Installed a ARH Magnum kit in my buddy's R1 grinding/scraping sound?

[Ike the GSD]

My buddy and I installed an ARH magnum kit in his R1 today, it's the same kit we installed in my HW80 not long ago and now his rifle makes this grinding/scraping sound and I can't figure out why? We installed the kit in exactly the same way as we did my rifle, the only thing I can think of is the cocking shoe is rubbing on something, but why wasn't it rubbing with the factory parts? I took the action out of the stock and I couldn't see any metal shavings or any place that showed metal on metal contact. His rifle was made in 1991 and has the old style shoe. Is there a way to convert the older rifles to the new style cocking shoe ? I need help fellas I just don't know what could have happened.🤷‍♂️ Thanks guys👍

Wes

[Toxylon]

 I went through the exact same thing with my old HW80, as detailed in my HW80 thread. To fix it, I bought and installed a new type cocking shoe and the scraping / friction vanished.

You can fit a new style shoe into an old HW80, but you need to make a little extension to the stock's cocking slot, internally, for the new style shoe to have room at the end of the cocking stroke. If you don't, the gun won't cock.

[Ike the GSD]

I went through the exact same thing with my old HW80, as detailed in my HW80 thread. To fix it, I bought and installed a new type cocking shoe and the scraping / friction vanished.

You can fit a new style shoe into an old HW80, but you need to make a little extension to the stock's cocking slot, internally, for the new style shoe to have room at the end of the cocking stroke. If you don't, the gun won't cock.

Thanks for responding so quickly Duke 👍 Is it the kit causing this? The rifle wasn't doing this before we installed the kit, do you have to modify the new style cocking shoe as well or is relieving the stock wood sufficient?

[Toxylon]

I installed a Titan #8 spring, with a new factory rear guide and a Delrin custom tophat, into my HW80, and the cocking stroke degraded like I've never seen, despite the #8 being a lightweight spring of correct length for the 80.

As far as I could tell, the springier, livelier new spring forced the very-loosely-fitted cocking arm to lean heavily into the cocking slot. Never have I seen such loose cocking arm fit, as on my Dianas etc. the joint is almost slow to move, but I was told that shimming the looseness out would induce galling.

When you order the new type cocking shoe, you must make sure you get the shoe for the HW80. Some parts suppliers have one code for the new type cocking shoes, when there are actually two different types: one for the 26mm guns such as the HW95, and the other for the 30mm guns such as the HW80. If you installed the 26mm shoe to a 30mm gun, the shoe would tear up the outer surface of the receiver tube with the first cocking attempt.

Some people have reported a need to judiciously file the new type shoe to fit an old HW80, but I didn't need to do any filing. I still stoned the sharp edges off, and lubed the shoe heavily, as a precaution. The slot extension inside the stock was all it took. I made mine as small as possible (some clearance, obviously), since the trigger guard front screw hole is quite close, and I don't want to weaken the stock. 9 mm long, 7 mm wide, 3 mm deep. Many people have made theirs bigger. Your call.

[Ike the GSD]

Thanks for your input Duke, unfortunately the problem is worse than just upgrading the cocking shoe. I asked Mark611 what the problem could be and he said the grinding noise was coming from the piston contacting/galling the top of the compression tube😬.  Taking the rifle apart confirmed what he said, and there's about a 5/16" wide gouge on the top inside of the tube that starts about where receiver grooves are. He said that smoothing it out with a ball hone or a slotted dowel rod and emery paper should correct the problem. If honing the tube works, I'm going to suggest he upgrades the cocking shoe to the new style, it can't hurt and I figure it might offer more support than the old style shoe. Thanks again Duke, I appreciate your help👍

Wes

[mikeyb]

Once the galling is smoothed out can the piston skirt be "buttoned" to prevent metal-to-metal contact in the future?

[Ike the GSD]

Once the galling is smoothed out can the piston skirt be "buttoned" to prevent metal-to-metal contact in the future?

Hey Mike, I'm not really familiar with buttoning a piston but I think converting to a new style cocking shoe will mitigate some of the problem by limiting how much pressure the cocking arm can press/push against the piston. My limited understanding of where buttons are positioned on the piston makes me think that's not an option with this compression tube, the groove/gouge is pretty deep and wide, I'm concerned that regardless of what we do the problem will exist to some degree, but we'll see, all we can do is try. Just for curiosity's sake I put my old spring and guide in his R1 just to see how it acted and the grinding almost but not quite went away, that leads me to believe the spring load/strength has something to do with what's going on along with the unsupported old style cocking shoe. I'm kinda new to this so I'm just speculating but,the rifle appears to have been doing this for a long time, the piston has a rough spot that mirrors the gouging in the tube and I think polishing that alone will move us in the right direction. Just so you have an idea about my feelings on this, I looked at new compression tubes on Chamber's website this evening LOL! They cost 139.99 British pounds which translates to $176.89 😬 I'll add updates as we move along👍

[mikeyb]

One example.

http://anotherairgunblog.blogspot.com/2014/03/webley-hatsan-patriot-piston-buttoning.html

Many ideas out there. I've never needed to button a piston (yet) but I can imagine it working well to eliminate any metal-to-metal contact

[KWK]

Once the galling is smoothed out can the piston skirt be "buttoned" to prevent metal-to-metal contact in the future?

Hey Mike, I'm not really familiar with buttoning a piston but I think converting to a new style cocking shoe will mitigate some of the problem by limiting how much pressure the cocking arm can press/push against the piston. My limited understanding of where buttons are positioned on the piston makes me think that's not an option with this compression tube, the groove/gouge is pretty deep and wide, I'm concerned that regardless of what we do the problem will exist to some degree, but we'll see, all we can do is try. Just for curiosity's sake I put my old spring and guide in his R1 just to see how it acted and the grinding almost but not quite went away, that leads me to believe the spring load/strength has something to do with what's going on along with the unsupported old style cocking shoe. I'm kinda new to this so I'm just speculating but,the rifle appears to have been doing this for a long time, the piston has a rough spot that mirrors the gouging in the tube and I think polishing that alone will move us in the right direction. Just so you have an idea about my feelings on this, I looked at new compression tubes on Chamber's website this evening LOL! They cost 139.99 British pounds which translates to $176.89 😬 I'll add updates as we move along👍

That area should get a very little dab of grease when assembling to protect the skirt.
Smooth out the galled area with abrasive on a dowel. Back and forth. No need to hone the whole tube circumference.
If you button it the buttons can straddle the worn area. You said it's 5/16 wide.

[Ike the GSD]

Once the galling is smoothed out can the piston skirt be "buttoned" to prevent metal-to-metal contact in the future?

Hey Mike, my buddy and I have researched putting a derlin ring on the rear of the piston in addition to polishing out all of the compression tube defects, the groove is so deep I don't think we can completely eliminate it but once we smooth it out the ring should ride there fairly easy. We ordered a ball hone from Granger and it should be here today. My buddy is going to order a stick of derlin 1 3/4 and turn a portion of it down to make the ring, we're going to use the rest to make spring guides👍 I'll keep everyone posted on our progress.

Wes

[Ike the GSD]

Once the galling is smoothed out can the piston skirt be "buttoned" to prevent metal-to-metal contact in the future?

Hey Mike, I'm not really familiar with buttoning a piston but I think converting to a new style cocking shoe will mitigate some of the problem by limiting how much pressure the cocking arm can press/push against the piston. My limited understanding of where buttons are positioned on the piston makes me think that's not an option with this compression tube, the groove/gouge is pretty deep and wide, I'm concerned that regardless of what we do the problem will exist to some degree, but we'll see, all we can do is try. Just for curiosity's sake I put my old spring and guide in his R1 just to see how it acted and the grinding almost but not quite went away, that leads me to believe the spring load/strength has something to do with what's going on along with the unsupported old style cocking shoe. I'm kinda new to this so I'm just speculating but,the rifle appears to have been doing this for a long time, the piston has a rough spot that mirrors the gouging in the tube and I think polishing that alone will move us in the right direction. Just so you have an idea about my feelings on this, I looked at new compression tubes on Chamber's website this evening LOL! They cost 139.99 British pounds which translates to $176.89 😬 I'll add updates as we move along👍

That area should get a very little dab of grease when assembling to protect the skirt.
Smooth out the galled area with abrasive on a dowel. Back and forth. No need to hone the whole tube circumference.
If you button it the buttons can straddle the worn area. You said it's 5/16 wide.

My buddy and I decided to install a ring rather than buttons because we felt it would offer more support to the piston. I'll keep you guys posted👍

[KWK]

You think you will hone the groove out? And it will never be concentric from honing. I wouldn't hog out that tube. Hones aren't for stock removal anyway.
Really, the delrin ring would pass right by the grooved area if fitted well. Just like a piston and rings pass by the ports in a two stroke engine. Delrin is an outstanding bushing material.

[Ike the GSD]

You think you will hone the groove out? And it will never be concentric from honing. I wouldn't hog out that tube. Hones aren't for stock removal anyway.
Really, the delrin ring would pass right by the grooved area if fitted well. Just like a piston and rings pass by the ports in a two stroke engine. Delrin is an outstanding bushing material.

We're not gonna try to completely hone out the area, we're just going to remove the high sharp spots.

[Ike the GSD]

honed/smoothed out the groove, polished up the tail of the piston moly lubed the contact points and put her back together and she cocks slick as a whistle👍😉  I'm not sure my buddy wants to install the ring now LOL!

[Mark 611]

Good job Wes!!! trial and error are the best teachers!