Increasing the velocity of your air rifle - possible?

[Basu]

Dear Master,
ARs are really full of mysteries.
SDB Sport has a swept volume of 39 CC and it has capacity to deliver 12+Fpe or 16+ jules in .22.
SDB Artemis has a swept volume of 45 cc and it has capacity to deliver 14+Fpe or 19 jules in .22.
So I turn out to be a confused person between your logic and my data.
All above data are out of the box energy.

Basu

[sam 47]

Basuda, SDB Artemis has 45cc!! now that is very nice then it should produce 15 fpe,, comparable to beeman r9 , but in practice in .177 it (r9) produces 13.5 - 14 fpe . Basuda, i think you and some other knowledgeable members should start a thread on basic air rifle physics!

[Master]

Basuda,
Thats why I am trying to decipher the mysteries of neither mountain, nor women, but AR.

[Basu]

Dear sam47,
I have seen there is always 1 Fpe minimum difference between 0.177 and 0.22.
My opinion is , Artemis is already over power vis-a-vis its weight.
No more power increase is desirable.
Mysteries of AR will continue......till eternity......

@ Master- your three subjects are equally critical

Basu

[prashantjha19]

Dear Master,
ARs are really full of mysteries.
SDB Sport has a swept volume of 39 CC and it has capacity to deliver 12+Fpe or 16+ jules in .22.
SDB Artemis has a swept volume of 45 cc and it has capacity to deliver 14+Fpe or 19 jules in .22.
So I turn out to be a confused person between your logic and my data.
All above data are out of the box energy.

Basu

Dear Basu Da, Sam47 and Master,

I was going through this rather old yet VERY interesting thread.

I find that Basu da's MV figures pertaining to Sport and Artemis (in .22) are actually only reconfirming and validating what Master tried to articulate when he quoted the thread from Gateway to Airguns in one of his preceding posts. Both the out-of-the-box energy figures cited by Basu da are just 01 fpe below what the suggested (Rsterne on GTA) 1/3*swept volume fpe calculation!! With some smart tuning that you all have been trying out, this 01 fpe increase looks very much achievable.

Further, Sam47, with his long personal experience with the Artemis .177, has cited the fpe figures he gets from his tuned gun.....and it only vets Basu da's opinion that it s only fair to expect at 01-or-so Fpe difference between .177 and .22 cals of the same model ARs. In fact, you will kindly agree (as I have also verified with some seasoned AR experts): in similar models, a .22 version tends to claim roughly a 20% augmentation in MV over its .177 counterpart (all other specs being same). Given the design limitations with our Indian ARs, I would assume that for us, while the increase in .22 cal (over its .177 counterpart model) may not be to the tune of 20%, they certainly can achieve a 5-7% increase (i.e. roughly 01 Fpe).

I am citing these arguments and trying to revive this highly deliberative thread more to seek you all once again into a focused discussion. I hope this kindles you all and other members into sharing their thoughts on the subject. Will look forward and with warm regards to all,
Prashant

Added in 1 hour 27 minutes 19 seconds:

Basuda,
Based on your information only I tried g smith spring. It fits reasonably tightly, but not very tightly. I think it may vary a little from spring to spring. In my case, one end feels more tighter than the other.

Sam 47,
Precihole claims its AR to have 16 J energy. On Precihole Scorpius, which was 0.22, I used to get around 15 Joules. But on Pegasus 0.177 in stock condition, maximum I got was 9.82 ft. lb. (13.31 J) with 7.6 gr G Smith Amateur pellets. With G Smith 27 spring, the AR seems to be reaching its advertised power, though I will have to wait and see if this velocity sustains after 1000 shots. But this proves that it is possible to get this power in Precihole 0.177 if one can find right spring. Somebody can try suitable Titan XS spring and tell us the results.

For measuring the FPS correctly, I have dedicated my fortune in purchasing Cadwell precision ballistic chronograph. I have avoided detonation as far as possible by applying very thin coating of PH supermoly on piston, spring and seal only.

Dear Master,
Greetings!
Close to almost a year after this post of yours, I am wondering if you have been able to ascertain if the power and performance in your PH with G Smith 27 spring has sustained please!!
Also, if you would want me to try the Titan XS spring (what you suggested in your post), please let me know where to procure this spring from and I will go ahead and try it out and let you know the basic details (I do not have a crony like many of you ).

Warm regards,
Prashant

[narach93]

I have dropped a vortek PG2K in my diana airking 54 and a diana 35 spring (from kihberg india) in my 1992 model IHP 35. The power is simply devastating. Both of them are subjected to continuous use in order to settle them properly. The diana had a weihrauch spring before. In comparision to vortek that was very weak.

[Basu]

To my mind , unless the gun weighs more than 4 kgs, it is not easy to hit target for those guns crossing 11 ftlbs.
In a springer the vibration is a crucial factor.

Basu

[prashantjha19]

Thank you, Basu Da and Narach93.

It will be interesting to await Narach93's update on accuracy of his IHP 35 post the gun settles down in the new config, as he says. Power, he has said, is already good. And the fact that the IHP 35 weighs some 3.5 kg or may be a tad bit less, let's see how consistent it is able to get on accuracy.

Will await your next feed, Narach93. Please also let us know any difference in spring buzz and twang you may be experiencing. Thanks again.
regards,
Prashant

[narach93]

Sure. As far as twang is concened it is almost reduced thanks to the information shared by Sri Basu et al. I did a slight innovation by inserting good quality plstic file cover cut into perfection and inserted into the inner dia of the piston in a way that the spring can be visible. Then I put three washers made from same plastic which were fitted in to the base of the spring guide (metal/procurred from kovibaazar). Also my veteran IHP 35 got a new synthetic washer kit ( from kovibazzar) . I have also put a synthetic washer(those used in toilet spray) as a top hat of the diana spring. I have also removed 3 coils from the trigger spring. Ever since I was using this gun for last 25 years I never felt so smooth cocking and almost no twang. Accuracy has improved a lot and I will definitely post the pic of my performance.
All ifgians must have noticed that the quality of discussion , the sence of brotherhood and offcourse regards to the
seniors that refects in this group is way ahead than the other international groups.

[prashantjha19]

Wow! That sure is something ingeniously innovative . The amount of thoughts you have put in clearly reflects how passionate you are with your guns. Much inspiring indeed.
BTW, I didn't get that toilet spray bit as a top hat washer. What exactly is that please? Does it fit into the spring ID and also serve as a thrust washer? Do pls help us figure out.
And you can't be more correct about the quality of engagement nurtured by the old timers on IFG. Like you, I have high regards for the tone, tenor and quality of discussions, and above all the considerate mentoring attitude of esp the senior members on the forum. Delightfully enriching.
Warm regards,
Prashant

[Master]

Dear Prashant,
Basu da is right about power. Though I am getting ~12 Ft Lb with Gsmith 27 spring (without spring top hat) fitted Precihole pegasus, it gives very sharp recoil. This makes shooting less pleasant. It requires immense concentration for accurate shooting and change in hold result results in flier. So after a month I went back to original configuration and 9.5 Ft Lb power. I think Precihole in 0.177 operates optimally in ~9.5 Ft. Lb., in contrast to 12 Ft lb claimed power.

For my Power requirements, I have Diana 350 magnum with PG2 kit. Diana 350 is a beast (and a bit loud too) and is used less frequently as my neighbors are worried about their safety !! So now I have SDB artemis and is getting accustomed to it.

Titan XS are 15 different dimension springs and you may choose one according to dimensions. You may get it from UK (https://www.gunspares.co.uk/) or from AI of tgg. But I think Gsmith 27 spring is good enough for precihole and Titan spring would be an overkill.

[russianshooter]

If in pcp air rifle break down a moderator,your rifle may be 50J-110J but need caliber 5.5 mm 6.5 mm or bigger because bullet more heavier than 4.5 mm

Added in 2 minutes 9 seconds:
for "pneumatics on springs" you need either stretch the spring or put a more powerful spring

[Master]

Dear Prashant,
To answer your question, I reassembled my Precihole pegasus with already used gsmith 27 spring. I have avoided extra preload given by spring top hat because I broke one new gsmith 27 spring with it. I have shot around 200 pellets, though not thousands. Five shot group (12 meters at sitting position) with Precipell field target (older gsmith manufactured, 8.32 grains) is attached. Recoil has reduced a lot and it seems to be accurate.

FPS values are 778, 805, 794; average = 792; FPE = 11.59 ft. lb. or 15.72 J.

[Basu]

This is quite good at such power.
It proves that Gsmith 27 spring suits well in PH.
BTW , have you trimmed the Spring guide ?

Basu

[Master]

Basu da, Spring guide fits very snug on the looser end of spring. I have not trimmed it. Top spring hat does not fit at all. I forced it on an earlier spring, but it broke after 15-20 shots. So I am using without top hat. I think ID of gsmith spring also varies from sample to sample, similar to Chirokee.