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Tuning Question for RAW TM/BM owners

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whitefox545

whitefox545

Member
Jan 4, 2017
340
46
pa, United States
Hi! all, This past spring I bought a used TM-1000 bench rest gun, upon receiving it I shot it a bit and was not impressed with it's accuracy so I ran a shot string and found it to be VERY inconsistent in shot to shot speed along with it's lacking accuracy. I then decided to take it apart and freshen the o-rings, springs and rebuild the regulator. when disassembling I found that the Inertia spring was broken and in many small pieces.
I then called Martin at USA Airguns as he was the builder of these guns, He said that he was very sure the broken spring was the problem so I bought a complete rebuild kit and all new springs for the rifle . I then carefully rebuilt the rifle and set the regulator back to be the same as it was set up before tear down. After the rebuild the rifle shot great, so much so I bought a F/Target stock for it and it became my #1 go to rifle for field Target. Indoor Bench rest season started a couple months ago and the gun has given me many 250 scorecards to date but lately it has been getting somewhat erratic throwing several fliers per card and when I shot it through the Chronograph it was shooting about 35 feet per second faster than I had set it earlier?? Today I took it apart as I was going to check to see if the regulator had changed and I found that the Inertia spring was destroyed again!!! I couldn't call Martin today (Saturday) so I went to the hardware and bought a spring that was as close to the correct one as I could find, put the gun back together and shot another shot string, It's right back to proper speed with a very low extreme spread and S/D. Have any of you ever broken that spring? I can't see anything wrong anywhere but will have to keep an eye on it I guess? Hopefully Martin can answer me this coming week as to what might be causing this to happen. Thanks in advance for any info on this. J.L
 
Odoyle, No problem there it's together correctly and I bought it from someone I know and I'm quite certain he did not know it was broken. I really didn't mind rebuilding it as know I can do it no problem. I like to be able to work on all of my guns. I would not mind paying to have them worked on but I HATE the stress of shipping and not knowing if you will get your gun back in one piece!!
 
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TM Hammer Stack.1607223083.jpg


This is the assembly sequence of the hammer. Make sure the hammer and the slot it rides in is not greasy. It only needs a very light coat of very light oil. I've never had problems with the inertia spring in all the years I shot my rifle.
 
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Odoyle, No problem there it's together correctly and I bought it from someone I know and I'm quite certain he did not know it was broken. I really didn't mind rebuilding it as know I can do it no problem. I like to be able to work on all of my guns. I would not mind paying to have them worked on but I HATE the stress of shipping and not knowing if you will get your gun back in one piece!!
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Good morning Jeff,



I would send a PM to members Motorhead or Bucketboy and run your problem past them to get some insight into what may be going on.

Either one of those 2 guys are pretty much Zen Masters of RAW tuning and repair.
 
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Thank you to all that responded!! I will make sure it is assembled correctly but I am 99.9 percent sure that it is. I took pictures of it the first time I rebuilt it so I do have a record of how it came apart when I got it from the original owner when I found it was broken the first time. I am also very interested in Scott's SSG devise as it would be nice to get more shots per fill as It's a tube gun not a bottle gun. J.L.
 
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Thank you to all that responded!! I will make sure it is assembled correctly but I am 99.9 percent sure that it is. I took pictures of it the first time I rebuilt it so I do have a record of how it came apart when I got it from the original owner when I found it was broken the first time. I am also very interested in Scott's SSG devise as it would be nice to get more shots per fill as It's a tube gun not a bottle gun. J.L.
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Gave you a link to read that should help you on the SSG over on the GTA .... As a MATCH gun where your not changing velocity and screwing around with HST settings ... An SSG devise is the Cats Meow for shot to shot consistency and fiddle free shooting. Just need to do a bit of tuning & fiddling initially to get the spring rate correct for the power your wanting. Once done set it and forget it.



Scott S
 
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Thanks Bucketboy!! That's a real nice one!! I'm still having the same problem with the springs I have several buddy's that have the same rifle with NO problems. I have looked and looked to see a difference or find something wrong but cannot!! It's definitely not put together wrong as some have suggested? I'm really stumped as to what is going on with mine? It only lasts about 40 shots and its deformed again and the gun starts to shoot bad again??? I have left two messages for Martin to please call me about this but no call?? Hope they are OK !!!! Good people for sure!! J.L
 
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Have a look into the hammer, at the very bottom there should be a small protrusion from the thread of the hammer pip, this it the thing the inertia weight hits, if it doesn’t stick out far enough the inertia weight smacks into the end of the spring.

If it is not there, the simple solution is to make a small bush that is the same Dia as the internal bore of the hammer with a hole slightly bigger than the spring Dia and slightly longer than the pip on the end of the inertia weight. Once fitted, the bush takes the hit not the spring.



this is a heavier through spring inertia weight that I make, it increases consistency and reduce action noise 



E446D312-6BEB-4BF1-AA05-8DF2CF0E23FA.1607978933.jpeg
8B037965-73E9-4E94-A28D-388A52BDC7CE.1607978934.jpeg




Bb
 
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Bucket Boy, Thank you for the tip!! I will check and see, I just went to the hardware and got a couple more springs one being slightly heavier than the last two I tried. Don't know what effect that will have but it shot the same speed with the same hammer spring adjustment. My gun is a 20 Ft. Lb. rifle for heavy varmint class so I have the double hammer spring in mine. I think you may have something there about the pip threads not sticking out far enough as I seem to remember it stuck out but not by very much. I will check tonight and let you know. I wonder if cutting the spring a little shorter will alleviate the spring (coil) bind I guess you would call it? you would think that the smaller diameter area on the Inertia weight would be plenty of room for the spring to compress without smashing?? Do you think the stronger spring will hurt the dampening effect of the weight? Again thanks for your help!! J.L.
 
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