GTA
Gateway To Product Reviews => Air Gun Mods and Tunes => : mcmi December 01, 2008, 09:36:53 AM
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Ok, Mod, if I'm posting this in the wrong category, please put it where it goes.
This thread is going to detail an entire TF99 rebuild. My goal is to have it done by Christmas 2008. I picked this gun up at Airgun Depot for 200 and change. It was a combo with a pretty nice scope. The mounts were crap. I threw them away 25 minutes after mounting the scope and shooting. I'll fix that later. For now, I want to make this gun right.
To start, I like this gun. It feels great in my hands and despite the shoddy interior, it actually shoots pretty accurately. That said, it isn't fun to shoot. Cocking it feels as fun as fingernails on a chalk board. Pulling the trigger is kind of like walking in mud, atop gravel with someone throwing grapes at the back of your head while calling you Nancy, or something similar. Basically, this gun sucks to shoot.
I'ma make it better.
Today I started with the easiest problem; the front sight. It's ugly and it stands up high enough to make an ugly shadow in the scope while sighting. Unfortunately it is not "removable" without a few sharp tools.
This afternoon I lopped off the ugly hoop with a band saw and prepped if for a quick weld. It's made of cast aluminum so it was quite easy to work. 25 seconds on the band saw and about 5 minutes on a belt sander with 400 grit. The hole where the roll pin secured it to a notch in the barrel end forces me to add aluminum before I can go further. I'll have one of my guys take care of this in the morning and I'll finish it and paint it flat black tomorrow afternoon. That'll knock step one off the list.
Then we'll work on a new piston.
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well, i am VERY interested to see how this turns out. keep us posted!(for anyone that might know...is this just an underlever of the 89?)
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I'm very interested too in seeing how this turns out as well.
I almost bought one of these as my first air rifle, I'm glad I didn't.
But, I'd like to see what could become of one with some work done to it.
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Nice start on the upgrade of your shooter 8) we'll be following along to check out your progress on her, nice work. :) Ed
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Quick update:
I had one of the guys fill the hole with weld this morning. It was a tough one. Aluminum is a bear to weld if there is any contamination on it. You have to clean it spotless before welding or you'll get pits and a poor weld. Cast aluminum (especially from China) tends to be full of contamination from within the actual material used to cast. That makes it especially tough to weld. Anyway, he did the best he could and filled the void with metal.
There was a bit of an overfill that had to be cleaned out of the bore of the part, but that was pretty easy with a reamer on the mill.
I sanded the weld off to get everything flat again and filled the small voids with body filler. Two coats of semi flat Krylon later, I left it to dry.
I put it back on the rifle a few minutes ago and took a couple of photos. I think it looks a lot better.
I'll tear this whole thing down tomorrow and start dimensioning the piston so I can draw up a print for that project.
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Looking great Kev, were following along. :) Ed
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I'm certainly following along too.
And wondering what kind of shop you're working in and what you do there.
But I want to know more about how this gun turns out.
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I'm probably boring you fellas to tears but I'm having fun with this. The fellas at work are all pretty stoked about participating as well.They're donating breaks to the build and I appreciate that. As much as I love to design and create, I'm not much of a metal worker. The guys at the shop are irreplaceable in that regard. The 'Library' here is also pretty amazing. By the time this project is finished, I'll owe a lot of thanks to a lot of talented people.
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Thanks Ed, I've been impressed with your work and I appreciate the positive feedback.
Crzy, I work for a large foam manufacturer. I design and help build the equipment that we use to convert extruded profiles into hundreds of different products. It's a fun job and I work with a pretty cool bunch of guys. Thanks for following along.
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It sure sounds like you like to be where you're working, using all the things that you use helps too.
And you got good people to work with too, work is no fun when you can't enjoy being around your co-workers.
I use alot of tools myself...mostly of the Snap-On and Matco brand, and enjoy making money with em'.
Thanks for sharing this project with us...don't stop now.
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Just a "Jack of all trades and Master of none" Buddy hehehe. The joy of airgunning is that I still learn something new everyday and I enjoy working on em almost as much as I do hunting with em, almost hehe. Ed
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im not bored!! Keep up the good work! tell your coworkers we said thanks!
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Ok, tonight I took the TF99 down to take an inventory of what parts need to be rebuilt.
I have decided that the compression chamber will not need to be replaced but I'm going to give it a serious polish job, inside and out.
The first joint on the cocking lever is flimsy. I'm going to have to tighten that up. It has some side to side sloppiness that I might be able to fix with some shim stock or perhaps a larger pin can be bored and installed with a tighter hole. The second joint is fine.
The receiver is is pretty good shape. I'll pretty much leave it as is.
The worst parts are the sear, safety and trigger. I'm rebuilding all three of these. The sear is 3 - .08" slivers of garbage steel that have been riveted together. It's pretty shoddy. I'll build a replacement out of some .25" cold rolled steel. The three individual stamped pieces of steel in the current sear are all mismatched and misaligned. Replacing this alone will be a huge improvement in the way this gun feels while shooting.
The safety is just as shoddy. It's triangle shaped on the finger end and it wiggles side to side in the gun. I want to replace this with a softer shape and shim the new one into the gun to make it feel solid.
The trigger itself is just a piece of stamped and formed .04" sheet stock with a cast steel insert at the top to contact the sear. It's junk and it really takes away from the feel of the gun. The trigger alone makes this gun feel cheap and shoddy. I'm going to cut one out of cold rolled steel and replace it altogether.
The piston is a stamped piece of hot rolled .08" sheet that has been roll formed and pressed into a cylinder with a tapered end. The seal is leather with a nylon compression bushing to hold it on. I imagine that this is like most of these Chinese guns would use.I wouldn't be surprised if this piston fits 20 other guns. The choice of hot rolled sheet is more for the manufacturing ease of forming than it is for the purpose of it's use in a rifle. I plan to replace this with a turned piston of the same shape but made with a harder steel. It will wear better and back and forth more consistently. This should make the gun fire more consistently and that should help accuracy.
The last thing I want to replace is the spring guide/end cap. It's plastic now and I'm going to turn one out of hot rolled steel. I'll cover the guide rod with teflon shrink tubing to keep from having the spring rubbing on a steel guide and causing wear. That should be the easiest of the parts to replace.
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can't wait to see how it turns out! when do you think it'll be done?
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You mentioned cold rolled steel for the sear. Not to sound like a party pooper, but unless you plan on case hardening it, you may want to try some oil hardening or air hardening steel for that part. CRS won't hold up for more than probably 20 shots. If you take an old file and grind your part out of that, it would make an excellent sear. A file can be annealed so you you can shape your part, then you can re harden and temper that piece. If not, you can silver solder a hardened 'sear' to your sear arm and it should hold up forever. I don't have exact specs on hand, but, silver soldering will withstand several thousand psi before it breaks. Just my 2cents. Keep us posted on the progress. It's nice to see someone turn a piece of coal into a diamond.
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RCnMo - 12/3/2008 7:34 PM
You mentioned cold rolled steel for the sear. Not to sound like a party pooper, but unless you plan on case hardening it, you may want to try some oil hardening or air hardening steel for that part. CRS won't hold up for more than probably 20 shots. If you take an old file and grind your part out of that, it would make an excellent sear. A file can be annealed so you you can shape your part, then you can re harden and temper that piece. If not, you can silver solder a hardened 'sear' to your sear arm and it should hold up forever. I don't have exact specs on hand, but, silver soldering will withstand several thousand psi before it breaks. Just my 2cents. Keep us posted on the progress. It's nice to see someone turn a piece of coal into a diamond.
Would D2 work?
I could oil harden, that's not a problem. I figured the cold rolled would be 20 times better than what's in there but the current sear may be oil hardened, even as ugly as it is.
Thanks for pointing that out.
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Sound's like you got a plan and some of the part's are standard in CHINA shooter's, the piston and seal and probably the spring too. Coming along nicely. Ed
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shadow - 12/3/2008 7:45 PM
Sound's like you got a plan and some of the part's are standard in CHINA shooter's, the piston and seal and probably the spring too. Coming along nicely. Ed
Yeah, Ed, the machinery used to make this piston would be expensive to build and tune, so I would imagine it's pretty standard to most of the guns made in that facility, and is likely sold to others as well.
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I believe the current sear would be more wear resistant than crs or 1018. I've never worked with D2, but I believe it is a much better choice than CRS. If you can get D2 up to 64 rockwell, then you have tool quality steel. I think the problem with it would be the tempering process. If you can get a high carbon steel in the annealed state, I believe it would be perfect to work with. It's easy to harden and temper unlike the martensitic and precipitation hardened alloys. Carbon steel can be brought up hard enough to gall HSS drill bits and tough enough to make springs. I'm no metallurgist, but I work with crs and hrs all the time. You could even use crs to make the sear and have one of your buddies use a 70 or 80 series welding filler to build up the area for your engaging surface and grind it to the final shape. I believe that would be hard enough for sear work. Like I said earlier, CRS can be case hardened, but, it's time consuming and to do it to a good depth requires cyanide. It can be done with bone meal and a furnace too, but I would think just a plain old piece of high carbon steel hardened and tempered would suffice. Keep posting your progress, this is the kind of stuff I dig. If you have access to an old leaf spring, they are a good high carbon steel. It would have to be annealed so you can cut it, but it can be re hardened and tempered when you're done.
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RCnMo - 12/3/2008 8:13 PM
You could even use crs to make the sear and have one of your buddies use a 70 or 80 series welding filler to build up the area for your engaging surface and grind it to the final shape.
That sounds like the quickest and most economic solution. Thanks for the info. You probably just saved me whole a lot of work.
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Well, today was productive and conservative. After talking with one of my machinists in the morning, he suggested that rather than rebuild all of the parts, we should edit them to give them clean, hard lines and polish them all for smooth action. We still plan to build a new trigger and spring guide, but we're going to try to fix the rest of the parts.
Today, we dimensioned the sear and the piston - then removed material from each of the contact points. He welded them (as suggested below) and tonight I milled them back into dimension and polished them. All of the contact points now have very sharp, clean lines. Everything is smooth and clean. I'm pretty happy with the parts. Hopefully I'll get the safety and trigger done tomorrow and I can reassemble for a test run.
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WOW...looking good.
Coming along very nicely.
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Really slick.
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Thanks Joe.
It looks like this thread may not be the "total rebuild" I envisioned when I started it but I think the project is coming along well. I'm learning and having fun with it so I guess it's all good. I'm pretty confident that this rifle is going to turn out very nice when it's finished.
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Thanks Ralph. When I spoke with my top guy this morning, he was totally in agreement with your ideas. Once I mentioned welding the contact surfaces, he kind of brightened up and came up with the idea to just use what we have but give all the contact surfaces fresh metal with clean lines. I was hesitant, but after milling and polishing, I think he was right on target. Thanks to both of you for knowing your stuff.
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Hope it works out. It sure looks nice.
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Today I built a new trigger. I think it came out very nice. I left an additional .010" on the sear contact surface so I can tune it to release the way I like when I assemble tomorrow. I like a wider blade on triggers so I didn't round off the face very much. I polished it, but this will need to be done again after it's tweaked. I also polished the safety.
When I got home there was a care package for me from South Summit. The Center Point scope mount has arrived and there was also a B3-1 .22 in the package, heh. I can't wait to get into that baby.
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wow that b3 looks like it has some good grain, and not the glowing orange color the two of mine have been.
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Trigger look's GREAT! Kev, with all this upgrades on her she should be a real smooth shooter when your done. 8) Ed
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I'm impressed and anxious I also have a TF99 and your mods look great I might just try my hand at them.
Thanks
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Thanks for following along guys.
A bit more info: I cut the new trigger from a chunk of scrap D2 steel. It's a bugger to work but it's hard and it'll last for a long time. After I assemble it, and test the action, tuning will require heavy rasps, bench grinders and die grinder pads at about 80 grit. I'll work that down to fine grits (400 or so) before polishing the final job. Then I'll reassemble and test it again just to be sure I have what I want.
Once that's complete, I have to disassemble again to pull the spring guide because I want to finish this rifle with a steel one. I hope to have that done tomorrow but that depends on the trigger/action tune. I could spend all day getting that right. Maybe all weekend. We'll see.
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Well, I have reached a milestone. Today I assembled the trigger assembly and fired a few rounds out the back window. Whoa! what a difference this new trigger makes. I hardly had to tune it. It broke nice and clean. The action is silent and totally smooth. As good as any firearm I've ever shot. I still can't believe how smooth and clean it was.
I also made a saddle bushing for the safety. It was built with thinner material and left to float around in the .25" trigger housing on it's pin. This would allow it to rock from side to side. I built a saddle bushing to wrap around it and nest it into the assembly nice and snug. That cured the rocking and it moves nice and smooth now. The contact between the safety and trigger required a quick tune to slightly break the contact edge of the trigger. Once I did that they locked and unlocked very smoothly. The action between the two is solid and smooth. When the safety is on, there is no trigger jiggle. You know the trigger is disabled because it is stuck firm. Much better than before. It had about a sixteenth of an inch of slop from the factory.
This evening I'm going to go into the shop and polish everything again for a final assembly of the trigger components and that will knock one of the big jobs off the list. Then I'll start on the new spring guide. I have also decided to replace the plastic trigger guard with an aluminum one. It's an aesthetic improvement, but a big one. What's the sense in making this thing fire like a very expensive rifle if it's still sporting flimsy plastic parts?
Here are a couple of shots:
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Neat, I guess this thread has a new home. Sorry I posted it in the wrong area Mod. I'll pay more attention in the future.
I made a trip to the shop tonight and polished everything for the final assembly. I hope it's the final assembly, anyway. This trigger assembly is pretty tough to get together. It requires 3 hands and 7 thumbs along with a bit of luck. The sear goes in through the main spring opening. You have to position its action spring above it and pin it into place. The trigger then has to be slid into the housing while its action spring is compressed into position under the triggers spring retainer. Then it takes 27 tries to get the trigger into position for it's pin without letting the spring slip off. Wheew!
For those of you that have never seen this assembly, here's a pic of it completely assembled:
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looks like it really comin along nicely!
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Yup real soon he'll have a TF99 that they should have been pushing out of the factory in the first place hehehehe. But it's nice to take a ok shooter and bring out the best in her. Great work and more to come. :) Ed
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Very impressive. Can't wait to see it finished with groups.
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I drew up the spring guide today. For those of you that want the actual dimensions in a 3d file, download it here: Guide.skp (http://wtfitmfbs.googlepages.com/Guide.skp). That's a Google Sketchup drawing. If you don't have this software, get the free version here (http://sketchup.google.com/download/).
Here's a pic:
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can'w wait to see what the guns shoots like(you're gonna eventually post groups, right?)...this outta just about wrap things up, right? this really seems like an awesome project!
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Yes, Dave, I can't wait to post some groups. This whole project is about creating a straight shooter out of something that should have been a straight shooter from the factory. Unfortunately, I can't post pics of the "before" because I didn't take any. Not that this rifle was bad, It grouped 2 inches at 30 yards out of the box (with crap scope mounts) and impressed me with it's potential... that's really why I started this whole thing. I hope it works out well. I'd like to see this rifle perform as well as it looks.
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when do you think it''ll all be together?(i'm getting anxious!)
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Didn't work on anything today because we were swamped at the shop. Hopefully I'll get the spring guide done tomorrow or Wednesday. I'll have a shoot after that. I'll post photographs, too! (Imagine that?)
I still need to build the trigger guard but I can work on that in parallel. In fact, I'll probably build that tomorrow afternoon regardless of what else is going on.
It should be done this week. Sorry for taking so long. I'm not a professional.
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can't wait to see it all done!
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Well guys, I got the main part of the rifle done tonight. I'm pretty stoked with the results. This thing is perfect as far as I'm concerned. The only plastic left on the entire gun is the trigger guard, and I'll get rid of that soon :).
Tonight I turned the new spring guide. It's steel and it's a little heavy, but the weight compliments this rifle perfectly. It truly feels balanced now. I love the way this rifle shoulders and feels. The assembly was pretty quick and the scope mounted nicely with the new one-piece mount.
I popped off a few rounds out the kitchen window and I can not wait to get this thing outside and shoot some targets with it.
I'll do a 10, 20 and 30 yard group tomorrow and post results if I get home at a decent hour.
I hope the rifle shoots as tight as it looks and feels. This experience is unbelievable so far.
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Here's a shot of the new trigger and the spring guide without the plastic boot.
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Well done Kev! Can't wait to see how it groups.
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Very well done indeed.
It sure looks nice.
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Very good job Sir!
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Thanks guys. I'm pretty high on this project right now. Thanks for following along.
Ralph, I want to thank you for your suggestions regarding metal hardness. You saved this hard working slob a lot of after hours sweat. I owe you one.
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Anytime buddy. I'm not a pro at anything, just my 2 cents. I hope it holds up for you.
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wow, it seems to really be coming along...SHOOT IT!
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Well guys, I think I have what I wanted when I started.
I came home tonight and zero'd in the scope. That took about 20 shots at 40 yards. I had just enough time to shoot a few groups of five. Here are my last two:
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what size are those groups? nice shootin! looks like your efforts paid off! congrats on having a great shooter!
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Awesome buildup...I also have a QB36-2 and desperately need a diagram(or reassembly instructions) for the trigger group. I thiught with youtr thorough work you might have some info.
Glen
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Glen, this whole project started because I was so impressed with the detailed posts and the sharing of information on this site. There are a few guys that really give a ton of info. I was schooled with some simple searches. I just wanted to join in and add to that pool. I hope others do as well. This is a good, clean American hobby. Kudos to each and every one of the guys that help make this site a place to read and learn. Information is power, guys.
I'll do some scale drawings of the trigger system and upload them for you. It might take me a couple of days, but I'll get them up. It's a pretty simple system and any adjustments you want to make to the trigger action and feel require adding or removing steel. Maybe I can explain some of that as well. I'll certainly try.
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Dave that's a US quarter in there. I had a single jerked shot in one of the groups but it looks like either of them could have been covered with a quarter, aside from that. Both groups had two pellets through a single hole (they were 5 shot groups) and both were at 40 yards (38 and change). I can't shoot any further than that from my kitchen window and it's cold out in the evenings right now.
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Kev, although I don't own a TF99, I've been intrigued with the work you put into yours. This will be one for the archives. If you decide to do another detailed strip/fix, I'm all ears. You do fine work my man.
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your project inspired me to dig into my QB362(tf99). The spring was broken in 5 pieces. ordered new one, deburr and polish internals. However when i finished tearing it down, i was left with a lot of springs, pins and other tiny parts to reassemble for the trigger. I have searched the forum and haven't found a drawing,so your offer to help is greatly apreciated.
You are right. this a great hobby that i am enjoying with my son(B-1 youth) I cant wait to get mine up and running.
Glen
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Nice groups, I suspect they'll get better as the gun gets broken in.
You did a fine job, almost makes me want to get a TF99.
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Hey Kev that is nice job! I have TF99 as well and I did some stock improvments on it and tried to make new seal for it as well. But as you stated the original trigger is not so good and I like what you did with yours. I wanted to make spring giude but I have no lathe. How much would you charge for it if I kindly ask you to turn one out for me? If you can of course.Mine is exactly the same rifle so the measurments are the same.
Thank you
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Anatoliy, it was never my intention to make parts to sell. I don't really have much machine time at work to dedicate to this stuff. Some break time and whatever time I can spend after hours is about all I have to build personal things. I'm going to have to respectfully decline. The drawing for the part is in the thread and you can take this to any machine shop to have it turned. It'd cost as much for them to do it as I would likely charge.
Also, Glen, I owe you some trigger assembly photos or drawings. Sorry I've taken so long but I've been a bit busy lately. I'm off for the Holidays though, so I'll get that stuff up for you ASAP. Most likely tomorrow.
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Thank you Kev! I totally understand what you mean. No problem for me. I really appreciate your pictures of the mods you've done to your TF99. I may follow your footsteps.
Thank you