View Full Version : Forster vs. Clymer no-go gage

September 20, 2001, 22:15
I used an RCBS Precision-Mic gage to obtain comparative measurements of the Forster and Clymer no-go gages.

The Forster gage is for .308 Win.
The Clymer gage is for 7.62 NATO

The difference between the two was .0025 inches, with the 7.62 being the longer of the two.

The Forster .308 Win. no-go gage is marked 1.634.

The Clymer is simply marked NO-GO.

September 21, 2001, 13:41
Cruffler just sent me this:

"The Forster gauge is not made to ANYBODY'S spec except for Forster's.
The Clymer gauge is made to SAAMI .308 Winchester standards.

There are NO SUCH THINGS as 7.62mm NATO headspace gauges.

There are only M14/M60 gauges, FAL gauges, and G3 gauges."

I think my head hurts.

R4 fan
September 21, 2001, 16:05
Ugh... I know mine does. After all the threads on guages, I STILL don't know what guage to get for my FAL. :(

September 21, 2001, 16:24
[quote] There are NO SUCH THINGS as 7.62mm NATO headspace gauges. There are only M14/M60 gauges, FAL gauges, and G3 gauges." [\quote]

Horse crap! There might not be any civilian 7.62 guages, but I'll guarantee there are military guages in the hands of contractors and the military. I've got some old military 30-06 guages as well as Clymer civilian guages. Their construction is a bit different, but if identical in critical dimension, they should give the same results when checking headspace.......They don't, so there is obviously a difference in spec due to the different intended use of the guns/ammo.

September 21, 2001, 17:00
I think anything between 1.630 and 1.635 on the FORSTER gages will be fine.

September 21, 2001, 20:13
Here are the numbers, as I understand them. They would indicate that not only are gary's measurements correct, they are entirely normal and expected.

1.630" Forster GO
1.630" Winchester .308 minimum
1.6315" NATO 7.62 minimum
1.632" Clymer GO
1.634" Forster NO-GO
1.636" Clymer NO-GO
1.638" Forster FIELD
1.638" Winchester .308 maximum
1.640" Clymer FIELD
1.640" NATO 7.62 maximum

The difference between Forster and Clymer NO-GO gauges is supposed to be .002"; gary measured a .0025" difference. I think we can spot him that five ten-thousandths as possible measuring error/gauge manufacturing tolerance/mic manufacturing tolerance/combination of any (or effect of the full moon).

With all respect to Cruffler, who I recognize as a proper authority, his opinions as quoted above are a real head-shaker. Forster standards appear to follow stated .308 Winchester min/max specs of 1.630/1.638"; notice the Forster range is also 1.630/1.638"? Furthermore, how many bolt gun owners (who shoot commercial match ammunition) do you know who headspace towards minimums, namely, 1.630"? Where do you think they're getting that measurement out of, thin air? Furthermore, Clymer standards appear to follow stated 7.62 NATO min/max specs of 1.6315/1.640"; notice the Clymer range just happens to be 1.632/1.640"? These are not just coincidences and I don't understand with my present knowledge why Cruffler would make such statements.

While measuring and crunching these numbers is certainly interesting, in my opinion the true bottom line is not a question of Forster -vs- Clymer or .308 Winchester -vs- 7.62 NATO, it is the actual numbers that count. I am reminded of the recommendations time and again by smiths I respect such as Gunplumber to set your FAL's headspace at 1.632" for safe and reliable use with the widest possible selection of ammunition. As I've stated a number of times (and bears repeating) the well-equipped FAL armorer would have a set each of Forster and Clymer GO and NO-GO gauges; this way you could more accurately set your actual headspace and measure how it changes over time. One might even argue to use a Clymer 1.632" GO for target headspace, a Forster 1.634" NO-GO, and use a Clymer 1.636" NO-GO as a FIELD gauge. (The latter is my personal practice as I never allow a rifle to exceed 1.636" even if shooting only NATO surplus.)


[ September 21, 2001: Message edited by: Radio ]

September 21, 2001, 22:44
In the Spirit of Ted, I have to say, ...EXCELLENT post, Radio.

p.s.- Gary, maybe this should run into FAQ down the road.

September 22, 2001, 09:44
Thanks for the thread. The fog is starting to clear . . . some. :D