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Pulse Rifle Thompson Extension
http://forum.alienslegacy.com/viewtopic.php?f=3&t=4365		 Page 1 of 1
Author:  LDR [ Thu Jun 19, 2008 2:58 pm ]
Post subject:  Pulse Rifle Thompson Extension
While putting together my PR build and getting the appropriate pieces i noticed that the end of my Hudson Thompson barrel did not fit into the Matsucorp metal vent. This was becuase of the sight, and wider part of the barrel tip. I was originally going to cut this end off, however after seeing various photos (some from prop store and some from Rob), i'm now able to see how the end of the PR was actually made. Sorry if this is old news!

One the top image below of the PR(thanks Rob), you can see the start of the wider section of the end of the thompson barrel marked '1'. The end of the thompson barrel is marked '2'.

In the second picture of the thompson these areas are also marked '1' and '2', however on the PR they have obviously removed the sight located in the red box.

So if making a PR from real steel thompson, do not cut the whole end of the barrel off, just the sight section.

The third picture shows the extension from a pulse rifle that is on the prop stores website. This extension obviously screws into the end of the thompson barrel, making it long enough to match up with the length of the SPAS cage. '2' on all the images shows the end of the thompson barrel and the join of the extension. '3' shows the extension end.
Also interesting to note is '4', which shows a ring where i presume the metal vent part ended.

Is anyone here got any ideas on making the screw part extension? Can this sort of thing be bought off the shelf?

Hope this isnt old news, and hopefully it will be useful to other PR makers!

Lewis

Attachments:
PR.jpg
PR.jpg [ 67.94 KiB | Viewed 2600 times ]
Author:  Jester [ Thu Jun 19, 2008 3:18 pm ]
Post subject: 
nice bit of detective work dude i didnt know it :D ,the extension looks like a bit of threaded rod that has been drilled through or an old bolt which is what i would have used, then all you need is a tame blacksmith or engineer to cut the threads for you, you can pick up cheap tap and die sets on flea bay if you wanna do it yourself ,if you dont intend it to fire anything just araldite the parts together should be more than strong enough ,there may even be someone on here that makes them i dont know ,all the best mate ,Rob
Author:  Tarim-rex [ Thu Jun 19, 2008 4:39 pm ]
Post subject: 
might be the blank adapter
Author:  Bug Stomper [ Thu Jun 19, 2008 6:27 pm ]
Post subject: 
On the real steel Thompson the bottom of the front sight consists of a ring that slides over the barrel. It is fixed in place with a small lateral pin that just graces the barrel with half it's diameter (if you look closely you can see the slight groove in the barrel).
The pin can be seen on the airsoft replicas too (the barrel, the front sight and the pin are all one piece on these though).
The barrel extension has the same outer diameter as the front of the Thompson barrel e.g 19.05mm or 0.75" (this also means that all available barrel vents I know of are too small - that's why I did my own).
It acts as a restrictor/blank firing device by restricting the barrel diameter to less than half of the original size. This is necessary to build up enough gas pressure to operate the bolt (you have no bullet to do the job).
The front of the barrel extension shows a significant bevel and two flat faces for a wrench.

Cheers,
Stefan
Author:  LDR [ Thu Jun 19, 2008 8:00 pm ]
Post subject: 
Thanks Stefan, on the Hudson the front is all one piece to. So the sight will need to be hacksawed off.
I also noticed that the 10 hole vent i have, the ring at the front is way to small, shouldnt be a problem replacing that part though.
The barrel on the hudson is 22mm.

lewis
Author:  Jester [ Thu Jun 19, 2008 8:14 pm ]
Post subject: 
hey lewis if you can get it to me i will swap out the vent ring for ya should be really easy quick cut and shunt job , Rob
Author:  LDR [ Thu Jun 19, 2008 8:39 pm ]
Post subject: 
cheers rob, pm sent.
Author:  Bug Stomper [ Thu Jun 19, 2008 8:41 pm ]
Post subject: 
Lewis,

22.23mm (0.875")is the outer diameter of the sight ring. The actual barrel is "only" 19.05mm (0.75") at the muzzle. I'm not sure if this is replicated on the Hudson, but on the RS Thompson, the barrel extends about 1mm beyond the sight ring to the front. You should be able to use this as a guide for how much you have to take off your single piece barrel.

Cheers,
Stefan
Author:  LDR [ Fri Jun 20, 2008 9:27 am ]
Post subject: 
cheers stefan. Its all clear now. On the hudson the sight,ring, and pin are all molded onto the barrel, however as you say there is a slight lip so i can see where to file down the outer barrel.
thanks again for explaining.

right where do i get 19.05mm tubing from in the UK?

lewis
Author:  Jester [ Fri Jun 20, 2008 11:14 am ]
Post subject: 
try the steel section at your local B&Q in my local they do a 20mm black steel tube and if you dont want steel they do it in aluminium too the wall thickness is all wrong but it can be sleeved or thickened with the judicious application of filler and paint :D ,Rob
Author:  LDR [ Fri Jun 20, 2008 11:24 am ]
Post subject: 
funny i was just looking on their to. the wall is 1.5mm, which i presume is a little thin. Will measure the hudson later to see how big it should be.

trip to b&Q this weekend then!

lewis
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