Author Topic: .308 Texan titanium barrel tension  (Read 1662 times)

rcpro88

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Re: .308 Texan titanium barrel tension
« Reply #30 on: March 17, 2018, 09:36:44 AM »
Bob,

I'll see if I can get better pictures of the Texans barrel assembly. There is no way the barrel can move, it it rock solid and held in place with 9 set screws. Also the Texan wouldn't have grouped a .8" CTC 10 shot group at 130 yards if the barrel assembly was moving relative to the scope. The tension assembly mates with the receiver for 8-9 inches (I don't know exact measurement off the top of my head) and acts like a large 1 piece bushing with a length of 8-9 inches.

Everyone else, this is a few pics of my shot groups using a bipod off a bench.
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rsterne

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Re: .308 Texan titanium barrel tension
« Reply #31 on: March 17, 2018, 09:53:12 AM »
Sorry, I didn't realize your tensioning sleeve went inside the receiver.... must have required extensive machining for that?....

Bob
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rcpro88

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Re: .308 Texan titanium barrel tension
« Reply #32 on: March 19, 2018, 03:32:51 PM »
Bob,

I know you're Canadian but don't feel the need to apologize!

Pretty much on a stock Texan, the barrel has 2 bushings. Each bushing has a 4 holes and 1 tapped hole for a setscrew to secure the bushing to the barrel. The set screws from the Texan frame/receiver go through the holes in the bushing and set against the barrel. The bushings have a 1" OD and have an ID of 0.675. The bushings are first slid onto the barrel, then each are held in place by 1 set screw to keep the bushings from moving. Once to two bushings are secured on the barrel, the barrel/bushings are slid into the front of the Texans frame/receiver. Once in the holes in the bushings align with the tapped holes in the Texans frame/receiver. Then a total of 8 set screws are screwed into place and the Texans barrel is secured.
So to sum it up, on a stock Texan (Condor, Talon etc) the setscrews in the frame/receiver push against the barrel (but not the bushings), however, in return the bushings are pushed against the Texan frame/receiver.

On top of the set screws that hold the barrel in place, behind each bushing there is a retaining ring that seats on a groove in the barrel. Set screws provide great hold to gradual thrust/torque but can slip during an impact style force - like the kind produced by the Texans recoil. These are also used to align the bushings in the right spot on the barrel.

The bushings have to be located in the center of the barrel as behind them is the hammer/spring assembly - so the barrel is only supported in the center - leaving the ends vulnerable to vibrations. 

A modification people seem to have been making to the Condor and Talon is to make a single piece bushing. This way there is more contact area against the bushing/receiver as well as the barrel and the bushings to better support the barrel. Using a 1 piece bushing requires the removal of the first retaining ring. I will say that since the Texans recoil significantly more than its little siblings and the impact force generated by the Texans recoil is distributed among both the first and second retaining ring - I can't say for sure or not if only one will be fine.

So my design goes like this:
I removed the rear bushings retaining ring (the bushing closest to the Texans tank). I cut a much deeper groove in the barrel where the rear retaining ring originally was. Then I put my split ring in the groove and then retaining cup holds the split ring halve together. Since the split ring would be taking the compression force of the titanium tube, it would have to take a lot of load - as well as it has to withstand the impact force of the Texans recoil. A normal retaining ring or set screws would not have been sufficient at all. I actually turned a piece of mild steel to 0.670 and tried different things before carving into the Texans barrel. 
The retaining cup was press fit over the split ring, it's very tight/semi permanent. Combined with the friction produced by the force of the retaining cup against the split ring, there is no chance of the barrel rotating in relative to the retaining cup - so no set screw was needed to hold it in place.
Since the titanium tube has an OD of 1", it acts as one large bushing.
However I did drill bottomed holes (not through) in the retaining cup. This allows the rear 4 set screws that secure the Texan frame/receiver to prevent the new barrel assembly from moving due to the impact forces generated by the Texans recoil.

The barrel is only under tension from where the stock rear bushing was to the muzzle and does not reduce harmonics/vibrations prior to the assembly. However I see it like this: take a garden hose for example, the water goes where the end is pointed regardless if the hose is coiled up prior end of it. So even though I cannot reduce the barrels harmonics from the loading tray to the barrel tension assembly, I don't think it really matters all that much.

Make sense?
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rcpro88

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Re: .308 Texan titanium barrel tension
« Reply #33 on: March 19, 2018, 03:47:27 PM »
last few details:

There is no front bushing, the other end of the titanium tube is supported at the end of the muzzle.
There are no modifications done to the Texans frame/receiver - so this assembly can be dropped into anyone's .308 Texan.
The set screws that secured the frame to the front bushing/barrel seat against the titanium tube.
The set screw that held the end cap/cover thing on is also seated against the titanium tube.
A total of 9 set screws hold the new barrel assembly in place.
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rcpro88

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Re: .308 Texan titanium barrel tension
« Reply #34 on: April 03, 2018, 02:55:17 PM »
Check for my post called .308 Texan Exoskeleton Stock for build details/updates. I will post the results of the titanium barrel tensioning assembly once the stock is done. I will post them here. 
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Monkeydad1969

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Re: .308 Texan titanium barrel tension
« Reply #35 on: April 04, 2018, 05:24:59 AM »
I will definitely check out your new post.

Joe
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