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Converting a spring powered D34 into an N-Tec rifle

9/2/2016

18 Comments

 
First of all, and upon the good advice of the corporate counsel, the disclaimer:

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 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 designs and parts' shapes and dimensions are proprietary to Mayer & Grammelspacher and their Diana brand.


UUufff! That was a mouthful!

Anyway, let's start at the beginning:

Many years ago, an Argentinian designer came up with the idea that a piston airgun could be a far simpler device. So he set to work and came up with a peculiar gun where the lever moved the BARREL back. The barrel, in turn, pushed a floating piston that to its rear had a closed cavity that could be pumped up with air, or the air could be let out to reduce the energy stored in the compressed gas.
The lever then pushed forward the barrel and the loading was through a turn-cock arrangement like many old German guns.
That prototype evolved and eventually became a commercial model, BUT, as it sometimes happens in life, a pair of British subjects (we must remember they are not citizens), was also working on what they termed a "superior device". Superior in the sense that it utilized the TRADITIONAL piston airgun architecture with all its moving parts and peculiar triggers. So, in their zeal, they took the Argentinian designer to court and won the case.

I have always suspected strongly of all litigations around "inventions". Lately, the world has adopted the convention that the patent belongs to the FIRST TO PUBLISH, thereby eliminating the need to demonstrate the specific date of the "invention". Again, I dislike this because it plays into the hands of those corporations that have patent lawyers on retainer and whether they work or not, they charge a minimum monthly fee.

More and more we see all patents in our life (and death) owned by large corporations that can then jack up prices as they want (the pharmaceuticals are a perfect example)

Perhaps, coming back to the "gas-ram" invention litigation, the Falklands war was also a determining factor.

Whatever it may be, it is an undisputable fact that the Argentinians already had a "Gas-Ram" rifle in commercial production and being sold in their market when the idea was patented in the UK.

To the victor go the spoils.

Fast forward to the present day and after a little over two decades of exploitation, the patent expired.

And so, all of a sudden gas springs (different from Gas Rams) began cropping up everywhere. From the Crosman's of a few years ago to the Hatsans and Diana's of present day and interest.
DO note that HW made their own Gas Ram model under license of the Brits, whether sold as HW or as Beeman, it is the same gun.

Another thing that has evolved enormously is the science of materials. We now have materials that 25 years ago would have been unthinkable. From Titanium, steel and high strength aluminum alloys to highly complex polymers for seals we have at our disposal in economic terms things that in years past would have costed hundreds, if not thousands, of dollars and would probably have required a National Security clearance to buy.

The improvement in materials and availability of pure, dry gases has changed substantially what the old Gas Ram was.

I still remember about 17 years ago that I gifted a 0.20" cal. RX2 to my good friend Mike Pearson, airgun hunter extraordinaire.
As soon as he received it he took the pump and pumped it up to the max. Then he complained about how hard it was to cock and how inefficient the machine was.
That experience colored my perception of Gas Ram's (and gas springs, by extension) till the present.

I still fix the occasional RX-2 or HW-90, but after this experience I know that the REAL problem is that those designs and specifications are simply obsolete.

I have to admit that I tackled this project with some trepidation. The modifications made to the gun would be non-reversible, so the gun was modified forever. Something that IN GENERAL, I do not like to do. But the thirst for knowledge and the long term route that I have planned needed this first stepping stone and so we took a gun that was worth the effort.

And here comes another fact that should not surprise anyone: If you want an N-Tec gun, BUY an N-Tec gun. Between the cost of the parts, the original gun, and the labour you would end up paying TWICE what the original N-Tec equivalent gun would cost.

The only valid reason to attempt this conversion is if you have a superbly accurate 34 and you want to up the power.

Of course, it could be argued that it would easier to swap barrels, but sometimes the accuracy is also a function of how the stock fits the shooter and so, swapping barrels while expedient, reversible and economically savvy, does not resolve all the issues.

And there are no lessons learned in a purchase.

So, having explained a little of the background, let's get to the technical aspects
Picture
On the TOP, the N-Tec powerplant, at bottom, the traditional steel spring power plant utilizing a Vortek PG-2 kit with a Vortek Black-Ops seal specially designed for these guns.
The first thing that should call our attention is that the N-Tec unit is shorter than the traditional setup. This means that the pre-compression is very short.
This is one of the virtues of the gas springs: they keep a constant pressure on the end of the stroke and do not rebound as much as the steel arrangement of individual coils that we call steel springs. By eliminating the rebound of the piston, the gun is much more efficient, specially on long transfer port models, like the 34.

The second thing that should call our attention is that Diana ships their N-Tec triggers with TWO dumb pins. And the reason is simple: some parts could get out of place and cause severe problems upon assembly.
I have found that the usage of dumb pins, while not a necessity is a desirability because it speeds the process and helps prevent problems.
Some people say that they NEVER use dumb pins in the disassembly of their guns, of course, when queried, they have to admit that sometimes guns don't get assembled at first try, and the some pieces have become damaged when they fell out of place and the gun was assembled like that.
My grandma used to say that "to those that die of their own will, death is but sweet nectar".  Let everyone disassemble their guns in whichever way they like, LOL!

The N-Tec assembly is composed of 4 parts:
The piston
The gas spring
A plastic spacer/washer that fits between the gas spring and the trigger unit
The T-06 trigger unit.

In opposition to the traditional T-06 trigger, the N-Tec T-06 trigger is an "interference" trigger. That is, it grips the base of the piston's skirt and does not allow the piston itself to go forward. There is no claw, no plates, no balls. Just a ramp that, when the sear releases, allows the piston to slip forward, much like an archer's release
While some have complained about the N-Tec T-06 trigger, I found my units to be surprisingly smooth and consistent in their release. A true pleasure to shoot with, like the other T-06 triggers in the Diana lineup.

The piston lacks the stem and has a little longer body:

Picture
But all other dimensions are identical. Seal is the same.
Picture
Lever engagement and spacing are also identical.
Picture
At the bottom of its excursion, the piston aligns well.
Picture
But the point of insertion for the interference sear showed that there was a need for some relief.
Picture
The complete piston travel is also the same.
Picture
The trigger housing, however is wider. And so it needs to be. The forces that this trigger is subject to are greater than the forces exerted by the steel spring one.
An interesting characteristic of all T-06 triggers is that they can be adjusted out of the gun. By pushing forward the lever that is visible in this picture, the trigger is armed and the release can then be set to the user's wants.
Do note that the trigger housing is also longer, so that means relieving the stock inletting, but we'll see that later.
Picture
The receiver being milled.
Picture
Now the trigger can go in (tests performed without the gas spring). But there is something that does not quite allow full insertion, Yup!, the interference sear needs relieving.
Picture
And then the stock gets milled to the proper depth, width and the shelf that the trigger has is also incorporated.
After the rough milling some scraping got rid of all those whiskers and shavings.
Picture
Because the trigger housing is larger, the rear stock screw needed is much shorter.
Picture
Because the piston has a recess where the head of the gas spring goes into, it is important to assemble everything in a "train" in one continuous motion.
Don't forget to lube lightly the gas spring stem in any N-Tec system.
Picture
By the end of the day, nothing belies the fact that the originally sedate 12 ft-lbs carbine is now a 16 ft-lbs powerhouse.

While 16 ft-lbs may not seem much, do consider that it's twice the rifle's weight with the Vortex Crossbow scope installed..

Shot cycle is not harsh. Sudden, yes. Quick and Forceful. Very convincing. It also suprised me that the recoil is straight in line. No jump. Of course the rifle's architecture has something to do with this, and it is one of the reasons I am not in love with the current N-Tec offerings.

Apart from the 33.33% increase in power, the gun is easy to cock, even with the carbine's short barrel.

I cannot judgea accuracy right now. Some fantastic groups (3/8"@ 35 yards) and some not so good (1" at 35 yards). I think we need to let the old girl settle down to her new powerplant.

The N-Tec architecture is interesting even without the Nitrogen piston. Future work will involve doing the conversion in a D48. I do not expect the same level of energy output increase in the short transfer port models as opposed to the long transfer port models, but it will be interesting to see what happens there. Of course, the aim in the long run is to have a short-stroked, gas springed Diana 54, shall we call it the 540? LOL!

The new interference trigger opens a whole new avenue of interesting possibilities, so we will be doing some work there in the future.

The gas springs have come a long way from the old RX-2 / HW-90 technology.
New gas spring guns are smooth to cock and efficient in the use of energy, unlike the older specimens.

Hopefully, one day, Diana will offer a true Gas Ram, where the power output can be regulated by regulating the initial pressure in the gas spring.

Whatever happens, I am glad to have been corrected about my bad impressions of the gas springs.


Keep well and shoot straight!







​Héctor Medina
18 Comments
RidgeRunner
9/5/2016 05:38:56

Nice little package you have put together there. I do hope she settles down in the future. Likely with enough trigger time the two of you will get to know each other really well.

Reply
Hector Medina
9/6/2016 10:08:03

Thanks, RR!

Yes it is a nice package. Short, light and powerful. I do think I need a better scope for accuracy evaluation, and I have already added buttons to the piston. Now she is even smoother!

Thanks for reading!



Héctor Medina

Reply
Juan Alcántara
1/24/2017 18:51:13

Hi my dear friend, long time no see, just to letting you know just bought a gamo big cat in the morning, i miss this so much, but i´m gonna try to come back, there is a lot of things to say but maybe some day we´ll meet again, big hug to you.

Reply
Hector J Medina
1/25/2017 08:46:43

Alacrántara!

Happy to know you're alive!

Yes, I must say that a LOT of water has passed under the bridge. Life has a way of teaching us lessons, but what does not kill us makes us stronger.

Drop me a line through our contact page:

http://www.ctcustomairguns.com/contact-us.html

Un abrazo!







Héctor

Reply
Kristin
8/21/2017 20:19:03

Hi

Your D34 conversion to Ntec is impressive. It has been a year now and how has it worked out. What would you charge to convert a stock .22 D34?

Best regards,
Kristin

Reply
Hector Medina
8/22/2017 16:23:45

Hello Kristin!

Actually, I wouldn't change a thing.

The behaviour of the 0.20" cal conversion tells me that it would work just as well in 0.22"'.

Don't think the Muzzle Energy would increase as much (when comparing to the basic metal spring version), because the D34 has a limited displaced volume, but it would work very well.

You are right, it has been a year, and after a year, I have shot a few FT Matches with the gun and done not too badly:

http://www.network54.com/Forum/451309/message/1479146720

With that scope, I was not expecting top scores.

The gun is really accurate, having settled now at around 800 fps +/-
5 fps with the H&N FTT @ 11.43 grs

While it is not the most powerful gun in my arsenal, it is a joy to shoot.

Out to 35 yards, 5 shot groups groups from the seated FT position hover around the ½" c-c
It cannot reach the 55 yards mark with the same authority, but that is expected from the platform.

Lately I've been intrigued by the extremely affordable synthetic stocked Dianas. Specifically the Mauser version is very attractive, but I do think that the whole idea of doing this in a larger caliber would be better served in the 350 platform.
HOPEFULLY, soon, we will get the Mauser version in the 350 platform and that would be a gun that merits thorough testing.

Keep well and shoot straight!




Héctor

Reply
Mark Kelly
2/16/2018 19:49:42

Hector,
I have been reading your posts for years. Informative and appreciated! You remind me of Lt. Col. Steve Swartz (USAF Ret.) air pistol shooter. The scientific approach. I hope to meet you some day!

Best wishes,

Mark

Reply
Hector Medina
2/17/2018 12:04:26

Mark;

If any thanks are needed, it is us the writers the ones that should thank the readers. So thank YOU!

If you ever go to a Pyramyd Air Cup, or to an FT Nationals, for sure we will meet.!

Take care and shoot straight!


HM

Reply
Francois Williams
4/16/2019 14:33:24

Hi great article. I just got myself a 340 NTec in .22 and I am wondering if the power can be increased with say a magnum piston.Do the two pistons have the same dimensions. Will a 350 magnum piston fit into a 340 action if they both have a To6 trigger? Your thoughts on this would be appreciated.Thanx

Reply
Hector Medina
4/16/2019 14:44:37

Hello Francois;

Thanks for your kind words.

Personally. I would think it is not a good idea.

The balance between power/length & weight is a delicate one. And power is useless if you cannot hit what you want to.
But airgunning is all about experimentation, so if you do decide to go ahead and do it, then by all means, feel free to tell us how it went.

Of course, ALWAYS keep yourself on the legal side of power, wherever you live.

Thanks for reading, keep well and shoot straight!




HM

Reply
James Howard link
7/2/2019 21:28:49

Still trying to get some real world experience and advice from someone who has mounted a 350 and what scope they have had any success with

Reply
Hector Medina
7/3/2019 10:30:18

Hello James!

If you want a truly recoil-proof scope, then get a Vortex Diamondback. The new "Tacticals" with the First Focal Plane are very impressive and useful to airgunners, and their warranty is impeccable. Of course this is a $400 scope, but it is an investment, not an expense.
I cannot say the same of the Hawkes.

Crossbow scopes are also good alternatives, more "hunting" oriented due to weight and size, but good for shooting at 1" targets/prey out to 45-55 yards in the right conditions.
The Xbow scopes made by SightMark are very good and will be in the $200 range.

With these two scopes, you CAN use a fixed one piece mount, like the RWS "LockDown" mounts.

Personally, I use the Accurized ZR mounts more as an insurance policy than anything else.

Keep well and shoot straight!





HM

Reply
Stevie Osceola Power
2/6/2021 17:40:55

Hi, Interesting Article. Thank you. Can you tell me where to purchase a spring replacement for my Diana 340 N-Tec please? As I will have to consider the British legal-limit, so as not to break any laws. If you can give me advice on how to find a spring/Piston replacement, Approx how much please?.
Regards,
Stevie Osceola

Reply
Hector Medina
2/6/2021 22:03:03

Stevie
A conversion to steel spring set to 12 ft-lbs would be around the $180 mark.
And I would need to have the rifle at hand to fit the parts.
There is no way at present to reduce the power of the NTec units and guarantee that you will be legal. Too much variation between units, especially at the low pressures needed for the 12 ft-lbs level.
So, for ease of maintenance and cocking within the legal limits of the UK, my advice would be to change to a steel spring.
Contact me through the contact page if you are interested.

HM

Reply
Mohd Adeeb hussain
7/4/2021 01:08:50

Hello sir,
Very very impressive work u have done. I was planning to buy diana 350 N-tec but unfortunately diana discontinued its production so i bought 350 magnum springer. From so long i am planning to convert my 350 springer to N-tec with AR8 gas ram but i am just not sure about trigger unit of N-tec because the trigger unit of N-tec is little wider than springer t06 trigger unit so little space need to be removed from cylinder. Can you please share me dimensions of N-tec t06 trigger..say length width position of pins ,etc.

Reply
Hector Medina
7/4/2021 12:12:09

Thanks for your kind words.
While possible, I would dis-advise it.
You would need to change the piston and the trigger unit, not only the trigger unit.
Sorry that I cannot comply with your wishes, upon our best legal advise I posted this phrase above:

"Please do not ask for measurements or dimensions, Connecticut Custom Airguns cannot provide these data."
So, I cannot go against the advise of my lawyer.

If you are interested in getting the most power out of the 350 platform, there are springs that can achieve this, but then the gun becomes hard to shoot accurately.
ALL DIANA airguns are limited by their design to not more than 24 ft-lbs on a steady basis. The 350 NTec wasa a partial exemption because, given the cocking effort needed to operate it, no one was able to keep a steady shooting pace, so in that sense the gun was self-limiting.

A good tune in a 350 is about 22-23 ft-lbs with a custom guide and a good spring. That will give you accuracy and power enough to tackle anything worthy of an airgun.

Thanks again for reading, Keep well and shoot straight!






HM

Reply
Daniel
11/9/2023 00:32:10

Nice job Héctor!
I just bought a factory N-Tec D48 the other day (yes they do exist they named it Mod 48 Sniper, and Diana mounted a handsome shroud/silencer combo on it, seamlessly threaded together, which I always wanted on a 48/52 or 54 springer)
Before reading your blog I was actually planning on converting it to a traditional springer because I liked how they shoot (had their Airking Pro, and the older side lever cocking models before) and mostly because I have my doubts about the longevity of N-Tec units. This gun was made in 2017 after all.
Now that I see the effort you put into a conversion from a good ol' spring to N-Tec I might just leave it in their and start looking for a spare N-Tec parts maybe.

Keep doing your thing, wishing you all the best!

Ps. If you want see that unicorn Mod 48, I can make you some pictures.

Reply
Hector Medina
11/9/2023 11:47:56

Hello Daniel,

Thanks for reading!

I assume you live in Europe, ¿possibly Germany?

I heard some talk about wanting to use an NTec unit in a 48, and tested one, but the effort required for cocking was not commensurate to the energy output (which had to be limited at the TP due to the incompatibility of the European energy levels and the NTec's need for high internal pressure to work correctly), and I disadvised DIANA to continue with that project. Didn't know they had gone ahead.

So, Yes, I would like to have pictures of that "Unicorn". THANKS!

Please contact me through the contact page in this website so that we can exchange EMails.

Thanks for reading!





HM

Reply



Leave a Reply.

    Hector Medina

    2012 US National WFTF Spring Piston Champion
    2012 WFTF Spring Piston Grand Prix Winner
    2013 World's WFTF Spring Piston 7th place
    2014 Texas State WFTF Piston Champion
    2014 World's WFTF Spring Piston 5th place.
    2015 Maine State Champion WFTF Piston
    2015 Massachusetts State Champion WFTF Piston
    2015 New York State Champion WFTF Piston
    2015 US National WFTF Piston 2nd Place
    2016 Canadian WFTF Piston Champion
    2016 Pyramyd Air Cup WFTF Piston 1st Place
    2017 US Nationals Open Piston 3rd Place
    2018 WFTC's Member of Team USA Champion Springers
    2018 WFTC's 4th place Veteran Springer
    2020 Puerto Rico GP Piston First Place
    2020 NC State Championships 1st Place Piston
    2022 Maryland State Champion WFTF 
    2022 WFTC's Italy Member of TEAM USA 2nd place Springers
    2022 WFTC's Italy
    2nd Place Veteran Springers
    2023 WFTC's South Africa Member TEAM USA 1st place Springers
    2023 WFTC's South Africa
    2nd Place Veteran Springers

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