The "Nano-Strike" an exercise in efficiency

Disclaimer:
Modifications made to this pistol were performed by an experienced professional airgunsmith. And, proved safe in THIS gun.
No warranties are implied nor extended.
We have no control of what you do on your own.
If you do decide to make ANY modification to an airgun, be conscious of which elements are under force or pressure and realize that, even a "little pre-compression" or as little as 10 BAR's CAN cause SERIOUS bodily harm.
These modifications have not been reviewed, nor approved by DIANA / M&G, BuckRail, or ALTAROS Air Solutions
Again: Be careful! You are the only guardian of your health and safety.

"In the beginning"

When someone asked if I could take a look at his Bandit pistol, I sort of reluctantly replied with my usual questions:
1.- What's wrong with it?
2.- What do you want to do with it?

Answers came back forthrightly:
The regulator was not working properly
The person is a professional wildlife manager, mainly of iguanas and other non-native/invasive species in Florida.

Now, THAT piqued my interest and I offered to do the job for free as a support to the Wildlife Department.
My friend answered that that was not necessary, and he would pay for "whatever was needed".

Not often does a gunsmith get a "Carte Blanche" to create something outstanding, and so, the project started.

Upon receipt of the pistol I could see that something was not right.
Initial tests showed MV's all over the place. And a very low shot count (barely one magazine of 7 shots) between fills.)
So, a disassembly was in order.

The Process Starts

Part of the problem was the HUMA regulator and the "plenum" added. Dimensions simply didn't make sense, I searched in my ALTAROS regulator prototypes and found a very interesting one, vented and with the plenum already included. This was an experiment that did not pan out, but it could be the solution here.
Comparing the two "trains" I saw this:

At top is the HUMA regulator that seems very compact, but it wasn't working.The OEM valve on top was a bit smaller than the improved/HP Altaros valve (higher power), still, I decided to go with the OEM.
We also thought about using an extended tube, but the trigger arrangement would not allow it:

At the top is the OEM barrel, then the Stormrider-size tube and in the grip, the Bandit tube.​

As you can see, the brackets that hold the trigger parts in place are different.

So, a decision was made to keep the tube but use a longer barrel to improve efficiency.
An efficient airgun seldom needs a mod. Ineffiicent airguns do.
And we planned to make this a very efficient airgun,
So, a Lothar Walther blank was sourced and we started on the preparation. A LOT of lathe and milling/drilling work goes into making a good barrel from a blank:
-Creating the shank
-Drilling transfer port and locator holes
-Making the glands for the Orings
- and, most important: creating a good "leade" that will allow the pellet to pass the TP and arrive to the rifling centered and unharmed.

After the shank is created and the TP has been drilled/milled, the "leade" has to be cut.

It's a slow process of trial and error, subsequent pellets are pressed into the leade to ensure that the pellet enters the rifling unscathed.

Once the head passes without any tear or undue deformation

A little more takes care of the skirt

Testing with hard (Tin) pellets gives you a better idea. On the left, the OEM barrel, on the right the Lothar Walther

A view of the L-W riflng (this one is a traditionally rifled barrel) in 0.22" for a smaller caliber and high velocities, the Polygonal work better.

The new barrel is as long as the OEM WITH the mod. The blank was 16 mm's OD, as we planned on using a free floated barrel initially.

Cutting the ORings for the barrel seal also merits some attention. The glands need to be sized so that the insertion/extraction of the barrel will not cut or damage the ORings, in this case a bit more depth had to be given to the left gland.

Once the TP is properly "registered", it's time to drill the locator holes for the top of the action.

And the feeding can be tested. I like the SSS (Single shot shuttles) more out of habit than anything else, but I have found the magazines, for the most part, are troublemakers.

Once the action was an assembly, we could dedicate to the power source, this is the "train" that we settled in: Altaros vented regulator with plenum and the OEM valve

We started with a low pressure in the regulator (100 BAR in this case)

The valve and regulator were inserted in the usual manner for Altaros regulators

Air tightness and reg setting were tested / measured and we proceeded with testing

After some adjustments in the FFH unit, we were getting some decent speeds (for an 18.52 grs pellet)

And I thought I was done with it, LOL!

My friend had found the BuckRail airgun accessories page and wanted the "full Monty"

After some conversations with BuckRail, it was clear that they could not build a custom version of their "handguard", so considerable slimming of the barrel, and enlarging of the barrel channel in the handguard were in order.
Because milling plastic is a delicate exercise, it had to be done slowly and carefully

Taking careful measurements we arrived at the max OD that the piece coud receive, got a special cutter and proceeded SLOWLY

VERY slowly

REALLY slowly. Using a Stormrider air tube and some wooden pieces, we managed to keep the plastic printed piece in good / rigid grip and alignment.

After reducing the OD of the barrel substantially, we tested the fit and ensured that there was no pressure on the barrel at any point. That everything worked and that the fit was proper.

We also fit the stock support (what in a firearm would be the "buffer tube") using a specially designed and made adapter, so that adjustability of the FFH would be conserved.

And this was the semi-finished product. Semi-finished because my friend now wanted a mod.

So, we ended up with this. I have to admit it is a nice, clean, "racy" looking carbine.

At the same time this project was progressing, a group of friends were starting a thread in a forum about modifications to the Bandit and another about "Compact" hunting guns.
Problem is that there is "compact" and then there is "COMPACT"
Take a look at this picture:

From the Top: Ful size Nova Liberty, then a 3P / youth oriented Stormrider, then an Avenge "X" in semi-bullpup configuration, then a DIANA SkyHawk, also a semibullpup, but with shorter barrel and an airtube, and at the bottom, the Bandit conversion with the stock collapsed.

From 46" to 27" different purposes, different power levels, different architectures.
Interesting array of options we now have in our airguns.

If we compare the Bandit carbine to the other two that qualify as  "compact", we get this:

In this picture, the Bandit Carbine has its stock extended to "Adult size", and it is still shorter than the other two.

A few more pictures of details:

Attechment of BuckRail's stock support to the adapter

Stock extended

Stock and Grip Adapter setting

Junction of the forend/handguard with the grip adapter

Where it all comes together, action, barrel, handguard/forend, grip adapter, scope mounts and scope. Neat and clean.

And the muzzle end.

The results

All nice and dandy, yes, but what about performance?
A lot of airguns, especially in the low price brackets are very good looking, but when it is time to perform, they do not, so .... what about performance?

Well, I'll let the numbers speak for themselves:

From 230 BAR's (perfectly safe in THESE airguns) to the regulator pressure of 125 BAR, the little platform yields 14 perfectly good shots with sample Standard Deviations of between 6.1 fps to 3.3 fps over the 14 shots.

The efficiency of the power plant is quite good, yielding between 16.7 and 19.1 CC-BAR's/ft-lb

If we compare the efficiency of this little carbine to an AirVenturi "Micro Strike" (the only other platform that closely approaches this in dimensions and weight), as reviewed by my good friend Steve Sciali, the Micro Strike needs 41.8 CC-BAR's for every ft-lb delivered at the muzzle, so between 2  and 2½ times more effiicient.

I am already hearing some complainers voicing the objection: "¿Why care about efficiency? It's not like we handpump our airguns anymore, compressors are so cheap nowadays, why bother? Electricity is cheap!"

OK, yes, electricity is, in general, cheap; compared to what RF ammo costs. BUT, there are three aspects to be taken into account:
1.- Noise, if you are a hunter (as opposed to a game-sniper), you do not want excessive noise, and if an airgun is inefficient, where do you think the energy that is not put into the pellet goes?
Yes, some heat, yes; some vibrations (not so much in a PCP), yes, but mostly: NOISE! 
Steve comments that only ONE of his umpteen mods was capable of reducing the sound signature to decent levels. So, noise is one of the concerns in an inefficient PCP
2.- Compressors' lives are rated in hours. Filling this little carbine's 31.7 cc's available volume takes exactly 2 minutes with a Port-Air compressor. Filling the 80 cc's of the Micro-Strike, would take 2.5 times those 2 minutes or 5 minutes. 30 (yes, THIRTY) fills of the Bandit Carbine will take one hour of your compressor life. TWELVE fills of the MicroStrike will do the same.
Inexpensive compressors will last about 150-200 hours between services. So, taking 2½ times the fill times will reduce the number of fills between services to the compressor.
3.- Simply good engineering.

Of course, to each his own. To ME, it is important, especially in a "pesting" operation, to be able to take two magazines of shots per each refill. It carries a better "rythm" in the hunt, and allows less bother and strange noises.
IF I had a small "pony" bottle filled at 300 BAR's I can easily get a week's worth of shooting from an efficient gun, not so much with an inefficient one.

In the end, what should matter most to the USER, is the performance on target.

We have had miserable weather here in Maryland for the last month. We're barely seeing again our grass, and the forecast for this weekend is about 7" of snow. So I accepted an invitation to an indoor range just to test this gun.
Took a few of my special targets and proceeded to zero, check, and calibrate trajectory for this little carbine

This is the 10 yard zeroing target

¾" high at 10 yards should be close at 15-> 20 yards, and I tested also the drop to 25, about 1"

Because the range is a "Pistol" range, the range officers objected to me shooting supported on the table. So all testing had to be done offhand:

5 shots at 20 yards, iguana is about lifesize, and the red circle is where, in my experience, you get a "lights out" shot.

Another 5 with a little heavier pellets

Last test with the Predator PolyMags, not heavier but slightly less efficient in the barrel, this points to the fact of having a good scope with multiple aimpoints.

Conclusion

It was a GREAT project, I enjoyed it immensely, even in the face of the huge challenge presented by the small reservoir and the intrusion of the regulator into it.
My friend tells me he is happy, and that is what matters.
Hopefully, he will find the time to write a small "Guest Blog" for us about his "escapades" with the Bandit Carbine that, now, has a new name: The "Nano Strike"

;-)

Keep well and shoot straight!





HM

ADDENDA
If copying is the sincerest form of flattery....

A friend is touring IWA.

But he keeps abreast of what we do here on this side of the pond.

And, he just sent me these pictures:

Should we say that "brilliant minds think alike" or . . . 

It's going to be interesting to see the performance figures of this.

;-)

​HM