The TDR - Take Down Rifle
The idea was to build a compact gun that would break down and fit into a brief case,
be accurate, consistent and close to the UK legal limit.

The gun was to be based on the Chinese QB79 - this is a standard example



 Basic specification :- choked BSA barrel, longer bottom tube to give a larger pre chamber, modified valve, regulator adjusted to 1200 PSI
(MTC Mamba Lite) Chinese Bi Pod , My transfer port modification
The silencer fitted now has been printed from a 3d printer - Designed and printed by Albert  - Full details of silencer here

This pic shows original stock - ok but a bit rough                                                             A modified AGS stock from ebay lots of work with the Dremal and drill but I
                                                                                                                                            Think it turned out OK. - New photo just after a DIY re blue.


Took a shot string at the club today, not a disaster but I think a longer bottom tube will give a larger pre chamber which will help with this
as the bottle pressure is dropping the regulator cannot keep up  -  the reg is responding more slowly as the pressure is dropping
a little more power would be nice as well - so will up the regulator pressure.
The target is to get basically a flat line with little to no drop off as the bottle pressure is dropping until the pressure has dropped close to the regulated pressure.
All guns tested using the Blue Shot Android application - connected to the Combro Crono



30/09/13
Re visited today and fired a few more shots to get a feel of the power curve - starting with a 2500 psi fill - (different scale )
I am convinced the drop off is due to the regulator not being able to keep up as the main pressure is dropping off - the next step is a larger pre chamber to test this.
Quite an even drop off  really, still here are today's shots :-




31/12/13
Decided to revisit the regulator today, and thinking on decided to up the output pressure, stripped down and adjusted to 1200 psi this was done by adding some spare spring washers and some testing to get the pressure setting as required, the idea is a short sharp puff of air I think the higher pressure will improve the efficiency of the gun.



Very much improved shot string - a couple of odd readings but these were totally unsorted pellets so this may explain the odd high / low readings
I continued shooting until the power dropped to sub 11 ft lbs - this was on the 116th shot - very happy with this result considering 13 cu inch bottle 177 calibre and a very short barrel.
Very happy with the consistency / shot count now.
Fitted a neoprene (thin) cover over the bottle - the original was a rolled up mouse mat and a bit to thick, this lifted my eye slightly too high for perfect scope alignment, I bought a laptop slip (Samsonite) for 2.99 seems a shame to cut it up, but it has made the perfect cover for the bottle.

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