Barrel work question

[fat tony]

I have a rifle that I would like to get sorted out. The barrel is over indexed from the factory, making the use of iron sights annoying due to the cant. I suspect they over indexed it to get he headspace within range. This is a common rifle, a Marlin 336 dating from the 1970s. I know it might be cheaper to cut my losses & pass it on, but this is a pre-remlin rifle that I otherwise like. I am thinking about having a professional set back the shoulder, re-index the barrel properly, recut the chamber, recut the extractor, & reinstall it. How much would it cost for a professional to do this job? Also, can anyone recommend a professional to do this? I am not sure if the Gravel Agency is up to the job. Thanks, Tony

 

[cosmic]

Why would you embark on all this work assuming that the headspace would be out of spec if the barrel were re-indexed?

 

[fat tony]

I am looking for recommendations on a competent gunsmith well versed in doing barrel work, thanks.

 

[bearhunter]

I am surprised there aren't any decent gunsmiths in your area. But, there are several on this site that can do such work if they have the proper reamer. Not many smiths have a 30-30 reamer reamer any more or even access to one.

If you can find a smith with one, likely about a hundred bucks to chuck it up, set back the shoulder and recut the extractor slot and ream the chamber for correct head space.

Without seeing the rifle, are you sure it is the original barrel? Also, are you sure head space will be out of spec if the barrel is loosened off to top dead center? Marlin rifles are usually put together very well and factory QC was very good. It may have been over tightened by a smith or bubba.

Anyway, on top of the cost of the smithing, there will also be the cost of shipping, both ways. Add another $75 to a $100.

Elwood Epps, a sponsor on this site can do the job and from what I've seen of their work, do it well.

Guns and Gunsmiths in Nova Scotia

Manta has 3 companies under Guns and Gunsmiths in Nova Scotia

All Company Listings

Gunnery, The

647 Main St
Kingston, NS Canada


Loyalist Arms And Repairs Ltd

10 Brunt Rd
Harrietsfield, NS Canada


Gunnery, The

647 Main St
Kingston, NS Canada



Loyalist Arms And Repairs Ltd

10 Brunt Rd
Harrietsfield, NS Canada


Tronics Ltd

Gd Stn Main
Yarmouth, NS Canada

 

[guntech]

It's an absolutely horrendous job to set a lever action barrel back one turn...more work than fitting a new barrel. I would suggest having the barrel turned back that 1/2 of a degree to line the sights up and have the headspace checked if you are worried about it... that 1/2 of a degree in indexing will not affect the headspace. I suggest doing that by removing the barrel, lightly peening the shoulder of the barrel and installing the barrel with blue Loctite on the threads carefully indexing the barrel - not over the dead center line up...

 

[tiriaq]

Bingo!

 

[fat tony]

Thanks for the replies people.

 

[cet]

It's an absolutely horrendous job to set a lever action barrel back one turn...more work than fitting a new barrel. I would suggest having the barrel turned back that 1/2 of a degree to line the sights up and have the headspace checked if you are worried about it... that 1/2 of a degree in indexing will not affect the headspace. I suggest doing that by removing the barrel, lightly peening the shoulder of the barrel and installing the barrel with blue Loctite on the threads carefully indexing the barrel - not over the dead center line up...

Guntech,

What's peening? Is it punching the face to raise the surface around the punched areas?

 

[guntech]

Guntech,

What's peening? Is it punching the face to raise the surface around the punched areas?

I this case it would be the shoulder edge you are trying to deform slightly to effectively lengthen the shoulder so it would contact the face of the action sooner... it is slightly more effective than punching the face of the shoulder but either way only makes a slight change. You can also roll the shoulder edge with pressure for more displacement.

 

[fingers284]

It's an absolutely horrendous job to set a lever action barrel back one turn...more work than fitting a new barrel. I would suggest having the barrel turned back that 1/2 of a degree to line the sights up and have the headspace checked if you are worried about it... that 1/2 of a degree in indexing will not affect the headspace. I suggest doing that by removing the barrel, lightly peening the shoulder of the barrel and installing the barrel with blue Loctite on the threads carefully indexing the barrel - not over the dead center line up...

This^^^ Add a couple hundred to Bearkiller's guestimate for re-doing the front stock & mag tube to fit the change in distance from frame in the dovetails already cut in the barrel if you do it the way the OP has outlined.

 

[GunBoy]

it quite a big project, quite bit of work, something like this would take most of the day if not all day, but not impossible.

I have a rifle that I would like to get sorted out. The barrel is over indexed from the factory, making the use of iron sights annoying due to the cant. I suspect they over indexed it to get he headspace within range. This is a common rifle, a Marlin 336 dating from the 1970s. I know it might be cheaper to cut my losses & pass it on, but this is a pre-remlin rifle that I otherwise like. I am thinking about having a professional set back the shoulder, re-index the barrel properly, recut the chamber, recut the extractor, & reinstall it. How much would it cost for a professional to do this job? Also, can anyone recommend a professional to do this? I am not sure if the Gravel Agency is up to the job. Thanks, Tony

 

[BCRider]

I this case it would be the shoulder edge you are trying to deform slightly to effectively lengthen the shoulder so it would contact the face of the action sooner... it is slightly more effective than punching the face of the shoulder but either way only makes a slight change. You can also roll the shoulder edge with pressure for more displacement.

Now THIS is the sort of answer I like.

Guntech, for my own learning if this is done but one were to get slightly carried away with the peening could it result in the chamber becoming slightly pinched? Would running a chamber reamer in for a cleanup work to fix such a thing?

Obviously the best approach is to do this peening with lots of patience and a smaller hammer so this doesn't occur. But if it did?

Also would you make up a half round saddle to support the barrel while doing the peening?

 

[tiriaq]

I have peened and rolled shoulders. Peening involves gentle tapping around and around the very edge of the shoulder. It affects only the edge of the shoulder, nowhere else. For rolling, I use a commercial tool designed to roll a choke into cut-off shotgun barrels. Used like a pipe cutter. Tighten slightly, roll, tighten, etc.
Pretty much standard way of adjusting minor over indexing issues. You get one chance to pull the barrel to index. The displaced metal deforms as the barrel is brought to index. Go too far, and you've undone the work.
A much more complicated method is to machine the shoulder back, and install a breeching ring.
It is really easy to calculate the effect on headspace if a barrel is turned in or out. If the barrel threads are known, just determine what fraction of an inch change there is per revolution, then multiply that by the fraction of a revolution that the barrel is turned in or out. For example, if the threads are 16tpi, .0625 X 5/360, for a 5 degree change.

 

[guntech]

Now THIS is the sort of answer I like.

Guntech, for my own learning if this is done but one were to get slightly carried away with the peening could it result in the chamber becoming slightly pinched? Would running a chamber reamer in for a cleanup work to fix such a thing?

Obviously the best approach is to do this peening with lots of patience and a smaller hammer so this doesn't occur. But if it did?

Also would you make up a half round saddle to support the barrel while doing the peening?

The metal displaced is only close to the surface, it would never 'threaten' chamber or barrel specs. The same occurs when you stamp a caliber on the barrel... only the metal close to the surface is 'stretched' beyond it's elastic abilities... it does not go deep.

No support is needed other than laying it on the bench...

 

[guntech]

If the barrel threads are known, just determine what fraction of an inch change there is per revolution, then multiply that by the fraction of a revolution that the barrel is turned in or out. For example, if the threads are 16tpi, .0625 X 5/360, for a 5 degree change.

...with a 16tpi barrel that 5 degree rotation would change the headspace by .00086"... less than 1 thousands of an inch... so slight index changes in effect don't matter as far as the headspace changing.

 

[big boar]

Am I missing something? Why not just remove the front sight, fill the dovetail if one exists, file the excess and reblue. (If not fill the tapped holes). Then reinstall the front sight. Seems a lot easier than all the barrel work involved. Maybe it's just me but I thought the OP had a problem with the front sight being canted. Unless he has a headspace problem why bother with barrel setback? Not trying to step on toes, just thinking.

 

[guntech]

I think the rear site is canted as well... filling two dovetails and redoing them and making it look good is not that easy... considerably easier to just re index the barrel as already explained...

 

[fat tony]

Yep, thanks Guntech.

 

[big boar]

Thanks Guntech, not trying to step on toes. Just thought filling in some dovetails with cheap "fillers", filing, blueing and recutting was rather simple. You know better, thanks for the explanation.

 

[trevj]

It's an absolutely horrendous job to set a lever action barrel back one turn...more work than fitting a new barrel. I would suggest having the barrel turned back that 1/2 of a degree to line the sights up and have the headspace checked if you are worried about it... that 1/2 of a degree in indexing will not affect the headspace. I suggest doing that by removing the barrel, lightly peening the shoulder of the barrel and installing the barrel with blue Loctite on the threads carefully indexing the barrel - not over the dead center line up...

If peening would not get the amount of 'turn' required, would there be any use of the idea of skimming the shoulder enough to fit a shim or bushing ring in the gap? A ring has the advantage that it can be adjusted fairly simply on a lathe, while shim stock is easy enough to source in various thicknesses.

Thinking along the lines of the crush washers and such used to torque up against, and if a fella were to be able to work with a pretty close tolerance in mind, I'd figure that might be less work than a refit or set-back. There are punch jigs out there that will allow the workman to cut concentric circles out of thin shim stock, and I figure they would be a lot less intrusive than one stray hammer blow when peening, no?

Strictly theoretical on my part, but if ya started with steel shim stock you could pretty much sort out about how thick you needed, no? (Thread pitch, divided by the portion of a full turn required to have it torqued back into it's proper place).

Given that the rest of the slots, cuts, dovetails, etc., are actually where they belong, no? And that the headspace checks out.

Am I off base?

Cheers
Trev