Tenon Length vs Barrel weight

[Hombre0321]

Just started a new build, got a good deal on a Eliseo tube gun. It was a Palma rifle most of its life, and is in .308 with the usual sling shooter stuff sights etc. I have always been somehat intrigued by these tube guns and wanted one for F-Class Open. Orginal plans were to rebarrel it to 6.5x06 and use it mostly as an afternoon relay rifle when the wind usually gets up. Turns out it is a short action so I will have to change my plans there some.

All of my F-Class match rifles have very heavy barrels on them, 1.125 straight no taper. In looking at this new rifle which has a Remington 700 action with there short tenon I was just wondering when short is too short? At some point it has to make a difference...

Roland

 

[BoydAllen]

I think that it is a common misconception that longer tenons have some value in supporting barrels. As a barrel is tightened, the tenon stretches, and the axial load is taken by the first few threads back from the action face. On the other hand, the maximum diameter of the barrel where it comes into solid contact with the face of the action, does have some effect. Think of it as the down the wall dimension of an individual shelf bracket. Like the bracket, as length and weight of the barrel increases, the additional weight is trying to pull tenon out of the action like increasing the load on the bracket would put more pull on the highest mounting screw. If two tenons are the same diameter, and the barrels that they are machined to the same OD where they meet the action, there little advantage to the longer tenon. Alignment is created by the squareness of the parts, and the self centering nature of a V thread profile, having little to do with tenon length. As always, opinions may vary.

 

[Preacher]

What he said...
I run a few 700's with 1.250's and never noticed it to be a problem...

 

[LCazador]

I built two 1000 yard bench rifles on Bat actions , and my opinion is different from the two posts above . By the way , both of these barrels are straight 30 inch , 1.250" tubes . Having shot many trued Remingtons with barrels of similar weight , there is a definite accuracy advantage with the longer barrel tennon at the longer ranges with both of these barrels . I think that any barrel longer than 28 inches and heavier than 5lbs , needs a longer tennon to shoot better , my two cents from actual experience !! By the way 6.5X47 Lapua or Creedmor work quite well for that short action .

 

[BoydAllen]

Was there a difference in action configuration? Single shot VS magazine cut? If there was, this gets into bedding area and action stiffness rather than just tenon length, but I am glad to have the information. Bottom line, there was a difference. I wish that everyone that disagreed with me on line, had been so nice about it.

 

[Steve Blair]

While I'm not refuting L. Cazador's experience, mine is not the same. I have a Remington 40 XBR with a 30" straight barrel and have shot it at 1000 yards. It showed excellent accuracy within limitations of the 6BR cartridge. My two BAT 3LL147OCTPIC actions have 32" and 34" straight barrels but I don't think the tenon length contributes significantly to support, it is the action rigidity. Boyd is right about fastener behavior and bolting torque. The only way to measurably improve barrel interface rigidity would be to counterbore the action and perform the thread engagement farther from the action face. [br]

 

[6BRinNZ]

Its interesting...a while back Kelblys asked if there was anything they could do to improve their actions...a longer tennon came up...their response was - it made no difference and they wouldn't do it...

Probably like all things shooting - each situation has to be put into context in order to make a statement.

I liken this sort of question a little like ballistics - we all see anecdotal and on paper outcomes and draw a conclusion - its not until a ballastician says - nope that proposed cause can't produce that outcome that we have to rethink...i.e. no one disagrees with the outcome, but the ROOT cause can be something else.

I will be watching this thread with interest.

 

[Mark Walker in TX]

My Panda F-Class actions and 31" straight 1.25s seem to perform fine...

 

[Hombre0321]

Guy's great discussion and interesting responses, thank you all for contributing your opinions and your thoughts.

I have several match rifles, the one with the longest tenon is a Pierce. The rifle I have shot extensively has a Farley action it is chambered in 6.5x47L and it is on its second Kreiger 1.25 straight no taper barrel. This discussion got me to wondering what the tenon length on it was, this rifle is a switch barrel gun and I have barrels in the safe for it. So I pulled a 6 Dasher barrel out and measured the tenon. Just looking at it I thought "Man that looks short" The Farely uses an integral recoil lug that is on the action itself. The tenon measured .752 or 3/4".

Since this tube gun is the first Remington I own and not being familiar with them at all, I pulled the barrel off of the tube gun to measure it. Now as you guys know I am sure the Remington with its recoil lug that goes over the tenon. With the tenon installed or setting on the barrel the tenon meassures .750. So I guess clone means just that.

The Farley is a superior shooting rifle, I have shot some very good scores with it at 1,000 yds and it is on its second barrel in 6.5x47L that is a 1.125 Straight. So I guess my questions has been answered.

Thanks you Folks.

Roland

 

[Rtheurer]

Roland

Another option if your not convinced of the tennon length, is the Defiance Machine Actions. The Mutant is made for the RTS/R1 stock that gary makes. It has a built in Recoil lug so no washer is needed and at the same time provides a longer tennon. ( if it matters)
Check it out. http://defiancemachine.com/mutant-action/
I recieved mine last fall and boy oh boy is it nice.

RussT

 

[FroggyOne2]

Boys and Girls, Russ always has some very nice shooting rifles and he knows what does and does not work well!

 

[Hombre0321]

Roland

Another option if your not convinced of the tennon length, is the Defiance Machine Actions. The Mutant is made for the RTS/R1 stock that gary makes. It has a built in Recoil lug so no washer is needed and at the same time provides a longer tennon. ( if it matters)
Check it out. http://defiancemachine.com/mutant-action/
I recieved mine last fall and boy oh boy is it nice.

RussT

Russ, Interesting that you mention the Defiance action. Just yesterday in a conversation with my Gunsmith he mentioned the fact that Defiance was making a action that would drop in as a direct replacement for the Remington 700. I have one Defiance action now a Drop Port in Dashwer and like it a lot. After measuring the Farley action I have now, I am just not to sure at all how important the tenon length really is. This Farley has done very well for me with a 1.125 straight. I do like the idea of another Defiance action, might just be the way for me to go.

Roland

 

[LCazador]

Was there a difference in action configuration? Single shot VS magazine cut? If there was, this gets into bedding area and action stiffness rather than just tenon length, but I am glad to have the information. Bottom line, there was a difference. I wish that everyone that disagreed with me on line, had been so nice about it.

Boyd , good point ! You caught me there , my BAT is a single shot integral lug oversize action built off a 2 inch stock . That is not comparing apples to apples ! Touche !

 

[madderg]

If I remember my machining right the hold of threads is about 6 threads max...

 

[UltraBR30]

I think that it is a common misconception that longer tenons have some value in supporting barrels. As a barrel is tightened, the tenon stretches, and the axial load is taken by the first few threads back from the action face. On the other hand, the maximum diameter of the barrel where it comes into solid contact with the face of the action, does have some effect. Think of it as the down the wall dimension of an individual shelf bracket. Like the bracket, as length and weight of the barrel increases, the additional weight is trying to pull tenon out of the action like increasing the load on the bracket would put more pull on the highest mounting screw. If two tenons are the same diameter, and the barrels that they are machined to the same OD where they meet the action, there little advantage to the longer tenon. Alignment is created by the squareness of the parts, and the self centering nature of a V thread profile, having little to do with tenon length. As always, opinions may vary.

From what I get in your reply, a 1/4" of tenon length should be sufficient. Why are tenons as long as they are then or what am I missing in what you wrote?
Philip