Air Arms S.200S 0.177" Sporter Rifle . . . a few idle thoughts !

Over the years I have owned several of this particular series of air rifles starting with the first batch of XS40 Valiants imported as a joint product of Daisy, Air Arms and CZ.   All have been "comfortable" to hold and shoot . . . they posess that inherent feeling that each was made "just for you" !    So . . . as I now reach that point in life at which one must start to rationalise that the end of the shooting range road is not that far ahead . . . I did a lot of introspective thinking as to what air rifles would be the best for an old man to own for occasional plinking and not-too-serious target shooting, both paper and Field/Silhouette.

There's no doubt about it . . . fit as I try to stay, despite the onset of old-age related disabilities . . . one's ability to swing a large rifle to the point, or even to support its' weight, diminishes with the years.   So . . . two of the criteria that must recieve a thorough analysis are rifle size and weight.    Essentially this leads one to initially think of carbines . . . or junior-size rifles.    One such, that seems to fit both categories is the latest, single-piece stock version of the Air Arms/CZ S.200 . . . and it's available in both a pure low-powered target format, complete with aperture sights . . . or a non-FAC powered Sporter variant for scope shooting.

The photos below, courtesy of Pyramid Air, show the basic rifle, without sights, applicable to both formats.

Having decided that my S.200 12fpe Sporter variant would be one of the rifles that I could use for the, hopefully, many years ahead, my thoughts, as always turned to "How can I improve upon perfection ?"    One aspect under consideration was that of being able to vary the power level to allow it to be used as a "Winter basement target rifle" as opposed to its' primary role as a small pest hunting rifle . . . or the occasional dabble into Field Target or Silhouette competition.   From prior experience with the earlier XS40 units, I knew of . . . and had used the variable setting transfer port on the right-hand side . . . to optimise the power levels for accuracy and "sweet range" tuning.    But I also recalled that, from some old studies by Ian Pellant, to obtain higher power levels with those early units, a different hammer spring was required.   Common sense indicated that my S.200 Sporter already had such a spring factory installed ! 

Another aspect of "improvement" was, as always with my 'shooting rifles', that of customising the the stock to fit me . . . one simply cannot shoot well with an ill-fitting rifle !     I had already done a little whittling on the right-hand side of the wrist area of the ambi-contoured stock, and provided some relief clearance for my trigger finger and my chubby li'l ol' cheek on the left-hand side of the butt.     But . . . the rifle cried out for something more . . . !

A chance reading of a thread on the GTA Forum, led me to Dave Dunn out in the great northwest .    Thus the following . . . !

From: Mick K
To:     Dave D

Hi Dave ,

Somewhere recently I recall a post you made on either the Yellow Pages or GTA Forum with regard to your varying the power level on your S.200 from "Summer Plinking/Hunting" at 12fpe to "Winter Target Shooting" at 5-6fpe.   More on this in a few moments.

Having been talked out of all my older Valiant XS40 rifles by past students and others . . . I decided some while back to add a newer 12fpe S.200S to the "stable". This is one of the later units with the single-piece stock, manufactured in late 2008.    It shoots every bit as accurately as the earlier low-powered pure target variants, and will no doubt become one of my "Final Air-Rifles"    Needless to say, in keeping with my practice of the last 70-odd years, the stock has been "whittled on" to make it a somewhat better fit to my chubby ol' face and hands - lol.     Right now I'm considering some major changes in its overall configuration involving a lot of routing out of a few areas and re-glueing in/on replacement birch ply inserts before much more whittling and sanding . . . but that's not my reason for this message.

I recall that you had un-sealed the hammer spring adjustment plug at the rear of the receiver of yours and removed it . . . then had cut a screwdriver slot across the rear face to facilitate periodic power level changes.    I have noted on mine . . . the most recent variant(sic) . . . that the plug is NOT sealed and has a plain rear face with a small ~0.066" dia pin protruding from it . . . about 0.125" high.    My guess is that the CZ factory must use something like a small diameter pin-vise chuck to grip that pin for initial installation and power level calibration.    My only such pin-vise available these days is slightly too small and the jaws are too deeply recessed in the chuck body to access the pin . . . isn't that always the case - lol.

So my first question to you is along the lines of . . . "How tight is that adjustment plug in the receiver . . . does it rotate fairly freely against the hammer spring pre-load ?"    I may have to resort to gripping that tiny pin with a pair of old needle-nose ViseGrips to turn it to get it out for the first time.    One alternative I have considered is to lock it in the collet jaws of an old Dremel tool and keep my finger on the shaft lock in order to remove it.

The second question is along the lines of "How many turns" of plug rotation are you finding it necessary to unscrew the plug to change from 12fpe down to the 5-6fpe power level.    Are you then adjusting the transfer port needle plug inwards on the RH side of the receiver to balance air flow with the new basic hammer spring setting ?

Being old and not so brash and adventurous as I once was, I find I tend nowadays to see what others' experiences have been in similar projects before tackling them - lol.

Regards - May all your shots be in the X-ring,

Mick - The Fuzzy Limey

From:  Dave D
To: Mick K

Hey, Mick … good to hear from you.   I’ve enjoyed the many posts you’ve made.   Nice to know that some of mine have made an impression.   It’s really too bad that AA decided they needed to go to a one piece stock . . . it really is a big step backwards in my opinion.   That said, with some judicious whittling, it should be possible to make some serious improvement.   What I found most objectionable on the one piece stock was the bulkiness around the pistol grip area.   The older stocks had a very graceful, and useful, relief cut coming back from the trigger on both sides.   I have fairly large hands and long fingers, but that older stock design is much more comfortable to me than the newer one.   But I’m sure you know all this, so I’ll get to the reason for your email.

Yours is different from mine, in that mine didn’t have a pin.    BTW, mine’s a Mk. II as I understand these things.   Once I got the sealant out of the threads, I was able to turn the flat plug with a pencil eraser . . . a new one on a standard old #2 Ticonderoga pencil.   I seem to recall a little bit of spring preload causing problems.   I solved it by lifting the bolt and putting some forward pressure on it.   After that it turned pretty easily.   One thing to look for, on either side of the receiver on my rifle, in line with that cap/plug, there are tiny threaded holes for a set screw (I assume).   Mine doesn’t have any set screws, but yours might . . . I can’t see them tapping extra holes for no reason.   Once you back it out far enough, you could either Dremel a slot for a screwdriver like I did, or even drill a couple of holes for one of those two pin drivers . . . I think they’re called clutch bits.

As to setting, mine is running a little hotter than stock right now, I have it set at around 14 fpe.   That’s with the cap turned in 4 ½ turns from flush with the back of the receiver.   If you turn it in too far, you’ll interfere with the trigger, it won’t cock, or it won’t hold if it does cock.   Not sure, but I think I could get one more full turn before that happens, but that would be absolutely maxed out, and doing around 16 fpe.   Doesn’t hurt the accuracy a bit, but the shot count goes to hell.   As far as going the other way, I’m afraid that’s trial and error with a chronograph on hand.   Don’t remember for sure, but I think the basic setting is between 2 and 3 turns in from flush . . . And yes, the transfer port needle is definitely used for fine tuning.   The best setting seems to be around 600 fps with a ~8 gr. pellet.   That’s around 6.5 fpe, is scary accurate at 10M, and gives a never ending shot count.   I didn’t run any chrony strings with it after setting it up last winter, but I intend to do so this year (and make better notes!), and I expect a nearly flat shot curve for at least 60 shots, maybe more.

Like I said, the transfer port needle is an integral part of the adjustments, and has a lot more range than you might expect.   Just using the needle can vary the velocity by 100 fps or more, if I recall correctly.   Which is why you need the chronograph on hand . . . getting the balance right takes some time and testing. I use needle flush with jam nut as my base, at the current level I think I have it turned out 3 turns.   For low power, I think I had it just about flush.   I’m shooting high 800’s right now with an ~8 gr. pellet.   BTW, mine really likes JSB’s of all types, from the Express to the Heavy. 4.51 seems like the best head diameter, but it will happily digest just about any of them.   It’s also very fond of RWS R-10 heavies, I need to get a supply in soon.   I tried some of the other readily available "match" pellets, some were okay but the R-10’s were the best.   I still haven’t tried any Vogel’s, they’re on my list for this year.   If you have any other suggestions, I’m all ears.   Can’t think of anything else, Mick, but if I missed something, you know how to reach me.   If you have a critical question, or just want to call and shoot the breeze about airguns, my number is (xxx-xxx-xxxx). I’m on the West Coast (sort of), so that’s Pacific time, any time before 10:00 pm is fine.   Hope that helps.

Take care … Dave

From: Mick K
To: Dave D.

Hi again Dave,

Thanks for the prompt reply.   It would appear that there are several distinct differences between the old XS40's, your Mk.II and the newer unit I now have.   I had made a few minor adjustments to the transfer needle valve setting on the old Valiants to fine tune/extend the "sweet spot", but with no changes to the hammer spring settings.   All done over my chrony of course.

On the newer S.200 that I have, the needle valve screw is deep set in the port with a regular internal socket Allen-head.   The port is then blanked off with a dome-headed Allen cap screw . . . must be removed to access the needle valve.   I have not checked mine for range of adjustment yet, but the older ones could vary the muzzle energy by as much as 3-4fpe.   Ian Pellant, in one of his old articles, back around 2002 I recall, described some experimenting with both the hammer spring tension and needle valve settings of the original 12fpe units to obtain an extended "sweet spot range".   I'll explore this matter further once I master the hammer spring plug removal.   The best bet with this new plug will be to make a pin spanner . . . possibly a piece of, maybe 5/16" Dia, steel rod to fit in the threaded cavity, with a central hole to fit over the pin , and two small steel dowels, (1/16" Dia ???), inserted diametrically opposite each other.   Then drill two matching pin-holes in the cap that the spanner pins could engage.

My new unit . . . still has the two threaded holes on either side of the receiver that appear to go down to the rear adjustment plug.   The one on the left is "empty"  . . . the one on the right appears to have an Allen-headed set screw inserted to lock the adjustment plug.

Performance-wise, mine out of the box, is definitely shooting well below the 12fpe level with muzzle velocities around 755fps using JSB 8.4gr Exacts.   However the accuracy at ranges from 10~ 35 yards is more than acceptable.   At 10M the Exacts give better accuracy than any Match wadcutters I have on hand.   The best have been Vogel 4.50 Green . . . RWS Basics and H&N Match are just fair . . . Crossman and Daisy are plain P-Poor !    Crossman Premier Heavies, 10.5gr, shoot accurately, but are difficult to load smoothly . . . the domed head seems to catch as it enters the chamber and cockles over a bit . . . the Daisy's have the same problem but then they have that little ridged ring around the leading edge.   Beyond 10M. forget any of the wadcutters . . . most unstable at the velocities they're travelling.

My main reason for thinking of the power reduction is that I can keep myself at similar power to my JROTC rifle students . . . and not scare an already nervous HS Principal - lol.    A few years back one of my "Blind-Firing" training exercises with inexperienced Cadets left a few unsightly chip marks in the row of chalk boards on the wall behind our target frames !

I agree on the bulkiness of the pistol grip . . . but, at my age, I'll probably never be shooting in formal 10M competition again . . . I am free to do a little whittling on it.   So far I have removed a fair amount of wood from the RH lower palm/thumb rest area of the clearance "slot" behind the pistol grip.   This allows my right hand to lay in there in a more comfortable fashion regardless of shooting position.   I have moved the trigger to the most rearward setting, and rotary-rasped and sanded away a deep groove for the trigger finger along the upper edge of the pistol grip.   Far to much interference in that spot for my liking.   On the other side of the butt, I have now rasped and sanded out a sizeable cheek pocket for my antique face to fit . . . that way I can get my right eye comfortably behind the aperture of the "Paddy Field/Gamo" sights.

The relative slenderness of the lower palm rest area kind of worries me somewhat as a weak spot now I've whittled it away so much.   My thoughts at the moment lie along the lines of making a clamp-on jig frame that fits over the whole butt . . . designing a routing template for the left face of the jig that will allow me to rout out much of the left face of the butt from the rear of the pistol grip back to just ahead of the butt plate.   Then using 1/4" model aircraft Birch ply, epoxy in fillers to that exact size and shape to build up the overall thickness of the butt to higher than original and also to fill in the deep thumb slot behind the pistol grip on the left side . . . then do a partial routing/filling operation on the right hand side of the butt for just the thumb slot.   Then having now bridged and reinforced that large cutaway area, I can get back to work with rasps and sandpaper, reshaping it to suit my hands and face.   I'm still in the thinking stage on all that whittling at this point - lol.

Most likely I'll also trim just a hair off the butt to get a more realistic LOP.   I'm also thinking of deepening the forearm and extending it rearwards over the lower face of the trigger guard . . . another good spot for vertical laminations of Birch ply.

I'm guessing from some of your other posts that you have installed the complete AirForce Edge sight system.   I'm also assuming that the rear sight is of such a configuration that a regular height front sight is practical.   Would you say that the Edge rear sight is far superior in design and construction quality to the Chinese /Gamo that all the other CMP Sporter rifles are using ?   With cataracts in both my eyes and tri-focal glasses I hate the Gamo rear aperture . . . just a square-edged hole moulded in a plastic sheet . . . very blurry sight picture.   Same with the front apertures . . . cheap stamped sheet metal.

Regards - May all your shots be in the X-ring,

Mick - The Fuzzy Limey

From: Dave D.
To: Mick K.

Yeah, Mick,

Between CZ and AA, and target vs. other models, there have been quite a few variations and configurations of this little rifle.   Makes it tough to keep it all straight, especially when some of the changes have been incremental.   Your rifle is a case in point, on most of the later "Mk. III" rifles it looks like AA has tried to make it as tamper resistant as possible.   I’ve read several reports that say that the needle valve screw isn’t even there, and that the cap screw you described is just a plug.   At least it sounds like yours is still usable, so that’s a good thing.

Sounds like you have a plan on dealing with the hammer spring plug.   Sounds complicated . . . I think my solution of just carving a slot was a lot simpler.
On that subject, what I was calling a clutch bit is actually a spanner bit, and they come in a variety of sizes.   Might be simplest to just get one of those, and drill a couple of appropriate holes. ¼" hex drive insert bits, lots of drivers available.

These things can be funny on accuracy.   Mine has been excellent from day one for me, but it was a second hand rifle.   I traded an S400E Extra FAC straight across for it, and I’m pretty sure I got the better end of that deal.   A friend of mine, (Dano in TX), bought one like yours last year, and it’s only just now starting to shoot well.   Dan doesn’t shoot a lot, so I think it was simply a matter of barrel "seasoning", and getting enough pellets down the barrel.   Yours may well settle down after several hundred pellets through it.   And like a springer, it will probably change is pellet preference.   But why am I giving you advice on this, you’ve had way more experience with these things than I have !   Like I said before, the RWS R-10’s were the best match pellet in mine, and like you, the Daisy Avanti pellets were terrible.    1" groups at 10M was about as good as they got, which is mind bogglingly bad.   And really too bad, they’re very pretty pellets.   H&N Match and Basics, like yours, were also only fair.

With all the work you’re planning on doing on the stock, are you sure you wouldn’t be better off just getting one of the adjustable 2 pc. stocks for it ?
That’s what mine has, and I’m sure happy with it.   I still need to order some adjusting spacers, as I used all I got with mine to extend the LOP, so the cheek piece is all the way down.   I’d like to get it up a little, and I’d still like some more LOP.   I have long arms, it’s at 13 ½" right now, but I’d be more comfortable with another inch.

Yes … I do have the full Edge sight system, although I didn’t get the front sight until just a short time ago.   Then it sat until just the other night, and now I’m trading it off on a front sight from a Beeman R1.   Just didn’t like the look or feel.   The rear sight is outstanding, though, and yes, it works quite nicely with a standard height front sight.   Last winter I was using the front sight installed on the Daisy 753.   And also yes, it is FAR superior to the standard Gamo/Avanti/Air Arms diopter sight.   Virtually zero slop, and completely repeatable.   I’ve never shot one of the high end match sights, but I can’t imagine them being twice as much better as the price would indicate.   Also, I believe the aperture on the Air Force sight is threaded the same as the Gehman irises, so if you have something kicking around that you’re already happy with, it should thread right in.   The aperture it comes with is very small . . . small enough that I was having issues being able to see in the fairly low light area I was shooting in.   I drilled it out to 1/16", the smallest bit I had on hand, and it works very nicely for me.   That said, I’ve reached that age (50) where my eyes are starting to deteriorate, so I’m thinking of trying one of the magnifying diopter apertures.   Any experience with those, and any advice or suggestions if so?

Looks like dinner is on, gotta go. Take care.

Dave

From: Mick K.
To: Dave D.

Hi again, Dave,

I found a couple of hours this afternoon to do a little twiddling with the hammer preload and transfer needle valve settings.   Once the plug was "unlocked" it turned fairly freely.   Initially I tried increasing the velocity to be sure I could get the muzzle energy up to a steady 12fpe . . . opening the needle valve to about 2-1/2 turns from full closed did that OK.   The preload plug was in about 3-1/2 turns.   Was able to get around 50+ shots within a velocity range from 790 ~ 817 fps with an S.D. around 5.5fps.   That's quite satisfactory for my plinking/outdoor target shooting needs.

Tried a few totally different settings of both the hammer plug and needle valve before settling on one that gives me about 90 to 100 fairly uniform velocity shots with Vogel 4.50 Green Match pellets at around 600fps . . . that is enough to shoot a regular 3x20 indoor 10M match, plus sighters, on one tank fill.   Before each test set-up I re-filled the cylinder to an even 200Bar . . . ending pressure for each test was approximately 125Bar.   I put the results of the final test strings on a M/S Works spreadsheet, attached to this message.   If I were to close down the transfer needle valve a hair more I could hold it at the optimum 575fps that current match pellets are designed for.   May do that tomorrow, time permitting.

The final needle valve setting was 5/8 of turn open from full closed . . . the hammer plug was set to be flush with the rear face of the receiver . . . Should give minimum hammer spring preload without exposing any plug threads.

After I re-installed the barreled action in the stock I shot a few 10-shot groups from the Sitting position with elbows resting on knees, at 10M with both the Vogel Green Match and some older cheap RWS Basic pellets. Both types of pellets would group comfortably within the 9-Ring

Regards - May all your shots be in the X-ring,

Mick - The Fuzzy Limey

From: Dave D.
To: Mick K.

Thanks for the update, Mick, there’s a lot of good info that I suspect is going to save me some time.   One note … I think you may be over-filling a bit, although the manual says max safe fill of 200 bar, 190 is the recommended fill level.   That’s what I use, and it seems to work out nicely.   Of course, that may have changed with the newer rifles, but based on your data, it shouldn’t have.

I need to do some chrony strings with mine, I just checked my records, and I haven’t recorded anything since I got this little jewel last January.   As received, it was doing over 15 fpe with CPH’s, I turned that down very quickly.   Unfortunately, it wasn’t consistent with the pellets I used, and I haven’t kept any records since . . . just a few shots across the chrony to see what it was doing.   Time to rectify that situation.

Well, I’ve spent most of my day working in my winter chicken house getting ready to move my "girls" (and guys), so I’m covered with fine dust, need to head for the shower.   Sometime in the next few days I should be able to start doing some shooting again . . . I’ll do some testing and send you the data.    So 575 fps is the optimum, eh?   That gives me a benchmark to "shoot" for, now I just need to get some match pellets in stock.

Take care … Dave

From: Mick K.
To: Dave D.

Back again, Dave ...

Got back to the S.200 again this morning . . . weather a little calmer !   Did a little fine tuning on the needle valve setting.   Now at a hair less than 9/16 of a turn open it's pushing out Vogel Greens at around 580fps . . . the barest tweak would enable an exact 575fps.   Of course, manufacturing tolerances on either valve needle or seat configuration would vary this slightly from rifle to rifle.   On the other hand, with the older units having the "full-length" protruding needle valve and lock-nut, such as your Mk.II, I have no idea as to what settings should be.

You are, of course, correct in stating the nominal fill pressure for the S.200 as being 190Bar . . . I have been taking mine to the max 200Bar in order to evaluate the initial velocity curve and how many "out-of-sweet-range" shots may ensue.   So far it looks as if the "best range" for uniform velocities starts around 185~190Bar.

I decided, for the moment, not to rout out the LH side of the butt, but to just partially fill and re-contour that flimsy cutaway wrist area.   So, traced out the contours of the "thumb-cutaway" in the butt for a preliminary fill-in pattern, and started looking through my current stock of Birch ply this morning also . . . seem to have plenty of 1/32 and 1/16 on hand, plus a sheet of 1/8" Basswood . . . but NO 1/8, 3/16, or 1/4 inch !   I like the first laminate to be fairly substantial to act as a backbone, as it were.   Soooo . . . guess a trip to Hobbytown USA, or similar, is in the offing . . . once in a while I find some nice solid Walnut strips tucked away in their wood bins . . . always good for that "expensive" look !

I was thinking - a bad habit of mine - over the holiday about these E-mails. With a little editing, this series would make a nice li'l folksy article for posting on my coaching website ... or even over on the Tuning and Modifications threads on GTA.   Would you object if I did just that ?   Give some of the youngsters an idea of how ideas are swapped, and experiments started, among the "older" airgun fraternity.

Regards - May all your shots be in the X-ring,

Mick - The Fuzzy Limey

From: Dave D.
To: Mick K.

Morning, Mick !   Good to hear from you again.   I was wondering how things were going.   Still haven’t had any time to spend with my S200, although it looks like I might have my sights almost in order now.   I was able to trade off that AF front sight on a Beeman deluxe sight, and it looks like a friend of mine has some old Walther inserts that will fit, so that issue should be taken care of.   And I’m making progress on other fronts too, should be able to get my indoor range set up over the next week (I hope).   So maybe I’ll actually be able to do some shooting sometime in the near future !

Regarding fill levels, with mine, even a 2700 psi fill seems a little high … my "sweet spot" seems to start at about 2500 psi.   Again, that’s based on my current settings, but the first 5-10 shots are usually a little slow at a 2700 psi fill.   So your 185-190 Bar fill level seems to agree with my findings.

Regarding your stock modifications, you just reminded me of some material I have on hand that I have no use for, but that might be of some use to you.
Ever hear of a wood called Ipe?   It’s a South American hardwood, very dense, durable, and stable, and tends to look like walnut once sanded and finished. It’s very stiff, but I suspect it would respond to some steam bending if needed.   I have some strips I made up, mostly as an experiment in re-sawing on my band saw.   There’s a small variety of lengths and thicknesses ranging from 1/8" to 5/16" thick, 2-3" wide.   The thinner pieces are only about 1’ long, but the thicker stuff is about 4’ long.   If you’re interested, send me your address and I’ll send it to you.

And as to your posting our little string of emails here, I certainly have no objections, feel free to edit as you see fit.   If some photos would be of use, let me know what you want . . . I have a digital camera and am pretty good with my image editing software.   And I don’t mind taking my rifle apart !

Time to run again, it’s moving day for my chickens.   Keep me posted on your progress if you don’t mind, and I’ll try to do likewise, if I ever get around to making any !

Later.

Dave

SO . . . moving along a bit  . . . the initial power level situation having been resolved, we next turn our attention to modifying the stock configuration.   Firstly it involves "filling-in" that gaping cutaway behind the pistol grip - designed as a compromise to allow ambidextrous usage of the same rifle in a Club situation.  In my case, I did this with a mix of some 1/4" Poplar for the central backbone, followed by laminates of 1/16" Birch ply, suitably bonded with Loctite 2-part Epoxy, with a 5-minute setup time.

Below are some photos of the layup - and initial thumb-rest contouring - at intermediate stages . . . !