Excess headspace - Win M70 30-06 pre-64

[freddiej]

If memory serves me correctly the featherweights never had sights on them (my two do not). so a barrel set back will not only correct the problem; it can also make a very tight chamber. go to your preferred gunsmith, hand him 3 pieces of fired, resized brass from your sizing die as gauges, then have him headspace the rifle to your sized brass. this will insure your featherweight will keep the brass around for a very long time. problem solved.

 

[RAGGED EDGE]

I wonder what cataclysmic event happened that caused the original bolt to be replaced.

 

[Greyfox]

You mentioned that the bolt serial# does not match the rifles serial#. You checked the chamber with a go gauge. Did you also check it with a no-go guage?

 

[Scott E Ames]

"I wonder what cataclysmic event happened that caused the original bolt to be replaced."

Probably something like when my mom hid all the bolts from dad's rifles from us as children. Hid them so well they were never found again. 2 of them were pristine Japanese Nambu rifles brought back from the Pacific post WW2. I lucked out and found his 1911 and the samurai sword 20 years later.

 

[Stammster]

You mentioned that the bolt serial# does not match the rifles serial#. You checked the chamber with a go gauge. Did you also check it with a no-go guage?

I responded to my original post a few times, but just to clarify in one summary post:

1.) My Forester Go gauge chambered
2.) My Forester No-go gauge chambered
3.). I don't have an actual field gauge, but I made a "poor boy" one from a laser bore sight in conjunction with my comparator/caliper using the actual gauges in 1 and 2 above, but set to the length of a field gauge. It chambered.
4.) I further lengthened the laser sight gauge I referenced in # 3 until it did not chamber. It indicate the headspace created by this barrel/bolt combination is 0.003" over SAAMI max, which was consistent with what I measured with fired brass.

Basically factory brass goes in at 2.040-2.041" and comes out at 2.055" comparator length as measured by the 0.375" datum on the case neck.

Who knows why the bolt was swapped out. Maybe someone who had 2 model 70s and got them swapped by accident. Maybe this gun was reassembled by a beginner gunsmith from a donor barrel, receiver, and/or bolt. Who knows.

I've also never seen a pre-64 M70 FWT gun without factory sights.

 

[ntsqd]

Clearly setting the barrel back one full turn would be the best option, but since it appears that financially it isn't in the cards I don't see a problem with using dedicated brass. The wall thickness tapers in the region of concern, so if it is thick enough to be safe in the normally exposed portion I'm doubting that it tapers so radically that it is unsafe just .003" further down the case body.

Obviously the OP should veer from the norm only if they are comfortable doing so, but this is a veering that I'd have no problem with myself.

 

[Greyfox]

As was suggested previously, given the there are no sights, remedy seems to be either re-head spacing the original barrel to spec or replacing it all together. IMO

 

[ntsqd]

Will still need one full turn to put the barrel engraving right, and that will show to an experienced collector.

 

[Greyfox]

Will still need one full turn to put the barrel engraving right, and that will show to an experienced collector.

I think the mid-matched bolt rules it out as a collectible.

 

[ntsqd]

Maybe, maybe not. I still would want the barrel stamping to be in the right place.

 

[Stammster]

As was suggested previously, given the there are no sights, remedy seems to be either re-head spacing the original barrel to spec or replacing it all together. IMO

Mine has sights.

Anyone care to post a picture of a pre-64 30-06 FWT without factory sights ever installed? I haven't ever seen one. My rear is blanked, but the dovetail is still there.

 

[epoletna]

Sounds like you have a Frankenrifle. Who knows why it ended up that way? Might be rebarreled as well as having mismatched receiver and bolt.

You might consult with pre64win.com to see if they have a solution. Maybe a new (old) barrel, or different bolt? Then you don't perpetuate a Frankenrifle.

 

[Paper boy]

I purchased a 1961 Winchester Model 70 pre-64 FWT in 30-06 last year off gun broker. The gun is in great shape. However after closer inspection, I came to find out the bolt serial number does not match the gun.

I shot some factory ammo through it, and depending on the brand, it grouped anywhere from 0.8" to 2.5" at 100 yds. Kind of in line with my expectations.

I was going to work up a hand load to see if I could do a little better. I measured my fired cases with a Hornady comparator and realized they were very long. In fact they read 2.055". For reference, my go gauge marked 2.0487" reads 2.0425" with the same 0.375" collet. By my math, that puts me at a chamber length of 2.061", which is over SAAMI max length by 0.0025"-0.003".

I had no soot blow by around any of the neck of the factory ammo I shot (qty approx 30). Each round was individually chambered rather than fed through the mag well, so I don't think the controlled feed had any influence. I measured a few of the unfired remaining shells from the various 20 rd packs, and they came in at 2.040-2.041" on my comparator.

Now the questions I have:
1.) Is it truly unsafe to keep shooting factory ammo in this gun? Personally I don't think so.
2.). If I reload, and only bump the shoulder back 0.002" from 2.055", this to me now brings the tolerance of "case to chamber" well within the acceptable limit of any commercial cartridge. I don't see anything wrong with this approach and will dedicate a string of brass to this gun only. It's a hunting gun, so round count will be <20 per year. Also I see this as no different then those who fire form brass for 30-06 variations like the 30-06 AI or 30 Gibbs, and blow the necks out. Am I wrong here?
Seems to me the previous owner may have inadvertently created a wildcat when they swapped out the bolt. Maybe this will work to my advantage for more powder capacity.

It just doesn't make financial sense for me to have a gunsmith set the barrel back at this time, in order to shorten the headspace. Also I am not very optimistic I could find a replacement bolt to correct the problem.

Another other suggestions?

Thanks.

Things were very different back in 61. The mod70 was absolutly not scarce, nobody new it would be gone in 65. Because of this parts swapping was very common like we do today. I have several rifles and have always have reloaded specific ammo for each one. I don't shoot factory ammo due to inconsistancies that I just don't like. I would of course advise anyone to do the same. My opion only.

 

[montana west]

if the chamber is too long you can try 280 remington brass just trim the neck about a 1/2 mm and if this works your will always know the correct brass for this rifle.. 270 brass is a mm longer too but the headspace is the same as the 30/06 so it will not work