This January I started building my first custom rifle in 338 RUM.
MRC stainless action
Lothar Walther barrel
D'Arcy Echols McMillan stock
Six months later I am so sick of the process I have told the gunsmith to stop.
The biggest problem was the chambering. The first reamer from Pacific Tool and Grinding gave up the ghost with about 5mm left.The gunsmith blames the quality of the reamer and the hardness of the barrel. PTG sent me a replacement reamer but said that there are problems with having a fixed pilot reamer , which makes me wonder why they manufacture them and sell them if there are problems using them. If Lothar Walther barrels are so hard why don't they reccommend tungsten carbide reamers for their barrels. I now have a useless 338 RUM reamer and a partially chambered ( expensive ) barrel. To top it off the threads on the MRC action are apparently poorly done and when threading the barrel he had to cut the threads with a thicker cross section to compensate.
All in all an unhappy experience and I am not sure I will be doing it again for a while.
Mark

Maybe it's your gunsmith.Not bagging him,just throwing it out there.

MARK
what are you going to do with all those MRC actions...can leave them to waste
Daniel

I have heard about the different steel that Lothar-Walther uses and people have told me to contact Woody by phone or e-mail and ask for information on the specific procedures for chambering and threading their blanks.

At least you're ahead of me, I have an MRC action that I payed for back in Feb of 2002 at the gunsmith getting blueprinted. And the barrel and stock that I ordered back in April still haven't come in yet.

quote:

The biggest problem was the chambering. The first reamer from Pacific Tool and Grinding gave up the ghost with about 5mm left.The gunsmith blames the quality of the reamer and the hardness of the barrel.

Sounds like a gunsmith issue to me.
There isn't a barrel on this earth that is as hard as a high speed steel reamer. If there was, it would blow to pieces when it was fired because it would be so brittle.
Sure the material might be a bit tougher than average but it's still going to be softer than the cutter/reamer. High speed steel is like glass, exrtemely hard but brittle.

I'm a machinist by trade and I can tell you categorically either:

1. he was doing too many rpm's
2. he wasn't clearing the chips out often enough
3. not enough coolant/lubrication
4. he didn't rough out the chamber enough beforehand
5. excessive feed rate.
6. excessive runout
7. combinations of the above.

Hard barrel steel...bah....humbug!

quote:

To top it off the threads on the MRC action are apparently poorly done and when threading the barrel he had to cut the threads with a thicker cross section to compensate.

Chances are the the internal thread in the MRC action have been cut with a commercially available tap or at the very least cut with a single point tool in a CNC lathe or mill.
This critical feature in all likelyhood would have been checked with a go/nogo gauge prior to the action leaving the factory and it's very unlikely that it would be poorly done like this guy is saying.
A thicker cross section...what! Not cut as deep does he mean?
If this guy can't cut an external thread to match a tapped hole find yourself another gunsmith quick! That really is first year apprentice stuff.

Sounds like this guy is spinning you a load of BS to cover his lack of abiltiy/expertise and unfortunately it has already cost you time and money.

Chances are that the barrel is not be able to be salvaged if the external thread is rooted.
Also, the reamer has probably damaged the chamber irretrievably by either busting off in there (you didn't say exactly what went wrong) or it has work hardened the internal surface of the chamber so much that putting another new reamer in there will likely end up in the same state.
There's probably chunks of reamer still embedded in the chamber maybe too, no way I'd be putting a new $150 tool in there to find out.....

Just my 2c

What is an MRC action?

Mike the MRC stands for Montana Rifleman Company. Don't know what I'll do with the actions Daniel.
Avatar to fill in some of the gaps.
The gunsmith runs the reamer at 34 rpm.
The problem with the reamer was that with about 5mm to go it stopped cutting. The gunsmith felt the shoulder part of the reamer did all the cutting. We did not use a roughing reamer just the finisher.
I believe the threads on the barrel have been cut for the action but from what he said the action thread was not a typical thread.
So I am in the dark as I don't have the expertise to say where the problem lies.
Mark

quote:

with about 5mm to go it stopped cutting. The gunsmith felt the shoulder part of the reamer did all the cutting. We did not use a roughing reamer just the finisher.
I believe the threads on the barrel have been cut for the action but from what he said the action thread was not a typical thread.

Of course the shoulder did all the cutting, it's the first part that goes into the hole....if it cut too much on the flanks I'd be worried about the thing binding in there with massive chatter....
A finishing reamer should be used to take out the last thou or two, 0.025-0.05mm i.e. bugger all to get to the reqd. size. it merely 'wipes' the chamber to size and should give an excellent finish.
Even a roughing reamer sould only be taking out 0.25-0.5mm as a maximum.
Reamers are not stock removal tools they are finishing tools.
The reamer stopped cutting because either the cutting edges were damaged or the clearances for the cutting edges were lost.
34 rpm sounds about right so I'm guessing he's not running the right lube, not clearing the swarf, trying to take out too much material, excessive feed rate or simply letting the tool rub in the chamber and dulling the cutting edges.
With only 5mm to go he should be able to stone the inside of the cutting edges of the reamer to make it cut again unless the reamer is totally stuffed or burnt(lost its hardness) which after only 1 chamber I would find hard to believe.
A reamer properly used should cut dozens of chambers with no problems.

Thanks for your remarks Avatar. This is where it is difficult for a mug like me as I don't have the expertise to decide who or what is the problem.The advice I got was to only buy a finisher and basically did what I was told.
The real pain is that not only am I going to miss out on the 338RUM but I was already planning a 375 RUM with cerakote on all the metal work.Now I am very reluctant to build it and may be stuck with buyig factory rifles which cop a bagging on this forum.
Mark

Mark ,
Really not fair to tar all gunsmiths with the same brush because of one bad experience . Suggest you do a bit of research and try again .
John Giles at PSECO has a great reputation for metalwork . Builds a lot of top Aussie benchrest rigs .Good to talk to as well . Email pseco@optusnet.com.au

Yep Giles has a great rep up here.He is a fussy PITA but will do a great job.