Home Forums Hunting & Shooting Custom Rifles & Wildcats Headspace question...

When doing an install with a wildcat cartridge (or any other for that matter) is it a safe practice to the cartridge case as a "GO No-Go" guage..?


Scott

i've had a gunsmith ask for just the GO gauge and a reamer when ordering tooling for a cartridge that he diddn't have stuff for... i'd guess that if the headspace is snug on the GO, there will be no need for the NO GO

I only buy go gauges. Between the go gause and a piece of notebook paper, I think you are good to go. I don't headspace off of ammunition. Go gauges are around $30 for wildcats through PTG.

thank you.

There are reasonable arguments for both (or either).. For factory offerings I use a GO/NO-GO set.. But certain wildcats, or if a customer is very specific as to the case, bullet etc., on a wildcat, I'll ask for up to ten dummy rounds to be provided along with the other parts so I can not only test feeding etc., but I can (and have) used them for headspace.. However, I check all rounds provided, and allow .001-.002 over the tightest case.. Been doin' that for 12 years and not had an issue to date..

For setting headspace on a new barrel, you can use a new, unfired case.........just set it to just close nicely on the case.

IIRC, there's .004-.005" difference between Go & No-Go gages on most calibers, ( & that's more than a thin sheet of paper) but I've seen lots of factory rifles that will close on a No-Go gage so you really need a Field gage as well to check those rifles that do accept a No-Go.

Obviously a rifle set up to just close on a new case will not close on a No-Go if it was done properly.

MM

...only if it's been run through the full-length sizing die first, and measured for length.. You'd be surprised at how much variance there is in 'new, unfired brass'..

Most manufacturers of G/NG gauges make them .003 in difference.. If I get any newer factory rifle in that closes on a N/G, I'm making a call to the manufacturer..

I saw somewhere where a go gauge, with one piece of scotch tape, became a no-go gauge.

R.

That's why I said, above, that it must be measured afterward.. And because there are variations with brass - all must be resized and then used, not before..

As for newer rifles - I DO check them and have, to date, just one that closed on the NG.. I called Rem (it was a M700) and they sent me a call tag to have it shipped back...

As far as other types, such as Mausers or other types of military actions, those things are usually so loose that a few close on a 'field' ga.. I won't work with those anymore...

And to really complicate what Redneck said, the Milsurp actions that have been rebarreled and checked with a G/NG gauge only could have excessive headspace even if the bolt does not close on a NG. Let me clarify. If there is lug setback, when attempting to close the bolt on a NG gauge and it won't close will not give you a true measurement. If, when it closes on a Go gauge, and seems nice and snug, if there is movement fore and aft with the gauge in place and the bolt closed, the headspace could be excessive. The only way to check this now is to place a dial indicator on the bolt and check for any movement. Understand?

That's some scary stuff right there. Would have NEVER thought to check. Thanks.

Yes, that's true & another good point to make.

MM

Well, yes & no................depends on how you think about it.

Everything has tolerances.........the NoGo represents
the "mean" of the HS tolerance, the Field Gage represents the "Max" dimension but doesn't mean it's "bad".

IMO, a new factory or rechambered rifle should not be intentionally set up to close on a NoGo, but as long as it doesn't close on a Field gage, it's safe & perfectly usable.

What it does say however, is that it'd be a good thing to keep an eye on and measure occasionally.

Also one should be careful about setting shoulders of fired cases back too far with a standard set of dies as that could lead to premature case head separations.

MM

Sure do.. I've had several of those in with set-back lugs.. Just another reason why I will not touch those types of rifles any more.. I'll stick to M70s, thank you..

Safe (close on NG)? Maybe... Perfectly usable? Not for me.. Also more critical depending on chambering. I bought a brand-new Marlin 1894 in .45LC.. Bolt wouldn't close on a NG.. Took a few shots and checked the brass.. The diameter above the web was .012 over nominal!! No way was I going to shoot any more ammo in that chamber.. It could very easily have resulted in split cases.. I called Marlin, explained what I had and they wanted the gun back with the brass for inspection.. Long story short, they installed a new barrel with a proper chamber...

When I got it back, fired cases were .005 above the web - about average for the course..

Maybe I'm not understanding..........

But diameter of the fired case is usually related to pressure or the diameter (too big) of the chamber.

Stretching or lengthening of the case is usually related to excessive headspace.

Your case sounds like the former; can you elaborate?

MM

Exactly.. Read the post again.. I stated the bolt would not close on the NG.. However, the chamber was way out of spec... That's why the new barrel.. This malady had nothing to do with excessive headspace..

I kinda asked this question on another thread and never got a for sure answer. How much difference between shoulder length of a fired case and a full length re-sized case is too much? I had a light primer strike that I think was because of frozen moisture in the firing pin but want to check the shoulder set back to be sure. miles

The question depends on so many variables that it is truly difficult to answer..

It can depend on whether this a factory barrel or custom, and how it (chamber) was cut.. Depends on the HS, and how it was achieved.. Depends on your goals and even the chambering..

For most of my reloads, I have a lot (as in specific lot #, not 'a lot' meaning 'many') of brass dedicated to a certain rifle.. Those are fired once, then neck sized thereafter after carefully trimming to length.. This is especially important when dealing with belted rounds.. Doing that can enable 5-10 reloads before tossing the lot.. There are several rifles that I full-length size for, and even those are not sized according to the die instructions, but just a 1/4-1/3 thread shy (after testing a sized case in the chamber).. That prevents the shoulder from being bumped back too far.. But each die set is different and it can depend on the die manufacturer - although they're 'supposed' to be all SAAMI spec'd.. I've had GO/NO-GO gauges from one company that measure differently from another company.. I built one rifle for a guy using Clymer gauges and the customer had some Forster gauges that indicated slight excessive HS... Neither of us could figure out exactly why.. I got the rifle back and verified I could not close the bolt on my NO-DO.. I also got one set of gauges about four years ago that were mis-marked.. THAT caused all kinds of grief until I finally figured it out.. The replacements came asap with a note of apology.. Also had two customers that got brass from a single manufacturer that were SO varied in size etc., that nearly all had to be fired once just to get chamber uniformity.. One guy was nearly tearing his hair out questioning a chamber I cut since the brass kept splitting until I suggested he take a couple of new brass and cut them lengthwise and compare thickness.. He found one side very thin, the opposite side rather thick.. He tossed that lot out and got new stuff from another manufacturer and all his troubles went away..

These kinds of things can drive us all batty..


Your light primer strike could also be from a little tidbit of brass that got into the striker cavity and prevented a full strike.. Disassemble the bolt and clean out the body interior and try again..

Let us know what you find..

+1 on necksizing &setup of FL dies & resizing..........pretty much exactly as I do it & as pointed out, very important on belted cases.

Lee, got the clarification on the Marlin issue...........just wasn't positive because it was in a HS issues thread.

MM