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Posted: 2/13/2007 12:43:37 PM EDT
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CMP has Clymer gauges for .30 carbine, .30-06, 5.56, and 7.62 (but not .308) for $36.95 each. MidwayUSA has Forster gauges in those calibers plus .308 for about $14 less per gauge. Is there any reason not to by the Forsters? The Forsters are multi-caliber gauges. Does that work well? Do I need the "field" gauges as well as go and no-go? What exactly is a field gauge as compared to the go and no-go in the same caliber? Well, looking further, there are no 7.62 or 5.56 NATO gauges at Midway. Damn it. Will the .223 field gauge and .308 field gauge tell me anything about 5.56 and 7.62? Also, does anyone know a good place to get these gauges for SAAMI and NATO rounds? One other question: In my thread about my Polytech M14S, someone noted how many parts have to be US parts before I can put the FS/bayo lug on it. I can't find the dang thread. So, how many US parts and does that count include the FS/bayo lug? |
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To keep it simple for myself, I use the dimension numbers to think about M14 type rifle headspace. If a M14 type rifle gages 1.634 " or less I know I'm safe with commercial .308 or military surplus ammunition. I have a 1.638 " gauge that I can use if I want to use NATO surplus ammunition if the rifle swallows the 1.634 " gauge. HTH The Forster .308 gauges I have are also good for measuring .243 Winchester barrel headspace. I don't know jack about the M1 Carbine so I can't answer on that part of the topic. I bought the Forster gauges from www.brownells.com |
| larry, I purchased the Forester gauges from MIdway USA. I ordered both the field and NO GO. It is a little trickey to reassemble the bolt once you check the head space, but it is worth the trouble IMO. I really liked the Forester product and it has served me well with headspacing all my CMP rifles. You can't go wrong for the money. |
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HTH, from the 02/11/07 draft of the Third Edition of M14 Rifle History and Development: Table 29: M14 Type Rifle Headspace Dimensions Reference GO (inches) NO GO (inches) FIELD REJECT (inches) SAAMI 1.630 1.634 1.638 Drawing F7267000 Rifle, 7.62 MM, M14 Revision AH dated January 24, 1986 1.6355 1.6405 (No Go) Drawing F7790476 Rifle, 7.62 MM, M14 NM Revision D dated April 10, 1969 1.6355 1.6385 (No Go) 1967 National Match Rifles - U. S. Army Materiel Command 1.6355 1.6385 (No Go) AMU M14 MTU-NM Manual 1.631 1.635 (No Go) MIL-R-45979 dated 24 Sep 76 Military Specification M14 NM 1.6355 1.6385 (No Go) TM 9-1005-223-34 August 1971 and TM 9-1005-223-35 July 1968 1.6455 (Field Reject) DMWR 9-1005-223 October 1971 1.6355 1.6415 allowed maximum, 1.6375 desired maximum (No Go) TM 02648C-24&P/2 July 2000 1.632 1.638 (No Go) |
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GO, NOGO, FIELD are essentially Minimum, Maximum, and Dangerous. Generally, GO and NOGO are used when barreling, GO and FIELD are used to check to see how safe a rifle is to shoot. If you go to Fulton's site, there is an good write up regarding the 308 vs 7.62 NATO. Basically, they are the same cartridge with different chamber tolerences. The NATO chamber being slightly longer to allow for variations in ammo from the different countries. If a rifle is chambered with a NATO max chamber, it is generally recommended that one not fire commercial ammo in it. The brass in commercial ammo is generally thinner and may not stretch enough to safely seal the chamber, and rupture. Kuleck states in his Website, that their examination of many NATO and SAAMI spec rounds shows that the external dimension are virtually the same. So, both ammos can be safely shot in a Commercial SAAMI chamber, but only NATO spec in a NATO max chamber. With regards to the 223/5.56 NATO, there is a somewhat different situation there. There have been reports of people shooting military NATO spec ammo in a SAAMI chambered gun, and getting the loaded round stuck in the chamber. Some NATO spec chambers seem to have longer throats/leads, and ammo is often loaded to work in that. So, putting a longer or differently profiled military cartridge in a tighter SAAMI chamber sometimes results in the bullet getting stuck in the throat. I have not heard of that problem with the 308/7.62 NATO. |
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