Headspace concern

[jgrass]

 I have a M 70 fwt. 308 and observed that the brass leaves a slight cylindrical mark around the base about 1/8" from the ejector cut. I checked the head space with a no-go clymer gage and the bolt closed.
I checked with a clymer field gage and the bolt only went half way.
My question(s)/ concern(s) are:
     should there be any safety concerns?

     does this situation make the rifle less accurate(deer hunting rifle), it currently shoots 2-3" groups
     should I neck re-size only when hand loading and is this brass OK to reload

     should I have the rifle repaired and is this a big job. What can I expect to pay and can you recommend a  qualified gunsmith for the if required.
 
      This is a special rifle to me and I don't want to ruin it. I still want it to appear original with the markings the in the proper positions.

Thank you,

JGrass

[gunnut69]

As a general rule if the rifle won't close on a field guage it is likely OK to shoot. Though most smiths will not pass on a rifle that closes on a NO GO as it does have an out of spec headspace measurement and this increases the liability for the smith. I would likely not be too troubled by the headspace but would partial size the cases used in this rifle. Just run them into the standard full length die until the shoulder is kissed but not set back. This can be checked using a smoked neck or a majic marker to define the amount of neck sized.  Groups of that size are not great today but are perfectly adequate for most hunting. If the headspace bothers you give Winchester customer service a call. They were always great then I had a bad experience with them. I bought a 'SUPER GRADE' and noticed that the super grade marking wasn't on the floorplate. Per their instructions I sent the plate back and after 6-8 weeks of no calls I called. They didn't have the plate, said it had not arrived.. The post office delivery confirmation said otherwise.. Spent the whole summer trying to work it out then a call to them one morning was answered by Browning Customer service.. They said they couldn't replace the palte but instead replaced the entire bottom metal!! To fix the headspace problem one pulls the barrel and lathes off the shoulder and face the thickness of a single thread. The chamber is then re-cut to the correct depth.. This guaging process is delicate and any force used will slightly damage the chamber or the guage and give false readings.. If the field uage won't allow the bolt to close I'd work on getting better accuracy and not worry too much about the chamber.. Some of the Featherweights were made by Winchester with a bedding material that looks much like hot glue! It will disintegrate after some time from the recoil.. My 6.5x55 shoots groups less than 1 1/4 inches and another in 308 owned by a close friend shoots quite well also..

[jgrass]

  Gunnut thank you for your great response. I will go with the less intrusive fix(s), besides it gives me more time to fiddle on this project, reloading, firing and playing with the darn thing. I will let you know how I make out. I really appreciate your valuable assistance.

Thank you,

JGrass

[gunnut69]

You are most certainly too kind.. Just an aside as I reread the question I noticed the reference to the bright ring around the case.. This is not really too exceptional. It's called the expansion ring and is one thing that can be used to monitor pressure. The expansion of this ring changes with pressure changes and measuring a factory round for a baseline can give an idea of the pressure a load is generating.. There are many pitfalls. Brass of differing makers can react differently as will brass that has been once fired... Still it is comething that is normal in most bolt action rifles..

[jgrass]

Gunnut, just a follow up to my headspace concern. All good. I went to the range yesterday and found the Win PowerMax 308-150's shoot well, 1-2 inches for three shots, the fourth starts to open. All good for the fwt barrel.
Hornaday and Remington don't do as well, 2-3 inches. Thanks for the help.

I have another issue I will post with a pic, my 270win pierces the primer on the Hornaday130 superperformance ammo! I felt the "tingle" on my face after firing. All three rounds I fired had the same thing happen. The firing pin protrusion looks the same as my other M70's. Not sure what to do next.

Thanks,

JGrass

[gunnut69]

There are several things that can cause primer piercing, ecess firing pin protrusion and of course hadspace issues. Also firing pin tip shape and looseness of the firing pin in it's hole in the bolt face. The Superformance ammo may be loaded to higher than normal pressures and for longer durations and may be part of the problem. What is the age of the rifle in  question and has it shown any problems before? Has the bolt be apart recently? Have you tried this rifle with other ammo? Are the primers on the pierced rounds flattened? Some of the possibilities can lead to serious danger..