What does all this mean on M1 Garand CMP TAG?

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ACES&8S

ACES&8S

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This is my 4'th Garand & I never had a Garand with all the CMP stuff that goes
with it.
I like WW11 stuff & I admit my ignorance as to the Garand Muzzle readings & things
on the tag shown here so help me!
With the previous ones, I have learned to reload for them & I shoot them now & then
& they all group & function perfectly.
I seldom buy a used rifle without shooting it or at least giving it a good look at rifling &
other important things, and this one has a low serial # & good looking rifling with plenty
showing on the military test round applied to the muzzle.
My question is what do all these #s & things mean on the Tag in attached photo??? !!!
I need to know these things & just spent time today trying to learn it but everywhere I
looked they always speak in abbreviations which I am supposed to already understand.
All the stamps & markings just got me in a mix because I have 3 different mfg of the Garand
with enough stamps on the to confuse me but did get some history lessons.
The serial # on this one is in the timeline of June 1942 but the barrel says January 1952.
I don't know if that is a good or bad thing.
You don't have to be gentle with any criticism I need to learn this stuff. Tag On Springfield Garand.JPG
 
seems like you know how to look up the receiver's serial # which indeed does look like a 1942, which is a nice WW II receiver. At some point it was re barreled with the barrel manufactured in 1952. The muzzle and throat readings show it has some wear but still should be a real nice shooter. To me, you got a nice M1. Service grade, probably came with a new, black walnut stock. If you want more, I suggest going over the the M1 Garand forum at the CMP site and asking your questions.
 
Muzzle of 1+ shows little muzzle wear, from what I've read some new barrels measured around 2 during the war. Throat reading of 3 or less is generally considered good. But it's a 60+ year old barrel, sounds like you got a decent one if the rifling is sharp.
 
As far as different mfg parts. It has probably been rebuilt at least once before the CMP did their inspection/rebuild.
 
A muzzle erosion of 1 is new. I have gaged a number of new barrels that were 1.0 or a little more, the crown makes a difference. I have gaged new barrels that that had throat erosion which were 2.5, I would have to look if any gaged a 3, but I would not doubt it. After market match barrels will gage 1.0 or less, but they are cut with a different reamer.
 
the readings for throat and bore erosion. I have heard conflicting reports on whether they are graded on a scale of zero to five or a scale of zero to ten. normally with CMP guns 5 is rare, usually at that point they must be put in the stack for their service special grade or something (new stock, new barrel, new parkerizing). 1+ (halfway between a 1 and a 2 but closer to 1) is very good, a step down from brand spanking new, 3(looks like they were originally going to grade it as a 2, but changed their mind and demoted to a 3) is just a little wear on the throat. you might try seating handloads a tiny smidge longer, but otherwise you shouldn't need to give it special treatment over your other garands.
 
Muzzle gauges used for the M1 are generally marked zero to five. Throat erosion gauges are generally marked zero to ten.
 
the barrel being newer than the rifle is neither good or bad. most of the M1s were rebuilt at one time or another and it wasn't uncommon to be rebarreled. I have a 44 manufacture M1 that still received a 52 dated barrel sometime post war. if everything is original and dated to match then you actually would have a fairly rare piece, worth much more than the $750 you paid for a service grade M1. normally CMP catches them and auctions them off as collectors grade rather than adding them to normal stock. collector grades will normally go well over 2K.
 
So maybe I got it & maybe I don't, like the muzzle reading being 1+, does that mean it
measures .309" instead of .308" ?
And the throat being a 3 might mean it is .003" beyond the original rifling contact with the bullet.
Or did I just make you guys shake your heads?
And as for the original other parts I really am a novice at that.
My basic understanding of the Garand is historical of course as well as knowing how
they function & reloading ammo for it which took a lot of study.
 
it's more of a subjective scale. 0 means brand new, 5 means it's almost a smooth bore. throat means that it's got some wear but not enough that it's going to be an issue. it really doesn't necessarily have to do with the physical diameter.
 
ACES&8S said:
So maybe I got it & maybe I don't, like the muzzle reading being 1+, does that mean it
measures .309" instead of .308" ?
And the throat being a 3 might mean it is .003" beyond the original rifling contact with the bullet.
Click to expand...

If you have not done so already, do a search on line for M1 throat and muzzle gauges and you will see what they look like.

Over on the CMP web site, there is lots of information on care and maintenance of an M1. There may be a discussion on throat and muzzle wear and gauges but it has been a while since I perused the pages so this memory maybe a figment of my imagination.
 
cfullgraf said:
If you have not done so already, do a search on line for M1 throat and muzzle gauges and you will see what they look like.

Over on the CMP web site, there is lots of information on care and maintenance of an M1. There may be a discussion on throat and muzzle wear and gauges but it has been a while since I perused the pages so this memory maybe a figment of my imagination.
Click to expand...
I have looked at several videos & written versions on this & they all seem to think everyone who watches them knows
what their abbreviations stand for & the terms they use as well. It can get frustrating at times.
I looked on Midway for the gauges & I must not have learned the proper name for them, they usually have
about everything.
 
Sistema1927 said:
You got a good one. It should give you acceptable accuracy.
Click to expand...
It is very accurate using military issue ammo marked - 30 cal M2 with 8 round clips.
Walked it right in to dead center at 30 yards then attacked our 100 yard with impressive results.
I never used any of this ammo because I figured it would never be accurate enough but it is.
I don't think I will try my reloads in it because it is accurate enough as it is, & I don't want
to wear it out.
My reloads in the other Garands are tighter groups & consistent but I like this M2 stuff.
 
Ok, the gauge does not measure distance per se. The gauge is marked off in uniform increments, so the reading is an integer and not a calibrated dimension. This drawing shows how a throat erosion gauge is used:
T-gage.gif
A muzzle gauge works similarly:
mw10.jpg
Both of which are far more precise than poking an FMJ in the muzzle. Particularly for repeatability.
 
"RM1-Service/SA" - means it's a CMP Service Grade rifle with a Springfield Armory receiver.
"6X9053" - is the receiver serial number, a low, six-digit '42.
"11-20-15" - is the date it was CMP inspected/gauged for sale.
"1-52" - is the Bbl. date, meaning that it has been re-barreled at least once.
"ME = 1+" - means the muzzle erosion gauged ~ 1.2 (0.3012")
"TE = 3" - means the throat erosion gauged ~ 3.0 (0.3030")

As for barrel erosion:
Given: Bore Dia. = 30 Caliber = 0.300"
1. The Throat generally erodes at a rate of 0.001" (or one erosion number) for every 2000 rounds fired.
2. The Muzzle generally erodes at 1/3 the rate of the throat.

Given: A new post-war ('52) barrel with average gauge readings of ME=0.5/TE=1.0
Given: Maximum barrel service life is TE=10.0 (0.310")

Your Bbl. should have:
~ 4000 rounds through it. (3.0-1.0)2000, and therefore (2.0)/3 + 0.5 = 1.2 ME
~ 14,000 rounds of service life left. (10.0-3.0)2000.
(although accuracy may start falling off in ~ 10,000 rounds (3.0+5.0=8.0 or 0.308"))




GR
 
Last edited:
how does 1+ equal exactly 1.2 and how does 8+1.2=12?
that math makes no sense to this one.
actually none of those figures make any sense to me... and I have to teach Binary math for a living.
 
tahunua001 said:
how does 1+ equal exactly 1.2 and how does 8+1.2=12?
that math makes no sense to this one.
actually none of those figures make any sense to me... and I have to teach Binary math for a living.
Click to expand...

It is the way the CMP gauges their rifles.

"1+" means "more than One, but less than 1.5."
"1-" means "less than One, but more than 0.5."

1.1 < (1+) < 1.3, mean 1.2.

As for "8+1.2=12?"

...You pulled that out from somewhere else, as it does not appear in my post.




GR
 
Last edited:
CapnMac said:
Ok, the gauge does not measure distance per se. The gauge is marked off in uniform increments, so the reading is an integer and not a calibrated dimension. This drawing shows how a throat erosion gauge is used:
View attachment 799775
A muzzle gauge works similarly:
View attachment 799776
Both of which are far more precise than poking an FMJ in the muzzle. Particularly for repeatability.
Click to expand...

That info is valuable ! I need one of those gauges to se what my other 3 measure. Tahunua001 sent me info on one.
According to Garandimal & others I have several thousand rounds left in this one which I will probably
never get done.
I have an H&R [ I Think it's H&R ] that I run most of the time & my son has it next door right now
and I haven't heard it bark all weekend.
 
ACES&8S said:
That info is valuable ! I need one of those gauges to se what my other 3 measure. Tahunua001 sent me info on one.
According to Garandimal & others I have several thousand rounds left in this one which I will probably
never get done.
I have an H&R [ I Think it's H&R ] that I run most of the time & my son has it next door right now
and I haven't heard it bark all weekend.
Click to expand...

This Gauge looks good, and appears to be identical to my Stone-Axe Combination TE/ME gauge that is very good.


41-32Mno2oL.jpg ​




GR
 
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