My new Benjamin NP Limited Edition: Part 2

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1

Today’s report is a second installment from our blog reader RifledDNA, a.k.a. Stephen Larson. He’s modified his new Benjamin NP Limited Edition and wants to tell us how it’s going.

If you’d like to write a guest post for this blog, please email me.

Over to you, RifledDNA.

Benjamin NP Limited Edition
Benjamin Nitro Piston, Limited Edition. This is what the rifle looks like out of the box.

Today is part 2 of my new NP Limited Edition, and we’ll look at what’s changed on the .22-caliber rifle since I took it out of the box, what pellets it likes so far and the accuracy I’ve been able to achieve. I wrote an earlier part 2; but the day after it was finished, Crosman alerted me they had a new stock for me. A few days after that, my order of pellets would arrive. It made sense to wait until these things were available for inclusion in this report. Both packages arrived, the stock was installed, the pellets have been tested and I can now tell you everything that has happened in one big mess of journalistic chop suey.

First, let’s see what I’ve changed on the gun. In the first report, I told you how uncomfortable and misconfigured the grip and trigger assembly seemed to me. I’m used to pistol grips, and the Benjamin NPS was designed for one. I knew that a stock with a pistol grip that fit properly must be found.

I approached Crosman and asked for a Benjamin Legacy Jim Shockey stock based on the fact that rifle is similar to my rifle and both have the highly angled forearm screws. While these things are true, the receiver tube of my NP Limited Edition is 1/8th of an inch wider than the tube of the Legacy NP, and the forearm screws are not located in the same place.

The screw holes needed to move an inch back to line up with the screw holes in my rifle; and the stock above the trigger, where the end of the spring tube rests, had to be notched, allowing the stock to open wide enough to receive the larger diameter receiver — say that 5 times fast!

Benjamin NP Limited Edition notched stock
I notched the stock at the back so it would relax and accept the larger NP Limited Edition spring tube.

Benjamin NP Limited Edition screw holes
The forearm screws had to be moved back about an inch.

Anyway, the action has now been fitted into the new stock, and it makes me very happy. Although it’s Mickey-Moused in, it’s solid. While someone might notice the screws are now in a different spot, shooting yields no problems. Quite the contrary. It fits my hand wonderfully, and the trigger is easily accessed and is in a location that feels natural to me. Thank you, Crosman!

Benjamin NP Limited Edition new butt
The new buttstock has an adjustable cheekpiece.

Benjamin NP Limited Edition new stock
The new stock and modified rifle now fit my shooting style.

I told you about thinning the trigger in the first report. I also told you the barrel is shorter, down to 10.75 inches. [Editor's note: You did? I can't find any reference in Part 1 where you told us how long the barrel is.] I originally had plans to shorten and rethread the barrel to put the shroud back in place. I wasn’t able to get the barrel threaded; and different configurations, though effective for the noise level, were not making me happy. I found that the unmodified level of noise is not offensive, anyhow and have abandoned the attachments. The short barrel is simple and manageable. For my style of shooting, ease of movement means making the shot.

I also removed the anti-beartrap safety and can now decock the rifle. I think the ability to dencock is very important and have done so countless times already, so I’m glad I did this. [Editor's note: Removing a safety device like the anti-beartrap device cancels your warranty protection and places the liability for any accidents with the gun squarely on you.]

The trigger modifications improve performance; the shortened barrel improves performance (I believe); the stock that now fits me better improves both performance and appearance. Removing the anti-beartrap device gives me the option of decocking the gun.

Two more performance mods were applied. First, the breech seal was replaced with a nice, thick leather one. I noticed a change in the discharge sound when I did this, and it seems the gun loses no pressure at the breech with the new seal. It may have been losing air with the thin factory o-ring. The difference in contact area of the seal is about 10-fold, so I would hope it seals better!

Second, while the barrel and breech were off the gun, I opened the transfer port by just a hair, maybe one-sixty-fourth of an inch. Without a chronograph, I can only tell you these things haven’t hurt the performance. I believe they’ve probably helped velocity and have definitely helped accuracy. The short barrel and powerful Nitro Piston have the pellets hitting their marks as soon as the trigger breaks.

That brings me to the pellets. I had very little pocket change to scrape together an order of pellets, but I did manage to buy three and get the fourth tin free! I ordered two tins of Beeman Round Nose. I had good luck with Beeman Pointed pellets in a .177 Crosman TR77. At ~3 bucks a tin, these .22 domes work surprisingly well. They’re also very soft, which helps with energy transfer. They were the second most accurate pellet.

The two other tins I bought were JSB Exact Monsters and RWS Superdomes. The Monsters were bought to test the powerplant’s limits with pellet weights. My Ruger Blackhawk Elite spring rifle rebounded when a too-heavy pellet was used, and I wondered if the Nitro Piston powerplant might act the same. It doesn’t. It shoots them smoothly but not very accurately.

The most accurate pellets were the Superdomes. They also seem to run very fast. Again, no chrony, but on a super moist rainy day they were creating supersonic cracks. Shooting in dry weather they did not, so either the moisture lubricated everything to send them supersonic or wet air cracks more easily. Interesting.

The RWS Superdomes shoot like laser beams. Since I bought the NP for small game hunting, I shot a 10-shot, 20-yard group with one extra shot, a first-shot-counts test right out of the bag at a small liquor bottle (not mine, found it on the ground on the way to the shooting spot). That shot went dead-center on the 1.25″x2.5″ body of the bottle. That’s good plinkin’ in my book.

I set up a 5.5″ Caldwell Orange Peel target on the side of an old 4-slot toaster, settled in on the canvas folding sports chair rest and put ten Superdomes in a group that’s covered by a nickel. The hole in the paper target looks quarter-sized, but the holes in the toaster metal show 5/8 inch center-to-center. Two shots opened up the group, but 7 or 8 went into a little under a half-inch group.

Benjamin NP Limited Edition target
Ten RWS Superdome pellets at 20 yards made this group. It looks larger on paper than it really is.

Benjamin NO Limited Edition toaster group
The holes in the toaster metal show how tight this group really is. The coin is a dime.

All in all, I’m very happy with the NP. With the new stock and short barrel, I can achieve hunting accuracy out to about 35-40 yards using the pellets I’ve tested so far. If another pellet shows up that shoots better, and I keep shooting the gun well, I can see this NP easily shooting an inch consistently at 50 yards.

That’s about it. Besides a little more trigger time and work (it’s still a little creepy), the gun is in top form with no more changes to be made. I’m now just heading out to enjoy the fruits of my labor as often as possible. When I get a chrony, I’ll let everyone know to be on the lookout for part 3. Until then, thanks for reading!

43 thoughts on “My new Benjamin NP Limited Edition: Part 2

  1. RDNA
    Well it looks like that gun is hitting good in more ways than one. Pretty accurate and pretty hard.

    But you said you were setting in a chair. Did you have a table the gun was resting on? Or were you sitting in the chair with your arms resting on your legs. I like shooting either way.

    But the main thing is. Are you satisfied with the gun now.


    • Sorry, I was kneeling with one elbow in the seat and forearm rested on the back of the chair, the folding canvas allowed it to really conform to how I would be comfortable. This seems like a good way for me since I am constantly shooting different places.


      • RDNA
        You may of just invented the best shooting prop for out in the field. I wonder if a person could get away with that at a field target match. Sometimes they wont allow a chair.

        You would have to say… But Mr. Official I use it as my gun rest. I don’t set in it. ;)


        • It is a really effective rest, portable, it conforms to your position instead of you having to wrap yourself around it. It should catch on, people will ne surprised how well it works.


  2. G’day Stephen,
    Looks like you spent a lot and time and money to get what you wanted.
    But don’t you think it now looks like BB’s $100 PCP?
    May have been better to use a Boyds’ stock?
    Cheers Bob


    • Terrible grammar!

      G’day Stephen,
      Looks like you spent a lot of time and money to get what you wanted.
      But don’t you think it now looks like BB’s $100 PCP?
      May have been better to use a Boyds’ stock?
      Cheers Bob


      • Actually I didn’t pay a dime for the stock, I made a stink and explained that I felt the stock to be, technically, a defective part, in my book it was, but crosman was kind enough to entertain me and send the stock as warranty part. Im sure this was unprecedented and unlikely repeatable, I made more of a stink than I should’ve.



  3. RDNA,

    I liked the idea of shortening the barrel. On a sproinger, more than about eight inches is a waste except as a cocking lever. I can well imagine that the cocking force is not for wimps.

    Would I be correct in assuming that you are using a silicone oil for your leather seal to reduce the chance of detonation? The manual for my 1906 BSA recommends a couple of drops of oil every 50 pellets or so and also if it has not been used for some time as the seal will dry out.

    I too would prefer that style stock, most especially since I have good size paws and it would fit my hands better. I have heard complaints of the cheek rest screw not holding well. If you experience such, a dab of Locktite on the screws might help. Also you can fit a little foam underneath it and that will keep it from sliding down if the screws do get loose.

    I question removing the bear trap though. My concern would be the sear letting go unexpectedly while my fingers were in the way. Yes, I would have a grasp on the barrel, however with familiar repetition mistakes are often made.

    All in all, it sounds like you have been having a lot of fun with it.


    • I suspect the removal of the beartrap is less problematic than one might suspect. This general type of trigger mechanism is pretty common… and I have had them fail on me and allow the breach to slam shut unexpectedly. But on both, the beartrap was in place and working.

      All it really does is prevent the user from pulling the trigger. But if there are other problems (like the quickly wearing sear I had on an early-model Quest) this will do nothing. It’s not at all like the anti-beartrap on the RWS sidelever series that positively blocks the action open.

      As a side note… the OLD Legacy series was rather unique in that it was American-made. The visible part of the trigger group suggests that this is essentially the same platform. If that’s the case, I hope it still is made in this country…


      • The trigger on this NP is supposed to be American (NY) made, and from taking things apart it looks to be very solid, simple, tough, etc… it has a very positive and secure safety mechanism so I am not worrying about the trigger letting go, like I said its still a little creepy, definitely not a hair trigger. The bear trap is a free agent, so Removing it isn’t effecting any other action parts, so I figured it wouldn’t be any less safe than a gun that came without a bear trap, like my blackhawk.


        • If it’s the same as the old Legacy (and I have little doubt that it is), it is mechanically the same as the Quest/older Gamo style. The big difference is that the geometry is a little different – it actually replicates the GRT trigger conversion for the old Gamo’s, and gives a true two-stage trigger. The spring pressures are high enough to insure the trigger is self-resetting if it is only partially pulled without firing, but this means it’s also heavier than it otherwise would be.

          The really nice thing about the design, though, is the way the trigger can be removed without decompressing the spring.


          • I checked the trigger and mine does not return, but I removed a coil from the trigger spring, it had some serious preload and way too stiff trigger pull. It still had about a .25″ of preload when I put back together. I don’t recall if it was returning before I trimmed it.


    • I use silicone in the chamber port, but only am going to do that every thousand miles, the leather seal dries pretty fast so I’ve been rubbing it with petroleum jelly, letting soak in then wiping it off so none is getting near the barrel or port. The thicker oil last longer in the seal, but yeah, don’t want any getting in. I use hoppes elite for cosmetic cleaning/oiling, For linkage and pivot points I use ultra discbrake caliper lube, its more like a grease and sticks in the joints nice.


      • With that power level, you could end up with a serious detonation using petroleum. I soaked my new seal in silicone oil for a week or so before I installed it and add a couple of drops in the loading port every once in a while and let it run down into the chamber for a couple of days and soak in.


        • I know that, oh boy do I know that. My first airguns, besides the gas guns, got a lot of exercise in detonation… I never knew the wrong oils were the ones I used back then. In all honesty, I have no fear of detonations, or even of damage from detonations, but do concern myself with the oils used in the sake of seal preservation. Im very careful to wipe any extra petro from the breech. I would like to know the exact composition of this nps seal so I can more carefully match an oil with it. Have you ever tried moly lubes?


  4. How did enlarging the transfer port help the accuracy? You really need a chrony to see what affect there was. Also, any problems with the breech seal will show an improvement in velocity after fixing. Are you sure you want to say that the factory breech seal leaks in these guns?


    • If the transfer port was 1/8″ to start (seems to be a common for sproingers), I’m not suprised he saw an increase in velocity. I’ve noted the same thing on the old Gamo/Quest platforms – but only in .22 cal. The .177′s didn’t seem to care that much. I’d go to 3/16″, but that meant I couldn’t routinely use that tube for a .177 gun, since the pellet could fall into the compression chamber if I wasn’t careful.

      As for the breech seal, I’m not surprised. The RWS 34 series were notorious for leaking seals, and shimming them would sometimes bring velocity up by 100fps or so. I’ve seen some breakbarrels leak so badly that the puff of smoke shooting up from the breech was reminiscent of a flintlock…

      I am tempted to suggest that shimming the original (rather than replacing it with leather) might prove to be a more satisfactory solution over the long term.


      • After reading Toms report and finding that a .22 does best with T.port at just over an 8th inch is why I opened the port TO an 8th inch, it was just smaller than an 8th.


    • Not that it improved accuracy, performance. But I can only guess this based on sound and the literature I read from Tom that investigated optimum transfer port for a .22.


  5. RDNA, just curious – did you consider this stock? I believe it would have fit your action without modification.

    http://www.pyramydair.com/s/m/Benjamin_NPS_Air_Rifle/2055

    Also, in the stock I believe you’ll find there is a guide rail for the roller that is mounted on the rear section of the cocking link. Were you able to verify that the clearance and alignment between that rail and the roller were close to the original?


    • I first went for the carbon fuaxber stock but they don’t have them, I believe the Nps, and probably a few of the other first NP models, are going to be cut from the lineup with the Np2 coming out. Im sure the NP limiteds mix and matching is from an inventory move. I was told none of the NP stocks were available but I pushed and made the suggestion for the legacy stock. Despite the having to custom fit, it is a great stock for this .22.


  6. Thanks for the write-up RDNA. Just for your education, the speed of sound will change based on temperature, humidty and barometric pressure – these all affect the density of the air which will increase the speed of sound (less dense equals less resistance to the sound wave) or slow it down (more resistance hence easier to break the sound barrier in high humid conditions).

    Gee, I hope I got this right but I will look forward to corrections from the superior engineering talent on the blog. I do remember getting a true false question wrong back in grade school because I marked “false” to the stipulated “sound travels at something something miles per hour” and of course, I knew it was variable. I hope that teacher is deaf now!

    Fred DPRoNJ


    • That was what I first figured, talking to gunfun when it was happening, it was cool to hear though! I’ve tried to answer some other questions but getting errored, if they don’t show up, I didn’t neglect you.


      • Nope, not worried that you didn’t respond. In the meantime, I double checked my response and I was correct. “The greater the inertia (i.e., mass density) of individual particles of the medium, the less responsive they will be to the interactions between neighboring particles and the slower that the wave will be” See:
        http://www.physicsclassroom.com/class/sound/Lesson-2/The-Speed-of-Sound

        So when the sound wave slows down in humid air (the trap here is people think the air is less dense because the water vapor dilutes it but actual Physicists say you need to consider the entire medium – the air/water vapor), it’s speed is slower and therefore you can break the sound barrier at a lower speed. Doesn’t mean your pellet is going faster, just that the sound or pressure wave is going slower.

        Fred DPRoNJ


  7. Hi RDNA,

    I enjoyed your write-up. I really enjoy reading about the mods that people make to their guns. wouldn’t have made all of the mods that you did (the bear trap removal scares me), but I understand your reasoning. Moreover, I respect you for altering this gun to your tastes. It takes a little intestinal fortitude and experience to start sawing and drilling. There are probably some fine guns that should be left alone due to their heirloom quality and value, but a gun of this nature-it’s just begs for the inventive tinkerer.

    Best of luck on the gun.
    Rob


    • Thanks Rob, I enjoyed writing it. Almost as much as I do cutting and drilling, lol. Almost. Your very right that these 200$ and under springers are perfect for chopping to your liking. And if you don’t go so short that it can’t be cocked its a easy way to get a little more power. Im a full blown tinker freak, I sharpen knives till my wife yells at me, lol.


      • I know it’s a big task, but would you mind writing up what you did with your Blackhawk? If not as an article, then just in the comments segment…although it would be a natural addition after BB does hid Airhawk review. I’d like to apply what you are doing to my Airhawk, but it’s obvious that you have more experience than me and following your trail would probably stop me from doing something stupid.
        Rob


        • I can tell you real quick a rundown, the trigger got a seriously shortened spring, enough to hold it in, but almost half the length. This made it very light, I think it was 3 pounds. With the adjustment screw rounded and polished were it contacts it has zero creep. The spring can be left alone but as long as you smooth that contact, its a whole new trigger and takes 5 minutes. The barrel got the chop and crown to 13″, the handle was put back on and glued but over hanging the muzzle about an inch and a quarter, then ported for a little “brake” action. The lube tune is very easy because the you can hold it down vertically with something under the end and with get the pin out by hand, with a little shove and elbow grease I didn’t need a compressor, but it was a little tough, nothing crazy. With it all apart a good cleanin and wipe with the lube that’ll work, bam, full chopped and tuned Hawk. After its all done I can’t see any way to make this a better gun for 100$. One thing about the hawk trigger, if you dissassemble past the first trigger pin and spring its a wicked pain to line the sear stuff back up. I don’t think I needed to get into all that to take the piston out, the whole assembly will come off together I believe.


  8. Interesting write up. I would not place too much faith on the sound difference on a wet/humid day as an indicator of velocity. Damp air being denser will keep sound closer rather than dissipating like on a clear day.


  9. RifledDNA, nice project. Why do you like the pistol grip? Yours looks more like a target version than a tactical one.

    B.B., a zen question would be just what is a semi-auto? When you single-load your AR for the amazing accuracy, that seems to be in effect a bolt-action rifle. In a similar vein, my M1 has been modified to be an MOA rifle and that was done largely through adjusting the gas system so that the movement of the piston interferes with the shot as little as possible. It seems like this is getting towards what you are doing with your AR. Without piston movement is there any difference between a semiauto and a bolt-action? I would speculate that it might be in how tightly the action locks up and how precisely it chambers the round, but your AR seems to suggest those are not really factors. Anyway, I hope to maximize my results with the precision reloads.

    Matt61


  10. OK, folks, need some help.

    I have a new Benjamin Marauder w/synthetic stock. I am filling with a 4500 PSI carbon fiber tank. I am in the process of trying to refill the air rifle for the third time. Both the first and second time to refill the Marauder, I had a problem trying to bleed off the air tank hose. I refilled to 3,000 PSI and closed the air tank fill valve. But, when I tried to bleed the hose, the pressure in the rifle bled off at the same time.

    I left it hooked up and pressured up for several minutes thinking there might have been enough heat to cause a problem. I went back to the instruction manual for the M-Rod and it suggested that I should try cocking the rifle and leaving the bolt open. I tried that and it didn’t help. Finally after about 15 minutes when I tried it again, it bled off correctly. This exact same thing happened on fill number 2 and now I am trying fill number 3 and I am in the same spot…….unable to bleed the hose off and disconnect the fittings.

    I would really appreciate your help if this has happened to you.

    Thanks,
    Jerry


    • Jerry,

      Some of the air inlet valve have return springs and others don’t. I’m thinking the Marauder does.

      The trick, if there is one, it to crack open the bleed valve fast — after the tank valve has been closed, of course. So — close the carbon fiber tank valve, then crack open the filler hose coupling bleed valve very fast. The sudden drop in air pressure should start the rifle’s inlet valve moving, and the pressure inside the reservoir should slam it shut.

      If that fails tp0 work, put five drops of silicone chamber oil into the rifle’s fill nipple before connecting the tank. The oil will be blown in on the fill and all internal seals should then seal properly.

      If that fails to work, there is some dirt on the valve seat of the inlet valve in the rifle. You might be able to blow it off with a rapid fill, followed by a sudden bleed. This worked most of the time at AirForce, but I was hitting the exhaust valve (which on AirtForce guns also serves as the inlet valve) with a rubber mallet. The sudden opening of the valve usually blew away any dirt.

      B.B.


  11. I was opening the bleeder valve very slowly and trying to watch the gauge on the rifle to see if I was loosing air. I tried opening the bleed valve quicker and it bled off properly. I assume that was the problem all along.


  12. BB,Off subject.Just received my hill pump and 24″ 25 cal.barrel.The barrel is a tack driver so far but the rain has ended any more fun shooting.The hill pump is causing problems. It is not preforming correct because its trying to push me back up when I push down then It will take many spells that it will pull back down on the up stroke and I mean its all you can do to pull it up.Then if ya let it relax for a minute it will stay in the up position like it should so you can push it down again.I tyred it on the Mrod and the same thing happens?And I’m only pumping from 2000 Thur 2500 psi and its not getting hot.I’m doing the wait a second thing at the end of each stroke.Then it will preform perfect for say 10 strokes then go back getting weird again?Any input would be appreciated.


    • Steve,

      I trust that you did nothing to the pump? You didn’t wipe the grease off the pump shaft, did you? That will destroy the pump almost immediately.

      Your third-stage valve isn’t opening properly. Send the pump back for repairs.

      B.B.


      • BB,No I did not wipe the grease off the pump.I have not done nothing but assemble it.I ordered this because of your advice never to fool around with a pump because conditions must be nearly dust free and I don’t tear into anything that I don’t know about.OK now this morning the pump worked perfect?Go figure.I’ll give a day or two to see what happens.Still will probably send it back even if it continuous to work good because a pump of this value should not have done that anyway even a lesser value one.I know PA will make it good for me just somewhat disappointed. And Hill has a life time warranty so it will all work out for the best.Thanks for the reply.


  13. RDNA,

    The time is late. I read your report early this morning, and thought about it all day. I enjoyed reading about your experiments with this rifle. Well done, Sir, and I look forward to your next report.

    RB


  14. Actually, I might have missed something, but I honestly don’t see the value in this review. After all the mods, which the average consumer will not do, the gun tested is nothing like the one I will buy. So the review is of little value to someone looking to know how the gun he buys “off the rack” will perform.


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