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View Full Version : Question about Go / No-Go guages


GeeDog
02-10-2013, 10:50 AM
Hello everyone. Hoping you can help with a question. I've recently acquired a Mosin 91/30 and a Yugo M48BO Mauser and have heard discussion about go / no-go guages for (I believe) checking the bolt face and / or firing pin extension. I'm wondering if this is primarily to check for excessive wear that could lead to no fire issues, or is it primarily to test the clearance after reassembling a bolt after cleaning? I don't have a guage for either rifle, and would like to know just how important it is, and if very important, where would be a good place to buy them.

SVT-40
02-10-2013, 10:58 AM
If your not replacing a barrel or bolt you don't need them.The only thing these gauges do is measure the size of the chamber.

littlejake
02-10-2013, 11:02 AM
Headspace is a safety issue. Excessive headspace can cause case head separation with hot gas and brass blown back at the shooter.

It's not required to be checked frequently -- but, best checked when a new C&R is acquired -- before firing.

In C&R guns, it's sometimes the result of a non-matching (none fitting) bolt in the receiver. Wear and metal fatigue can increase headspace.

The field guage (the longest gauge deemed safe) is commonly used to check headspace.

GeeDog
02-10-2013, 11:44 AM
Sounds like something I should have. Neither rifle has been shot yet. I'm not too worried about the Mauser. It's so clean and matching s/n's I'd be very confident shooting it as-is. The 1942 Mosin looks like it's seen some action and looks like it's definately worthy of testing before firing (both of them). I'm guessing they are plentiful, inexpensive, and comparable in quality? I'll attack them on Google this evening and bone up on them. I've never had rifles before that need little tools to check tolerances. Learning something new from old guns every day.

littlejake
02-10-2013, 12:31 PM
Brownells has a Forster field gauge for 7.62x54R for $28.99

http://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/forster-headspace-gauges-prod19183.aspx?avs|Cartridge_1=7xzzx62x54R

The 8x57 Mauser is out of stock. Their part number 319-418-152WB

Since the average person seldom uses their gauges; you might find a Calgunner who would be willing to loan you a HS Field gauge.

I only have .303 brit and .30-'06.

DennisCA
02-10-2013, 3:07 PM
Do you mean this?

Mosin Nagant Bolt Cleaning Tool

Amazon has them $9.99, so does ebay

littlejake
02-10-2013, 6:10 PM
no, he means one of these:

http://www.brownells.com/userdocs/skus/l_319418152_2.jpg

GeeDog
02-12-2013, 2:57 PM
Isn't there also some other gauge to measure the length that the firing pin protrudes from the bolt face too? This probably won't be my last Mosin, so I supposed I'd better get all the tools.

empirearms
02-12-2013, 8:16 PM
Isn't there also some other gauge to measure the length that the firing pin protrudes from the bolt face too?

Yes, there is, and it is present in just about every cleaning kit you and obtain for the Mosin Nagant. :oji:

PM your name & address to me and I will be more than happy to mail you one at no charge whatsoever. :shock:

As for headspace, the 7.62x54R cartridge headspaces on the RIM of the case, thus the headspace data is only crucial if you are planning to reload the cases you fire in that rifle (they may not fit other rifles after reloading, but will function just fine in the rifle they were originally fired in). If just shooting milsurp ammo headspace is nopt as crucial than you have been led to believe in 7.62x54R or any other rimmed caliber (such as .303 British). :rockon:

GeeDog
02-12-2013, 8:48 PM
PM sent. Thanks.