Barrel Tuners (not rimfire)

[stinkitup]

Thanks for putting the findings up Tony. Do you add a large bearing plate at the action end eg just larger than tube and then similar at muzzle with a nut over on end? Wanted to do this with my swede ai...oh well next time around maybe

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[Tony Z]

Hi Ryan. This action i did for Jeff has a shoulder in the sleeve that a spigot ring sits in. The front receives and centers the tube. The rear has the action butt up to it and both were glued in situ. So the entire ring is a 360 degree recoil lug that transfers all the recoil through the sleeve and never stresses the action or its glue. A failing of some sleeved actions. Essentially the action delivers a firing pin and a pressure containment plug, the bolt head.
To answer directly, the spigot/recoil ring allows the bored inner tube to snug in centered perfectly. The nut is a reverse of the spigot, threaded to tension the barrel, compress the tube which has been outside turned to be perfectly concentric.
To test the set up i zero the rifle, put on the tube and tension while the barrel is hot. Let things cool and fire the barrel. If the POI is more than 1 MOA out with the tube on, something is drastically wrong. Sometimes a barrel may be bent enough to change POI by some margin. But i don't like seeing that. If it shoots well and doesn't fling one back toward toward the original bare barrel POI, then it's good to go. Some barrels just do that. Maddcos, Kriegers and Harts usually don't.

Today i shot four groups at 300 yards with the Re15 and 175 SMKs. Two primers and two seating depths. Fed 210s and BR2s. Ten thou in lands and ten thou out. There was a reversal of results with 210s wanting to be jammed, but BR2s wanting jump. Quite common that you see this as tubes are very good at staying on plane with velocity only forming the group and POI. Group shift is due to me running a boil not load doing it. The last group was shot on a right to left boil. All the others were on a left to right. 22 shots in 10 minutes with the last group, CCI BR2s and ten thou jump coming up at 0.650". Typical of tubes not going erratic when lots of shots are fired.
Tomorrow i will try plus or minus 3 tenths of a grain of Re15 to see if some of the vertical flattens out. Going off the square rule, double the range, four times the group size in equal conditions, i would expect around a 2.5" group at 600 yards. At best. OK, but a world away from Harrison and the BIBs.

[stinkitup]

Thanks Tony appreciate the time to put that up. Who knows what the future will bring but will save that info. Is that tube like a 50mm eg just big enough to slip over?

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[Tony Z]

Ryan a tube the diameter of the action is good. Smaller is no issue. Butting up to the action where the tube has been bored for a neat fit over the barrel, that has been parallel turned for a bit, is ideal as it transfers heat into the tube especially if it is lubed with that heat sink grease. Or copper antisieze.
I have done a heap of barrels that have had a step machined onto them where the tube OD matches that of the barrel knox form, or slightly under. It may seem or look odd, but takes sporter barrels to varmint type profile. Works very well, often better than if it were a solid varmint barrel. The one year i shot the Madden in Brisbane, 1999 i think, i took out 100 yard small group at 0.133" with just such a setup in a 6BR. In an Omark action of all things. Only way i could get to 10.5 pounds. Omark actions are heavy. The barrel pictured is it. The tube was drawn at 1 1/8" OD and 60 thou wall in 6061 alloy at T7. Sadly discontinued for some years now. There are metrics close, but tensile strengths are rarely above T5 these days. Barely acceptable for the high torque we use.

[stinkitup]

Thanks again!

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[Tony Z]

Never got out last Sunday but did today. Only went to 200 yards as the rain has made for some very soupy mirage with 100 % humidity. Wind was down to a slight right to left drift. Very overcast and dark. Conditions this scope sucks in where 30x was it.

Loads were Lap cases with holes drilled to 85 thou, 175 SMKs jammed 10 thou and Fed 210 Ms. Reloder 15 from L to R at 42.7, 43.0, 43.3 and 43.6 grains. Same as last week, all 22 shots fired in one session with no cooling time.

The result is typical of tubes with little distinction at this short range. A couple of the groups border on one holers with a spoiler or two due to boil or a touch of wind. Biggest group by over 200 thou, the first with the wild shot left on a gust was 0.670", the smallest the second at 0.310" both look promising. The last group has the last four into less than 200 thou where it certainly needs a repeat. The day itself was wasted due to the range being limited and as such i learnt fuckall except that a 308 can be made to shoot very well with the right powder and bullet. For those wondering, 2208 is the reason i use Re15.

Because of time running out for our first 600 yard match next week, I'm going to repeat the four loads at the match.

[DSD]

Ryan a tube the diameter of the action is good. Smaller is no issue. Butting up to the action where the tube has been bored for a neat fit over the barrel, that has been parallel turned for a bit, is ideal as it transfers heat into the tube especially if it is lubed with that heat sink grease. Or copper antisieze.
I have done a heap of barrels that have had a step machined onto them where the tube OD matches that of the barrel knox form, or slightly under. It may seem or look odd, but takes sporter barrels to varmint type profile. Works very well, often better than if it were a solid varmint barrel. The one year i shot the Madden in Brisbane, 1999 i think, i took out 100 yard small group at 0.133" with just such a setup in a 6BR. In an Omark action of all things. Only way i could get to 10.5 pounds. Omark actions are heavy. The barrel pictured is it. The tube was drawn at 1 1/8" OD and 60 thou wall in 6061 alloy at T7. Sadly discontinued for some years now. There are metrics close, but tensile strengths are rarely above T5 these days. Barely acceptable for the high torque we use.

Isn't the difference between t5 and t7 the time in the oven?
What are you saying is discontinued 6061 or t7 or just the imperial size?

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[Tony Z]

Many of the useful sizes of tubes, by that i mean common barrel and action ODs and IDs, have been discontinued . The most desirable magnesium and silicon alloy tubes, or 6 series, are not available in the sizes they once were. The magnesium alloy series 5 are not in the higher tensile in the useful sizes any longer. The thinner wall tubes of 5xxx in the lower tensile yield on compression where the thicker wall tubes are too restrictive in application. Series 7xxx, or zinc alloy aluminium like 7075 etc, are not offered at all where the higher tensiles of 7, 8 and 9 etc, would be highly desirable. But because of the brittleness, very poor corrosion resistance and non weldability these tubes are of little demand and thus of no commercial need.
Lithium alloy? Never seen or heard of it for general sale or use anywhere outside of NASA or on the A380. Often alloyed with copper thus has a prefix number in series 2. Without copper is 8. No idea of tensiles, it's just super light and is cheaper and as good as titanium in certain applications.

Now this is very important. No matter what tube you use, it must be seamless extruded. Port hole extruded structural tube may look perfect and even measure perfect, but it has a seam. You won't see it without an Xray, but it's there and only becomes apparent with a high pressure failure. The cockhead selling the stuff won't even know. The difference between success and failure with a tube is down to two things outside of the machining. It must be seamless tube!!! And it must not yield.
I can guarantee with 100% certainty that of every tension tube failed attempt in this country, it will have been because the wrong tube was sourced.

Tensile strengths are not about just heating and quenching. Alloy ingredients determine tensile strengths during the precipitation or age hardening processes. You can heat, slow cool, quench and age aluminium to your hearts desire. Without the right composition you are never going to achieve the desired result.
So the next logical question. Why not titanium or carbon fibre or even stainless steel? Titanium due to its manufacturing process is not desirable and fails. JR and i went down this road with the yanks 15 years ago and came to the conclusion that it has the numbers, but not the result. Everyones attempts ended in failure.
Carbon fiber if you look very closely past the hype is the last material that should be used. For one it shrinks with heat. That is exactly wrong way Corrigan of where you want to be. Second it contains heat. It is an insulator. Another undesirable trait. Resonance, possibly same with titanium, is a factor that is not there. Not exactly sure resonance is a requirement but i do know that in a tension tube configuration carbon fiber in a centerfire rifle fails dramatically. Looks cool for the 99.99% of dumbos, but is really bad at its job.
Stainless steel? Well nothing about stainless says it should work. Welded seam tube walks a barrel in the direction of the seam. So that's out. Balustrade tube walks groups everywhere. Drawn hydraulic tube in stainless has the numbers but walks shots vertically. Anyone who works with stainless knows exactly why. Stainless did to tubes what Reloder 22 did to Alliant. One bad egg screwed it where everyone only relays the bad result perpetually and most often without first hand experience.

The tubes used successfully here and in the US have been seamless extrusions of 5xxx or 6xxx alloys in tensiles at or above 5 preferably. JR has sent cut lengths of tubes to the US because they at one time were unable to get the right material. It may all sound too hard basket, but with the right material, it really is easy.

[DSD]

Ok so to simplify the question to a level you can understand is the difference between 6061 t5 or t7 the time in the oven or the difference between 6351 t5 or t7 the time in the oven not is 6061 t5 the same as or acheived the same way as 6351 t5?
Wouldn't all extruded tube realistically have a seam as it all had to run around the die to be hollow?
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[Tony Z]

OK to simplify the answer to a level you can understand. No. The "T number"designates a process where the alloying elements are in solution with the aluminium and then quenched. It is not a specific strength measurement like in steel alloys and is certainly not time in oven. 5xxx at T5 is not as strong as 6xxx at T5 where the temperature and time to achieve T5 is different for both alloys.

As for seamless as in truely seamless you may need to consult doctor google. Process has been around for a very very long time. While you're there search precipitation or age hardening of aluminium alloys.

Is it just me or is this line of questioning projecting an image of oxy, tongs and bucket of water? Go for it. Good way of identifying seamed or seamless tube. Let us know how it goes.

[DSD]

Still comparing 5xxx to 6xxx is not what i asked.
I asked the difference between 2 metals of the same composition wih 2 different ratings ie 6061 t5 vs 6061 t6 or 6351 t5 vs 6351 t6, this you did not answer, you can only bluff if the other person does not know the answer.

[Tony Z]

DSD i think i have spelt it out pretty convincingly that i was after specific alloys of types and at tempers for the minimum requirement for a stretcher tube application. I think it is pretty obvious that i have outlined that the temper designation ascends by number thus implying higher yield and tensile strengths in the same material.

You mentioned 6531 a couple of times. A rather obsure and little known alloy but in the engineering game we have come across a few useful people. One of which, long retired but still accessable and still fully capable, is regarded as the best at his trade of specifically stress testing and heat treating that particular alloy, or rather, pressure vessels made from it. If you want pm me and i can pass on his contact.

[Tony Z]

Today we finally got to shoot our first 600 IBS match for the year.
From the drop measurements i had out to 300 yards i calculated the velocity to be around 2550 fps with the 175s working on a 0.495 BC. Using the ballistics program it worked out that from a 200 hundred yard zero to 600 yards an elevation of almost exactly 14 MOA with 2 1/4 MOA left for the wind.

In the sighter period the first fouler went 2 inches low for a 9 at six o'clock. Second went 1.5 inches high for a 9 at 12 o'clock. Came down a quarter minute for water line at 13 3/4 minutes and that is where elevation stayed all day. This works out to 2565 fps with the 43 grain of Re15 load. This barrel is the best 24 inches cut from Jeff H's Hart barrel that has done a lot of rounds of competition as a 30 Redneck. So i expected it to be shy of the 2600 fps you would normally expect with the standard M118 load.

I shot two seating depths, 10 thou in, 2.820" OAL and 10 thou out 2.800" OAL successively in both targets. The next 30 shots were shot without cleaning or any elevation adjustment.
First group went 2.178" and 46 score. Second group went 3.732 and 48.1 score. One shot up high in the 9 ring at 12 o'clock and another low 9 so i suspect seating out is showing vertical.
Second time around first group went 2.925" for 48.1 score. Second group went 2.956" for a 44 score. Again the seated out from lands group went vertical.

Aggregate for the day was 2.9xx and 186.1 score. Jeff had a 2.6xx agg and the same 186.1 score. He also screwed around with seating depths so neither HG put down great aggs. Had we both used set loads it would have been tighter in both aggregates I'm sure.

Where this is good is that i took an old barrel in a realistically non event cartridge like 308 and tested through 400 to 500 rounds the potential of for and against a tuner to myself. Many may disagree, but i could not do in 400 rounds with a tuner what i could do in less than a 100 rounds with a stretcher tube. What is also good is the 308 gave away over 600 fps and a fair amount of BC to be able to be within a bullets diameter of aggregate over four targets. I put this down to the tubes ability to not let the POI shift at all during heating or fouling. None of the test groups at 200 or 300 yards were jagged. This gun shoots OK. Not competitive, but OK. It is possible to string together a number of groups and be led to believe you have a shooter only to find the combination fails in competition at the longer range. This was not the case here.

My next update will be with a way slicker bullet in similar weight to be shot again at 600 yards in three weeks at our next match. After that the barrel gets pulled to become a die making donor. Then i will install a stretcher tubed 636 to get ready for Narromine later in the year.

A few pics from today show Alan's 7JAT LG, Shane's 300 Rednex LG and Bill's 6 BR LG built on a really sweet dual port Omark action.

[Tony Z]

The time for the Narromine 600yard match is fast approaching. The 636 is looking promising but i feel time is going to see it undercooked. Mainly because test sessions are frought with fucken dreadful mirage, even at dawn. Late afternoons suck because air density mixes this time of year with warm and cold layers giving unseen vertical conditions. This year has been ordinary for testing.
Today i got to 200 yards, fuck all wind but fucking dreadful mirage. The Re15 charge looks sorted, the seating depth still uncertain. The groups may look reasonable but mirage could easily destroy or improve a group. So again inconclusive results.

Next week the boys shoot LR while i go down to a mates property to pick a shooting time that suites me. Four bullets to be tested head to head at 600 yards. At this stage of development this gun should be drilling groups under the 2s at 200 and under half inch at 300 yards. Still a way to go but the tube is doing its job in retaining a perfect POI in a very wide range of temperature i have tested it in. From 7 degrees to 30 with zero shift of the base load of 32.5 grains Re15 and gauge measurement of 3.720", or 30 thou bullet jump. The two lower groups are 10 thou out and 5 thou jam, look promising but still inconclusive. Tubes do that. Very little change up close with large powder charge spreads and seating depths that need far longer range to actually determine if the change has altered group potential. Change a lot of stuff and groups vary little with any tube barrel i have ever had anything to do with. Not cut and dry as a bare barrel.

Going off the square rule for extended range using the base load, the aggregate at 600 yards would be just under 2.8 inches as it stands now if it were shot with the same conditions. As JR would say, it should be thrown on the wood heap. It has to get under 0.2" at 200 to agg 1.8" at 600. Or 5.0" plus 40% increase for ten shot groups being a heavy gun for a 7.0" aggregate at a 1000 yards.

[macca]

Your right about a crappy year for testing. Wind and dust here for the last few weekends. Abnormally warm for us and mirage more like November.
45km an hour today with complete drop offs.
I think I will be shooting my old load and barel.
Good luck on your testing.