chamber snafu question for smiths

[slophish]

My custom rifle I've waited for 6 months to get is 95% complete, all thats left is duracoat. My smith informs me this morning after test fire the chamber has a crown in it. The rifle is a 7 rum with a 30 inch 1in7 twist lilja. If I rechamber in 7 rum he'll have to cut off an inch, /ubbthreads/images/graemlins/confused.gif that bugs me, I put the thirty on there to burn all that powder. Should i just shoot it? Should I wildcat it? Should I rechamber and knock an inch off it? Can it be repaired and left as is? Thanks.

 

[MagMan]

I guess it depends on how nice you're feeling and when you want your rifle back. The smith is the one who screwed up while boring/reaming your chamber so he should stand behind his work and buy you a new barrel (which may take a while) or make it up some other way and get it back quicker.

With a 29" barrel & break it will still fit in a standard rifle case. /ubbthreads/images/graemlins/grin.gif

I'd probably let it go at 29".

I'm sure someone around here has a 30" they'll sell you at a reasonable price.

 

[Coyboy]

Do you trust that smith enough to do it right the second time he tries? Did you ask him what went wrong that he put a "crown" in the chamber.

If you trust him give him the option of ordering a new barrel and giving you what you asked for. Or take it at 29" and have him shave off the bill.

If you don't trust him, then you the fool for taking it to him in the first place. /ubbthreads/images/graemlins/wink.gif Pick it all up and take it to someone reliable with a good reputation. Make him eat his fudged up labor. After all you don't want to end up with a 27" tube after he tries a few more times.

If he was truley respectful of what you asked for he would make it right.

 

[James Jones]

I've chambered a few guns but I've never heard of having a crown in the chamber. I'm guessing that he has put some sort of oversized area in their which is a terrible problem and will cause you greef till its fixed.
It it were my gun I would at least have him refund some money to have sombody that knows what they are doing recut the chamber.

the differance between 29 and 30 inches is gonna be nill so having an inch lopped off shoulden't be to big of a deal but I would definatly have sombody else rechamber it.
One of the causes for gouging up a chamber if guys runnig the reamer in to fast trying to take to much material out at once or trying to use the finish reamer to do the whole job instead of boring out the chamber area first then making the final cut with the finish reamer , also if its a SS barrel some tend to cut kinda "gummy" and need plenty of fluid when the chamber is cut.

But I'f I had boogered up your barrel I would cut it back 1" and rechamber it so you could have somthing to play with while the replacement 30" was on its way. You bought a 30" barrel cause thats what you wanted and I'm sure you paid extra for it so thats what you should end up with.
I would definatly ask how he managed to get it "crowned"

 

[Black Diamond 408]

Sounds like somthing went terribly wrong! /ubbthreads/images/graemlins/shocked.gif I can't emagine what he did to do that to a chamber, The reamers have pilots to keep things straight, wonder if the pilot was too small, or like what was previously mentioned, he may have run the reamer too far with out cleaning and gauled the chamber, then had to polish out the marks and ended up with a larger dia at the shoulder area. Sounds not good. /ubbthreads/images/graemlins/mad.gif 29" bbl would not change much over the 30" tube, but that is not the point. If i made the mistake, i would offer to fix the problem or buy a new bbl...customers choice. Out of hundreds of barrels i have installed the only problem i have encountered was bores that were so out of center it was hard to chamber them, (cheapo's) 30" bbl i dont think it was a cheapo. So i would look else where for the problem. Sounds like a smith error, but it can happen to anyone. You could possibly have the chamber improved, but that still might not cure the whole problem. I would give him a chance to rectify the problem. But dont settle for a bad chamber job.

 

[slophish]

Thanks for the replies. He is a good smith and a perfectionist. I think this one caught him by suprise. Spoke to him a little bit ago and he wants to replace the barrel, he thinks the reamer may have a flaw. He has chambered enough to know, so I won't question him. I think after reading the replies here I'll have him lob an inch off and rechamber. I don't want to become one of those guys who has no room for errors in life, it's just too **** short for that. Anyhow good smiths who are willing to try any hairbrained idea you come up with are hard to find /ubbthreads/images/graemlins/wink.gif. So I may have to let this one go, I'll let you guys know what I find out tomorrow.

 

[Fiftydriver]

Slopish,

I assume by crown, you mean that there is a ring in the chamber and when you fire a round the fired case has a raised ring around the case somewhere.

This is generally caused by not using enough lube and taking to deep of a cut per pass as you chamber the barrel.

If he takes an inch off the barrel but used the same reamer as is and he feels the reamer is the cause of the problem you will get the same problem. I would say he simply "rolled a chip" as he was chambering and could not polish out the ring.

When chambering a barrel for a round like the RUMS, I like to take no more then 26 thou in depth of cut at each pass with the reamer. If you figure how long the chamber is on a RUM case you realize this is ALOT of passes with the reamer but it also insures that your fluted do not get compressed with chips and if you use enough lube pretty much insures you will not ring a chamber.

As a fellow smith, the correct thing to do would be to give your smith the chance to correct the problem. At least he was honest with you about the chamber so that shows his good qualities right from the start.

He may have just gotten in a hurry and I am sure will not on the second time around. He already lost all his profit having to refit the shank, rethread and recut the chamber so he obviously is more worried about good service then anything else.

Give him a chance to correct it and then if the second time around is no different I would take it elsewhere.

Good luck,

Kirby Allen(50)

 

[James Jones]

Hey Kirby and BlackDiamond and quick question for you guys.
When you chamber a barrel do you use a roughing reamer then the finish reamer or do you use an under sized drill to make the first cut?
the few barrels I chambered I used an undersized drill to rough the chamber area out then a small boring bar to get withing a few thousands and finaly the finish reamer , its a lengthy process but I've had realy good results thus far but I was wondering if theirs an easier way?
also what lathes do you guys use?
Slopish , sorry if I jacked you post

 

[Fiftydriver]

JDJones,

I use a carbide drill bit 40 thou smaller then the diameter of the shoulder of the finish reamer. I start by reaming the barrel blank until the reamer shoulder is cutting full diameter, then take a drill cut 0.300" deep. Then go back to the reamer.

I repeat this until the chamber is cut to proper depth. Drilling only 0.300" at a time allows the live pilot on the reamer to remain fully in contact with the bore as you ream yet still only have to ream around 20 thou larger in diameter then the predrilled hole.

There are many ways to skin the same cat. As long as the pilot always has full contact I would not say one way is better then any other.

I have a big Jet GH-1440ZX lathe. This is not their bench model but their 5200 lb model!!

Kirby Allen(50)

 

[slophish]

Fifty, it was the reamer as I had a chance to look at it today. It was a 4-d rental. The trailing edge on the reamer was ground incorrectly. This seems to be one of those things that teaches experience after the fact. Cutting speed was @ 105 rpms, plenty of cutting fluid. He took many passes and went slow. Now looking back he said he would see the flaw in the reamer and it is just one more thing to check before cutting commences. Here are some pictures I took for reference. Hopefully the resolution allows you guys to see the details. They immediatley shipped another reamer, it's the one on the right, the flawed one is on the left.Thanks for looking. [image]

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The irony in this situation is the second reamer they sent won't fit in the bore. /ubbthreads/images/graemlins/crazy.gif

 

[Fiftydriver]

Slopish,

Thats good that the reamer had issues, another example of the crap shoot you take rented reamers.

It almost looks like someone had that reamer made with a built in chamber chamfer at the base of the reamer but it seems to be a bit to far forward and that would not work with all rifle types anyway.

Good he found the problem.

I am a bit sorry to see that the original reamer is a Live piloted reamer and the replacement is a solid piloted reamer. Generally the solid pilot reamers will not allow you to cut a chamber as perfectly aligned as you want as you can not fit the bushing perfectly to the bore diameter so there is some clearance between the nose of the solid pilot and bore.

Basically it looks like that original reamer has been whittled back far to many times and is in need or being retired. That **** throat section has got to be 2" long. That does nothing for stiffness of the reamer and at times can cause some harmonics to be generated in the reamer when cutting.

Hope it works out well for you.

Kirby Allen(50)

 

[Black Diamond 408]

JD,

I cut my chambers about the same way Kirby does. I have tried all methods from roughers to finish reamers to the undersized drill method, which is the fastest by far. Currently I use an Enco lathe i bought new in 77, before that i used a South Bend 10", it worked very good, but took more setup time.

Dave

 

[Black Diamond 408]

Slophish,

I guess we all didn't get what you were talking about with the Crown in the chamber. I can see from the pics that reamer is no good. I dont like to rent reamers, you never know what your going to get. Allways get an removable pilot with several extra pilots so you can get it to fit right.

Dave

 

[308 nate]

Slophish,
Sorry to hear about your frustrations.
I also agree with the guys that don't like to rent reamers. I personally will not rent a reamer other than from a buddy and I will also only use piloted reamers.You will probably be O.K with your gunsmith using the solid reamer as you will be following the chamber that was cut with the piloted reamer, that is if the correct pilot was used. If a customer whants me to chamber a rifle in a chamber that I really don't want to tie my money up into I will buy a new one and when a job is finished I resell it. Resale on a once used reamer is very good and I usually end up having no more into it than I would have renting it.

As far as how I chamber it is very similar to Kirby and Dave.I have built collets that slip over the barrel with a radius on the outside and then I chamber through the headstock chucking on the collet. The radiused collet eliminates stress on the barrel caused by the chuck and then I dial in the bore to within .0001 on both ends of the headstock, I then face and thread the end of the barrel Then like Kirby I start out with the finish reamer with the correct pilot until the case body portion of the reamer is approx. .100 recessed in and then I also go in with a bit. Depth depends on pilot to shoulder distance in that .300 -.400. I se a bald eagle floating reamer holder and depth of reamer plunge between cleanig varies depending onthe reamer...anywhere from .015-.040. I also encourage if you can find a gunsmith you can trust locally to stick with him as we all can make mistakes and as a gunsmith myself I will back up my work 100%
well, hope your project goes well. The 7MMRUM is an awesome caliber, in fact I have a 7MMRUM match throated for the heavy 7 mils, and it makes a heck of a nice long range hunting round.
FWIW,
308nate