Gentlemen

Finally after a few tough years the gunsmith has decided to finish my 600OK here in Australia

We were building it on a P14, but I've purchase a brand new CZ550 magnum to build it on

He rings me today and advised me that the bolt and chamber are very very slightly off center

Now it's not always a problem he tells me unless you have a case with a head the size of the 600OK, which takes up most of the bolt face, and without the little lip he thinks case extraction my be a problem

He tells me hes worried there wont be a safe amount of the bolt face left to hold the case in place

How much is NOT ENOUGH

He also advised that if he cant get it right, it might be simpler to turn 10 thou off all of the 600 OK case heads

Im at a loss here, not sure what to ask him to do, what are my options

Any advice will be welcome

What is "very, very slightly off center"?
Has he opened the bolt face to the 600 OK rim diameter yet?

The rim left around the bolt face normally measures about .025 to .030" thick. You can probably take it to .020" if you had to.

The bolt face does end up with a very thin rim around it, but it will be fine and strong enough for normal function of the rifle. You just need to be careful with it when the bolt is out of the action. Don't drop it or bang it against something.

I wouldn't start messing with your brass if you can help it.

Ok, you write that you started with a new action. I presume the barrel is new too? Did it come chambered or did your 'smith chamber it? He says he needs to open the boltface 10 thou, that means the system is about 5 thou off according to his measurements.

First, I would recommend determining what part of the equation is "off-center". If the receiver is at fault then send it back for a replacement. Likewise with the barrel. If the chamber was cut by the 'smith and it is off center then I believe it is his responsibility to replace the barrel. If the 'smith opened the boltface, is that job not centered? That would be his problem too. I don't believe I would accept a job that had that much misalignment, even if it could be accommodated by opening the boltface more.


Bob
www.rustblue.com

quote:

Originally posted by ShortandFat:
Gentlemen

Finally after a few tough years the gunsmith has decided to finish my 600OK here in Australia

We were building it on a P14, but I've purchase a brand new CZ550 magnum to build it on

He rings me today and advised me that the bolt and chamber are very very slightly off center

Now it's not always a problem he tells me unless you have a case with a head the size of the 600OK, which takes up most of the bolt face, and without the little lip he thinks case extraction my be a problem

He tells me hes worried there wont be a safe amount of the bolt face left to hold the case in place

How much is NOT ENOUGH

He also advised that if he cant get it right, it might be simpler to turn 10 thou off all of the 600 OK case heads

Im at a loss here, not sure what to ask him to do, what are my options

Any advice will be welcome

It was alreAdy threaded and screwed into a P14 action at approx 26 inches, the P14 bolt face and chamber were fine

I own the reamer

When I brought the CZ it was chambered in 458 Lott

The 600 barrel was shortened 4 inches to 22 inches and the chamber was recut

It was when he was head spacing the barrel that he tells me it was grabbing on one side

I'm told the chamber is centred, the bolt face is centred, so I can only assume the action thread is slight off centre maybe 10 thou, so when the bolt slides in its not a perfect match

He said he's seen once or twice before and it's in guns where the firing pin might strike slightly off centre

But he tells me on normal magnum or rigby bolt heads a bit of "slack" is acceptable, but he tells me there just isn't enough meat in the bolt to open it up any more

His other option was to take 10 thou off every case head, so I can only assume it's out about 10 thou out

Reg

Post a pic of the primer strike. Slightly off center is no problem; if it is the receiver that was made off center, and you got it used, nothing you can do. Ten thousandths is not much; true, we all want them perfectly centered, but it ain't a perfect world. Reduce the case heads is the best option for me. No more from the thin bolt face rim.

Some good news

The gunsmith opened the bolt face 6thou more and it's working

He said there is only 19-20 left on the lip of the bolt face, so I'm going to have to be careful

He tells me the receiver is slightly off center, and tells me quiet a few are that way

I suppose the only time you notice is in these extreme situations

Reg S&F

You'll be ok with that as long as you're careful handling the bolt while it is out of the action. There is no stress in that thin rim during function of the rifle; at least not enough that would damage it.
Let us know when you make it go bang.

I'm not a gunsmith and I didn't sleep at a motel recently but when an action is trued isn't it trued to the centerline of the action (the bolt bore)?

When the threads are single point cut the action is set true to the bore of the bolt. Right?

Then the threads on the barrel are cut true to the bore. Right?

The chamber is also cut true to the bore. Right?

So how can the action be out by 0.010" if the smiths work is properly done?

quote:

Then the threads on the barrel are cut true to the bore. Right?

Bet the bore is not true to the od of the barrel. Then cut the threads and the bore is off center.

Bet many "assume" the bore is in the center and simply chuck up the barrel and cut threads. I had a contoured barrel that came off center.

quote:

Originally posted by PaulS:
I'm not a gunsmith and I didn't sleep at a motel recently but when an action is trued isn't it trued to the centerline of the action (the bolt bore)?

When the threads are single point cut the action is set true to the bore of the bolt. Right?

Then the threads on the barrel are cut true to the bore. Right?

The chamber is also cut true to the bore. Right?

So how can the action be out by 0.010" if the smiths work is properly done?

P14 (pattern 1914),,,, the bolt action rifle, made under contract, for the British government during WW1. #1) made under war time pressure, didn't need to be perfect, just good enough. #2) Forged receiver, Not conductive to being "straight", as made in the day. It, most likely, fell within tolerances when made. #3) Single point those square threads? Why bother, the action is what it is, a 'surplus' military action. #4)They are massive compared to modern actions. Many have been built into classic hunting magunm rifles. Same goes for the P17, basicaly the same rifle , only chambered in .30-06 and for the U.S. government to 'ease' the shortage of 1903 Springfield rifles upon the entry of the U.S. into WW1.

He didn't use the P14; he is using a CZ550. I assume the smith did not re-cut the threads con centric with the bolt race, which most hunting rifle builds don't need.

quote:

Originally posted by dpcd:
He didn't use the P14; he is using a CZ550. I assume the smith did not re-cut the threads con centric with the bolt race, which most hunting rifle builds don't need.

I may be a bit of a perfectionist but when I had my one custom rifle built the gunsmith (Dan Cohen of Renton, WA.) trued the action just as he does for his match rifles. The camber was cut for hunting - giving me some room for the neck to expand but the gun (in 358Win.) shoots under half inch groups at 100 yards.

I don't think I would accept a professional job that was not trued and concentric - that is what you pay for.

PaulS,
You are a perfectionist, But how do you or your gunsmith know if the bolt and receiver bore are concentric to the barrel threads? How would your gunsmith correct for it?
Not jumping on you or anybody, but how would you or your smith correct it.

What action was your custom built on?
Off center threads can be re-cut after you center the receiver up with a mandrel and held in a fixture whilst turning it in the lathe. Not all smiths can do, or do, that. And that tooling is expensive and all customers don't want to pay for that work, nor is it usually needed on a hunter.

quote:

Originally posted by dpcd:
What action was your custom built on?
Off center threads can be re-cut after you center the receiver up with a mandrel and held in a fixture whilst turning it in the lathe. Not all smiths can do, or do, that. And that tooling is expensive and all customers don't want to pay for that work, nor is it usually needed on a hunter.

I have built customs on 4 Kelbly's receivers, a Farley, a Nesika, 2 Bats, a Stiller drop port and 3 Stiller Predators. I have worked on a few others. The above mentioned receivers were for me and my rifles.
You are correct. The receiver can be bored and then the threads single pointed from that operation.

Sorry, I meant PaulS; he said he had one custom built.
I see you use only the high end stuff; good. I have to use old Enfields and Mausers.

dpcd,
You know that I have a lot of mausers and a couple Enfields. Ain't no fleas on them. The aftermarket receivers were bought and built into rifles. I'd get a wild hair, sell one and build another. My Kelbly's were as good as I have had and no fleas on the rest.