doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Winchester model 42 chokes

I have measured a lot of chokes and bores over the last 30+ years, and have used spring leg calipers to transfer the measurements to micrometers, inside dial calipers and CSP bore and choke dial gauges. All work, but the CSP gauges are the easiest to use. I have measured a number of M42 skeet chokes, and all were 0.005" constriction based on bores of either 0.409" or 0.410".All the Remington .410 skeet chokes that I have measured in 11-48, 1100, 870 and 3200 guns were also 0.005" constriction. I own or have owned in the past a number of o/u guns with Purbaugh and Briley sub-gauge tubes, and all of them measured 0.007" of choke in the .410 tubes (fixed choke). I much prefer the 0.007" constriction because I like the way the targets break better.

Bill, I am now using the CSP Professional Bore Gauge.

http://www.brownells.com/.aspx/pid=6808/Product/CSP_PROFESSIONAL_SHOTGUN_BORE_MICROMETER_SET

My favorite gunsmith uses one of these so I had been keeping an eye out for a set. I found an older, complete 6-gauge set on eBay, cheap, from a retiring gunsmith. Wooden case, heads, setting rings for .410/28/20/16/12/10 gauges. I don't think I'd be willing to pay Brownell's price for that set, new, but used is a different story. It works and is more accurate than I am.

I checked my inside measuring dial caliper on a zeroing ring and my VC (vernier caliper) is right on. I was not sure of my .398 to .402 muzzle measurements of six Model 42 skeet barrels, but now I am sure. Now, all we need is an accurate bore measurement, which apparently above our pay grades. Keep trying.

OK, I got out my "small hole gauge". It's much easier to operate than I remembered and very repeatable. I measured a 1940 skeet barrel and a 1942 full barrel. Both bores are right on .410. The muzzle of the skeet barrel is .399 and the full barrel is .385. We're talking 11 thousandths for the skeet and twenty five thousandths for the full. .011 is a lot of choke for a modern .410 skeet gun. However, it was probably just right in 1940.

If you want a cheap, really cheap, way to measure the bores and chokes on .410 shotguns and the bores on rifles from the muzzle, go on ebay, search "small hole gauge" and you will find four gauge sets for about thirteen bucks and up. The largest of the four will usually be .400 to .500. They are what I'm using to measure the Model 42 barrels. They are just long enough to get past the choke, but they make it. You will need a micrometer or, preferably, a vernier caliper with dial or digital readout. I think they are about six bucks today.

I'm resurrecting this thread having followed Eightbore's suggestion vis-a-vis the small hole gauge set. Took some time to get the "feel" down. These gauges are not calibrated, so I used a marker to scribe before withdrawing to choke section. Numbers were extremely reproducible, though. Thought I'd share the numbers - sequentially: bore, choke, maximal constriction. Guns are Win M-42s, except as noted.

1934 mod .406, .401 for .005
1933 rd bbl skeet .406, .399 for .007
1960 mod .408, .402 for .006
1947 mod .407, .401 for .006
1946 full .406, .390 for .016
1919 M-20 full .408, .392 for .016
1949 SR skeet .415, .405 for .010
1954 2.5" SR skeet .411, .400 for .011
1934 skeet rd bbl .406, .401 for .005
1937 rd bbl skeet .406, .403 for .003
M-37 full .404, .384 for .020

So that gives me a range of .404 - .415 for bore diameters among my sample.

The three prewar skeets (all round barrels) have max constriction near middle of choke section, though nowhere near the flare of a WS1.

Both postwar skeets, all my field 42s, a M-37, and a M-20 have typical taper to max constriction at end of barrel.

Also, note the greater amount of constriction in the postwar skeets vs the prewars.

Finally, here are the numbers on a Browning repro M-42 that has Briley choke tubes: bore .408. IM .394, M .397, LM .400, Skeet max constriction .400 at waist flares to .402 at muzzle (hmmm.....now where have I seen that before?).

Sam

Sam, it's a pain to scribe a mark and try to reproduce the position. Once you tighten the gauge, knock it out through the breech. Don't try to get it out the muzzle end.

Now you tell me! Guess I should have asked, but enthusiasm got the better of me.

Sam