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Spiral Lock threads on tenon?

The spiraloc thread system works. I used to do fatigue testing of fasteners for the Auto industry. That being said I cannot bring myself to threading a barrel shank in that manner. You can make your own tool by putting a small angle on the tip of your normal cutting tool. Spiraloc will sell you the inserts, just tell them your a gunsmith.
We used to build cannon breeches at a company I worked for there were a few in our lobby. The threads on those were square or modified trapezoid as I recall. They were a centralizing thread fit meaning the flats on the od and id aligned the barrel. Square threads were used by a lot of those old actions etc. garand, springfield etc. Someone fixed the newer actions to use a v thread. I always felt some flat or coned areas on the tennon would be and improvement over just the v thread. I think the European actions incorporate this technology. Grunig and others.
 
The spiraloc thread system works. I used to do fatigue testing of fasteners for the Auto industry. That being said I cannot bring myself to threading a barrel shank in that manner. You can make your own tool by putting a small angle on the tip of your normal cutting tool. Spiraloc will sell you the inserts, just tell them your a gunsmith.
We used to build cannon breeches at a company I worked for there were a few in our lobby. The threads on those were square or modified trapezoid as I recall. They were a centralizing thread fit meaning the flats on the od and id aligned the barrel. Square threads were used by a lot of those old actions etc. garand, springfield etc. Someone fixed the newer actions to use a v thread. I always felt some flat or coned areas on the tennon would be and improvement over just the v thread. I think the European actions incorporate this technology. Grunig and others.

I agree with Sam

Personally i think to improve the rigidity of a typical barrel tennon, will require a complete re-design.

Something like sandviks capto connection.
 
Use to have the 30 degree angle ground on the threading inserts at the rifle shop I worked for years ago just as SamLS stated. Much cheaper than buying the actual spiraloc inserts, if you have the ability and optical comparator to verify the work.

For what it is worth, I never saw a difference in accuracy on my own comp rifles between them and the standard V thread. I wouldn't waste the money or time. Stick with the standard V thread.
 
May I ask a thread related question while so many experts are here? I have an old Winchester Model 55 Takedown 30-30. The threads on the barrel are ground off on 4 sides. Same with the action. I can line up the cuts, push the barrel into the action, twist it a quarter turn and it's tight. Inserting the tubular magazine locks it in position. It seems this system would ease barrel switching on some of my other guns. Is the system only good for hunting gun accuracy with mild cartridges?
IMO, yes
 
I see a lot of evidence in this thread of fellows who are not familiar with Vaughn's book having opinions that do not involve any actual testing of their own. In his book, Vaughn mentions that typical benchrest calibers and barrel weights probably make this a non issue. He did his testing with a caliber and barrel weight that are not typical, or even seen on a benchrest rifle, nevertheless there is a lot to be learned if one takes the time to actually read what he wrote. He did, and presented an alternate barrel to action joint. He also mentioned that another way (other than Spiralock threads) to improve the joint would be what Alex mentioned, tapering the tenon, OR action thread. My early Stiller Viper has an insert that was thread milled so that the threads are intentionally tighter toward the rear of the action. This was discontinued for reasons of simplicity in later versions. We are seeing some very large calibers in some of the very long range competitions and for those situations there may well be some significant unloading of the action face/barrel shoulder under peak pressure.

On the difference between a nut and integral shoulder, consider the effect that tightening each has on headspace measurement.
 
This is an old thread but coming back to this subject with 5-6 more years experience I still believe there's no accuracy in the thread joint. Its not moving. I never post this because I have a lot of respect for his work but Vaughn is wrong here. The way he tested if the barrel was moving was flawed. The device he installed in the muzzle to measure if the barrel moved cant repeat good enough to be used in that way. If you have ever used the range rods you know you can dial it in take it out and put it back in and it will be off. The thread joint just doesnt see a lot of stress. The main force is on the bolt face and back of the bullet. The barrel is not seeing those same forces. Theres not a lot of force trying to unseat the shoulder.
 
Screw a barrel on and torque it to your normal lbs/ft torque with a quality torque wrench. After you've fired the rifle a bit, remove the barrel using the same torque wrench and compare the torque values.
 
Yep. :) Provided they're adequately tight to start with, barrels don't shoot loose. They shoot tight.
 
Pressure expanding in all directions. Think about it.
The bolt face area is very small compared to the chamber area.
So while shared, most of the force manifests at the barrel threads, in both thrust and expansion.

I've mentioned it before here,, straight threaded bolts (like a typical shouldered barrel), pipe threading, and studs (like with a barrel nut) have different connection qualities. They are not equal.
Vaughn suggested that it mattered. Maybe not to anyone here.
 

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