Benjamin HB22 – Part 2

by B.B. Pelletier

Part 1

Today I’ll shoot the Benjamin HB22 air pistol for velocity, plus I’ll also do some interesting pneumatic experiments to demonstrate how these guns work. As I test this gun, you’ll see that a multi-pump is really a self-contained airgun experimental lab. Because of the length of these tests, I will do an accuracy report in another part of this report.

First test: How many pumps?
This test demonstrates how velocity varies as you add pump strokes to the gun. There are some interesting side effects here, as well. I will also cock and fire the gun after each shot to determine whether any air remains in the reservoir. I used a 14.3-grain .22 caliber Crosman Premier pellet, which is identical in weight and shape to a .22 caliber Benjamin Sheridan Diabolo.

Pumps—–Velocity—–Air remaining?
2*————236—————No
3————-288—————No
4————-326—————No
5————-355—————No
6————-377—————No
7————-390—————Yes
8**———-405—————Yes
9————-414—————Yes
10————425—————Yes
11————429—————Yes, lots
12————432—————Yes. Enough for a 2nd shot
2nd shot—-256—————No
* Below the recommended minimum number of pump strokes
**Maximum recommended pumps

Benjamin recommends a minimum of three pumps and a maximum of eight for this pistol. You will notice that starting at the seventh pump, there was air remaining in the gun after the shot. I went beyond the recommended maximum number of pump strokes to see what would happen. In an air rifle, the power usually begins to decline right away. With this pistol, it kept increasing, although the amount of the increase diminished with each additional stroke.

By the 11th stroke, the air remaining in the gun after the shot was significant, so following a try with 12 pump strokes, I cocked the pistol again, loaded another pellet and fired a second time without pumping. Notice that the second shot has greater velocity than the gun had with two pump strokes.

Before you decide that additional pump strokes are the way to go, let me tell you that the strain on the pump mechanism was enormous. After the 10th pump, I could barely pop the pump handle away from the tube, and the pressure to close the pump handle probably reached 50 pounds. If you did this regularly, you’d wear out the pump mechanism to the point that a major rebuild would be required. In fact, if you look at the data, it suggests that this particular pistol is better off with a maximum of just seven pumps strokes instead of eight.

How consistent?
This test demonstrates how consistent the velocity is for the same pellet and same number of pump strokes. Once again, I used a 14.3-grain Crosman Premier domed pellet. Every shot was the result of five pump strokes.

Shot——Velocity
1————-340
2————-338
3————-340
4————-340
5————-341
6————-340
7————-341
8————-339
9————-340
10————341

You don’t get consistency this good from a regulated Olympic 10-meter target rifle costing $3,000. I expected this, because I’ve seldom seen more than six f.p.s. shot-to-shot variation in multi-pump rifles when I did this test, but this is the first multi-pump pistol I’ve tested this way.

Fast vs slow pump strokes
Does pumping the gun fast make any difference? In this test, I will pump the first five shots with a slow and deliberate pump stroke, allowing two seconds for air to rush into the compression chamber when the pump handle is fully extended. That will be followed by five shots using a rapid pump stroke. I will pump as fast as I can for this one. In both tests, the gun will be pumped a total of five strokes per shot, and I’m still using Premier pellets.

Slow pumping
Shot——Velocity
1————-340
2————-339
3————-338
4————-339
5————-339

Fast pumping
Shot——Velocity
1————-339
2————-341
3————-340
4————-340
5————-340

Not much difference, is there? In fact, all 10 shots fit neatly into the other 10 of the consistency test.

You will also notice that the pistol got 355 f.p.s. on five pumps in the first test, yet in both the test for consistency and the test for how fast the gun was pumped, the shots never got above 341 f.p.s. What’s happening there? Well, I did test for remaining air and found none, so that’s not the explanation. I do know the count of the pump strokes was correct, so maybe the best way to check this test is to do it again the same way. Premier pellets once again.

How many pumps? (second test)
Pumps—–Velocity—–Air remaining?
2*————224—————No
3————-275—————No
4————-311—————No
5————-340—————No
6————-358—————No
7————-376—————Yes
8**———-388—————Yes
9————-399—————Yes
10————407—————Yes
11————418—————Yes, lots
12————424—————Yes. Enough for a 2nd shot
2nd shot—-275—————No
* Below the recommended minimum number of pump strokes
**Maximum recommended pumps

This second test was conducted after the consistency test and the pump speed test. Note that the air remaining in the gun after shot 12 is now equal to three pumps! After this test, I chronographed the gun five times on five pumps of air and got five identical velocities of 335 f.p.s. So it seems the over-pumping is having an immediate effect on velocity – lowering it rapidly. I do not intend conducting more testing of an over-pumped gun.

This is the first hard proof I’ve ever seen that over-pumping harms a multp-pump pneumatic. Perhaps it happened so fast because this is a pistol, and the springs have to be smaller to fit inside the smaller valve mechanism. Whatever the reason, the top velocity has definitely been reduced.

I want to impress upon you the fact that each air pistol will be unique. How you treat them will also determine how they perform. If one owner follows the instructions and another routinely over-pumps his pistol, the first pistol will be faster than the second one right away, pump for pump.

Tomorrow, I’ll do the accuracy test, plus I’ll do another interesting velocity test.

30 Responses to “Benjamin HB22 – Part 2”

  • Anonymous Says:

    Very interesting. The pump pistols and rifles I used were seldom pumped more than 5 times unless shooting game. Some of the pistols were carried under my car seat in the dust and wet BUT always with a pump or two of air in them. The abuse they took and kept shooting amazed me.

  • Anonymous Says:

    B.B.

    Thanks for doing this report. Just wondering, is this a new out of the box Hb22 from Pyramid, or one you’ve had for awhile? I’ve heard reports of a cheap finish on the powder coating and on the grips. Whats your take?

    Thanks,
    Andrew

  • Anonymous Says:

    BB

    I am after a PcP pistol preferably multishot, but would accept a single shot if needed. While there are dozens of non competition PcP rifles for sale, i can only seen to find competition pistols? The reason i dont want a competition one is purely cost.

    Amy suggestions?

  • JR Says:

    B.B. Off topic: I picked up a used Nightstalker over the weekend. After reading your post from 2/14/06 (and all the comments),
    I am sure that the clip advance mechanism is not working properly. (half moon cuts on the front of dome pellets) I planned on taking it apart, thinking it might just be a spring, but then I read your comment telling someone that EVEN YOU would not reseal a Nightstalker because of its complexity. Would your advice be the same to someone who has successfully disassembled (and re-assembled) other guns?
    Please advise. JR

  • B.B. Pelletier Says:

    JR,

    I don’t advise it. Send the gun back to the dealer or to Crosman.

    B.B.

  • B.B. Pelletier Says:

    PCP pistol,

    What about the Evanix AR6? Falcon also makes a precharged pistol.

    Over the years many precharged pistols have been made, but the demand has never been high. So today the choice is limited.

    B.B.

  • B.B. Pelletier Says:

    Andrew,

    Thgis is a brand-new HB22. The finish is not cheap, but paint never lasts as long on metal as other finishes.

    B.B.

  • jj Says:

    Hi BB,

    Good workout of the HB22, and very useful results.

    Looking forward to tomorrow’s post.

    jj

  • Vince Says:

    JR, you might wanna call Crosman Customer Service (800-724-7486) and talk to them about it. SInc you bought it used, I’m guessing there’s no warranty on it. If nothing else, however, they might be able to get you an exploded diagram and list of service parts available or at least give you a clue as to how much a repair might cost.

  • Anonymous Says:

    BB

    thanks, that Falcon looks great, and comes as an 8 shot repeater. Just what i was after.

    Thanks again

  • Anonymous Says:

    BB

    i recently purchased an AA S410 and while the rifle is very well made, the accuracy was all over the place. I put 2 tims of pellets through it and still the groups were 3 inches at 25M, simply not good enough. So, i took the barrel out and JB Pasted it as you have described in your blogs, and a miracle happened!!! It now shots 1 hole groups at 25M. Its hard to believe its the same gun. Could you explain what exactly the paste does? and how therefore its accuracy is improved?
    Its so good, yet it seems to be a very well kept secret, apart from your readers of course lol

    Thanks for turning my new gun in to a very nice piece of work

    Frazzle

  • B.B. Pelletier Says:

    Frazzle,

    Your S410 is now shooting the way it ought to. When barrels are made and blued, they aren’t plugged on both ends, so the insides get blued, too. At the end of the bluing process the barrel is dipped in a special oil that is supposed to neutralize the bluing salts. If the caustic bluing salts are not 100 percent neutralized (and they usually aren’t) they continue to rust the barrel.

    That’s why a new barrel will make a clean dry patch brown. It’s removing rust. We find that in Lothar Walther barrels on the finest airguns, so there’s no shame in what you found, though the poor accuracy is a bit surprising.

    The JB paste is a micro-fine abrasive that’s too fine to harm the steel barrel, but it’s murder on rust deposits. It removes them completely.

    JB Paste isn’t supposed to be a secret, because this is one of the reasons it exists. The other is to remove copper and brass fouling from a steel barrel. Benchrest shooters use it for that.

    Isn’t it great when something works the way it’s supposed to?

    B.B.

  • Joshua Says:

    B.B.

    Great post I’m looking forward to the rest of this series.

    Do you think that your findings on the accuracy for the HB guns will translate to the EB guns – do they have similar barrels?

    Are the barrels long enough on these pistols that the caliber makes a difference like it does on rifles for how much energy is transferred to the pellet?

    -Josh

  • Anonymous Says:

    Maybe I’m ahead of you but what is the weight of the trigger pull?

    Thanks.

  • B.B. Pelletier Says:

    You are ahead of me. Tomorrow.

    B.B.

  • Anonymous Says:

    BB

    now you have explained what the JB paste actually does, it is amazing that the accuracy of the rifle has been so hugely increased. It cant be anything else though, as the pellets are the same (JSB Jumbo’s), the shooter is the same (me), same range, same scope and same location for shooting. I did wonder whether there may have been a small metal filing left in the barrel that was scoring the pellet and mayne changing its flight path? I did use a metal brush to apply the paste but i would have though a pellet would remove anything that a brush could?
    While it would be interesting to know what has occured, ill have to call it witchcraft for now :))

    Cheers

    Frazzle

  • Anonymous Says:

    BB

    Valve lock is the term used to describe a velocity drop when a Multi-Pump-Pneumatic gun is overpumped, right? What exactly is it? Just curious after reading this very insightful article.

    Thanks and as always good work,Kyle

  • Anonymous Says:

    BB,

    what do you think of Allen Z custom airguns? (A theoben rapid mk2 with his shroud and quick fill).

    Thanks b.b.

    -sumo

  • Vince Says:

    Question on using JB paste – I seem to remember that 10 strokes (back and fortg = 1 stroke) is recommended. During this process is more paste periodically introduced into the bore?

  • Anonymous Says:

    Vince

    i have used the paste on a few guns now, and i find that you call tell when you have done enough strokes as the brush starts to glide rather than need to be forced through. Personally i also prefer to remove the barrel if at all possible as that paste gets everywhere and can be tricky to remove from crevises. Personally, i have found that 1 well loaded brush is sufficient to do the job.

  • B.B. Pelletier Says:

    Kyle,

    When a striker-type valve is opened, the hammer forces the valve open against the pressure of the valve return spring and the pressure of the air inside the reservoir pressing against the valve. When that pressure becomes too great, the hammer cannot force the valve open long enough to exhaust the air. That is the onset of valve lock.

    Valve lock is complete when the hammer cannot open the valve at all, and the gun refuses to fire. Since the valve is sealed, it won’t leak down over time, usually.

    B.B.

  • B.B. Pelletier Says:

    sumo,

    Alan Zasadny does good work. I have had guns modified by him. He was one of the pioneers who first turned 10-meter rifles into field target guns.

    I don’t know the setup you mention, but anything Alan makes will be good.

    B.B.

  • B.B. Pelletier Says:

    Vince,

    All I have ever said is 20 strokes in each direction. No additional paste is used. Just fill the brush initially.

    B.B.

  • Anonymous Says:

    BB,

    sorry. I was off on the name but you got what i was try to say. I heard he was best with rapids. He fits custom shrouds on the gun and drills a hole in the tank and fits a foster quik fill on. Thanks.

    By the way… This will be just like when i got the airwolf… maybe i should just buy things… without and questions… i know how accurate they are… I have one already… I want another… DOT dot dot…

    so the real question is do i get an az mod mk2 or an mk2 without any mods.

    -sumo

  • B.B. Pelletier Says:

    sumo,

    If you have the money, I’d get the Zasadny rifle. You will always know you got the best.

    B.B.

  • Anonymous Says:

    When buying airguns, money is no object lol. I will see what i can do. The words that got me were “the best”.

    Good news : My airwolf should be with me on thursday. its all in the works / story of my life.

    -sumo

  • Anonymous Says:

    I just looked again at the Hunting Master AR^ by Evanix (big sigh!). I’ve looked at it quite a number of times. I have several hesitations, however, not the least is the price. However, the Pyramydair web site shows this:
    Starting at 3,000 PSI with a 11.9-grain RWS Hobby pellet:
    1st shot: 922 fps
    10th shot: 685 fps

    Starting at 3,000 PSI with a 28-grain Eun Jin pellet:
    1st shot: 701 fps
    6th shot: 628 fps
    10th shot: 423 fps

    I don’t understand with such a decline in fps a shooter can maintain any kind of accuracy. I’m not sure, if accuracy suffers as I think it should, if this is worth it.

    Michael in Georgia.

  • B.B. Pelletier Says:

    Michael,

    What you are seeing is honest velocity reporting.
    Also, you are talking about the pistol and not the rifle. Big difference in the amount of air.

    None of the other air pistols get anywhere near this power and they all have limited shots, too.

    For accuracy, count on one cylinder per fill.

    B.B.

  • Anonymous Says:

    BB,
    Thanks! I don’t suppose there is a conversion to CO2 is there? Probably would get more shots and more consistency, but probably would lose power. I’m starting to think I will have to change to a rifle, and maybe a different shooting position than I’m used to because of the shoulder problem. Hmm.

    Michael in Georgia

  • B.B. Pelletier Says:

    Michael,

    No CO2 conversion. It would lose about 2/3 of its power.

    Sorry.

    B.B.

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