doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Measuring chambers New idea ???

While in the process of building a benchtop barrel thickness gauge it dawned on me that this idea could be used for measuring chambers with some changes. Here is something I quickly threw together, it is easy to see when the forcing cones are reached, no guess work. Laying the barrels on a flat surface and sliding the tool into the chamber is simple. No need to have a real rigid probe as you are just looking for the change of thickness, what do you guys think?? Yes I know the 3” mark is in the wrong place.

Jim A.

Looks like it should work

Agree with Joe.
As you go down the chamber you should be getting a gradual thinning of the wall, then as the cone is contacted there would normlly be a quick reversal as the wall gets thicker upon entering the cone. A careful study of this will also reveal why lengthening a chamber results in a thinner wall, but the cone can be lengthened considerably without a resultant thinning.

The best gadget I've ever saw to measure a chamber was a tool that Ken Owens had....I don't know the technical name for it but it was a dial indicator with two levers on it that were about 3 inches long.

No reason that quick blips of the indy needle in combination with the depth scale won't give you some indication of cone beginning and ramp. Also no real difference from a wall thickness guage other than shorter internal and external legs. I've done this with a w/t gauge but with the scale on the internal rod to see if there's a quick reverse of needle movement at a certain graduation--say 2.75". And thanks for the help on the Parker Trojan, Jim. Worked out fine; stoning both sear nose and hammer notch on the right got right hammer cocking earlier. Have now checked for jaroff loading two, shooting one barrel then the other, loading two, shooting the other then the one. Fixed for now; didn't attempt to reharden anything. See what happens.

jack

Joe;
I don't really recall now just what the "Catalog" name of the idicators you described was. In the Machine shop we referred to them as "Frog Legs". As you say they are about the best it gets for measuring chamber depth.
The cheapest you can go & get adequate reliability is a 6" flexible scale. Just hold the bbl up to put the cone in a shadow & measure to the shadow by eye. With a little practise one can quite easily read it to within the 1/64" markings of the scale.

I believe this is the gauge Joe was describing, I have 1 that I've used for years and it works well the only problem is that both legs are inside the bore and the depth is difficult to read. Also new is about 100.00.



Using a wall thickness gauge works except for the size of the thing, a bore gauge will work also, again not really portable. I have a set of chamber gauges, but its guess work on the taper of the chamber on each gun.

This gauge is cheap to make a 10.00 dial gauge from Harbor Freight, a 1x4x6 piece of wood and the probe. it can be a 3/8 wood dowel. I have tried it on several barrels, you can see precisely where the forcing cone starts and it is portable. Making it a little longer, the forcing cone length could be measured.

Jim A

You know where you can buy a gauge with the legs on it ?

Joe, McMaster-Carr has them in their catalog, 115.00; also a couple on Ebay, search for inside dial caliper, 40.00 to 50.00 current bid.

Jim A.

Sorry but if you want to measure chamber depths stick to a graduated plug gauge. As a wise American once said "If it aint broke dont fix it."