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Factory Left-Handed Air Arms NJR100 Vintage FT Rifle

Discussion in 'Gun Gallery' started by cloverleaf, Mar 15, 2014.

  1. cloverleaf

    cloverleaf Super Moderator Staff Member Mod/Admin

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    So, here's another one from the bugeoning collection :p

    This rifle came to me quite by chance about 18 months ago. Given its age, spec, condition and orientation it would have been rude not to..

    The rifle is a 1991 Air Arms NJR100 in a proper, original left-handed, Nick Jenkinson-designed walnut target stock. Being *EDIT* a later *EDIT* model the gun has a silver breech block (would have preferred black but can't have everything!).


    The Air Arms 100 series appear little-known in airgunning circles. They were introduced in around 1990/1991 as a replacement for AA's first attempt at a PCP, the Shamal. In 1996 the 100 series was discontinued with the introduction of the 300 series; the forerunner to the current S400 and S500 range.

    The 100 series was designed to cover all bases through the use of a modular design. The entry-level rifle was the SM100; an unpretentious, unregulated beech-stocked sporter with a round cocking knob and sporting trigger. Next up the tree was the XM100; being of similar spec to the SM but featuring walnut sporting woodwork.

    Moving away from sporters and more towards target guns, the TM100 used the same basic action as the SM and XM rifles, but with a stippled, adjustable target stock, regulator and excellent "Olympic" trigger. Finally the NJR topped the range by adding an even fatter and more adjustable FT type stock and chromed swan-neck loading bolt.

    In keeping with the modular design, the nice bits from higher-end models could be specced as options on the lower-spec guns.

    Despite their age the 100 series guns still hold up reasonably well in comparison to today's offerings; all but the most basic models had quick-fill adaptors (although the parts are a swine to source now) and the olympic trigger can still hold it's own against more modern designs. On the down side, the guns aren't particularly air efficient (both regged and un-regged setups), the regs can be tempremental, and they can feel a little crude in use as the striker and valve gear are all over-sized and correspondingly heavy.


    Splendidly this particular gun is fitted with an Airmasters / Dave Welham reg, which is immeasurably superior to the original pressurised offering (one of the standard rifle's few weaknesses, IMO); giving greater consistency, reliability, temperature stability and far better efficiency. I get 100+ shots from a 160bar fill pressure down to the circa 90bar reg pressure.

    The rifle is also fitted with a very nice air stripper (I think this might be a Welham item too) and has had the front cylinder band removed (a common mod) but is otherwise standard - a rarity in itself given how FT shooters like to tinker! Bar a few light scrapes and scars it's in excellent condition.


    Unfortunately the action is not true-left hand. LH stock and RH action was as good as it got back in the day and somewhat shamefully IMO AA have only ever made one true LH FT rifle; the Pro-Target. The orientation of the bolt is fine from a sitting or bench-rested position, but is a pain in the arse for standers unless you have a table upon which to rest the muzzle.

    In use the rifle is extremely pleasant - stock fit is excellent due to its design and adjustability; offering excellent support, comfort and eye alignment. The only gripe I have is the interference with the "thumb up" position by the curved bolt handle.

    The trigger is absolutely sublime and easily the best unit I currently own - the first stage is silky smooth with no hint of hang-up or drag, while the second stage is clearly defined and breaks like glass. I currently have it set somewhere around as light as it will go; the first stage tops out at 80g (0.18lb) and the second breaks at around 160g (0.36lb). A little lighter than the standard 1-2lb weight for sporting triggers, but utterly safe and predictable thanks to the unit's excellent, true 2-stage design.

    Off the bench the rifle is as accurate as anything else I own and I've printed some pretty satisfying standing groups with it too. The rifle shows its age with a leisurly shot development time of 9.5ms; around 1.5ms slower than most modern sporting PCPs and getting on for double the time of modern target guns at 5-6ms.


    Since its purchase I've really fallen in love with this rifle - it's a comfortable, accurate, useable, relatively unmolested relic from the infancy of FT; when most guns on the circult were British and when every British manufacturer was trying to get in on the action.

    It appears built up to a standard rather than down to a price (I believe these rifles cost about £800-900 in 1991!); fit, finish and quality are excellent and there are some nice features sadly lacking from modern alternatives (ability to remove the loading bolt without stripping the rifle, cylinder depressurisation valve and sear engagement inspection hole).

    Aside from the gun's capabilities, it has a charm, character and honesty I find lacking in modern target guns; and I appreciate it as much as a well-engineered, aesthetically-pleasing object as I do as a well-shooting rifle.

    In my ownership the gun's had all of a new inlet valve and short of a better reg pressure / striker setup I'm happy to leave well alone in future!


    Anyway, enough waffling - a few pics. It's currently wearing a Sidewinder 4.5-14x42 on adjustable B-Square mounts, which suits it really well - although ultimately I'd prefer something a bit more "period correct":

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]


    Hope we like :)
     
    Last edited: Sep 21, 2019
  2. Pidlar

    Pidlar Big Poster

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    We do! Thanks for sharing.
    Regards Stu.
     
  3. paddy d

    paddy d Engaging Member

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    Very nice sir, fantastic photos
     
  4. surrey shooter

    surrey shooter Donator

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    Lovely mate.
     
  5. cloverleaf

    cloverleaf Super Moderator Staff Member Mod/Admin

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    Cheers guys :)
     
  6. The Robin

    The Robin Super Moderator Staff Member Mod/Admin

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    That is one stunning rifle, enjoy
     
  7. Dsmith

    Dsmith Engaging Member

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    Had a look at a friends one of these last week. Amazing piece of kit
     
  8. Soximus

    Soximus Busy Member

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    Behind you! Mwhahahahah Just kidding. Christchurch
    Knew this was one of your posts the second I saw the amazing pics....lovely gun....
     
  9. Steve g

    Steve g Donator

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    Rate nice and cracking pics:up:
     
  10. cloverleaf

    cloverleaf Super Moderator Staff Member Mod/Admin

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    Thanks all :)
     
  11. Paddler

    Paddler Donator

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    Thanks for a trip down memory lane... I had the SM 100.. happy days.
     
  12. chevin

    chevin Keyboard Hero

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    Excellent write up and pic's, very nice well done.
     
  13. den77

    den77 Donator

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    That's a lovely rifle mate first dibs on it if you decide to sell please
     
  14. Ganton Gunner

    Ganton Gunner Super Moderator Staff Member Mod/Admin

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    they are very good rifles indeed and that one is a fine example :up:
    I also own a NJR100 and I will say it shoots as well as my ev2's etc. and any gun I have ever owned
    I just wish my camera skills were 1/2 as good as yours so I could show mine off :(
     
  15. Brooksy789

    Brooksy789 Donator

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    Looks a beautiful rifle. How does the trigger feel, looks weird being very straight and not curved for the finger.
     
  16. Paddler

    Paddler Donator

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    Yeah was a weird trigger.. It's Air Arms ' Olympic ' trigger unit. I slapped one in my sm100 pre NJR. Once I set it so light it almost seemed like you think the gun to shoot. Lots of premature emissions :eek:. Especially if you gave them butt a firm tap without a finger on the trigger !!! I let a few shots go when settling down to shoot on field target lanes, losing the points!
     
  17. cloverleaf

    cloverleaf Super Moderator Staff Member Mod/Admin

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    Thanks and certainly - can't see it going anywhere soon, though :)


    Ta! The blade feels fine - not really noticeably different from curved blades if I'm honest.


    I suspect yours wasn't set up correctly then - it's a true-two-stage unit meaning you can make the second stage very crisp and light while keeping lots of lovely sear engagement when the trigger is forward and during the first stage. It's a common mistake for people to completely adjust out the 1st or 2nd stages - effectively making it into a hair trigger with very little sear engagement, that's potentially prone to go off if knocked or looked at funny :p



    So, I've had this rifle for around 2.5yrs now and it hadn't been to bits to any significant degree (must be a record for me :D)

    Driven by the desire for a few measurements (transfer port diameter for this reason, air capacity to calculate approximate air efficiency) and plain curiousity since it reputedly has a Welham reg, the gun came apart a bit more earlier. I took a few photos mainly for my own reference, so they're far from comprehensive and certainly no guide to stripping the gun.


    First the bolt housing / barrel / muzzle assembly were removed en bloc..

    [​IMG]

    [​IMG]



    There was a touch of corrosion under the breech block, but nothing terrible or visible with the block fitted:

    [​IMG]



    The tranfer port bush / insert came out and was measured at 3.0mm ID..

    [​IMG]


    Next the rear cylinder plug and striker assy were removed. The adjustable striker appears to have been short-stroked at 7.0mm, with a fair amount of spring preload. The plastic insert in the spring is a (factory standard) damper / "de-twanger".

    [​IMG]


    The striker is a portly sod at around 124g (an S400 item is around 45g).

    [​IMG]


    The gun was depressurised using the very thoughtful bleed valve in the inlet valve assy - a useful refinement that no doubt fell victim to the accountants in later models. Here's the inlet and QF connector - these (and the corresponding female part) are like hen's teeth and to be guarded with one's life. The thread on the inlet is standard 1/8BSPP male so other connectors can be fitted - however none I've found so far are the correct size and shape to allow proper fitment of the fill valve cover, which attaches to the QF coupling.

    [​IMG]


    The inlet valve from the rear. The black plastic ring in the centre is screwed into the housing and retains the valve spring and valve assy. This part should actually be a particulate filter (an off-the-shelf 1/4BSP "silencer" for industrial applications) however I knackered mine when filling it too quickly from empty and haven't got round to sourcing a replacement yet.

    [​IMG]


    The exhaust valve assembly and regulator. The valve housing is the large brass part to the left of the image, and appears standard. You can see the counterbore for the transfer port bush / insert at the top, flanked by two tapped holes for the loading bolt housing bolts. The hole near the rear of the housing is for one of the retaining bolts that holds the valve in place inside the cylinder.

    [​IMG]


    Rear of the exhaust valve housing - the valve stem is extremely fat at 5mm diameter..

    [​IMG]


    Everything forward of the brass exhaust valve housing is non-standard and fitted in place of the standard (dodgy) Air Arms reg. Note the Nylon valve seat / output pressure adjustor and brass locking nut, as well as the entry hole in the side of the front aluminium section.

    [​IMG]

    Given the lack of breather hole in the gun's cylinder I'd been concerned that the reg wasn't vented to atmosphere, and would hence fail like so many other, earlier reg designs that slowly pressurise, gradually dropping muzzle energy until the gun would no longer fire.

    Some of you might already have noticed the lack of O-ring on the exhaust valve housing - this is because the talented Mr. Welham has sealed the front of the reg instead, venting it out of the side of the central smaller OD Aluminium (which also contains the pre-valve plenum), which in turn is open to atmosphere around the circumference of the seal-less valve. Very tidy :up:


    Since this area is open to atmosphere (and this rifle used to be a working FT gun, so probably out in all weathers) I did find some corrosion inside the cylinder - in the form of some localised light pitting that had no doubt been caused by a small amount of moisture trapped between the reg body and cylinder wall. This didn't seem too bad (and is in a section subject to no internal pressure) so was cleaned up with a phosphor-bronze brush and sealed with some oil.


    The approximate effective volume of the cylinder was measured and calculated (at around 232cc, excluding the reg plenum). Historically this rifle has always been very frugal with air - having some shot strings, fill and refill pressures and cylinder volume allowed me to calculate it's relative efficiency to just over 9bar.cc per ft/lb with DS Heavies - a value that doesn't mean a lot on its own, however making it the most efficient .177 PCP I've tested.

    By comparison the next best rifle is the (very efficient) Daystate Mk4 at around 10bar.cc per ftlb (although admittedly this was with AA Fields and I suspect it could do better with Heavies). Air Arms 400 series PCPs are usually around 13-18bar.cc per ftlb depending on pellet used, and the full length HW100 around 15bar.cc per ftlb.


    Ultimately the gun will get a re-seal and a damned good setting up, but it's going well enough to leave it alone for now until I have more time and enthusiasm. I really must get this rifle up the range more too - it's a fantastic, characterful piece of kit that deserves to be used.. only problem is it's so bloody heavy with the sidewinder fitted :eek:
     
    Last edited: Sep 21, 2019
    Blackmax, talent and raven hunter like this.
  18. trackman

    trackman Active Member

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    As a lefty it was good to see your rifle ;looks like its well maintained. Thanks for the pictures.
     
  19. nat

    nat Donator

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    Very nice indeed, i love to see classic rifles like these,:up: i remember shooting along side Mr N.Jenks himself with one of these, even let me have a go, think i may have drawled all over it :eek:.might be a bit rusty now!!!

    My mate used to hunt with a Shammel.

    Great pics too, Atb,Woody.
     
    Last edited: Dec 1, 2015
  20. cloverleaf

    cloverleaf Super Moderator Staff Member Mod/Admin

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    Thanks for the positive comments chaps - glad we like :)
     

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