Need 308/7.62 headspace help

[cheese1566]

Working on an Ishapore 2A in 7.62 NATO. The gun was still very dirty and full of the dirt, cosmo, and blackish paint. The previous owner of it managed the small town gunshop. His father is a very well respected rifle builder and they both run the three man store. He shot this gun a few times before passing it to me. Since then, I have scrubbed, cleaned, and reparked the gun. No filing, sanding, blasting, or buffing to the bolt head.

I borrowed a set of Forster 308 WIN headspace gauges from another member. I stripped the bolt, including the extractor-cocking piece- and firing pin. Carefully using the Go and then the No-Go gauges, I found the gun failed miserably!!! When the No-Go gauge goes in, the bolt closes with ease and has a little "jiggle". I can see a small space in the exposed locking lug near the bolt handle. I will try to measure the gap with a feeler gauge. I do not have a Field gauge on hand.

After some research on Google, I see info that the rest of the world used large chambers for military use and variety of ammo. Like what we do, but maybe larger...
I also found some info on the CMP website (http://www.odcmp.org/new_forum/topic.asp?ARCHIVE=true&TOPIC_ID=38712) and another milsurp site that I should rather be using a military set of 7.62 NATO gauges.

I thought 7.62 NATO and 308 WIN had the same case specs, just different pressures.

I would take the gun up there, but the young smithy isn't cop friendly. I may have to take it up there and see what pop says.

Need help.

[mike in co]

actually some of the numbers are diff...and then there is a field gauge for 7.62.

i'll see if i can find the numbers.

mike in co
308 win/saami
1.630 go
1.634no go
1.638 field reject
7.62 us army
1.635 go
0.xxx not listed
1.6455 field reject

[docone31]

There is a difference.
I do not use .308, I fire 7.62 and reload it. I use a Collet Die.
I have had great luck with it.
No issues so far.
Once you fireform the cases, they are for that rifle anyway.
I have fired at least 20 reloads on the cases I had used.

[JSH]

what you describe sounds pretty common for those rifles. i have freind that had one and he used 06 brass to make his as it was long as well as being a bit large in diameter

[opentop]

You need to try a field guage.

[Larry Gibson]

Using .4 datum gauge (D) in my Stoney Point headspace Gauge I get 1.6258 on a Forster marked 1.630.

I also have a US Field Service gauge that was inspected at Rock Island Arsenal on 21 March, 2006. It measures 1.6375 on the Stney Point gauge. The required componant dimension (headspace) as listed on the accompaning DA 3023 is 1.6415 +/- .0002. The actual gauge dimension (headspace) is listed as 1.64166.

Thus we see the Stoney point gauge is measuring very clos to .00418 less than the factory/arsenal measurements. The measurements of the "Field Service" gauge fit within the measurements of the 7.62 US Army measurements listed by Mike. Thus a bolt closing on the Field Service gauge but not closing on the Field Reject gauge is still "serviceable".

I suggest if you have access to a Stoney Point gauge that you;

Form a .308W case in your FL die with the decaping pin removed using an '06 case (8x57 requires less triming) with the die backed out a full turn.

Trim the case short so there is no possibility of the case mouth hitting the chamber case mouth and giving a false feel.

Turn the FL die in 1/16 thurn at a time setting the shoulder of the formed case back a tudge.

Try that case in the rifle.

Keep turning the die in 1/16th at a time testing the case in the chamber each time. You are looking for a tight closure of the bolt without crushing the shoulder.

When you have the tight closure of the bolt on a the case then measure the headspace of that cartridge case with the Stoney Point gauge. That will give you a very close measurement (not exact but close enough) of the chambers headspace.

Larry Gibson

[cheese1566]

Well, I put it together and it seemed to tighten up a little up. Must be from the firing pin spring and extractor spring/tension. But the Forster 308 No-Go is still loose and I realize the spring tension has no factor in the safety of proper headspacing.

I did put some once fired 7.62 brass into the chamber carefully with it hooked in the extractor. The brass moves freely into the chamber, but is snug and easily comes out when the bolt is opened. I bought this brass from a fellow member who shot it from his M14.

I guess I will try the local gunsmith and see if he has any 7.62 NATO headspace gauges.

Looks like I will be trading my 308WIN die set for a neck sizer set this Saturday at Cabelas.

Funny thing too is that all the numbers match on this gun: Bolt, receiver, barrel, nose piece, stocks, sight, yada, yada, yada...

[nicholst55]

Most people working with milsurp 7.62 NATO rifles will not use Forster gauges because they tend to be on the short side of spec; try a set of Clymer (or Dave Manson) gauges instead. In this particular case, the consensus seems to be that if the bolt will not close on a Field (Reject) gauge, that headspace is acceptable.

These rifles were (re)built in what was a rather primitive 3rd World country at that time. The chambers were on the generous size so that they would chamber and fire any available 7.62mm NATO ammo. No thought was given to reloading the brass.

I would suggest forming brass from a longer case as mentioned above, and setting the shoulder to headspace in your chamber. Keep it segregated from any other .308 brass you use and dedicate a FL die to this particular rifle/brass combo. That should be a workable solution, if not the easiest thing in the world to do.

FWIW, a guy on another forum thoroughly cleaned the wood on one of these rifles, and then carefully bleached it and refinished. It's walnut under all that dirt, grease, and grime, and his rifle really turned out nice.

Good luck!

[StarMetal]

I wonder if a new bolt head would take up some of the excess headspace? Gun Parts has these for $12.50 SMLE NO 1 MKIII, NO 2A MKIII ISHAPORE

Joe

[cheese1566]

I took it to the local smithy who is very well known in the area for custom bolt guns. He actually shot this gun with his son before the son sold it to me. When they shot it, they did not see any deformities in the brass with new ammo.

His SAAMI Field gaude did drop right in though, but he did not have any NATO spec gauges.
He said I could do two things:
1. Remove the barrel, turn it, reset it back one turn, the re-ream the chamber to 308 dimensions which would easily start about $100 in work right off the bat.
2. Or he said to use the once fired brass I have, neck size it, fire form it to the chamber with a regular load, and then keep neck sizing; keeping those cases unique to that gun only. He said that would work as long as the bore and chamber are concentric-give or take.
His thoughts were to do solution #2 as long as I was using as a plinker and not doing a lot of shooting with it, especially with full power loads.

I like #2 also. I guess I will keep my FL dies set and look for a neck sizer in addition. I may tinker with forming 30-06 down to 308 in the future.

[Larry Gibson]

Concur with #2.

Larry Gibson

BTW; heater works great, thanks.