Question?

[Nvreloader]

Guys

Since I am sadly lacking in experience, I would like to find some answers to this question, as I don't know etc.

You have a air rifle, a Qb 79, 22 cal, HPA,
You want the best tune ability, reasonably obtained, either with 13/3000 tank or tethered tank,
so you can tune/adjust for the best ballistic's levels for performance, for all pellets weights, from 14 thru 30 gr weights.

Would you build for 800, 900 or 1000 fps, then using a SSG, tune/adjust down to the level needed or wanted,
depending on pellet weight being used, at the time/need?

As reported here, heavy weights of pellets SEEM to shoot better at a higher fps, than the lighter weights etc.

You thoughts/suggestions?

Tia,
Don

[nervoustrigger]

Don, there really isn’t a single universal state of tune that is going to allow you to properly evaluate a range of pellets that varies all the way from 14gr to 30gr.  By “properly evaluate”, I mean run them at a velocity that isn’t so fast with light pellets that accuracy is impaired, or so slow with heavy pellets that the trajectory is so loopy that range precision becomes onerous.
 
If you are interested in taking an approach that is most likely to yield great results on the first try, tune for 25-30fpe with the JSB 15.9gr and 18.1gr.  Every QB I have ever worked on has produced remarkable groups at that state of tune.  And quite honestly, when the day comes that I don’t get those results, I will know it’s the barrel.  The redesigned Monsters are promising in some barrels but the constraints of a QB79 (pressure and plenum volume) make that one a non-starter.

[ranchibi]

Don, speaking in general terms, most .22 pellets and barrels in those weights do best at speeds of 850-950fps. It is also dependent on each individuals barrels lands/harmonics too. I have a Daystate Regal and a Brocock Compatto, both in .22. With JSB 15.89gr pellets they both shoot about 900fps and with JSB 14.35gr about 940fps and with JSB 18.13gr about 850fps. The Compatto has a high and lo power dial and with 15.89gr pellets 770fps on lo (with 14.35gr, 820fps). So, by using different weight pellets I can customize my shooting by just using different weight pellets and with nothing else being adjusted. I hope this helps! What Jason said above about FPE fits these speeds....just saw his post as I was posting

[Nvreloader]

Thanks Guys

I do have a longer pressure tube coming, to replace the OEM psi tube.

I guess, what I should have asked for this questions, is this,

14 to 18 gr pellets, I need some where around 950+ fps,
18 to 25 gr pellets, I need some where around 1100+ fps,
with the new psi tube.

Then, I can tune/adjust down for the best ballistic's/accuracy as needed?

Right now, I have these max fps,
SSG-Max
3000 psi - Reg SP - 1340 psi,
14.3 gr = 880-883-882-881-884= 882 fps av = 3/4" group at 40 yds,
15.8 gr = 855-854-855-857-857= 855 fps av = 3/4" group at 40 yds,
18.3 gr = 820-816-817-818-819= 818 fps av = 3/4" group at 40 yds, 
21.1 gr = 775-774-771-776-777= 774 fps av = 3/4- 1" group at 40 yds,
25.3 gr = 725-721-722-718-721= 721 fps av = 1'' + group at 40 yds,

So, I need to up the fps/psi, to have a better chance to reaching the fps/psi levels, for EACH pellet group weight?

I found out, I am beating the dead horse, with the small plenum of the 79 etc,
even thou I have added Delron poppet head and all the little tricks, you guys talk about etc.

But, I am NOT sure, if I am doing all these tricks, correctly either.

Waiting for the Pony Express...........

Tia,
Don

[ranchibi]

Don, those numbers are very good. I don’t know how accurate it is shooting with those numbers but, accuracy trumps FPS...you’ve got very good numbers! In a post on an Urban shooting with JSB 16gr with numbers very close to yours was taking squirrels at 75yds....

[Nvreloader]

Thanks Randall

I have dismantled and reassembled this 79 so much, I'll have to get new screws and parts to keep it shooting, LOL.

The accuracy keeps changing from removing and attaching the scope every time,
even thou I have a mark to replace back to the same place, along with the valve adjustments etc.

I have been playing with the SSG, turning every 1/4 turn for adjusting the accuracy, which slightly adjust the fps etc,
so far 1/2 turn (24 tpi) seems to be the best results so far.

I am averaging 10-15 starlings every day, even with the cross winds blowing 20-40 mph for the last 2 days,
I had 2 starlings side by side, POA on the first one and DRT on the second one, with that shot,
these pellets sure do drift a lot, with 90* cross winds.   

When the new pressure tube gets here,
I should have around 6"+ of more plenum space to work with,
which should improve the ballistics/adjustments, I have now with the OEM plenum of 1" etc, at the present time,
running tethered from the 4500 psi > down to 3000 psi reg set.

Then I'll have to tune LL again, with the newest valve rework etc, working on this 79 has turned into more work than my PB's.
Then I'll have to redo the LDC, to make it more mouse phart quite again, it seems to be getting more louder, the higher fps, I build to.

Back to the shooting/bench.......

Tia,
Don

   

[Hoosier Daddy]

18 to 25 gr pellets, I need some where around 1100+ fps,

I am more of an accuracy guy not speed or energy so excuse my simplton question...but.
 Isn't this a pretty tall order?

[Nvreloader]

Scott

I agree with you and ALL the other enablers 1000%, speeds fine, but, accuracy is final.

From the info I am getting, and if I understand it CORRECTLY,
and I'll refer to Jason and Randall's info, converting from FPE to fps for Jason post,
he reports that between 25 to 30 fpe is the best range, for 15.9 and 18.1 weights,
and I do understand each and every weapon is different etc.

The fps to reach Jason fpe estimates, is as follows, (if I have chair gun ballistic app, set up correctly,
and I cannot find where to enter the bbl length), which will make a difference etc.

14.3 grs = 25 fpe = 887 fps to 30 fps = 975 fps,
15.9 grs = 25 fpe = 844 fps to 30 fpe = 924 fps,
18.1 grs = 25 fpe = 784 fps to 30 fps = 859 fps,
and I added these weights, as I have a great interest in them,
21.1 grs = 25 fpe = 730 fps to 30 fpe = 800 fps,
25.3 grs = 25 fpe = 667 fps to 30 fpe = 730 fps

With the plenum/volume I am working with right now (OEM 79, about 1"), I see that I am handy capped,
as I have the following results, (when the new larger plenum gets here and installed), I hope my testing results will improve.

I have these test results so far, 
SSG-Max 20" bbl length,
3000 psi - Reg SP - 1340 psi, tethered to 4500 psi >to 3000 psi reg, (very consistent results, so far),
and I used the highest fps needed, as it is better to have more, than NOT enough, I hope.
14.3 gr = 882 fps av, 975 fps for 30 fpe = I need approx 93 fps more,
15.8 gr = 855 fps av, 924 fps for 30 fpe = I need approx 106 fps more,                                                                           
18.3 gr = 818 fps av, 859 fps for 30 fpe = I need approx 41 fps more,
21.1 gr = 774 fps av, 800 fps for 30 fpe = I need approx 26 fps more,
25.3 gr = 721 fps av, 730 fps for 30 fpe = I need approx 9 fps more,

If i can bring up the fps to 950-1000 fps, I should have enough fps to reach these fps reading for all the weights listed,
and IF the tuning results show less is needed, then I am Fat Dumb and Happy, LOL.

Then hopefully, I can use the SSG, reduce psi tank levels, set points etc,
to adjust/tune down to the approximate fps/fpe levels needed, then do a final tune/adjustments, for the best accuracy,
for what ever pellet weight I am using, at that time.

Is it not easier to tune/adjust down, than reach for higher levels, which requires more building etc.

Or am I barking up the wrong tree, with my thinking?

Any suggestions/thoughts are greatly appreciated, as I am getting more confused, the more I read, and attempt to understand it all.

Tia,
Don

[nervoustrigger]

Don, sorry, I wasn't saying that energy level is optimal for all pellets, just that the JSB 15.9 and 18.1gr have been very accurate in QBs in the 25-30fpe range.

If your barrel seems to like the Baracudas and Monsters, and you can get the mustard to run them at 800-900fps with the longer tube, by all means give it a go.

[rsterne]

I don't know where you got the idea you should be running 18-25 gr. pellets at about 1100 fps.... but I wouldn't run ANY pellet that fast.... nor do I think you will get that kind of FPE in a QB (48-67 FPE) and stay under 1800 psi.... I agree with Jason, run the 16-18 gr. JSBs at 850-950 fps (ie about 30 FPE) and be happy with that.... Trying to make a gun adjustable over a wide range is a really poor idea, IMO.... too many compromises to make....

Bob

[Nvreloader]

Jason
Thank you,
Well, I guess I screwed up again, Sorry, I am trying to learn........really, I did NOT mean to throw you under the bus. 
it's kinda hard for me to adjust my thinking to FPE, when all I have used is FPS terminology, even thou they produce the same results.......don't they? 

I thought, your were recommending those fps levels, for all those pellets weights,
your best results have been in 25 to 30 fpe range which = 850 to 950 fps range, for the 15 thru 18 gr weights only.

Those heavy weights seem to be shooting OK, as far as I can tell, so far, but the velocity range makes for a lot of guessing at POA for 40 yds drop. LOL

Do you have SWAG for the velocity range for the 21 thru 25 gr heavy weights?

I plan on retesting all the pellet weights, with the larger plenum etc, and keeping the same 3000 psi tank levels, 1340 psi reg set point etc,
as the consistency I am getting so far, is very good IMHO, with what little I know, and subject to change, from testing results.

I want to try them on the Crows that are eating our chicken eggs, we used to get 6-8 eggs a day, now it's down to 1-2 per day etc, if we are lucky.
I centered one, with a 14.3 gr pellet @ 850 fps+, and it flew over 50 yds, before it took a dirt nap.
The local warden told me, it was OK to shoot the ones causing the problems, so they have been added to the NO FLY list,
along with the Starlings, Magpies and coyotes around here.

Tia,
Don

[Hoosier Daddy]

Jeezus...
That made my head hurt. But I think we are all on the same page here.
 

[Nvreloader]

Scott
You think your head hurts, try looking at it from my side of the fence............

You guys are all on the same page, except me.......I am left with foggy notions, I think.
I know the drugs the VA is giving me, is messing with what little bit of brain matter, I have left.  LOL

Then Bob, sneaks in here and throws me another curve ball.  LOL      
I didn't see Bob's reply, until I did a refresh on this section.......

And I am getting OLDer............

Tia,
Don

[Hoosier Daddy]

Sux don't it... 

[ranchibi]

Don, you are having fun tuning it...that’s  AWESOME! When you are adjusting the FPS you will see what works best for accuracy for the different weight pellets. FPS shooting too high will cause the pellet to tumble leading to bad accuracy and sideways hitting of paper! LOL! Trial and error but most of all learning and enjoying

[Nvreloader]

OK Bob,
I know now, I was way out in left field, in thinking, (dangerous for me), I had to run the heavy weight pellets faster,
than reasonable or safely for the best results, That's what I get for thinking.......................out loud again......

But, I am confused again by this information, and I am NOT starting a whizzing contest etc, etc, etc,

"Trying to make a gun adjustable over a wide range is a really poor idea, IMO.... too many compromises to make...."

And Here I go again, thinking out loud,    and do not think I am NOT starting a whizzing contest etc, etc, etc,
I don't know or understand all the answers or why, it should not be done.

I thought the reason for the SSG, is to use it's adjust-ability , to tune/adjust to different psi levels, and to get into the most useful/accurate and safe range,
for what ever pellet weight you are shooting, or do you just build for a very narrow range only?

I have adjusted from 880+ fps down to 630+ fps, with 6 turns, (24 tpi), I have 6 more turns on the adjustment screw, before I run out of adjustment,
with 3000 psi tethered, 1340 SP, 20" bbl length, from the limited testing I have done.

Please help me to understand where I am going wrong.............

Thank you, and for every ones help, even thou you all, are on a level, way above me, 
I, for one, greatly appreciate it, really, and then I'll go stand in the corner until it sinks in. LOL   

Tia,
Don

[Nvreloader]

Scott

You don't the half of it, the more I read, the less I under stand. LOL 
And I wonder just how many others here, are in the same boat.

I still say,
all these ENABLERS, should have a online course here, to have a reasonable chance of UNDERSTANDING,
what is being said, and between the lines.  LOL

I would probably flunk the course........several times.........

Tia,
Don

[Nvreloader]

Randall

I think, I am having fun, just not sure yet,
I feel like I have lead boots on, and the life ring is just at my finger tips, I can touch it, but just can't grab it, yet. LOL   

I understand the accuracy part,
but, shooting at TOO high of a velocity causes the pellets to tumble, can that be done in a air rifle?

I had a spiraling problem, but that stopped for the most part, when I got into the 800 fps range,
But, I can still see about 1/16 to 1/8 turn of spiraling, even at those velocity's, at 40 yds.

I thought that shooting at TOO low a velocity, caused pellets to tumble.......
within safe regions, and it was better to be faster, than slower, if you have a choice.

I know from my PB's, that's was the direction/option to work for, shooting a 75gr (22 cal) bullet at 2900 fps,
leads to side profiles, at any ranges, but running at 3600/3800+ fps, safely and the results on dead on for accuracy, out to 800+ yds etc.

I am quickly learning, the error part, along with tearing the 79 apart, and putting back together correctly, I can do it in my sleep...........LOL

Tia,
Don

[ranchibi]

Don, we are all learning and “trying” to help one another here, the reason for forums! I think pellets react differently than bullets because of the skirt, and I think why pellet manufacturers design them for optimal performances at certain speeds because of the lighter weight combined to work with the skirts to keep them stable in flight. Many people are trying out slugs I think for that very reason, higher FPS without wobbling. PCP’s are evolving at a very fast rate in the last few years and it doesn’t look to be slowing as of yet. I think PCP’s are getting so efficient that pellets will be evolving also at a commensurate rate...look at JSB’s newer Monster offerings, more stable at higher speeds. I think pellets dictate what PCP manufacturers bring forth. I liken it too the fishing industry where braided line much thinner and stronger than monofilament has let reel manufacturers make smaller, lighter more efficient reels with greater drag capabilities....they compliment each other. I have learned a lot from this incredible forum and something new everyday!

[nervoustrigger]

A pellet's stability is best at low velocities.  Not saying that makes it desirable to shoot at low velocity because they are stable enough at up to about 950fps, generally speaking.  Above that, it degrades very quickly and is at its worst at the speed of sound (around 1125fps at sea level).

This subject came up in the redesigned Monsters thread if you're interested:
https://www.gatewaytoairguns.org/GTA/index.php?topic=136347