I am trying to get a .338 Lapua mag rechambered to a similar chambering with less body taper and a 38 degree shoulder. The result is similar to the .338 Xpress.

The smith has pointed out that with this kind of rechamber, due to the reduced taper, the shoulder on the reamer is going to be the first thing that will contact the existing chamber, somewhere between halfway and one third the way along, and that this will cause a vibration, and will probably cause an imperfect chamber.

What can be done to mitigate this kind of issue, is it a common thing to encounter with rechamber jobs?

Chattering of the reamer may or may not occur. Filling the flutes of the reamer with a heavy grease or with modelling clay (plasticene) will reduce any tendency for the reamer to chatter. Regards, Bill.

Will the pilot engage the bore before the shoulder starts cutting? If so, don't worry. Don't worry anyway. I have done similar things with no issues.
I do question why even make this alteration at all. But it's yours.

No, the cutter will start cutting before he pilot engages the bore, so it starts unsupported.

Like Leeper says, fill the flutes and chamber with modeling clay. Run the reamer in slowly until the pilot picks up and you're generally OK. It's just a bit messy. The old guys used to put a few cleaning patches on the reamer. It does work, but the odd time the reamer will go in a bit crooked. VanOwen used raw, brown, bees wax which worked pretty good. Bees wax also works as a lubricant and cleans up easier than modeling clay. You just work it with your hands for 5 or 10 minutes and it gets soft and mushy like the modeling clay.

I've found that shotgun cleaning patches work amazingly well at stopping chatter.

Wrap the reamer with waxed paper from the grocery store. Easier to clean up and you won't believe the results.

quote:

Originally posted by Jim Kobe:
Wrap the reamer with waxed paper from the grocery store. Easier to clean up and you won't believe the results.

I've tried this but it didn't work for me at all. That's when I tried the shotgun patches. I suppose different circumstances demand different solutions.

quote:

Originally posted by Jim Kobe:
Wrap the reamer with waxed paper from the grocery store. Easier to clean up and you won't believe the results.

I've heard of this solution a couple of times Jim. Paul Lafeve used to swear by it and claimed the reamer cut through the paper easier than the cloth. Also, the wax is one hell of a high pressure lube and I actually use paraffin threading compound when I thread those gummy Tikka barrels for brakes. I have meant to try it but I haven't had a reamer chatter since I started holding them in ERs. It is on my to-try list though.

I've used cloth, waxed paper, paper towel, plasticene, and heavy grease, and have been happiest with the grease as a preventative and the cloth to correct a badly chattered chamber. I had one brought in which looked like one of those H-K fluted chambers (the college in Calgary used to have a gunsmithing/machining class for hobbyists and some projects required remedial work. I have to add, some of those "hobby" projects were exceptionally well done).
I have only experienced serious chattering with Clymer reamers. I had one 7x57 reamer which was a chattering SOB. An old machinist told me to grind away one cutting edge on the body and try that. I had already replaced the reamer so I thought I would give it a try. It worked! I cut a couple chambers with that reamer with no chatter at all. Kind of an extreme measure though so I really can't recommend it. Regards, Bill.

I had some old Hartford, hendricksen and Guild reamers that would have given you grey hair Billy. Glad I sold them all with my wildcat reamers. Most of those were from our childhood before they started grinding double relief and staggered flutes on them.

Enlightening to hear that I'm not the only one that experienced "Clymer Chatter".

Beware of some of the old Clymers that used a universal leed angle..i.e. their own, nothing to do with SAAMI or CIP

The ones that drive me buggy are the reamers that like to dive. I've had 3 or 4 of them over the years and until they get the black, felt pen mark of depth they can sure piss you off. I don't piddle around with dial indicators and such for chambering (which would solve this problem if I used them). I lock up the apron and use it as a stop for the tailstock so that it always returns to zero. Then I just use the marks on the tailstock barrel and hand wheel for depth. Every once in a while I will get a reamer that won't stop cutting and if there is any slop in the tailstock barrel the fool thing will add an extra .005 to .015 inch after I have begun to slow down my advance and stop the hand wheel. It's not a problem once I've black-balled the reamer because I just snug up the barrel a bit and it stops this aggravating tendency. But it sure does piss me off when I use a new reamer or customers reamer and I get caught.