BAM B40 – Part 2 Power

by B.B. Pelletier

BAM B40 – Part 1

Today, I’ll look at the shooting aspects of the BAM B40 underlever spring rifle. First, however, I want to tell you what I found with the trigger.

Adjusting the trigger
I removed the action from the stock to examine the trigger. It appears to be a copy of the Air Arms TX200 trigger but much cruder. The crosspins are so loose they fall out when the unit is turned sideways and bumped. I doubt this trigger can ever perform like a TX200 trigger without a major rebuild that would cost more than the price of the rifle. So, the question is, can it be used as is? For that, I tried to adjust it.


B40 trigger looks similar to a TX trigger, but the workmanship is poor. That results in a sloppy trigger engagement.

There are two adjustment screws, and they do have an effect on the trigger engagement, but nothing I tried gave me what I was after. What I wanted was a definite first and second stage, with a pause between them that could be discerned. I never got it. Instead, the best I was able to achieve after an hour of trial and error was a single-stage trigger with a very light pull and buckets of creep. I doubt it even goes 8 oz., but my trigger pull gauge doesn’t go down that far, so there is no way to tell for sure. My advice is to leave the safety on until you are ready to take the shot. It’s a shame that the Chinese were able to do so well with the rifle and then failed to get the trigger right. Maybe someone out there has learned the secret of how to adjust a B40 trigger, but I sure haven’t.

Firing behavior
The B40 cocks a little harder than the TX, but just as smoothly. The anti-beartrap ratchet works in exactly the same way, catching near the end of the cocking stroke. And one quirk of both the TX and the B40 is that the trigger must intentionally be cocked during the cocking stroke. If the lever doesn’t come back far enough, the ratchet will hold the sliding chamber open and the gun will look like it’s cocked, but you will not be able to release the chamber to slide back forward. All you have to do is pull harder on the underlever and the trigger cocks and the safety sets.

Shooting is still just as smooth as a TX, and that’s after 75 shots on the powerplant. Some guns loosen up after several dozen pellets have run through, but this one doesn’t show signs of that yet.

Velocity
After rereading my first post, I should have tested it with Gamo Magnum pointed pellets, but instead I tried it with Beeman Kodiaks and Crosman Premier 7.9-grain pellets. The Kodiaks gave an average velocity of 833 f.p.s. with a high of 841 and a low of 825. That’s a spread of just 16 feet per second over 10 shots, which is excellent for any spring rifle and unheard-of for a Chinese rifle. I am amazed by the power, too. The energy calculator on the Pyramyd website says that’s 16.34 foot-pounds of energy. By comparison, my well broken-in TX200 delivers an average velocity of 823 f.p.s. with the same Kodiaks. The spread was 23 f.p.s. and the muzzle energy was 15.95 foot-pounds. This is a result I never would have believed if I hadn’t seen it for myself!

In the B40, the light 7.9-grain Crosman Premiers gave an average of 909 f.p.s. with an extreme spread of 22 f.p.s. That’s a muzzle energy of 14.5 foot-pounds. The B40 goes against the common result of light pellets being more powerful than heavy pellets in a springer. My TX averages 933 f.p.s. with a spread of 19 f.p.s. and an energy of 15.27 foot-pounds. Apparently it also runs contrary to the norm with these two pellets.

The next report will be about accuracy. I have mounted a 3-9x Leapers scope on the B40, so both rifles are scoped equivalently. If this Chinese rifle continues to perform like it has, it will be a real airgun value and I will have to eat my words. I’m hoping that happens!

12 thoughts on “BAM B40 – Part 2 Power


  1. Hi BB,
    I have read some things about oiling pellets lately. I have tried a Teflon based stuff that is also used to oil high tech bicycles, but it seems to diesel a bit in my Spring gun (Mendoza RM600). I have read on some german web sites that they recommend WD40, others recommended Ballistol (a multipurpose oil for gun care), obviously using very little. Do you think that would work?
    Thanks
    Volker



  2. Volker,

    When I lube I use FOP-10, but I generally don’t lube pellets for use in spring guns. The exception is any and all Crosman pellets because the antimoney they use to harden their lead makes the pellets lead the bore at high velocities.

    B.B.



  3. Turtle,

    Here is the straight scoop, the way I know it. Pyramyd got these rifles when they purchased Airgun Express. They had heard a lot of reports that this and that were bad on the gun, so they became gun-shy of the model. It is Chinese, after all, and they dropped their Chinese guns a while back because of returns.

    You may have noticed that I started this series with a disclaimer that mentioned some bad press I had heard. Well, that was it.

    I’m still undecided whether or not the B40 is a worthy airgun, but each time I test it, I get closer to believing that it is. If it passes the long-range accuracy test, I will let my voice be heard. If it fails to pass, then in my opinion it will be just another pig wearing lipstick. I can live with the bad trigger if the gun can shoot. (How about that? Most airgunners would PRAISE a 6-ounce trigger!)

    The same thing happened when I tested the Gamo CF-X. Do you remember how I went into it kicking and screaming because CF-X guy begged me to? I went into that series thinking the worst because in the past, that’s what I have seen from Gamo. Only their Shadow 1000 and their Hunter 1250 were worth a darn, as far as I was concerned. But when I saw what the CF-X can do, I had to revise my opinion of the whole company. Now the Viper Express shotgun has me wondering again, but I guess everybody has a bad day.

    B.B.


  4. B.B. on the subject of lubing pellets, do you spray the FOP-10 in the tin and shake the pellets around? I’m thinking about lubing to cut down on cleaning time.
    scopestop



  5. scopestop,

    Yes. I put some felt material in the bottom of a tin, then drop 30 drops of FP-10 on it. Then I put in a single layer of pellets at a time. You don’t have to shake them. The oil seems to migrate around them all on its own.

    B.B.


  6. I’m not finished with the B26. I was hoping that the BAM B40 trigger would teach me what I need to do to the B26 trigger, since the TX200 trigger that the B40 copies is a copy of the Rekord trigger that the B26 copies.

    It looks like I will have to approach the B26 trigger as if it was an R9 trigger, instead.

    B.B.


  7. BB,

    Just to say thanks.The posts are very fun to read.GREAT stuff.And your right up there I did beg you for a cf-x post LOL!!!

    Well thanks for all the posts and keep it up its great and I really enjoy it.

    CF-X guy


  8. I’ve been working with a .177 B40 of the latter production larger breech/barrel variety and comparing it with the TX200HC. I haven’t tried Kodiaks, but this one likes Crosman 10.5 gr. premiers, developinp over 16 fpe and as accurate (1.25 inch groups)as the HC at 50 yards if held well through the shot. The HC is a little easier to hold through the shot, at least partly because of the trigger. I too tried to get the trigger to match. I got the loose but feelable first stage that I prefer but the letoff stage is just a little mushy compared to the crispness of the TX that I like. Overall I’m impressed with the fact that it compares favorably with the TX.


Leave a Reply

Your email address will not be published.


8 + 7 =

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>