Underlug improvements

[quickdtoo]

As some of you know, I'm working on a home brewed improvement on the underlug to make it a bit stronger since it has 2 weaknesses, it's soft material and  may wear or set back over time, specially with the higher pressure calibers, and it has a hole in it that doesn't provide any support or wear surface against the hinge pin in the frame which is made of much better metal.

My first step was to remove the ejector parts including the forward roll pin. An ejector fits the cutout in the underlug perfect, just like they do on the other end, so I used an old ejector I had for the insert. After annealing the ejector cuz it's too hard to cut or drill,  I cut a piece of the ejector that was just long enough to fill the cutout, plus support the ejector spring on the other end, compressing the spring approx 1/8" more to give it a little more tension, just as putting a BB ahead of the spring does.

I drilled the forward ejector roll pin hole out to .1365" then cut a piece of  Warne torx wrench tool that is .137" in diameter that comes with their rings, to use as a cross pin. I tested one, it's apparently good tool steel and will take a beating before it breaks. Then I drilled the piece of ejector material thru the cross drilled hole so the insert could be anchored in place.

Then it was just a matter of reshaping the insert so it had the same contour as the underlug pivot, then used JB epoxy to shim as described in the barrel fitting instructions.

The guinea pig barrel is a standard contour 22" .308 Winchester barrel that's been rechambered to .300 Winchester Short Mag, the original owner shot the barrel loose on his frame, the results being the underlug was set back enough that it's loose on over 20 of my late model frames. His frame was undamaged and still worked fine on his other barrel.

After I get it all fitted, I'll work up some start loads using AA MagPro powder, if I find any, SW was out earlier this week. Johan at AA recommends it as a starting point due to it's lower pressure, I should be able to achieve .30-06AI velocities with 150gr bullets, with case head thrust comparable to the .270 Winchester that's safe in the Handi.

If the underlug still sets back again, the next experiment will be to heat treat the underlug. I was going to do this all in one step, but decided to try the heat treating in a second step if the insert was insufficient. That will be done by running cold water thru the barrel that's laying in wet carpet, then heating the underlug to cherry red with a MAP/Oxy gas torch, then quenching the underlug in a bath of used motor oil. I've used this technique for heat treating knives and other metal tools, so it will be interesting.

Tim

Insert and pin


Installed insert with pin partly installed, insert darkened for clarity

[McLernon]

Hi Quick:

Did you receive my pm? I have concerns with your plans to use high strength steel for under-lug mods.

Mc

[quickdtoo]

Mc, the only stronger steel is the cross pin to support the insert that adds surface area to the pivot, the entire lug isn't any stronger, just more surface area and thus less stress per square inch of surface. The pivot is still only as strong as the entire underlug, but spreads the load over more area support the hinge pin.

Tim

[knight0334]

Very interesting idea!!

Be sure to let us know how well it works.    Hopefully this might be a cure when using the hotter cartridges.

[myarmor]

Good post Tim. When I was reading it I was thinking about heat treating the underlug as you later described. Personally I believe this maybe the better way to go, but I am no metallurgist.
I look forward to hearing more. And I see you and Mac are working well together on the 300 WSM barrel 
Keep us posted...


-Aaron

[quickdtoo]

I'm no metallurgist either, and I'm concerned that since the underlug is designed soft, it's sort of a failsafe to prevent a catastrophic failure that I would be defeating if I heat treated the underlug to the point that it would handle higher pressure, but might also make the welds brittle and the lug would detach causing great bodily harm, the Encore blow up makes me a little wary.

Thx,

Tim

http://www.rugerhunting.com/forum/viewtopic.php?t=2469&sid=49e24ee86ade69504c310cd646208cc7

[knight0334]

With that in mind, have you considered just spot treating or case hardening the pivot point??

[myarmor]

Man thats a dose of reality and sobering to say the least! And that banana peel is from the chambered end
I would make several phone calls to qualified individuals for some advice on this. I am sure Mac has some resources to direct you too. Then again you probably already have.
Be careful Bro....

[Mac11700]

I looked real careful at that picture..and read what was said about it...and am wondering here...Is that a factory barrel? Was there more holes drilled into the barrel to for the scope mount..? Just seeing a picture of a busted barrel means nothing to me if I don't know all the particulars of everything...and until some one can get the barrel into a lab to be checked completely...I certainly wouldn't want to rule out operator error as well...

Staying with the 50.000 psi loads that Johann suggested shouldn't be a problem ...even if you didn't do anything else but shim it and fit it to a receiver properly..Now...try to make it where you can shoot full pressure loads...I wouldn't do it..

Mac

[quickdtoo]

With that in mind, have you considered just spot treating or case hardening the pivot point??

Yes, that's an alternative I have considered, will wait and see how the current mod  works first tho.

I'll be happy if I can close to 3100fps with 150gr Nosler moly partitions, won't be trying any full power loads, start data is 72.5gr at 2929fps, 43.4kpsi in a 24" barrel.

Tim

[smokinjoe5150]

Tim, why don't you just hard face the latch shelf area and re-cut it. That way, you would have a hard contact surface and a softer backing for strength.
 Do you know what the lug steel type is? It may not have enough carbon to harden properly. I doubt that it's 1095 or similar.

[quickdtoo]

Joe, that won't work cuz the underlug is already too short for any of my frames, my version of hard facing is adding a feeler gauge blade to the pivot to take up the slack. I thought about cutting the pivot back even further, then making a shoe of better material to cut a new pivot in, but that's an option for later, since I'm doing this by hand, it's not easy, I worked for over 2 hours on the first insert when I realized I alread had the insert material on hand in an ejector, but it's not big enough for a complete reface.

OTOH, for an already tight action, doing a hard facing treatment may work very well, maybe Kasenit??

Tim

[smokinjoe5150]

I was speaking of adding facing with a Hard Face welding rod like the Stoody 1105 which will return a rockwell of between 38 and 42.
 I think Kasenit will turn out too hard when applied to any appreciable depth, and if it's applied in a shallow mode, you're not going to get the depth you want.
 Are you not worried about warping the hell out of the assembly.......a red hot lug, a water cooled barrel and then an oil quench?

[quickdtoo]

Joe, I'm not breaking new ground here, Ricci Price has sucessfully welded on his barrels using an air mister to cool the barrel with no warping, but I'm more worried about making the underlug and barrel end up in 2 pieces, this is a home brewed project, I don't and most of us don't have the equipment to weld, so I'm trying to keep it simple and do what most any of us can do at home with minimal equipment, so far, using a cheap drill press is as complex as I've got!!

On a related issue, J-B Weld advised me that J-B Weld epoxy has a compressive strength of 10,733 psi, which compares to J-B Stik at 10-14kpsi, and I've had much better luck with it adhereing that JB Stik.

Tim

[Fred M]

Tim.
You are doing ok by just heating 1" of the underlug. Heat sink the rest of the lug. The hollow underlug  will not transfer much heat to the barrel if you wrap it with piece of wet carpet and shield the barrel while applying heat to the underlug.

The underlug maybe low carbon and may only get slightly harder, just stay with cherry red and dunk only the underlug in used motor oil which has lots of carbon. No big deal.

I am going to do a similar job on my two Handies, I am tired to keep tightening the lug. My friend is an expert welder and he sees no problem with the little bit of welding. This is no rocket science.

The only objection I have is that insane cartridge, only the very slowest powder is applicable and not too much at that. It will work. I will look up a load on QL.

[quickdtoo]

Thanks Fred, I just didn't want to ruin what I've accomplished so far before I find out if it actually helps or not, the heat treating will be the next step if it isn't enough. I added a heavy latch spring to the frame and did a trigger job while I had it apart today.

Tim

[Fred M]

Tim.
Had quick look at QL, it looks as though your not getting 3100ft with a 150gr bullet in that 22" barrel. I am actually very surprised how little that 300WSM offers.

The very slow powders will not work at all. 68gr of XMR3100 will do 2853ft @ 46,1 Kpsi with a full case of powder.

100% filling ratio or 65.5gr of XMR4350 @ 56.5 kpsi will do 3070ft. all in a 22" barrel. The big case head of 0.5xx will generate a lot more back thrust than a 06 at the same psi.

So by the time you load the cartridge down to 50kpsi you are not even equal the 30-06 in velocity. With some very accurate case dimensions the back thrust can be calculated

Please note the above are not loading recommendations only predictions subject to corrections depending on case Ho2 and a few other items.

This is hardly outdoing the 30-06. As matter of fact a 308 is not all that far behind.

Please note. The 300WSM Pmax is 64542psi Piezo CIP.

[quickdtoo]

Fred, the AA MagPro data looks very promising, I'll have to give it a try first If I can find some. Their max load shows 3222fps in a 24" barrel at a pressure of 54.8kps, but that's about 5kpsi too high, so I'll have to use a mid load as best. MagPro was their recommendation, not mine.

Thx,

Tim

[Fred M]

Tim
This is strange Mag Pro with a 150gr bullet and 71gr of powder only develops 41554psi and 2867ft/mv and only burns 85% of the powder in a  22' barrel.

According to QL this powder is much to slow for the 150gr bullet???

[quickdtoo]

Hmmm, maybe QL is a little off?? Can that 2" of barrel make that much difference?

Tim

[Fred M]

Tim
Maybe, could be, somwhere  in between. Case volume who knows. Try it to find out for sure.

[quickdtoo]

Yup, ultimately that's the only way I'll find out for sure. I looked at a lot of other data, there are no other powders that show pressure under about 50kpsi for starting loads. There could be some, but they don't show pressures.

Tim

[tuxdad]

Just be careful Quick !!

Would hate to see something bad happen to you... After all, you are a fixture around here, and in a few other sites.. Would hate to hear you were taken to the ER or worse behind this...

Tux

[quickdtoo]

Thx, I'd hate to see anything bad happen to me too!!

[cascadedad]

Tim, when you finish, let me know and I will drive over and shoot it for you.

I could be your test pilot so to speak.  After all, I am expendable around here. 

[quickdtoo]

I'm not too concerned about the loads I'll be using, if I were, I wouldn't risk one of my frames on it!! I've also been known to tie a rifle to an old tire and pull the trigger with a long string, but that was just to proof a new muzzzlelaoder barrel or powder drum install.

Thanks anyway!!

Tim

[quickdtoo]

Just an update since this thread may have left ya hanging!  I've made this improvement to 3 barrels so far, the .300WSM, .500 S&W and a .270, none shot loose in 60-90 shots, the 300WSM had action flex issues long before I reached 30-06AI velocities, best I could do without incurring a gap between barrel and frame after the shot was ~3000fps with 150gr bullets, equal to standard 30-06 velocities, so that barrel became a donor for the 6.5x55 Shilen barrel project.

The .500 and .270 have lots of full pressure loads thru them and the improvement is maintaining a tight lock up, the .500 has seen some max loads of with RR 700gr cast bullets with lil'gun at over 1400fps, as well as max 350gr XTP and 440gr CP loads, still going strong. 

Tim

[McLernon]

This thread is an "Oldy-but a Goldy".

 I think another strengthening idea would be to complete the welds right to the end of the lug adjacent to the pin. I don't know why NEF stops them short. These short welds have got to be contributing to the set-back problem. Note the force on the lugs recess is back and up at an angle.

P.S. A reinforcing weld could also be added to the two ends as well.

JMO

Mc

[McLernon]

Hi Tim:

Have you ever considered adding this bit of weld right where it is needed?

Mc

[quickdtoo]

As I've stated before, I don't have a welder and most here don't either, as Ricci Price has shown, with proper care, welding can be done on a barrel without damaging it, but that's not within the capabilities of most here. 

Tim

Joe, I'm not breaking new ground here, Ricci Price has sucessfully welded on his barrels using an air mister to cool the barrel with no warping, but I'm more worried about making the underlug and barrel end up in 2 pieces, this is a home brewed project, I don't and most of us don't have the equipment to weld, so I'm trying to keep it simple and do what most any of us can do at home with minimal equipment, so far, using a cheap drill press is as complex as I've got!!

On a related issue, J-B Weld advised me that J-B Weld epoxy has a compressive strength of 10,733 psi, which compares to J-B Stik at 10-14kpsi, and I've had much better luck with it adhereing that JB Stik.

Tim