Author Topic: 208K  (Read 545 times)

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Offline Baggawind

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208K
« on: December 12, 2017, 11:10:16 AM »
I,ve been doing a lot of work on springers lately, namely short stroking a couple of rifles ,  HW97K , TX200HC , and , I have to say , am very pleased with the results, as are the customers. The TX in particular is a delight to shoot after shortening the stroke by 12mm. The owner is getting pound coin groups at 55yards , freehand with it !!  So, buoyed with the results, my attention turned to my SMK 208. Now i,ve already done a total rebuild on the internals, new Titan spring, spring guide, top hat , sleeved and buttoned piston and an Aussie seal and I thought it was all worth while as it was a really nice rifle to shoot. But now, after reducing the stroke by only 8mm, it is totally transformed. I made a barrel weight for the shortened barrel and raised the cheek piece a little. I,ve also done a trigger mod thought up by a guy on the Chinese Owner forum. Now i have a very predictable , light let off , much better than the standard unit. I now have a very capable rifle ,  with a fast action , very accurate and great balance , good enough I believe , to compete at HFT with as well as a bit of hunting.


Offline IceBlerk

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Re: 208K
« Reply #1 on: December 12, 2017, 11:53:16 AM »
Looks nice, Baggy.

But what is "short stroking"? (No need for any smut, Gambo.)
..........so I packed up and went to the pub.

Offline Baggawind

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Re: 208K
« Reply #2 on: December 12, 2017, 02:39:09 PM »
Short stroking is simply reducing the distance the piston travels, usually by adding an extension to the piston or fitting a longer sear rod. Not all springers are suitable for modification but some , like the later TX200,s have along stroke designed for the American market , where there are no restrictions on power. My SMK has a stroke of 88mm , far more than required for the UK market , so I reduced it by 8mm. by making a piston head extension. The firing cycle is now very fast with very little felt recoil.

Online Gambo

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Re: 208K
« Reply #3 on: December 12, 2017, 07:13:57 PM »
what is "short stroking"? (No need for any smut, Gambo.)

Awwwwww, shucks!! :-\ :-\

Offline seagate

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Re: 208K
« Reply #4 on: December 12, 2017, 08:58:59 PM »
 Nice looking rifle Mel.
 What are you making the piston heads from?
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Offline Baggawind

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Re: 208K
« Reply #5 on: December 12, 2017, 10:16:00 PM »
The 97 head was made from acetal , fixed with a screw threaded into the sear rod. My SMK was made from aluminium , clipped over the piston end and fixed with four radial grubscrews. The TX was a Jim Tyler idea. It is just an acetal plug 12mm long, pushed into the cylinder and sealed with an o ring and a tapered transfer port drilled through the middle. I have to say that rifle, in the hands of its owner, is pcp accurate and a delight to shoot.

Online Gambo

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Re: 208K
« Reply #6 on: December 12, 2017, 10:41:37 PM »
an acetal plug 12mm long, pushed into the cylinder and sealed with an o ring and a tapered transfer port drilled through the middle.

I've read about that idea before.......but have to say it does go against the accepted theory of keeping the transfer port as short as possible for the reduction of lost volume, and therefore greater efficiency.

However, if a rifle is still making close to the legal limit even with a long and voluminous transfer port, then I would suggest it doesn't matter a great deal.....unless FAC power levels were being chased.

Offline IceBlerk

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Re: 208K
« Reply #7 on: December 13, 2017, 07:44:03 AM »
Am I right in thinking, Baggy, that you do this "tuning" exercise to improve handling rather than to affect power?

You change the amount of travel of the gubbins inside the gun so improve stability, yes?
..........so I packed up and went to the pub.

Offline Baggawind

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Re: 208K
« Reply #8 on: December 13, 2017, 10:32:37 AM »
In manner of speaking yes. The idea is to reduce the felt recoil.

Offline seagate

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Re: 208K
« Reply #9 on: December 13, 2017, 10:20:02 PM »


  ''In manner of speaking yes.''   :)
I plink , therefore I am.