Fix for a short chamber

lmorrison17 · Jan 22, 2016

Here Is the deal.
I have a 700 with a Kostyshyn barrel in 308.
A few years I had another barrel chambered 30x47 for it and a kiff bolt installed.
I ended up selling the old bolt.
Now I've sold the 30x47 barrel and when I reinstalled the old barrel it's coming up .013" short on headspace with the new barrel.

I can push the shoulders back to get the brass to chamber but this swells up the bases and often the bolt gets tight at the top of the rotation and makes extraction difficult.

This also leaves out factory ammo without having to re-size that through a die with the bushing removed. PIA

One smith said he didn't recommend just running a reamer in deeper.
He says the chamber should be cutoff and the barrel re-chambered and refitted.

But it's only a 20" tube and I don't want to loose the length.

It was suggest to me also to try another factory bolt.

I also in my research discovered a pull through cambering reamer but it's expensive to just fix one chamber.

Are there any other options?

Thanks

E.Shell · Jan 22, 2016

The reason your gunsmith suggested cutting it off is because firing the rifle 'work hardens' the chamber walls/shoulder and a reamer may not cut it, and/or the reamer will be damaged trying. Cutting back the barrel and pre-boring the new chamber allows the reamer to cut barrel steel of normal hardness. Your pull-through reamer will likely not cut it as is.

0.013" is a LOT and I doubt normal bolt variation is going to give you this much, but maybe it will.

smdub · Jan 22, 2016

Why wouldn't you just run a reamer in deeper? Many barrels are sold on the short side so you do exactly that to get the barrel to match your bolt. You only need to chop off a thread and set the barrel back if the chamber is too long. A reamer doesn't fix that

Edit: I was typing when Ed was typing his. His explanation, as always, is a good one. He knows a **LOT** more about this than I do.

Ed, the depth of the hardening depends on the barrel material. Do you know how deep it goes typically for 41xx or stainless?

E.Shell · Jan 22, 2016

smdub said:
Why wouldn't you just run a reamer in deeper? Many barrels are sold on the short side so you do exactly that to get the barrel to match your bolt. Maybe your smith just wanted to make more money? You only need to chop off a thread and set the barrel back if the chamber is too long. A reamer doesn't fix that

His gunsmith is not being dishonest.

A new barrel has not been work hardened by firing. Barrels like ER Shaw and other short-chambered barrels come with a short chamber that will be cut to correct headspace BEFORE firing.

ETA to your ETA: The depth of hardening is not more than a few thousands, but the steel can be hard as glass.

smdub · Jan 22, 2016

E.Shell said:
ETA to your ETA: The depth of hardening is not more than a few thousands, but the steel can be hard as glass.

You really have my curiosity peaked

IME You just can't harden stainless or 41xx all that hard from just a work function. Wonder if carbon from fouling is also dissolving into the steel and surface hardening it. I learn something everytime you post.
Though I used a surplus barrel to fix my Hakim and reamed the chamber to correct the headspacing (there is a thread here on my saga w that gun and it's original bulged bbl.) It cut as easily as a new barrel. It definitely had been shot a bunch before.

E.Shell · Jan 22, 2016

smdub said:
You really have my curiosity peaked IME You just can't harden stainless or 41xx all that hard from just a work function. Wonder if carbon from fouling is also dissolving into the steel and surface hardening it. I learn something everytime you post.
Though I used a surplus barrel to fix my Hakim and reamed the chamber to correct the headspacing (there is a thread here on my saga w that gun and it's original bulged bbl.) It cut as easily as a new barrel. It definitely had been shot a bunch before.

I cannot speak to the metallurgical process that contributes to increasing surface hardness in steel that doesn't typically harden, but can tell you the following:

1) Even cartridge brass will work harden. Why else anneal?

2) I personally knocked the edge off a brand new PTG .22-250 reamer trying to take a M-70 chamber in another 0.005" in a well used chrome-moly barrel. I didn't even get one dust-size shaving of steel out - even with increased feed pressure, it simply would not cut and just rolled off the reamer's cutting edge. Returned the reamer to PTG for sharpening and was told to expect this from used barrels.

3) Jeff Walker, a friend and owner of Walker Custom Rifles, and I discussed this in depth and Jeff routinely refuses to attempt this operation due to predictable reamer damage, and if compelled, will want you to provide your own reamer and accept any damage that occurs.

4) I have had to re-cut the incomplete throat on several brand new Savage .308 rifles that would not freely chamber a FGMM 175 factory load and even though they may have had a few rounds through them, this area is still easily cut. The notable thing here is that the throat probably has the highest exposure to alloying with carbon, yet does not take on additional hardness to a noticeable extent, so introducing carbon as a byproduct of combustion seems an unlikely cause.

Hit and Run · Jan 22, 2016

Concur with post on reaming a used barrel. If you still wanted to attempt (I wouldn't)
http://www.4-dproducts.com
is a company that rents reamers.

smdub · Jan 22, 2016

Ed,
Oh med carbon steel and stainless *DEFINITELY* work harden. Didn't mean to imply they didn't. Anyone who has ever run a lathe or mill has figured that out the hard way

Just I don't think it can get "glass hard" (but that might just be our differing definitions). There is just an upper limit. 4140 for example will only go to mid 50s HRC even dumped into a bucket of water from a glowing hot state. Thats pretty darn hard but I would think a M2 HSS reamer would still go through it. Maybe some reamers are made w/ softer stuff? I don't know. I mostly buy Manson but the one I used for the Hakim was a PTG. Metallurgy is a cool science. Next time I bump into some folks I know that understand these things WAY more than me I'll ask what might be going on.

E.Shell · Jan 22, 2016

By "glass hard", I mean it is harder than a very good quality reamer's cutting edge, which itself is harder than Chinese arithmetic.

I have cut chambers that cut smoothly and easily, and I have cut chambers that seem vary in hardness as you go, but the M-70 chamber I mentioned above would not even scratch. When Jeff and I discussed this a few years back, he said he would not put one of his own reamers into a fired chamber. Says it is almost certain to ruin the reamer and if a customer insists on jamming a reamer in there, he can bring one with him.

lmorrison17 · Jan 22, 2016

Well at least now I know why. I didn't see where 4D had the pull through, but after that i did another search and found a place that does rent the pull through.
FOr an extra fee I can have it insured against damage.

This is 416R barrel with 1105 rounds on it.

I might try borrowing a factory bolt if that works I may be looking for a used bolt.
But then there is no guarantee that if I find a used one that it will work.

Maybe sell this barrel to someone with a factory bolt who is maybe willing to have it shortened and re-chambered and put that money towards a new tube.

I hate to loose it as it is extremely accurate but a rather slow twist of 14.

I'll haveto think on it some more.
Thanks for help everyone, I learned something today.

clandestine · Jan 22, 2016

You should listen to Ed. I too have seen the work hardening destroy brand new reamers.

1K rounds through that tube has certainly hardened it to the point that its not prudent to ream.

Your smart choices are to cut the chamber off if there is sufficient material to do so and deal with the short barrel or buy a new barrel.

Jerry M · Jan 23, 2016

How about getting a wide recoil lug and have it machined to the proper thickness that will give you the proper headspace?

http://www.brownells.com/rifle-part...ngton-700-oversized-recoil-lug-prod26369.aspx

Good luck

Jerry

E.Shell · Jan 23, 2016

Jerry M said:
How about getting a wide recoil lug and have it machined to the proper thickness that will give you the proper headspace?

http://www.brownells.com/rifle-part...ngton-700-oversized-recoil-lug-prod26369.aspx

Good luck

Jerry

Great suggestion! :party29:

clandestine · Jan 23, 2016

Jerry for the win.

Fix for a short chamber

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