Author Topic: tx mk3 177 tin bum short stroke.  (Read 5952 times)

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Offline landymick

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Re: tx mk3 177 tin bum short stroke.
« Reply #20 on: May 24, 2016, 02:36:45 PM »
Loose stock screws ?


Offline seagate

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Re: tx mk3 177 tin bum short stroke.
« Reply #21 on: May 24, 2016, 04:36:05 PM »
Here's a exerpt  of what I posted on the AAOC  yesterday. -

I've been thinking about the poor consistency all day at work racking my brains as to what I've got wrong .


 This afternoon fired 10 falcon accuracy through the chroney, there was a spread of 18 fps and averaging 10.6ftlb,same sort of poor consistency with other pellets aswell so it's not the pellet.
 I can't remember the last time I gave the barrel a clean,it could be years ago.Gave It a pull through with a fag filter and it came out like a chimney sweeps brush,so 6 more goes had it clean.

 These are the numbers for jsb made pellets,after a thorough decoke. What a vast difference it makes.

 Each over 12+ shots.
 7.3grn high 812 low 802 10.5 ftlb -10fps spread. - slight power drop in these particular pellets after barrel cleaning.
 7.9grn high 818 low 807 11.7 ftlb -11fps spread.
 8.4grn high 797 low 793 11.9 ftlb - 4fps spread. - so it's likely been over the limit before the barrel clean.

After removing the remaining 2 power shims.

 Each over 20shots.
 7.3grn high 813 low 801 10.6ftlb -12 fps spread -removed 2 shims and the velocity remains the same.

 7.9grn high 798 low 788 11.0ftlb -10 ftps spread.
 8.4grn high 787 low 776 11.4ftlb -11 ftps spread.
 Overall happy with the results though I wouldn't object to shaving off a little more velocity off.

 

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Offline seagate

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Re: tx mk3 177 tin bum short stroke.
« Reply #22 on: May 30, 2016, 09:33:55 PM »
Took the front slip washer out yesterday as the velocity had crept up a little as the hw seal wears in,not to worry as it's got a  polished steel washer already stuck in there so..just looking to bring the velocity down a little ,very happy with the result, now sat at a garden friendly 775-780ish fps-10.5 ftlb, consistency has tightened up a little.
 The thing i'm most happy with is the assembley lube off tinbum,it's more a paste than a grease,it just leaves the seal lip shiney wet,not a bit of it shifts anywhere where it shouldn't.
 Overall it's been a good thing to short stroke the tx,speeded things up a fair bit and reduced lumpiness,it feels like a different gun.
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Offline Gambo

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Re: tx mk3 177 tin bum short stroke.
« Reply #23 on: June 01, 2016, 07:53:31 PM »
very happy with the result

So the job's a gud'un then Nick. 8)

Offline seagate

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Re: tx mk3 177 tin bum short stroke.
« Reply #24 on: June 01, 2016, 08:25:15 PM »
I'm thrilled to bits with it :) :) :).
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Offline seagate

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Re: tx mk3 177 tin bum short stroke.
« Reply #25 on: June 11, 2016, 09:39:16 PM »
Just had a plink with it, velocity has over the last 1000 shots or so crept up to a whopping 815+fps with express, chairgun calculates 11.7ftlb . I think it might be worth removing the titan spring and giving the original airarms spring another chance now the hw seal as worn in . It'd be ideal at around 760 fps.
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Offline seagate

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Re: tx mk3 177 tin bum short stroke.
« Reply #26 on: June 19, 2016, 07:03:10 PM »
Titans springs out.
The standard tx spring is back in  along with  3 shims.I see in the near future it might want a shim removing as it's sat at a between 780-790, time will tell. It feels the same to shoot as it did with the titan,maybe a touch harder to cock but..
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Offline seagate

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Re: tx mk3 177 tin bum short stroke.
« Reply #27 on: July 30, 2016, 11:06:12 AM »
It's had a spring shim stuck down the piston for a few years, just managed to get it out with a little heat to swell the piston diameter.

 Just looking at it all in bits and  with the idea of calming it down abit. I think a day of swapping springs and piston weights could be in order.
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Offline seagate

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Re: tx mk3 177 tin bum short stroke.
« Reply #28 on: July 30, 2016, 05:18:20 PM »
Today's been fun and games,been doing a bit of experimenting with different springs ,shims and piston weights.  And what ever spring,shim and piston weight arrangement is used,aafield 8.4  always make the most power with aaf 7.9 close behind depending on piston weight arrangement .
 Titan springs back in ::) ::) :).
 I started off with the intention of shaving down the velocity but.. went the opposite way with out detriment.
At close of play and over all best shooting cycle is with  a titan spring with the 4mm tinbum thick delrin slip washer under the top hat,shooting aa express 7.9 and vintage webley mosquitos any where up to 800 fps,much more than this it starts to get a little noisey at the pointy end.
 At close of play it's sat shooting very nicely at 11.2ftlb. Recoil is sharp but short. With aa field it make a little more power but is maybe a touch more recoil and noiser at the pointy end. 

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Offline Gambo

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Re: tx mk3 177 tin bum short stroke.
« Reply #29 on: August 01, 2016, 06:54:10 PM »
At close of play it's sat shooting very nicely at 11.2ftlb.

That sounds about perfect! :)