Barrel TQ and Headspace Crush Measurements

[Tokay444]

We might have our “own little microcosm here”, but more than a few of us know what it takes to do that.

And we know how to prove it.

There used to be a Gunsmith in the Houston area that built high end rifles for those that could afford them. He also touted that his “Rifles Achieved Benchrest Accuracy“ in a hunting platform. I would watch him at the local Gun Range testing the next customers Rifles. They simply took his word that their money was indeed buying his claims.

Their ignorance kept him in business. If they ever took their Rifle to the range and found out the truth, he always had that…..”you didn’t do your part” thing to fall back on.

It is pretty common for people to throw extreme accuracy figures around when those people have no concept of what it actually takes to achieve such performance. In our “own little microcosm” we do know what it takes and have to actually prove it, on a regular basis.

Those that cater to the Tactical Sniper Rifle crowd, whether that crowd be individuals or government agency’s, can tout their rifle‘s ability to feed reliably, extract and eject empties efficiently, be ergonomically functional, or possess any of the other parameters that govern that particular genera. These attributes are often just as difficult to achieve as extreme accuracy and are probably more important than the rifles ability to achieve sub .200 accuracy, even in 3 shots.

It would be pretty silly for me to take one of my Benchrest Rifles to the field and duplicate the performance of a Platform designed for that application.

However, what that Platform will not do, with the ammunition advertised, achieve the level af accuracy and precision that it takes to “shoot 0’s and 0nes” out of a cold barrel.

And there is a very easy way to prove this. Actually sit down and do it.

I have a nice 30/06 that I built on a 721 action that is assembled with the finest parts. I performed all of the necessary machine work. It feeds reliably, extraction and ejection is flawless, and although a little heavy at 10 pounds with the big NXS Nightforce sitting on top, it is reasonably functional in the field with it’s HS Precision stock.

With my own tuned handloads, it will shoot 3-shot “threes” off the bench.

That is a far cry from “0’s and Ones”.

The rifles do it in the hands of their owners.

 

[Edd]

I first read about Tac Ops tightening to 500 ft lbs a year or so ago. Ever since I read that I've been wondering if they do the finish chamber reaming after the barrel is screwed on the action.

 

[butchlambert]

I first read about Tac Ops tightening to 500 ft lbs a year or so ago. Ever since I read that I've been wondering if they do the finish chamber reaming after the barrel is screwed on the action.

Why?

 

[mike mccormick]

“When attaching the barrel to the action, Tactical Operations again uses their own unique process which involves using torque settings of 500 ft-lbs. They originally used 150-180 ft-lbs, but then upped that to 250 after a while. They then discovered that they could reduce cold bore shot movement if they went to 500 ft-lbs which is what they do.”

Can't move if it is friction welded in place....how do you suppose they hold the action and barrel?

 

[Mark Buettgen]

I would be curious to know just what kind of barrel vise/holding system they are using that would hold a barrel getting torqued to 500 fp's and not damage either the exterior or bore dimensions.

 

[Dusty Stevens]

I would be curious to know just what kind of barrel vise/holding system they are using that would hold a barrel getting torqued to 500 fp's and not damage either the exterior or bore dimensions.

Ive been to a bunch of fastener schools from hydraulic bolt stretching to just hydraulic wrenches on huge fasteners for turbines, talking like 4-10” bolts. Ive put stuff together with torque multipliers by hand to 500lbft and aint no remington wrench or barrel vise ive ever seen would get to 500. I gotta change my marketing

 

[jackieschmidt]

Threaded joints are designed to work in tension. For years, large engine manufacturers (and hot rodders), do not rely on a torque figure to achieve tension, they actually measure the amount of stretch achieved, and strive to achieve this regardless of the actual toroque.

I would be curious to know just what kind of barrel vise/holding system they are using that would hold a barrel getting torqued to 500 fp's and not damage either the exterior or bore dimensions.

I am installing a new barrel on my 6PPC this evening…………

 

[Mark Buettgen]

Threaded joints are designed to work in tension. For years, large engine manufacturers (and hot rodders), do not rely on a torque figure to achieve tension, they actually measure the amount of stretch achieved, and strive to achieve this regardless of the actual toque.

I am installing a new barrel on my 6PPC this evening…………View attachment 1317849

That's funny stuff right there!!

 

[kendog]

Ive been to a bunch of fastener schools from hydraulic bolt stretching to just hydraulic wrenches on huge fasteners for turbines, talking like 4-10” bolts. Ive put stuff together with torque multipliers by hand to 500lbft and aint no remington wrench or barrel vise ive ever seen would get to 500. I gotta change my marketing

If 500 is good, maybe 5000 would be better!

 

[Dusty Stevens]

If 500 is good, maybe 5000 would be better!

Youd have to take some off the cone end once it stretches that far. Im still floored by this market cornering of the zero and ones shooting factory gold medal 308/168 for $7000. It has really messed up my mind.

 

[wwbrown]

Threaded joints are designed to work in tension. For years, large engine manufacturers (and hot rodders), do not rely on a torque figure to achieve tension, they actually measure the amount of stretch achieved, and strive to achieve this regardless of the actual toroque.

I am installing a new barrel on my 6PPC this evening…………View attachment 1317849

Now your talking. Get that wrench on the 721 you mentioned to get it shootin' in the "0's" and "1's".

 

[SKWERLZ]

I also use around 75/80 ft/lbs. but I always put a witness mark with a sharpie pen so I can see that the barrel did indeed advance..

I have rifles that have had barrels screwed on and off so many times that I would not have a clue as to the number.

Nothing ever changes as far as the critical measurements go.

Same here

 

[SKWERLZ]

Threaded joints are designed to work in tension. For years, large engine manufacturers (and hot rodders), do not rely on a torque figure to achieve tension, they actually measure the amount of stretch achieved, and strive to achieve this regardless of the actual toroque.

I am installing a new barrel on my 6PPC this evening…………View attachment 1317849

Yep
I have a rod bolt stretch gauge.

Or they calculate stretch and go initial torque and specified extra degrees or rotation like Duetz diesels and many other engines.

 

[jelenko]

Do these bolts ever need to come off? If so, can they be used again?

 

[SKWERLZ]

Do these bolts ever need to come off? If so, can they be used again?

Torque to yield bolts shouldn’t be reused.

 

[shortgrass]

Threaded joints are designed to work in tension. For years, large engine manufacturers (and hot rodders), do not rely on a torque figure to achieve tension, they actually measure the amount of stretch achieved, and strive to achieve this regardless of the actual toroque.

I am installing a new barrel on my 6PPC this evening…………View attachment 1317849

I've got about 6' of of 3"XH that we can slip over that handle for a bit of add leverage.

 

[rayporter]

a good name for the rifle after that would be 'twisted sister'

 

[Alex Wheeler]

Id be curious to hear the whole story on this 500 ft. lb. thing. I build a lot of lr hunting type rifles and test them for cold bore shots. I have never experienced a problem with cold bore shots out of the group (and I test this at 1000 yds) with my normal 75 pounds or so. Sporters to heavy barreled elr type stuff, doesnt matter. My guess is that if that amount of torque did fix a problem, its masking the real problem.

 

[hpshooter]

I am installing a new barrel on my 6PPC this evening…………View attachment 1317849

Use to keep a 4 foot version of that by my office door in the foundry I worked in. If we lost power to the continuous mixer for the chemically bonded molding sand the drill was for one of us to grab the wrench and rotate the mixing auger by hand until all of the sand was out before the sand set up in the mixer.

The wrench we had was the Aluminum bodied version made by Rigid. If I had been thinking ahead to doing any barreling work I could have kept it when that operation was sent to Mexico.

 

[dnellans]

Id be curious to hear the whole story on this 500 ft. lb. thing. I build a lot of lr hunting type rifles and test them for cold bore shots. I have never experienced a problem with cold bore shots out of the group (and I test this at 1000 yds) with my normal 75 pounds or so. Sporters to heavy barreled elr type stuff, doesnt matter. My guess is that if that amount of torque did fix a problem, its masking the real problem.

TACTICAL OPERATIONS TANGO-51 – FULL REVIEW

It was time to take the latest version of the Tango-51 out for a full test and see how they still hold up.

www.snipercentral.com

This is all I know. I didn't really mean for this to turn into a thread about their process, it was just to note that people are clearly doing everything from barely any TQ to a huge amount.