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  #71  
Old 12-17-2012, 03:36 AM
M14 M14 is offline
 
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Originally Posted by hmelect View Post
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.
I call that a pop. More noticeable if you close it on an interference fit, then gently open it. You will feel a slight pop as it breaks loose from the bottleneck area. The answer is no, it shouldn't happen, because you shouldn't force a bolt to close on a gauge, it should close with no pressure at all, or you could damage your gauges. Navy builds were kept to different tolerances, and then changed again later. First IIRC, they were around 1.636, then later they began tightening them up for headspace, to around 1.633 when they started shooting them in matches alot. What is your no go measurement written on the gauge ? If it is a newer gauge at 1.634, the rifle is fine because it popped, meaning it is slightly less than that no go, so around 1.633. If it is an older 1.636 Winchester no go, it is fine too, because it is right at NATO minimum of 1.6355....and that would be my guess for your Navy rifle. Either way, you are good to go. Congratulations for having the presence of mind to buy some gauges and check your headspace. You sir, are an intelligent man that will live long.
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  #72  
Old 12-17-2012, 10:15 AM
hmelect hmelect is offline
 
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Thanks for responding. Neither of the cmp gauges are marked with any measurement so I am not sure what to say as far as which measurement they are, but I just got them, so they are brand new guages. I guess I am smart enough to know I need to check, so thanks for the compliment, but I have ordered a number of other guages from Brownells today to confirm that the rifle will be good to go. I ordered a Clymer .308 field gauge to match what I have, and a set of Foresters 7.62 go, no go, field too. So after I get those I will try it again.
So justs to confirm how to use the gauges, you put them in and slide the bolt forward with two fingers very lightly?
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  #73  
Old 12-17-2012, 11:20 AM
nf1e nf1e is offline
 
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Quote:
Originally Posted by hmelect View Post
Thanks for responding. Neither of the cmp gauges are marked with any measurement so I am not sure what to say as far as which measurement they are, but I just got them, so they are brand new guages. I guess I am smart enough to know I need to check, so thanks for the compliment, but I have ordered a number of other guages from Brownells today to confirm that the rifle will be good to go. I ordered a Clymer .308 field gauge to match what I have, and a set of Foresters 7.62 go, no go, field too. So after I get those I will try it again.
So justs to confirm how to use the gauges, you put them in and slide the bolt forward with two fingers very lightly?
Just remember to strip the bolt first. Just the bolt body sliding loose in the receiver. Clean chamber and do not force the bolt at all on guage.
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  #74  
Old 12-17-2012, 12:29 PM
M14 M14 is offline
 
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Quote:
Originally Posted by hmelect View Post
Thanks for responding. Neither of the cmp gauges are marked with any measurement so I am not sure what to say as far as which measurement they are, but I just got them, so they are brand new guages. I guess I am smart enough to know I need to check, so thanks for the compliment, but I have ordered a number of other guages from Brownells today to confirm that the rifle will be good to go. I ordered a Clymer .308 field gauge to match what I have, and a set of Foresters 7.62 go, no go, field too. So after I get those I will try it again.
So justs to confirm how to use the gauges, you put them in and slide the bolt forward with two fingers very lightly?

No problem, you are welcome sir.

Yep, use your middle finger up in the magwell on the bottom of the bolt and your thumb on top the bolt. Place them about in the middle of the bolt body or a hair forward of the middle for balance and feel. With an assortment of gauges, you should be able to pick up the feel of the difference between a resistance fit, and an interference fit. The pop is an interference fit, so you know that already. The resistance fit is less tight, but still not your actual headspace. You want a smooth closing with the ever so slight feel of the friction between the bolt face and the back of the gauge where they touch each other. It is difficult to descibe to someone, but I will try.

I set my chambers at 1.6325 - 1.633, I found this works best for all ammo. To do this, I have gauges in my collection of tools that go from 1.630 to 1.640, and in addition, the NATO set that starts at 1.6355 This one half thousandths gauge comes in handy many times, and has helped teach me the feel of a half thousandths in my fingers. It takes lots of practice. If a bolt closes on the 1.632 gauge with no resistance of any kind, and will not close all the way on the 1.633, then it is close to 1.6325, If it has the slightest friction on the 1.632, then I look at the amount of the gap under the bolts right lug and the shelf with the 1.633 gauge. This is a 1.632 chamber. You can actually learn to see one half thousandths in the gap under the right lug between the shelf with practice and feel.

The biggest mistake I see people make in checking headspace, is the bolt is not shut all the way down on the shelf. This can be as much as two thousandths off on a good reading. Many things can cause this, Number one is bolt roller impact, Number two is humps in the shelf or high spots on the bolt lug bottom or burrs, or both. Number three is the bolt contacting the back of the receiver ring, Number four is the right bolt lug front or back, or both, contacting the radius turns at the bottom of the shelf in the cut-out for it in the receiver.

The second biggest mistake I see, is the left lug contact. I work on rifles that many so called armorers have built, and they are all screwed up. If the left lug is not contacting in the receiver, it is impossible to get a viable headspace reading...period. The flexing of the bolt and the sideways crabbing action because of contact on one side only, when closing on the gauge, will skew the measurement. I just worked on one that came directly from a well known builder, that had a .005 gap at the left lug, and severe bolt roller impact. It was an Armscorp receiver. There is no way the headspace was taken accurately under these conditions.

Get you a flexible neck light or snake light (bore light), and load the chamber with a spent cartridge and stripped bolt, this puts pressure on the bolt rearward to simulate in battery conditions, extend the flexible neck of the light up under the left lug area and in the magwell. Hold your eye directly over the left lug looking straight down at it, then move the light forwards and backwards under the left lug joining place with the reciever lug (the crack between the two), then move your head forward and backwards at the same time, do both slowly. When you line up your eye and the light with the crack just right, you will see light streaming through if the left lug is not contacting at all. I recommend fixing this problem before proceeding with headspace measurements, because they will not be accurate for the rifle.

First you should make sure the bolt roller is not restricted or having impact at the right lug shelf on the receiver before checking headspace. Put hard pressure down on the right bolt lug while in battery with an empty chamber, then try to turn the roller. If it does not roll, it is impacting there. It needs to be relieved on the receiver before proceeding with headspace measurements. Another check is to use a piece of thin paper under the roller, close bolt with applied pressure as before, and try to remove or slide the paper from under the roller. Make sure paper is under the roller only and not trapped on the little step down at the receiver shelf.

Let us know how you progress with the new gauges, and what you determine as your final headspace, and how you determined it. We will be here to help, barring any unforeseen calamities arising. Best regards......Rip.
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  #75  
Old 12-17-2012, 02:05 PM
hmelect hmelect is offline
 
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Thanks again for the replies. I will let you know how it goes when I get the other gauges. Thanks, Jim.
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  #76  
Old 12-25-2012, 05:37 PM
hmelect hmelect is offline
 
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Okay here are the results of my new gauges. The bolt would close on a .308 go , it would close with a "pop" on the .308 no.go, it would not close on a .308 field gauge. It would close on a 7.62 go, it would not close on a 7.62 no go nor a field gauge. So I think I am good to.go for both 7.62 or .308. Right? Thanks Jim.
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  #77  
Old 12-25-2012, 08:10 PM
nf1e nf1e is offline
 
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You are good to go with both.
Now it's time for your range report with whatever you decide to feed it.
They are hungry and oh so much fun to keep fed.
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  #78  
Old 12-25-2012, 08:59 PM
Sailormilan2 Sailormilan2 is offline
 
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Originally Posted by steelap View Post
I just checked my order from Brownell's - and am not happy.

The
319-000-006WB 7.62 Nato Maximum Chamber Gauge Mfr Part: HG762NATOMAX is right.

BUT, the Forster headspace gauge sold as
100-010-714WB 7.62 Go Gauge Mfr Part: HG30816330SP is NOT the HG762NATOmin gauge - it has a length of 1.6330, not 1.6355 as shown for the HG762NATOMin on the Forster website. The gauge itseld is not marked by Forsters as 7.62, but rather as .308/.243.

I am trying to understand why Brownell's would sell an improper gauge (1.6330). Too short for a 7.62 GO (1.6355), too long for a .308 GO (1.630).

Any suggestions on what caliber or purpose to use this headspace gauge?

By the way, neither has the relief cut for the extractor.

I just got a set of Forster gauges from Brownells, and I ran into a similar issue as you regarding the 7.62 NO GO. I ordered a 308 FIELD, a 7.62 NATO NO GO, and a 7.62 NATO FIELD. What I got was:
243-308...FIELD..1.638
243-308............1.640
7.62 NATO........ 1.6455 MAX

Gauge #2 should have been marked 7.62 NATO NO GO. It has the right part number(100-010-715), but the label on the case says 243-308 NO GO GAUGE. But the gauge itself does not say what type of gauge it is, just the caliber and length.

I already have two Forster 308 gauges and they are marked:

243-308...GO.........1.630"
243-308...NO GO....1.134"

Both of these should be the proper markings for the 243-308, so I don't understand how the 7.62 NATO No GO could be labeled 243-308 1.640. From what I understand, the 1.640 is actually longer than 7.62 NATO NO GO, but shorter than 7.62 NATO REBUILD MAXIMUM GAUGE. I also think that the NATO FIELD gauge should be marked as FIELD, not "MAX".
I have written to Forster and am waiting a reply.
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Last edited by Sailormilan2; 12-25-2012 at 09:02 PM.
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  #79  
Old 12-25-2012, 09:47 PM
longunner longunner is offline
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Quote:
Originally Posted by hammonje View Post
Uh...why not just use 308 Win gauges like the rest of the world and MAKE LIFE EASY.

Unless you are trying to find out if a 7.62 NATO Navy B/R is in spec. I have been able to confirm headspace on every commercially built M14 I own with my Forster gauges so they must be OK. The armorers I know use 308 Win gauges, not 7.62 NATO.

Why do you guys want a 7.62 NATO chamber??????
+1

The only difference between the 7.62 and the .308 is pressure. The .308 has higher pressure than the 7.62. That's why load data is seperate.
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  #80  
Old 12-25-2012, 09:54 PM
Sailormilan2 Sailormilan2 is offline
 
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Quote:
Originally Posted by hammonje View Post
Uh...why not just use 308 Win gauges like the rest of the world and MAKE LIFE EASY.

Unless you are trying to find out if a 7.62 NATO Navy B/R is in spec. I have been able to confirm headspace on every commercially built M14 I own with my Forster gauges so they must be OK. The armorers I know use 308 Win gauges, not 7.62 NATO.

Why do you guys want a 7.62 NATO chamber??????
Quite frankly, hammonje, I for one, don't want a 7.62 NATO chamber. I would prefer to have a 308 Win chamber. In fact, I have converted 3 Polytechs to 308 Win from 7.62 NATO and built up a Tanker Garand in 308 Win, rather than 7.62 NATO.
However, since the NATO chamber is longer, and swallows the 308 Win gauges, I need the NATO gagues to see where I stand.
With a worn IHC 65 series bolt, my Navy BR passes the NATO NO GO and FIELD. I am hoping that with a new 65 series bolt, I can shorten the headspace enough that I don't have to have some ammo that is specially loaded for the longer headspace that I have to keep seperate from my other 308 Win semi autos.
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Last edited by Sailormilan2; 12-25-2012 at 09:58 PM.
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