choosing between precihole nx 100 and sdb artemis.

[targetpoint]

I am not going to compare between ph nx100 and Artemis but if any makes a choice to buy Artemis then I will say go and get it.But be ready to practice a lot as it needs lot of dedication,proper techniques and has long break-in period of nearly 700-1000 pellets.After that what you will get is really a gem and will feel proud owner of a airrifle that has the capability to blow off the head of a matchstick. For group shooter,you will definately get 1/2 inch CTC most of the time with proper pellet as I do.
thanks.

[Niks]

In the video of Precihole vs SDB there seems to be 2 glaring errors. First, the average velocity readings as chronyed by the maker of the video using a light (0.7 g) pellet are as follows:-

Exactly, I look again at the video clip and i didn't see shooting precihole air rifle. Is this a video editing issue or fake video?

[targetpoint]

I don't know how to post video here and wish to be educated in this aspect.I made two videos where I am knocking matchsticks from 18m and other one where I am trying to light up a matchstick from 10m.
Our respected Basu Sir and dear Sam47 already enjoyed the video as I had sent it in their what's app.
This is only to show the accuracy of my Artemis and quality of precipell pellets.
Thanks to SDB and Precihole that we are getting such a good products in our country.
Thanks.

[prashantjha19]

Sounds great!
I am looking to know the specs of the Artemis and SDB Sport actions please.....more specifically the Stroke and the TP dimensions (Dia and Length). I understand they both have 25mm bores.
Will greatly appreciate any help please.
Regards,
Prashant

[targetpoint]

Dear Prashant jha,
Since my Artemis is in its optimum state giving good accuracy and power so I will not fiddle with it as per the advice of our Basu Sir.
I don't have SDB SPORTS till now but going to add one in my arsenal hopefully.
Don't mind but may I ask why you are keen to measure the internals?
Basically for tuning purpose-I only like to use tight fitting spring guide and top hat(if required)fabricated in lathe,Cherokee spring,moly grease(precihole),few thin washers(if needed).
Even though if you really need the measurements you may contact the manufacturers or other members our forum who have good knowledge of how to measure all these can help you.
If you intend to buy one don't hesitate both the guns are too good.
By the way we both have same sounding name.
Thanks.

[Basu]

Our member Sam 47 & Srirup Dutta have both the guns.
While chatting they have shown inclination towards Artemis.

Basu

[prashantjha19]

Dear Prashant jha,
Since my Artemis is in its optimum state giving good accuracy and power so I will not fiddle with it as per the advice of our Basu Sir.
I don't have SDB SPORTS till now but going to add one in my arsenal hopefully.
Don't mind but may I ask why you are keen to measure the internals?
Basically for tuning purpose-I only like to use tight fitting spring guide and top hat(if required)fabricated in lathe,Cherokee spring,moly grease(precihole),few thin washers(if needed).
Even though if you really need the measurements you may contact the manufacturers or other members our forum who have good knowledge of how to measure all these can help you.
If you intend to buy one don't hesitate both the guns are too good.
By the way we both have same sounding name.
Thanks.

Dear Targetpoint (Prashant!!),

Thanks much for caring to revert! And my apologies for getting back so late (For some strange reason, I do not get notified of new messages on threads of my interest so I can get to know if there is a new response..... Only when I visited IFG today could I notice that you and Basu Da had kindly reverted on my query!!)

To your question about why I am keen to know the internals: ....I am on a small project of sorts (if i can call it a project, i.e.!!). I am working on one of SDB's earlier model ARs (which I believe is the predecessor to all their new gen ARs (incl Artemis, Sport and all)) - to understand what they did to bring the new ones in the legal limit range. Since I know the bore size, there are just three aspects they would have altered - the stroke, the TP volume and /or the TP location. The barrel size on all SDBs is already in excess of what we need for optimising muzzle output.

I absolutely agree with you - both the guns are terrific!...as are their GenNex and Apache.
BUT, look at all these new generation SDB ARs ....and the first thing you begin to notice is the Bore size. These are the same as what is currently going around the world over for mid-range ARs including Weihrauch, AirArms, and many Diana models. However, here in India most continue their fascination with the good old 28 mm -the so-called-Indian-standard bore. All the models we talk of -Classic 45, 65, 50, 2000, 200...and also the PH ones....are all 28mm compression tubes.

However, there is enough research to conclude that you do not need anything beyond 25mm (even less, if you can further improve the firing cycle efficiency) to sweetly attain the legal ME. SO why are we stuck with the bulky ones?? Must be our fascination with all things big!! I was looking for answers when I banged into the SDB Mod 27. (I had exchanges with Basu da on this, too, sometime back!!). I bought one (and am planning to get another one to make alterations!!) TBH, I was first fascinated by its Bavarian stock (am tired of the Monte Carlo ones) and the sweetly flowing profile. Then I noticed the other specs....which were a revelation. Lubed, tuned and added a synthetic seal to get a 77mm stroke.

What a sweet AR it has become !! ...(all at less than half the cost of the new models!!). However, like most things in India, this model didn;t seem to do well here (if you look around, you will get tons of info on all the bulky models, but absolutely nothing on this gem of a model -the Mod 27 which is smaller, lighter, shoots like a whisper when tuned well, cocks with one finger, and yet competes neck-to-neck with the likes of Precihole Spartan that I have in terms of shootability and ease of handling....and may be just a tad low in power. So, I assume, its ME is in the range of 7-8 ftlb.

My works on my SDB Mod 27 tells me that its specs (bore, stroke, SV) are all similar to HW 77, 95, 99 and some others that all produce close to 12ftlb. For sure, our 27s do not match that. I am looking into the WHYs....and WHAT all (out of the three I mentioned above) have SDB done to get this to that level!!
And it's great to know we share our names!!

@ Dear Basu Da, I know Sam47 is the person to answer my queries...and wish he reads this thread one day, and respond. Meantime, will love to hear from you of your thoughts on what I shared above. Why do our local guns have all so much lost volume in their TPs? I have a strong hunch SDB have shortened the length (and may be also increased the Dia to 3.7-4mm) in their new models. And if not by so much, then they would have compensated by increasing the compression stroke. Can you please confirm from what you would have noticed on your Sport please!

Thanks for your inputs and enriching the discussion...
Best regards,
Prashant

[prashantjha19]

I recall having seen somewhere (probably on this or another forum) that the SV of SDB Artemis is 45cc and that of SDB Sport is 39cc. Anyone...who would want to vet or context these figures please???

With the same compression tubes that they both have, their strokes work out to roughly 93mm and 80mm respectively.
Now, my Classic Mod 45 (which has a 85mm stroke and a bigger dia tube) has an SV in the range of 52cc. And yet, the max ME reported for this AR is in the range of 10.5FPE; whereas the new models with lower SVs are said to produce MEs much closer to the legal limit or above. (SDB sure would not have invested so much in their new ARs as to have changed the location of the TPs, I am pretty sure. So, the topside location
of the TPs typical of break barrels in India and elsewhere is ruled out as a factor.)

Much of this in ME in the older models, as I now discover, was owing mainly to two factors: One, the use of massive springs by us all, and two, the size of the TP. the 45 TP is in 3.7mm league. Anyone tried a different one please??

I deployed a much smaller spring (212 mm only; though its rate went high), made the piston heavier, and with a bare 22 mm preload, there's a perceptible enhancement in its ME and firing cycle behaviour. There's no snap. As a bonus, it has become so much more easier to shoot. The cocking effort is less than even that of my Mod 27 AR. The surge is much tamed. Of course, the recoil and hold sensitivity remain, what with a 85mm stroke!
To get around this long stroke, I am next going to work on its TP dia (and if push comes to shove, and it does not produce the 12FPE, then on its length, too!!).

Any ideas, comments and suggestions are most welcome please!
Thanks all in advance!
Prashant

[Basu]

Let me say my Sport gives max 12.8 fpe and not 13.8 fpe as wrongly reported by me somewhere.
This is after the use of a different spring.
What I noticed in Sport that internal of receiver is far better than my SDB 45.
The length of transfer port is less than 45.
I am sure that there is no piston bounce at all.
Neoprene breech seal and synthetic piston seal help to generate vicious power.
Artemis holds the prospect to touch legal limit any day.
With regard to the topic , NX has superior single stage trigger yet Artemis or Sport have noticeable less recoil even at that power.

Basu

I had the experience with SDB 45 that softer spring have more ME than harder one.

[prashantjha19]

Thank you, Basu da.
The inspiration to deploy softer spring in my 45 first came from you. Then I also noted that fine breed adult 12fpe ARs the world over use springs of rates in the range of 6N/mm but with just 220 mm lengths. And my tweaking on these lines has been most rewarding.
Thank you also for letting me know the TP length of Sport is smaller. By how much,....you could keep in the back of your mind, and measure out the next time you service your Sport please.
Also, do you note any difference in the TP dia (vis-a-vis the 45)?
And how would you advise me to improve the cylinder internals of 45, Basu da.? As it is, it has a quiet even finish and tolerance through out.
Lastly, should I try a smaller dia TP and increase the stroke further? It can stretch 10 mm further if I work on the piston. What do you say?
Of course it will elongate the shot cycle and further increase hold sensitivity, ...but would it be worwora try please? Do pls let me have your thoughts.
Thank you again for your support.
Regards,
Prashant

[Basu]

Dear Prashant,
The thread has shifted from it's real topic.
However I will try to give my observations.
I think the dia of TP is same as that of 45 in both Sport & Artemis.
As per Cadrew , 3 to 3.5 mm diameter gives optimum power.
By reducing dia , there might be a chance to increase in peak pressure but that equally increase the chance of piston bounce.When the Piston bounces there is a sudden drop in peak pressure which may result in drop in velocity.
To my mind a bigger stroke length should be coupled with larger TP.
Tx 200 has a TP of 4.00 mm as per my information.
If the internals of your 45 is well polished then you can not add anything to that.
One thing often comes in my mind that is to polish ID of spring to make it more resistancefree.

Basu

[prashantjha19]

Thank you, Basu Da! So much appreciate you taking time to kindly respond to our queries and share your insights.

Will surely implement your suggestion of polishing the ID of springs I use.
Basu Da, Cardew's observations are pretty valid....Only that today (after 40-50 years of his experiments) we may be dealing with a diff breed of ARs (than his HW35s!!) - Much longer stokes than his under 70mm as well as greatly refined set of pellets with low start pressures. Also, we are today mostly looking to do away with any deliberate prospects of dieseling, too.

Finally, like you say, it is all going to be a coming together of the stroke, spring energy, piston weight and, at last, the TP.

I got to learn somewhere though that all things equal shorter strokes complement wider TPs, and vice-versa. So, Let me first shorten my 45's stroke to something in the range of 70mm, and see how it behaves. I have a long shaft piston spare. Will report back.
By the way, the TP dia on my 65 is lesser than on the 45 -Both same 2.8mm SDB comp tubes. And the one on another Kolkata brand (Can-On) is just out of this world (just 2.5 mm). Also, it is the first one I saw with an inclined TP. The inside hole (almost centered) is wide (some 4mm). Incidentally, Basu da, this gun has the best shot cycle. So, I opened it to replace its monster spring, and then check if it behaves same. I will also check how much of its quick and vibe free shot cycle is owing to its short 72mm stroke. I should be able to update you in some days.

Thank you again. And is there anything we could do to move this to a new thread please? Am a nerd on all this, so someone pls guide.
Best regards,
Prashant