book.

DDA

A big plus on Andrew Jones book. It dissolves some long held myths and confirms that shooting technique is more important than messing around with chokes and such.

Just tried to buy the book -- $49.95 on Amazon! No way.

So what's the synopsis?

And please dumb it down a bit. I was an English major.

Thanks

OWD

On a link from Dr Andrews' site yo can get a fair number of pages from his book on line.

Synopsis is that shotgun patterns seem to follow the law of Gaussian distribution which means that roughly 60 per cent of the shot is in the central 1/3 of the max spread of the pattern. This is observed in all chokes, spreads and distances. Ergo you try to put the center of your pattern on the target and forget the fancy stuff, in other words technique is paramount, ballistics not so much.

This was a very rough synopsis.

Have had a choke epiphany recently with a 1906 damascus barrel OE 16g Smith with barrels cut from 30" to 29". Hunter Arms 16g chokes were about 1 1/2" and indeed the choke constriction is now slightly less than 1/2"; .005" right and .010" left and patterns a nice IC and Mod. How can that be?
On my 6th case of RST 3/4 oz. at 1100 fps skeet loads.

Choke specifications from the L C Smith Plans & Specifications book show them in 12ga having a choke cone of 1 9/16" in length follow by a parallel section of 1" length at the muzzle. Specs are not given for the 16ga but likely similar. thus cutting the barrel by 1" would do little except remove the parallel, the constriction in the form of a "Short" taper choke would remain.
Most companies who used the taper choke such as Lefever & Fox etc used a much longer taper but no parallel at all. Full choke in my Lefevers generally runs around 4" in length.
This drawing is not dated so perhaps early LC's had a different configuration. Whatever the case my thinking is sounds like very useful patterns, don't fret it, just enjoy them.

I use screw chokes about as often as Stan does. If I need different chokes for a different course, I shoot a different gun or change chokes at the beginning of the shoot and leave them there. My biggest win in sporting clays was when I entered the course with my .410 equipped with modified and tight modified choke tubes. I had a handful of 3" shells in my bag for the really long shots. At that event, no ammo restrictions were in place in the .410 event. I ran the birds on the first station and was so ecstatic over my success that I forgot I had choke tubes or 3" shells. I won the .410 event overall with tight chokes and 2 1/2" shells and never looked back. I won't identify the shoot, but the competition was pretty rough for a non competitor like me.

You are correct Miller, for 12g. To be clear, I measured the bore and constriction using a Stan Baker gauge to which I affixed a fabric tape measure.

About 2008 I issued a request on the 16g site for 16g choke measurements and a number of respondents provided data for Parker, Fox, Baker, Ithaca, and Smith guns. Almost all had a choke length of 1 1/2 to 2 inches with a very short parallel section at the muzzle.

The pre-1913 16g Smiths that I have owned; 1911 OOE, 1906 2E, 1906 OE, all had about 1 1/2" choke lengths.

16g Parker guns made from 1891 to 1927 with chokes from .002 to .040 all had a choke length of 1 1/2" to 2". I think Dave Miles and Austin Hogan provided the data.

Fox 16g doubles made in 28', 33', and 37' (? measured by Dave Noreen) were found to have chokes about 3 1/2 inches long in the tighter choked barrels BUT a 1936' 32-inch barrel A-grade had full chokes of only 2 1/2 inches.

Drew has just clarified that, regardless of maker, choke length is variable among and within makers. I kind of knew that considering the number of Fox and Parker factory orders I have seen where chokes are modified both tighter and looser and barrels cut, yes, barrels cut, to result in the desired choke.