barrel Setback advice needed

S

skinnj1

Guest
I am fairly new to chambering barrels, have done a couple but they started out as blanks. Past setup was not as hightech but got acceptable results... through the steady rest with muzzle held in buck tru-chuck (after cutting new center at muzzle end with kiff pilioted 60 degree reamer and turning muzzle end down)

I now have a nice barrel I would like to re-use. Originally it was a Dakota 76 longbow in .338L that I would like to remachine to fit a 700 action. I already have a .338L 700 bolt fro Dave Kiff.

The barrel is a heavy enough contour (enough "meat" in the shank) that I could cut off the old threads and start fresh but I would like to retain as much of the original length as possible so...

Could I face off enough threads to get past the Dakota extractor cut, counterbore barrel for 700 bolt, and turn shank down appropriate diameter/length to be able to pick up the remaining seven threads and cut the additional threads I need, then reaream to appropriate depth?

My plan was to make a two peice bushing for the headstock as described by Mr. Schmidt and indicate the chamber with one of kiff's rods. Anybody have a better Idea?

Thanks
 
Forget the seven threads

skinnj1 said:
Could I face off enough threads to get past the Dakota extractor cut, counterbore barrel for 700 bolt, and turn shank down appropriate diameter/length to be able to pick up the remaining seven threads and cut the additional threads I need, then reaream to appropriate depth?

Anybody have a better Idea?

Thanks
Click to expand...
,,,,,,,,,,,,,,,,,,,,,,,

And start with a fresh tennon.

Or do your really want to go to all this trouble just for the sake of "seven threads"?

Shoot better
Peter
 
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Though it isn't a question you asked, several gunsmiths would not recommend chambering a Remington 700 for the .338 Lapua case.

Read Dan Lilja's article of the Geske action, http://www.riflebarrels.com/articles/custom_actions/geske_action.htm

where he says:

Gerry has done this, and as we will see from the strength and bolt lug flex numbers, he has achieved his goal. If we use the 378 Weatherby cartridge as an example in calculating bolt lug shear strength, bolt thrust and bolt flex numbers, we can see just how strong the Geske action is. Using a simulated chamber pressure of 65,000 PSI, we find that the amount of bolt thrust generated by the big case is about 12,760 pounds. To resist this, the bolt lug shear strength is 72,620 pounds and the amount of bolt flex is .0015". To get an idea of how strong these lugs are, a Remington 700 bolt would offer just slightly more than half the shear strength of the Geske, at 37,480 pounds. Though I wouldn't recommend it, if we put a .378 Weatherby barrel on a Remington, the amount of bolt flex would be .0026".
Click to expand...
Emphasis added.

Other smiths have reported lug setback with the .338 Lapua in a 700, and by extension from some of Jim Borden's testing with the .404 case in a Winchester 1" tenon, there could be some problems with case extraction too. Yes, the Remington has a slightly larger tenon, but the .404 case has less diameter than the .416/.338 LM/.378 Weatherby as well.

And yes, I do know that some have chambered a .338 Lapua in a 700 anyway. Your choice.
 
Model 700

Remington sells the Model 700 chambered in 338LM.
 
Charles,
Thank you for your reply; I think it is appropriate (especially to someone with his first post). Actually I have read Dan's articles and think http://www.riflebarrels.com/articles/custom_actions/378_weatherby_remington_700_action.htm is even more germane. I'll readily agree that a larger Stiller/Surgeon/Peirce/Lawton would be "better" but do not see one in the cards anytime soon (I just had my first child so I'll be thinking about making chips much more often than making them...)
As you note several smiths have made them and now Remington has come out with factory rifles in this caliber so they are fairly comfortable with the platform and the 3:1 safety factor in today’s litigious age.
However it wasn’t until after talking with a well known "tactical rifle" builder who has built many 338L 700’s that I decided that I could live with the compromises presented with the LA700/Kiff bolt/M16 extractor combo.
When done this will not be a rifle that I have aspirations of taking it to Williamsport, only “competing” with a few close friends at LR-ELR distances (1000-2300 yds) at bowling pins and steel gongs…
SO does anyone have any suggestions on setup for someone with extremely limited experience (no hands on but have read as much as I could) with the through headstock method for a barrel that has a chamber much bigger than his indicator stylus?

Thanks,
 
700 .338Lapua

For or against, It'll always be a bad compromise. As I've said it before.

It's like fitting a family of five into a two seater sports car. They all may be crammed in and be taken from A to B.

Shoot better
Peter
 
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I understand that if you had any extra money, you would get an "appropriate" action. And that you aren't intenting to compete at Williamsport. And that Remingtion is now apparently offering the .338 LM in the 700.

I would still suggest that a .338 on a full length 404 case is a much better proposition in a 700 action. That would be the cost of a new barrel, about 25% the cost of a new action. And I suppose a reamer. If, as it looks, you do your own work, you could make dies, otherwise that too would be a cost.

But for anyone else -- this is, after all, a public forum, please consider a .338 on the .404 case, esp with an action having a 1.062 tenon. I know a number of people who have had success with this -- in fact, I know more people successful with the .338/404 than with the .338LM, but that may speak only to who I know.

Good luck in any case.

As for indicating in the barrel, as I understand what you're going to do, you are not "chambering" a barrel, but deepening an existing chamber by the small amount you plan to cut off the tenon. So, you indicate off the sidewalls of the already existing chamber, and that doesn't take a long stylus.

And as has been said so many times, the reamer will follow the existing hole. I don't know anyone who has tested to see just how far out a barrel can be & then deepen an existing chamber without *signigficant* problems, but I'd bet you could have it out a fair bit. Maybe someone knows?
 
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Barrel set back

Is the reason competitive shooters set back their barrels frequently to keep a fresh throat? I'm assuming a barrel set back requires running the chambering reamer the same amount the barrel was set back. Is this correct?
Chino69
 
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Charles E said:
And as has been said so many times, the reamer will follow the existing hole. I don't know anyone who has tested to see just how far out a barrel can be & then deepen an existing chamber without *signigficant* problems, but I'd bet you could have it out a fair bit. Maybe someone knows?
Click to expand...

I remember reading somewhere that a person tried to see how far out you could be with a floating reamer holder and still get accurate diameter dimensions (assuming that means round and true also). The story went that it was tried with a barrel that ran out .020. I'm not sure if they meant .010 and .020tir, but either way, that's a mile and a person could easily see that with the naked eye and get closer with no instruments (with some effort).

I suppose I could buy that .020 is possible. I doubt there's much more to get in a floating holder.

Personally, I would not worry about the muzzle end inside the headstock. Make a spindle bore bushing that's true, stuff the barrel in and indicate the other end. jmho.
 
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