Sorry it has taken so long to get to this stage but, as usual, life has been busy.
Anyway, before we go into the subject matter we, again, yield the floor to our "Esquire", friend, and counsel, that says:
The conversion done here was carried out by a professional gunsmith. No warranties implied, or otherwise are intended in this article. The milling operations carried out here are sensitive, not devoid of dangers and of a high precision nature.
Do NOT attempt this conversion if you are not completely qualified to do so.
This conversion has NOT been sanctioned by Diana nor by Mayer & Grammelspacher.
This conversion proved safe IN THE GUN that it was performed. We cannot guarantee that all other guns will receive the conversion in the same way.
Please do not ask for measurements or dimensions, Connecticut Custom Airguns cannot provide these data.
All OEM designs and parts' shapes and dimensions are proprietary to Mayer & Grammelspacher and their Diana brand.
OK, so that's out the way, ;-)
In the previous entries to the 430L we discussed the HISTORY, the Potential, and what I THOUGHT would be the FUTURE
How wrong I was! ROFL!
But We did try. And I say WE because I enlisted the help of someone who really knows about ergonomics and human-machine interfaces.
But the challenge was a little too high without substantial modifications.
As time went by, the project fell into oblivion.
BUT, as it often happens to me, one EARLY morning (about 03:30 AM) my 3 year old daughter decided to play "musical beds" and landed in our bed.
I could not fall to sleep again, and I started thinking about the complicated changes that would be necessary to reduce the cocking effort and increase the shootability of the 430L.
As part of those "thought experiments" I referred back to my own re-design of the DIANA 54 action, a short stroke piston that yields overall efficiencies of around 49% (quotient between work input on cocking and pellet energy at muzzle) with the right pellets; through a change in the length of the stroke and in the fulcrum point of the cocking lever. An aspect that has been dealt with in Steve Herr's excellent "Saga of a 56 T/H":
Part 1,- https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th
Part 2.- https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th4603110
Part 3.- https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th8042880 and
Part 4.- https://www.ctcustomairguns.com/hectors-airgun-blog/the-saga-of-a-56-th2541108
But, as an old Professor of Logic and Ethics once taught me: "If you want to truly master one theme argue Pro AND Against it. To learn what there is to learn".
And then is when it hit me in the face: We were going about this the WRONG WAY!
The change in Fulcrum point in the CCA WFTF D54 design was an opportunity afforded by the short stroke of the piston.
In the case of the 430L the action itself is already short stroked. The 430 is a short version of the 460. The 460 is a Magnum springer capable of delivering in excess of 21 ft-lbs in stock form. Of course everyone expects a "Magnum Springer" to have a commensurate cocking force, but no one wants that cocking force for a 12 ft-lbs yield.
SOME gain can be obtained by using an HMO piston (ORing sealed), and that allows a shorter spring with less peak cocking force to be used, but still nothing really dramatic, and the gun still had the same feeling to it.
And then it became obvious that IF for a short stroke you need a long piston, for a short piston you could have a LONG stroke. A long(er) stroke would require also a longer cocking arc, and therefore, you can pack the same work into the action for less peak cocking effort.
This thought also meshed into a nascent design of a simplified piston made up of three parts, easy to machine and produce, it also has demonstrated superb resistance to a FEW dry fires and superior efficiency and uniformity, the strength lies in new materials that were not available 40 years ago.
For central transfer ports it has an added advantage at High Power output levels (24 ft-lbs), but we'll discuss that in another entry dedicated to a special 0.20" cal. D54.
Coming back to the 430L ¿what happens when you use a short piston?, AND more importantly: ¿How short is short?
And so, it was time to make the chips fly, make the idea a reality and test it.
These are the results.
And, as such it is not surprising that the peak cocking effort goes down to 34#
One of the peculiar things about ergonomics is that a weight of 37# may feel "heavy", but a weight of 34# may feel "doable". Rationally, those 3# are "easy peasy", but when they are taken ON TOP of the 34# baseline, they become unbearable in a few dozen shots.
Under the current setup, you can cock the gun with the left hand while shooting with the right, or vice versa. Two handed cocking is not needed.
The other aspect is that the shot cycle is much improved. The mass of the piston just went down from 300 grams to 200 grams, and the cycle is just a sudden "thump".
Power-wise, the LS piston is no slouch; MV stats for 20 shot strings, AFTER 300 shots of "running in" with assorted pellets on the spring are:
JSB GTO's / 6.8.- 905 ± 6 fps for 12.4 ft-lbs
AA/JSB 8.44 / 4.53.- 796 ± 3 fps for 11.8 ft-lbs
BFT / 9.57.- 734 ± 3 fps for 11.5 ft-lbs
H&N FTT / 8,64 .- 772 ± 2 fps for 11.4 ft-lbs
But, as you can see, the lightness of the piston does favour light pellets.
Is this a drop-in mod? NOPE!
The stock requires some modifications and that makes us regard this modification under the same category as the conversion of the 34k Premium to NTec, or the conversion of the Mauser AM03 from NTec to steel spring with ABP.
For starters, the groove for the cocking linkage in the stock needs to grow, and then the cutout for the anti-beartrap safety also needs some lengthening.
Here are some pictures:
For the tests, we equipped the gun with a Bushnell Nitro 6-24X50 FFP scope in ZR Mounts.
And, how does it shoot?
Well, it seems that the 430L's characteristic "largeish" bore still prefers the Baracuda family, among them the BHE, and the BFT, but curiously enough, the gun also seems to like the FTT's
At 10 meters the accuracy is nothing short of exceptional: .
It is not a FT rifle (¿yet?!!!!) but it is perfectly usable in the East coast for squirrels and bunnies.
The black blobs in the above target are a little under ½" So, center to center, the BHE, the FTT 4.51, and perhaps the Baracuda Green, groups would all be in the 1" region.
Disappointing were the performances of the Crosman Premiers, but I truly expected that, given the bore of the gun.
Is there still some work to do?
Hopefully, I will be able to launch the run of special springs for this most peculiar platform (the springs would also be a natural application to the DIANA 280, which is the breakbarrel version of the 430.
And once the final power source (spring) and guides have been finalized, we can then tune the Muzzlepiece in a useful manner.
So, I am reserving the opportunity to come up with a Part 2 to this blog entry. ;-)
Thanks for reading, keep well and shoot straight!