Indexing switch barrel

[180pilot]

Have a need for a heavy SS take down rifle. So bought a new Alaskan Bush Hunter in .375 RCM. Have experience removing and head spacing Sav. barrels. Have another 116 in .338 Rum/ 7mm Rum. I would like to be able to assemble and take down rapidly, with just the barrel nut wrench. Since this has iron sights that have to come to same place each time, I'm trying to figure out a quick mechanical way to index the barrel and receiver. Since the nut covers the barrel where in meets the recoil lug, there is no place for an index mark between receiver and barrel. One smith over phone suggested using a pin between barrel and receiver, but I can't picture what he was thinking, as any pin would have to be below the threads.. or drilled through the front receiver ring into a hole drilled in barrel?
My current idea is about the front scope mount screw hole, as it goes all the way through and I can see the barrel threads. What if I drilled a small indent into the barrel threads through that hole when barrel is properly headspaced. Then used a slightly longer pointed front screw in the scope mount to go into that indent? I would back that screw out when installing barrel and screw barrel in until I see the indent, put screw back in tight to hold barrel in place and crank down the barrel nut. How deep do you think I could drill the indent without compromising chamber strength? This would not modify the receiver in anyway and allow other barrels to be head spaced in normal manner or "indexed" also. I guess the trick would be that the screw would put enough pressure on barrel and still be tight enough for scope mount. I could carry the long screw separately and only use for the indexing then take it out and put short one in? But could get lost, I suppose......so indent in barrel will have to be just deep enough so sides of screw will hold it but not bottom before mount is tight. Or if hole in barrel could be deep enough for 3 threads, just crank it in.

Anyone done this or seen one done?

[Apache]

I just use a witness mark on the barrel even with the barrel nut. Too deep, it disappears, back it out 1 turn or until it re-appears where it's suppose to be and I'm good to go.

[180pilot]

Good, unless different torque value is a factor, and knowing where that line is when you reach proper torque. The iron sights on mine are going to give a fair starting reference. So your system should work. How are you marking the barrel? Punch, engraver??? Got me thinking about putting some white or red paint into the small indent and just watch it line up with front scope screw hole....

[bsekf]

Witness mark on the barrel and nut, nut stays with the barrel. IMHO the difference in torque wouldn't amount to .0005, if that much. I still use my go/nogo gauge and if I was shooting something that could eat me, I would make sure a loaded round would chamber.

[stangfish]

Witness mark on the barrel and nut, nut stays with the barrel. IMHO the difference in torque wouldn't amount to .0005, if that much.

Marking at six oclock and putting one on the recoil lug will ensure repeatability as well.

[Nandy]

I set the headspace after dropping a few drops of loctite so it locks the nut to the barrel, let it dry 24 hours and then I dont have to worry a bout the headspace. You can torque it with your hands and generally take the barrel off with your hands too. make the barrel channel in your stock wide enough and you should be able to change the barrel without removing the action from the stock nor the scope from the action.

[Stockrex]

One of our mods posted that he uses an index mark and be on paper after barrel change
So yes it can be done

[180pilot]

As I said this is for take-down out of aircraft etc. I usually set my headspace using full re-sized brass as my gauge, so I won't be working brass between any difference between the barrel headspace and the die dimentions. However, with this having the iron sights, can't mess with that, hope chamber is close to dies, so stretch on first firing on virgin brass won't be too bad. Had that problem on 7mm RUM, cases only lasted 2 to 3 firings..with neck sizing only. Other problems with it made me rebarrel to .338 Rum. But, for a mud blood and Grizzly tracks around my tent, hunting piece, I do not want even a hint of drag closing bolt on cartridge. Just got look at delivered rifle at dealer yesterday, ( ten day wait now), it has the smoothest bolt of three SS 116's I have out of box. It's got the darn smooth nut and I think the accutrigger has to go for a dangerous game piece. I was able to pre-trip it just by putting sideways pressure on main trigger....:-0 Used bore scope on barrel and chamber, some rough reamer marks on lands last 1/2" of barrel, ( been seeing lot worse on some new Sav Barrels), but chamber/ throat area looked OK.

[Dennis]

I set the headspace after dropping a few drops of loctite so it locks the nut to the barrel, let it dry 24 hours and then I dont have to worry a bout the headspace. You can torque it with your hands and generally take the barrel off with your hands too. make the barrel channel in your stock wide enough and you should be able to change the barrel without removing the action from the stock nor the scope from the action.

Nandy, what is your process for installing the loctite'd barrel back on the action and getting the correct torque? How much torque do you think your setting it to? Your headspace is always set correctly with this method?

Interesting, I may start doing this. Not having to remove the action and scope is worth trying.

Dennis

[180pilot]

Yes, interesting, I assume you are using the Blue loctite with a breakaway of 230 inch pounds (19 foot pounds)? The temp range to 360 degrees should be adequate for a non-full auto. And, if you estimate the torque applied by hand added to the 19, should be close to amount needed to loosen barrel:


http://henkelontheroad.henkelna.com/LT-6540_AN_RemovableReliable_SS_v11_Final_Links.pdf

However on locktite sight the quote:

A: When we apply a threadlocker to a bolt and finger tighten a nut down, we let this sit for 24 hours and allow it to fully cure. We then take a torque wrench and break the bond. The initial reading on the unseated assembly is the breakaway value (remember, this is not torqued to a specified value such as 100 in lbs). This shows us the strength of the threadlocker alone. They then continue turning this and the average of four quarter turns provides us with our prevailing torque value. This shows us how much friction or drag is left to continue turning the nut. If for example, on the other hand, we torque the assembly down to 100 in lbs, and we use a threadlocker with a breakaway of 50 in lbs, the breakloose value initially on this seated assembly is 150 in lbs (100 + 50). The difference between what you torque this down to (100 in lbs) and what you breakloose at, (150 in lbs) is 50 in lbs and this is referred to as torque augmentation. The main function of any threadlocker is to maintain your torque. It's been determined that over time due to various factors such as vibration and side sliding, that you lose up to 30% of your on torque. The goal is to choose a suitable threadlocker that provides a breakaway value equivalent to 30% of what you torque the assembly to in order to maintain your torque over time.

I might want to use a non-marring strap wrench to make up that possible 30% instead of just hand tight ???

[Nandy]

Right now I am using the blue loctite since I will be changing the recoil lug and I would have to redo my headspace then but once the action is set up as I want it I will be using the red loctite. I have read about people using jbweld or jamming a piece of metal under the barrel nut on the end side towards the barrel and then adding jbweld but that is a little too permanent for me. All these methods to keep the barrel locked should be able to get undone with some heat from a torch at the worst case scenario (or so I have read).

I only torque the barrel with my hands so I cant really tell you what the torque value is. I have swapped the barrels many times, both using my hands and using the barrel nut wrench and I did not notice any changes on the force I had to use to close the bolt on the Go gauge and I was not ever able to close the bolt on the No-Go gauge.

I read much about these switch barrels when I got interested on it and all the info I got is from the internet so I took it with a grain of salt so I am doing my own testing as I go... I have shoot about 30 rounds on just the 30-06 and the barrel has never loosen up a bit. I read that a lot of the guys that switch the barrels on their remington use hand torque also and I have not read anything about the barrel coming loose. I have also read where some switch barrel users go to the extreme of having the muzzle end of the barrel cut hexagonal like a nut so they can torque the barrel.

For me the loctite locked barrel nut and the barrel torque by hand is working so far but again, I havent have shot much due to the ammunition shortage. For now I will continue checking my headspace with a gauge until I have shot a few hundred rounds and confirm my barrel is not moving. I am convinced it will work fine.

[180pilot]

I'm intrigued by bonding the nut to the barrel, and I have seen the hex muzzled Rems. Strictly for AK hunt, where rifle may get fired less then 5 times, hopefully, should not be an issue. It's been some time since I changed out a barrel and I can't remember how much friction there is in the Sav. threads? I seem to remember using an anti-seize when I put it together. And a light rap with a dead blow hammer on the wrench for final tightening. When I heat parts to release w Loctite, I do not use any flame. On small parts I hold a soldering iron against it until hot enough. Larger, I use an electric heat gun. If the nut is adequately bonded to the barrel, seems you could just tighten it against lug with the nut wrench? Think I would do some tests with the Blue LT, and see if any movement, if so go to the red. If you are tightening using a hold on the barrel, friction between lug and nut might move nut on barrel, I'm thinking. Using the nut which is now bonded to barrel, just takes the barrel for a ride, as it tightens against the lug...

Have you had any problem with loctite running between lug and barrel sticking it together????