Barrel Tenon Questions

[tlallijr]

 I am currently working on my second rifle build and am a little concerned on barrel thickness, what I have is a rice southern classic in .50 caliber with .016 deep round bottom grooves. The tenon's I have mic out at .038 and I planned on using 4 of them. I've installed the muzzle and breech ends where I have more barrel thickness. Now it's time to install the tenon's at the thinnest part of the waist (.750"). My calculations are .500+.016+.016=.532  .750-.532=.218
.218/2= .109 with a dovetail of .040 I will have .069 barrel wall left. My questions are:
Am I doing the math right
If so, is that enough barrel wall thickness
Is 4 tenon's overkill (42" barrel)

[Keb]

I use 3 on a 42" barrel and 4 to 5 on longer ones. Your math is correct. Just don't make the dovetail so deep if you are worried about it. The base of the tenon can be filed down.

[David R. Pennington]

I did a .40 swamped 44 inch and was concerned with the same issue. To be on the safe side I dovetailed the front and rear where there was plenty of meat and soldered the two middle ones. Peace of mind. I made the middle ones of folded sheet stock and wrapped them a little around the bottom three flats and soldered like I would on a round barrel.

[Dennis Glazener]

Is 4 tenon's overkill (42" barrel)

in my opinion yes! I never use over 3 for a 42 inch barrel, sometimes only 3 on a 44".

I would cut the dovetail .020" deep and soft solder it in place or you could just soft solder it without cutting a dovetail but if you have a thin web good luck getting the cross pin hole properly placed.
Dennis

[Dennis Glazener]

My calculations are .500+.016+.016=.532  .750-.532=.218
.218/2= .109 with a dovetail of .040 I will have .069 barrel wall left

I am not sure I am right but I don't add the depth of the rifling. I thought the caliber included the depth of the rifling. If I am wrong I have been figuring these wrong for years.

*afterthought*
After doing some thinking, which is hard on my old head, I think you are right to add the depth of the grooves to your calculations. I based this on trying to measure the bore on one of my .54 cal barrels with my dial calipers. Still would love for someone that knows for sure to chime in.
Dennis

[David R. Pennington]

Dennis you are right about hole alignment but if you fold the middle lugs out of sheet stock and solder them on, the difference in barrel diameter on swamped barrel works out so that shouldn't be a problem.

[flehto]

On the  narrow  portion of a  narrow  "waisted" bbl I always just solder them on....no dovetail. Plenty of web in this length......Fred

[okieboy]

 Re Dennis. I don't add rifling either. Most ".50s" have a bore of .490" and .010" is pretty common for rifling depth, which would be .005" per side. 005" is closer than what most people work to (how many people own a real depth micrometer in stead of a caliper with a depth rod of questionable calibration?).
 Of course someone is going to have a large bore and deep rifling, but in these days of precision barrels, that is going to be less common.

[galamb]

I used the same method as David with a 45 cal Southern Classic.

Dovetailed in the two at the breech and muzzle ends and then soldered the two in between.

Helped when it came time to pin alignment as well since the tabs extending down from the lugs were pretty well in line with each other (one less thing to have to measure and re-measure many, many, many times before I got the drill out)

[Mike Brooks]

I just make thin barrel tennons. All they do is hold the wood to the barrel. I always use 4 on 42" barrels.

[WadePatton]

Measured with pin gauges my .30 is .303" 

then you add the depth of rifling.

I really like using pin gauges for hole accurate hole measurement.

[tlallijr]

I have never soldered steel and can count on one hand the amount of copper joints I have sweat. Can someone give me a brief description? Should I wipe the oil from the barrel before soldering? Thanks Tony

[David R. Pennington]

No problem. Clean both parts shiny bright at the contact point. I use regular plumbing solder or 95/5. I like liquid flux and apply it with an artists brush. Most people overdo the flux. You only need a THIN film of it. Don't apply heat directly on the flux but work from unfluxed area toward it. When the flux starts to bubble and evaporate touch the solder to the metal and it should begin to melt. It is often preferable to "tin" both pieces before assembling. What this means is simply that you melt a thin coat of solder on both surfaces before assembling. Once both parts are tinned apply flux (sparingly) and assemble and clamp in position. Apply heat to the larger part first, again taking care not to "burn" the flux. When the solder melts the two parts will join and if the fit is tight no more solder should be needed, but if there are gaps you could touch the solder to the joint to add some. Don't disturb until cool and then take care to clean any residual flux off and then oil the bore good.