Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login

Site Notices
Posted: 3/10/2005 4:47:38 AM EST
Good question for Chuck as I see he's back.

I know SAAMI specs and military specs for the 30-06 Garand are different. Is there any established relationship between a Forster gauge and the military gauge?

In other words, what are the military headspace dimensions? I see them in the 1.9" range, while Forster gauges are in the 2.0" range. I realize the datum point is different, but it's very confusing.
Link Posted: 3/10/2005 5:58:42 AM EST
[Last Edit: 3/10/2005 6:04:46 AM EST by Spiff]
It is my understanding that it is perfectly acceptable to use the Forster gauges. My M1 closes on go, and dosen't close on no-go. Considering the age of the parts I build her with, I was very pleased when this occured.

I should add that I called Forster direct and they verified that is was ok to use thier gauges while headspacing the M1. And Jerry Kuhnhausens M1 shop manual mentions them.
Link Posted: 3/10/2005 8:10:43 AM EST
[Last Edit: 3/10/2005 8:11:28 AM EST by Southern_Raider]
I guess I should clarify my question. While I'm certain that using SAAMI gauges put the Garand in the correct headspace range when barreling, I'm also certain that closing on a SAAMI NO-GO does not mean the headspace is excessive. For that matter, closing on a SAAMI FIELD may not mean that the headspace is excessive.

I'm just trying to find the military headspace numbers as they relate to Forster numbers.
Link Posted: 3/10/2005 11:27:23 AM EST
Well, I have never heard anything about different gages for 30-06 for sammi and USGI. 30-06 is the same as M2 ball, dimentionaly speaking. If you have a rifle that closes on a foster field gage, I sure as hell wouldn't shoot it.

If the rifle closes on a no-go gage but doesn't close on a field gage, the rifle's headspace is starting to get to the point where it is excessive, but still safe to fire.

There are differences in 308v7.62 and 223v5.56. There are none that I know of for 30-06. If there are, please provide documentation as I have never heard of that.

Hope this helps.
Link Posted: 3/10/2005 3:42:14 PM EST
Link Posted: 3/10/2005 7:13:56 PM EST

Originally Posted By Chuck:
.30 Caliber M1 Rifle headspace should be between 1.940" (GO) and 1.950" (Field reject). 1.946" or less is arsenal re-issue standard. 1.950 or less in the field is fine.

Unless you have the military gage you will have to strip the bolt to check it. There are really no safety issues involved here, as long as minimum chamber size is there. General Hatcher used a grinder to induce massively excessive headspace without harm -- accuracy suffered, but that was it.

-- Chuck



isn't 1.946 field and 1.950 no go??
Link Posted: 3/11/2005 2:12:05 AM EST
Link Posted: 3/11/2005 5:19:47 AM EST
[Last Edit: 3/11/2005 9:08:06 AM EST by Southern_Raider]

You should be able to find commercial ".30-06" gages of these lengths.

Yes and no. This is the reason for my post. The numbers that Chuck posted (1.940", 1.946" and 1.950") come from the various army manuals I've found on the web. The problem is that the military appears to use a different datum point for measuring the chamber. To wit, look at the Forster gauges:
www.forsterproducts.com/Pages/gages.htm
The measurements given for their 30-06 gauges are 2.049", 2.055" and 2.058". Obviously these gauges are not measuring a chamber that is 0.100" bigger, so I was attempting to get a handle on how these gauges translate to the military chamber measurements. In other words, there is a fixed number I must subtract from the Forster sizes to get to the military sizes. The problem is that the individual Forster gauges do not correspond to the military gauges in function.

I don't have a fear of excessive headspace in my case, but I would like to understand the relationship here.
Link Posted: 3/11/2005 8:08:19 AM EST
[Last Edit: 3/12/2005 8:52:15 AM EST by raf]

Originally Posted By Chuck:
Do not sweat headspace! It's a gunstore commando topic. As long as you're shooting good, military M2 Ball it really doesn't matter. M1 rifles don't "blow up" from excessive headspace. They may get sloppy accuracy, but that's the limit.

--Chuck





Granted the rifle itself won't blow up, but what about the likelyhood of having a casehead separation.THAT is the real problem with excessive headspace.

That can cause you to be thankful you wore your shooting glasses and give you hours of fun picking stock splinters from your hands and arms.

Tim

Link Posted: 3/11/2005 8:56:35 AM EST
[Last Edit: 3/11/2005 8:57:26 AM EST by IdentityCrisis]


Do not sweat headspace! It's a gunstore commando topic. As long as you're shooting good, military M2 Ball it really doesn't matter. M1 Rifles don't "blow up" from excessive headspace. They may get sloppy accuracy, but that's the limit.



Seems kinda irresponsible to give such dangerous advice.

Link Posted: 3/11/2005 12:35:46 PM EST
Link Posted: 3/11/2005 2:12:09 PM EST

Originally Posted By raf:
Case seperations, again mentioned by Chuck, are of course a distinct possibility.



Try reading comprehension, he made no mention of it - I did.

Don't know about you, but I don't want 50,000 psi to suddenly become uncontained inches infront of my face.

I guarantee you it will split the stock, whether you'd be injured is another story, but better safe than sorry, and his advice doesn't cut it.


Originally posted by raf:
To give you an idea of how strong the M1 action is, Gen Julian Hatcher, in a scientific series of tests, finally ended up loading an entire cartridge case with proof testing powder (normal amount was a small fraction of the entire case volume}. Long story short, the rifle survived, and was still useable.



Go back and check again, I believe you'll find that although the action did not catastrophically fail, one of the bolt lugs did crack. 'Course if you believe Chucks' statement about headspace not mattering, you probably think this would still be a servicable "problem".

Tim
Link Posted: 3/11/2005 3:01:51 PM EST
Alot of 7.62 ammo has been accidently fired in 30 Cal M1's with no ill effect other than accuracy. The Extractor will hold the case head against the bolt face, firing M2 ammo in an M1 with excessive headspace will not cause casehead seperations. It will shorten the life of the brass though if you reload and full length resize everytime.
Link Posted: 3/11/2005 3:06:37 PM EST

Originally Posted By tangeant:
Alot of 7.62 ammo has been accidently fired in 30 Cal M1's with no ill effect other than accuracy.


Only by idiots.


Originally Posted By tangeant:
The Extractor will mighthold the case head against the bolt face, firing M2 ammo in an M1 with excessive headspace will notmight not cause casehead seperations.



Fixed it for ya, but hey, its your face, go ahead.

Tim
Link Posted: 3/11/2005 3:39:08 PM EST
Regarding 7.62x51 fired in a 30-06 M1, IIRC Franfort Arsenal performed testing of this around the time the M14 was being considered for adoption. Their conclusion was that it was OK to do in an Emergency, using USGI M59 (or M80) ball ammo.

Major Culver has written on his website (jouster.com) about unintentionally firing 7.62 in a .30 cal Garand at the National Matches when both ammunition was issued and he received the wrong one. He suffered no ill effects other than low hits on the target.

I would not make a steady habit if firing 7.62 in a 30-06, but would do so without hesitation if the choice was being taken prisoner by some zombie or murderous islamic wacko.

Link Posted: 3/11/2005 4:09:15 PM EST
Link Posted: 3/12/2005 8:35:24 AM EST
[Last Edit: 3/12/2005 8:38:31 AM EST by raf]
Link Posted: 3/12/2005 8:53:10 AM EST
Link Posted: 3/12/2005 11:46:22 AM EST
Chuck, thank you for posting this. I've been saying the same thing for years, and maybe people will finally stop using the NO-GO gauge as a test for used military surplus rifles.


Originally Posted By Chuck:
NO-GO is a factory/arsenal gage designed to allow the maximum service life in the field. Once the rifle is in your hands only the longer FIELD (Reject) gage has any meaning.

In order of length the gages are:

GO (minimum chamber length for reliable operation)

NO-GO (maximum chamber length for new rifles or rebuilds leaving the factory/arsenal)

FIELD (maximum length).

-- Chuck

Link Posted: 3/12/2005 12:39:09 PM EST
Link Posted: 3/13/2005 4:56:04 AM EST
[Last Edit: 3/13/2005 5:03:38 AM EST by Garand06]

Originally Posted By raf:
Who's talking uncontained? Isn't the bolt fully closed, and a cartridge of the proper head diameter in the chamber? We're not referring to a cartridge that will interfere with the bolt closing.



If the case separated, it is uncontained.


Origianally Posted by Garand06:
I guarantee you it will split the stock, whether you'd be injured is another story, but better safe than sorry, and his advice doesn't cut it.




Originally Posted By raf:
Didn't you say above what the rifle won't "blow up"? which is it?




Yes, and I don't consider a case failure that blows out the magazine area of the stock to be the rifle blowing up.



Originally Posted By raf:
To give you an idea of how strong the M1 action is, Gen Julian Hatcher, in a scientific series of tests, finally ended up loading an entire cartridge case with proof testing powder (normal amount was a small fraction of the entire case volume}. Long story short, the rifle survived, and was still useable.




Orignially Posted by Garand06:
Go back and check again, I believe you'll find that although the action did not catastrophically fail, one of the bolt lugs did crack. 'Course if you believe Chucks' statement about headspace not mattering, you probably think this would still be a servicable "problem".

Tim




Originally Posted by raf:
True, the bolt lug cracked, but you left out the rest of the story. Hatcher then fired 5,000 standard rounds through the rifle with the bolt whose lug was cracked with no ill effects. (HNB, Pg 206)

Why did you leave that information out?




Simple, I had completely forgotten that. (I'm only human, too )

Perhaps I am simply paranoid, and therefore incorrect in my position, but I will not fire any weapon that does not check out "normally" and I don't feel that excess headspace is normal.

Tim
Link Posted: 3/14/2005 4:52:54 AM EST
Back to my original question...Does anyone understand the relationship between the sizes listed on Forster gauges and the military headspace measurements?
Link Posted: 3/14/2005 6:17:09 AM EST

Originally Posted By Southern_Raider:
Back to my original question...Does anyone understand the relationship between the sizes listed on Forster gauges and the military headspace measurements?



Read my post above. There are no differences in 30-06 dimentions between the military and commericial, like in 7.62/5.56, that I'm aware of.
Link Posted: 3/14/2005 10:09:12 AM EST

Originally Posted By colt100:

Originally Posted By Southern_Raider:
Back to my original question...Does anyone understand the relationship between the sizes listed on Forster gauges and the military headspace measurements?



Read my post above. There are no differences in 30-06 dimentions between the military and commericial, like in 7.62/5.56, that I'm aware of.



Please reread MY posts. As I mentioned, gauges like Forster appear to use a different datum point when measuring the chamber. The gauges may be identical, but they certainly aren't labeled as such.

Furthermore, I think we've already established that a military rifle will close on a SAAMI field gauge long before the military gauge says the barrel needs to be replaced.

I'm NOT making the claim that there is a difference between commercial 30-06 ammo and military 30-06 ammo.
Top Top