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  #61  
Old 11-23-2012, 07:31 PM
steelap steelap is offline
 
Join Date: Oct 2009
Location: North AL
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I am going to take a deep breath and step back. Given my shallow depth of knowledge on this particular subject, I really need to shut up and listen.

"Life is Good!"
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  #62  
Old 11-23-2012, 08:53 PM
rojkoh rojkoh is offline
 
Join Date: Sep 2012
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Quote:
Originally Posted by Vos Parate View Post
My head is spinning. I have a 7.62mm receiver with a USGI barrel. Headspace was set to fire both .308 and 7.62 x 51. I plan on shooting milsurp 7.62 x 51 and reloading. Which gauges would be preferred for my situation?

Thanks in advance.
Tips and "tricks":

There are minor differences in the case between .308 and 7.62, but that's not the only issue (in your case you're fine with a 7.62 chamber). I have posted the drawings for both online (I have permission to use the SAAMI drawings).

Given all the variables in the current crop of "M14" type rifle products, it's really a question of knowing the chamber that you have, and than dealing with it. SAAMI is a reference, 7.62x51 is a standard, although there are many different types of 7.62 chambers (4 sets of drawings for the M14 NM alone).

Remember that 7.62x51 produced since 1980 is made for MG use. Which means accuracy is never as good as "good" 7.62 ammo (which was never great, except for some of the NATO ammo). Also understand that military brass is heavier than commercial (most).. which means either higher pressures and/or less case capacity. I'm working up loads in both Military cases (LC and WRA ball, M118) and commercial (Lapua and Norma). But given the differing applications, well.....

But it can be tricky to shoot 7.62 in a .308 chamber, depending on which chamber that rifle has. There are some pressure issues to watch and than if you use sloppy 7.62 in a tight chamber you can have extraction problems. Unless you don't mind using a taper reamer, it's best to know what you have ahead of time.... and avoid those little "headaches".

Art likes the Clymer and at the moment, I'm using the Forster, both are good. Get the min and Max

Last edited by rojkoh; 11-23-2012 at 08:58 PM.
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  #63  
Old 11-27-2012, 02:19 PM
TokiWartooth TokiWartooth is offline
 
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Location: New York
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Quote:
Originally Posted by rojkoh View Post
No kidding, have had talks with numerous people about all the different types of barrels and chambers. I also have talked with SAAMI about it.

Most crucial of all, MAKE SURE OF THE CHAMBER YOU HAVE!

Simple especial given the industry these days. As noted, I've seen chambers stamped .308 that were NOT (they were issue 7.62x51 chambers and not the NM chambers).

Semper Fi
Is the difference really in only what the headspace is? For instance, most of my GI barrels headspace at 1.633 - 1.634, which to me, is perfect for shooting a wide range of ammo.

Now... M118LR is a different story. I have a Barnett barrel specifically reamed for this. The barrel headspaces at 1.633, BUT the throat erosion measures a 4. This is not due to EROSION, but it's reamed like this on purpose due to the ogive and COL of M118LR (SMK 175s). M118LR reamers have deeper throats (no Linda Lovelace jokes please..)
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  #64  
Old 11-27-2012, 06:59 PM
M14 M14 is offline
 
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Quote:
Originally Posted by TokiWartooth View Post
Is the difference really in only what the headspace is? For instance, most of my GI barrels headspace at 1.633 - 1.634, which to me, is perfect for shooting a wide range of ammo.

Now... M118LR is a different story. I have a Barnett barrel specifically reamed for this. The barrel headspaces at 1.633, BUT the throat erosion measures a 4. This is not due to EROSION, but it's reamed like this on purpose due to the ogive and COL of M118LR (SMK 175s). M118LR reamers have deeper throats (no Linda Lovelace jokes please..)
Nope.

The throat (freebore) is longer as well in a NATO chamber, as allowed by specs, but not necessarily found shorter in all commercial examples.
0.1563 - NATO, and 0.1138 - SAAMI.

Good post and good point Toki.
Bore size is different too:
Cylinder bore - chamber
762mm - .3095 + .020
308 - .310.................one half thousandths more than NATO minimum.
Also not necessarily found in commercial examples.


Your example of the M118LR chamber is a perfect example. In that instance, it is the amount of jump to the lands. Not only that, but the diameter of the casemouth area is different too. Other custom reamers slightly change the bottleneck angle.

There was only one carbide finish reamer, with the proper pilot, in the country available for sale as of a few days ago for the M118LR. It now resides in my possession, to fix Steelap's rifle chamber. I buy a lot of stuff from them, but PT&G will not make them anymore, for me or anyone else, unless they order a bunch of them. This one was the only example left from a run they did for the military when they ordered them made for test reaming on G.I. chrome lined chambers.
By a stroke of luck, Dave at PT&G had put the last one in his locker. Said he didn't know why, but something told him to save one from the momentus run, if nothing else, for history's sake. When the military dusted off the mothballs from the M14 to get them to Afghanistan to our guys in a hurry, They were checking the headspace on them, and realized a few were short from the required minimum, especially in the environment they were headed too, there and Iraq. They ordered them to ream the shorter headspaced ones, and get them shipped quickly, and decided they would change barrels later in a case by case situation, as needed. I talked Dave into selling it to Steelap and me, and he did so, relunctantly.
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  #65  
Old 11-29-2012, 07:26 AM
TokiWartooth TokiWartooth is offline
 
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Location: New York
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Quote:
Originally Posted by M14 View Post
Nope.

The throat (freebore) is longer as well in a NATO chamber, as allowed by specs, but not necessarily found shorter in all commercial examples.
0.1563 - NATO, and 0.1138 - SAAMI.

Good post and good point Toki.
Bore size is different too:
Cylinder bore - chamber
762mm - .3095 + .020
308 - .310.................one half thousandths more than NATO minimum.
Also not necessarily found in commercial examples.


Your example of the M118LR chamber is a perfect example. In that instance, it is the amount of jump to the lands. Not only that, but the diameter of the casemouth area is different too. Other custom reamers slightly change the bottleneck angle.

There was only one carbide finish reamer, with the proper pilot, in the country available for sale as of a few days ago for the M118LR. It now resides in my possession, to fix Steelap's rifle chamber. I buy a lot of stuff from them, but PT&G will not make them anymore, for me or anyone else, unless they order a bunch of them. This one was the only example left from a run they did for the military when they ordered them made for test reaming on G.I. chrome lined chambers.
By a stroke of luck, Dave at PT&G had put the last one in his locker. Said he didn't know why, but something told him to save one from the momentus run, if nothing else, for history's sake. When the military dusted off the mothballs from the M14 to get them to Afghanistan to our guys in a hurry, They were checking the headspace on them, and realized a few were short from the required minimum, especially in the environment they were headed too, there and Iraq. They ordered them to ream the shorter headspaced ones, and get them shipped quickly, and decided they would change barrels later in a case by case situation, as needed. I talked Dave into selling it to Steelap and me, and he did so, relunctantly.
Where does Ron Smith get them from? Doesn't he ream for M118LR on his M25s?
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  #66  
Old 11-29-2012, 10:15 AM
M14 M14 is offline
 
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Location: south mississippi
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Yep, but he uses tool steel, unless he is doing a revamp of an old G.I. barrel. He has a few carbide reamers to choose from, but bought from other vendors that offer them. They are very expensive by piece work, cheaper by the dozens.

None were available that I could find, and I called several makers.
Houston, Oregon (PT&G), New Orleans, Chicago, New York. MSC in New York had a vendor they could hook me up with, but the order would be months out, so I called Dave back at PT&G and begged. Originally when I anticipated having to order a run of them, the order was three weeks out from PT&G, but I could hardly afford the size of the order needed to move forward with it. Dave is good people and I can highly recommend their services to anyone.

Last edited by M14; 11-29-2012 at 10:31 AM.
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  #67  
Old 12-02-2012, 04:26 PM
mikebaker1129 mikebaker1129 is offline
 
Join Date: Nov 2009
Location: Houston ,TX
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Quote:
Originally Posted by nf1e View Post
I got mine right here on estore. Clymer106 and 1203 7.62 NATO. I like the green for go and red for no go. They are also notched for the ejector and marked CMP. That always counts for something. They are listed there now and if you click on the description, you will see an nice photo that even shows 7.62 NATO. What could be easier.
+1
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  #68  
Old 12-13-2012, 01:36 PM
MyTurn MyTurn is offline
 
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I just received my order of the .308 go and no go gauges from the estore at CMP. They do NOT look like the ones pictured at the estore. Those show a pic of gauges that have 7.62 NATO and what appears to be CLY 2/10 marked on them. The ones I received ONLY have 308 WIN on them and are also marked CLY 611. Adds to the mystery, I guess. I intend to follow up with Clymer after the holiday as they suggested.
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  #69  
Old 12-14-2012, 06:41 PM
M14 M14 is offline
 
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The reason they are marked NATO, is they start at their minimum of 1.6355

Any gauge can be used, it is the length that matters. If you want a NATO chamber or close to it, use the SAAMI 1.633 gauge.

The numbers are the dates of manufacture on the gauges. NATO go and no go will be 1.6355 and 1.6375....a spread of only two thousandths.

SAAMI or Win. marked ones, should be 1.630 go and 1.634 no go, a spread of four thousandths, unless you have an older set, then the no go will be 1.636


Clymer Manufacturing Company
1605 West Hamlin Rd., Rochester Hills, MI 48309
Toll-Free Phone: (877)REAMERS
Phone: (248)853-5555 Fax: (248)853-1530
http://www.clymertool.com
E-mail: clymer@clymertool.com
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  #70  
Old 12-16-2012, 06:59 PM
hmelect hmelect is offline
 
Join Date: Dec 2009
Location: Apopka, Florida
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I have read this entire thread and I now have a headache. I purchased a set of .308 gauges from the CMP and tried them tonight in my Navy 7.62 mod 1 BR with two new stripped bolts. Both bolts closed on the go and the no go gauges. The no go gauge closed with a very light tap of my finger. Is that suppose to happen? Thanks for your replies. Jim.
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