making a no-go gage
I have heard that it is possible to make a no go gage by taking a new good quality unfired rifle round and putting several layers of masking tape on the base. This makes the case just a little longer and the bolt of the rifle should not close on it. Will this work?
Hlouie
Hlouie
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It would probably work after a fashion---but it's probably not a very good method, the problem being that masking tape is soft. The technique to use when using a conventional no-go gauge is to gently attempt to close the stripped bolt body with the gauge in the chamber. Although one is not to do this forcefully, I would think that masking tape layers would be subject to compression and cutting by the bolt face. Even a steel gauge can be ruined by attempting to close the bolt on it too forcfully, as there is a lot of leverage taking place. I have read posts on this Forum where members advocated using your method to ascertain how far out of headspace a rifle was by figuring the thickness of each added tape layer, but I've always been suspect of the practice. If you believe that your rifle is out of headspace you can learn a lot by using a micrometer or caliper to measure the dimensions of your fired brass and compare them to the measurements of unfired brass and to the SAMMI specs for a chamber for your cartridge. If you are a reloader you need only to reload your fired brass for that rifle without full length resizing (neck sizing only) to have a cartridge custom made for your chamber and to be in proper headspace for your rifle. But anyway, conventional headspace gauges don't cost that much, and gunsmiths usually don't charge that much to perform the task of checking headspace, so why not do it by the tried and true method? 0 -
I've allways wondered about using mechanic's Plastiguage. You can get it in .001" to .015" quite readily.
Anybody ever try this??
[?][?]barto
Forgive your enemies, but never forget their names.-JFK0 -
I've used tape as a down and dirty quick check. You should know the feel when you chamber a round and with 1-2 layers of tape if you don't feel much of a difference assume you have a spacing problem and take it to a gunsmith or buy yourself a head space guage (cost would probably work out to be about the same for either route).
For quite some time I've wanted to try the plasti-guage, but we have 2 autoparts places here ... both big chain outfits (the little guys got squeezed out along with the real hardware stores) looked for the stuff, couldn't find it and asked the clerk(s) in both places, they didn't have a clue as to what I was talking about. The one looked at me like "gramps ... feeler guages are made out of metal" and pointed to the pegboard display of feeler guages. I guess my part of the world has become strictly a "blister pack" world and don't bother to ask an employee because, if your lucky, they know how to use the register and forget about their having to actually make change.
Any body got a couple little pieces of "p-g" try it and let us know how it works, or send me an email and I'll give you my mailing address and I'll let everyone know how it works.
If you only have time to do two things so-so, or one thing well ... do the one thing!0 -
THE ONLY PROBLEM WITH THIS METHOD IS THE CASE IS AN UNKNOW DIMENSION. IF YOU START WITH A 'GO' GUAGE ALL CASES FOR A PARTICULAR CARTRIDGE HAVE TO BE SMALLER (-.002,-.004" ?)THAN THE 'GO' GUAGE. PLUS THE DIFFERENT MGF. TOLERENCES. I SEE CLYMER IS MAKING GO GUAGES THAT HAVE A SET OF SHIMS WITH THEM (IF GO IS .000", NO-GO IS +.005" AND FIELD IS +.010"). 0 -
Contender Man ........find better auto parts stores,maybe a NAPA or I think JC Whitney used to have it. It can't have sat on the shelf for months as it dries out.. Plasti-guage comes in a paper sleeve which has marks on the outside. There are also 3 thicknesses, I think, so one must know the range one is going to work in. Inside the paper sleeve is a strip that is about 1/8 inch wide of material (you get about 2 foot for $2.00 or less). What it is made for is putting inside the curved surface of engine bearings. When you torque up the bearings and remove the bearing block again, the deformed plastic is stuck to the crank shaft. You use the marks on the paper sleeve to compare(eyeball) the width of the deformed plastic strip. This deformed plastic strip gives the gap or tolerance. It is not measured by caliper or micrometer. I guess I don't see how it would give you a reading of any meaning on a flat surface of the bolt or shell casing, unless you can be sure that the dummy round is fully seated first. The plastic is about as soft as modeling clay (unless it is old and dried out, rendering it useless.) Glad to send some for trial, if you like. 0 -
If you are handloading you can use the tape method (but use a harder tape like Scotch tape) to set your dies. However, you dont know the dimensions of new factory ammo and by adding tape you still dont know it.
If you strip a bolt so you can feel that you're not crushing the tape and it easily closes on a factory round with .004 worth of tape, you are at the desirable limit of headspace. Accuracy will suffer with increasing headspace but the absolute maximum is about .010 where head separation will start to occur.
In higher pressure guns over 50,000psi, .004" may be the absolute maximum headspace.
For best accuracy, the gun should be at or very close to zero headspace.0 -
I haven't seen anyone mention this, it's sort of a Plastigage improvement. At one time I had a small amount of very fine lead wire, maybe .015 or.020 diameter and used that to verify just how much space I had between a "go" gage and the bolt face. The squashed wire can then be measured with a micrometer. Worked pretty good for me when I was fitting a barrel to an action.[:)]
Cheers,
OleDuk0 -
That's a good method of getting by with only one gage.
Using that method with a brass case might move the case shoulder as well as crush the solder.
I dont know how much force it takes to crush a Plastigage. It should be low enough so as not to move the shoulder of a brass case even a thousandth.0 -
Agree with v35!
OleDuk[:)][:)]0
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