Part 3.- Full Power Diana 430L
The same disclaimer applies!
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.
So, with that out of the way, let's get into what would be Part 3 of the "Gunsmith's Tune" series.
Full power means different things in different guns and to different people.
We had looked into the USA available springs for the 430 before and found a good performance with the long stroke piston and a Vortek spring from a kit, BUT we knew that the gun could deliver more.
The experiments performed with the Walther LGV gave us some ideas and the results of those ideas, as applied to the DIANA 280 have already been published, so we will not repeat ourselves here.
What we will report here is what happens when a FULL sixed Titan XS spring #1 is used in a 430L.
After installation, we were painfully aware of the increase in Peak Cocking Force (PCF) to about 46 #;
with H&N's BFT we were obtaining 842 ± 2 fps for a ME of 15 ft-lbs.
Accuracy was "Hunting good", as you can see from this target shot under windy conditions at 20 and 40 yards:
For a hunting gun it was good, as seldom in a hunt will you take more than a couple dozen shots, but for some target shooting, it was too high a cocking effort .
What was an interesting experience was that the accuracy of the BFT prevailed over a wide range of MV's.
So, now that the full power of the 430L had been found (15 ft-lbs is the top limit), it was time to use the same spring, but cut back to achieve a better cocking effort that would be sustainable for some target shooting.
Part 4.- What can we get for a 36# PCF?
Can we get good efficiency, with a good shot cycle, a usable PCF for a useful return in ME, with good accuracy?
Well, the answer is yes, with some qualifications.
Once the Titan XS #1 spring came back to me, we ran a benchmark and found that it was doing pretty much hat it had been doing before it was lent over (right after the LGV tests) at 14.9 ft-lbs.
Based on the tune of the breakbarrel "brother" of the 430, we knew we would have to lop-off 4 full coils, and so, after cutting, sanding, forging closed and relevelling and polishing the ends, we chronoed the best 3 pellets at :
BFT 9.57/4.51 .- 727 ± 5 fps for 11.2 ft-lbs
JSB 8.44/4.53.- 797 ± 5 fps for 11.9 ft-lbs
QYS 8.49/4.50.- 777 ± 3 fps for 11.4 ft-lbs
Right where we wanted to start! Good idea this one of taking notes, LOL!
And once we determined that the cocking force did measure up to close to 35#:
It is a very inexpensive scope, usually sold for less than $80 in various configurations
Amazon doesn't sell them anymore, even AliExpress does not recognize the "brand".
Go Figure . . . one more mystery.
So, what sort of performance, where it counts, is the rifle delivering now?
At 10 meters, with the proper timing and support it yields nearly match grade accuracy:
Moving back to extended ranges, taking the time to dope the wind, and supporting the gun in crossed sticks:
And at 72 yards, the gun delivers about the same (2.4 MOA's) / 0.69 mrads
Now, is this a FT gun? Nope!
It lacks the stock, the weight, the stability, and using 7X at 72 yards was an "interesting experience" LOL!
But the gun is eminently SHOOTABLE. It points well, it reacts well, it "stays in the shot" after recoil, it's comfortable to cock and easy to load with the loading port wide open due to the small scope.
It could be a great pigeon popper, or a tree rat - 'radicator.
And there is one more discipline that is dear to me and close to my heart: Siluetas Metálicas; where the shootability of a gun trumps hair-splitting precision. So, we did a test following the Pyramyd Air Cup distances, and shooting against the clock (53 shots in less than 4 minutes), and this was the result:
I took TWO ranging shots on each target, as I had an idea, of where the reticle of this peculiar (and "ephemeral"?) scope was going to take me and, as usual, the turkeys proved to be the hardest.
But I would take 7 misses with a "new" gun, of unknown trajectory, and just "guesstimation" aiming any time, LOL!
As interesting as the story is, it is quite fascinating how much MORE the platform could have yielded with a bit more real airgun engineering.
By no means is this the true MAX. But for expanding the capabilities further, we would have to alter the cocking linkages beyond what any, even the advanced, tinkerer would be able to do.
And, in so doing we would be touching on the heels of the 460, where this gun was derived from.
So, possibly, this points out to our USUAL way of doing things: Starting from the large platforms and seeing where we can increase the efficiency to the point where at least half the work put into the gun goes into the pellet.
We will explore that in the near future, when we develop the K-98 Mauser (by DIANA) into a ballisticaly optimized, 0.177" cal sniper games tool.
There is still some work that COULD be done with the 430L:
Some spacing of the spring could improve the shot cycle still further.
A heavier Top-Hat could improve the yield for the relatively heavy BFT
Different material ORings could increase the rail speed and the yield, though that would probably require a stouter pellet and runs the risk of changing drastically the very mellow shot cycle the gun has now.
We will continue using the Titan XS springs, they provide reliable, consistent energy over time and their tolerances work well for professional tuners that do not have the time to tailor a guide to a spring that is slightly different than the next one.
Apologies for having taken so long to finalize these two series. As for most of us, life has not been what it used to be before the "Year of the Masks".
Keep well, stay healthy and sane, get vaccinated, and shoot straight! ;-)