Cheap, beatup, sad, forlorn B2+ too much time = sniper rifle?

[Paul68]

Earlier I posted in the general AG gate about a B2 I needed identified, and the knowledgeable folks here were stumped for all of about .3 milliseconds. Well, this poor little spitter is getting a second chance at life.

I'm giving this thing the works. "dang" the torpedos, wing and a prayer, if it looks like a good idea do it, and all that. Since its value is about zilch, and just about anything will be an improvement, let's see what happens eh?

I've already done quite a bit, but as the pictures show, this is only the beginning.

I've honed and yes, POLISHED, the compression tube. While I fully understand the idea behind crosshatching, having over twenty years of experience in automotive rebuilding and restoration (Mopar nut whose vehicles have placed well in competition), I also understand the pluses and minus's of machining and how certain parts, materials, metals and chemicals react with one another. I feel that crosshatching is indeed a good practice, but that it is not taken far enough, and the process is not actually completed when it comes to tuning AG's. While most metal to metal crosshatching applications take into account the different properties of the metals comprising the cylinder and seal, and thus are intended to produce a "wear to fit" seal between metal seals and metal cylinders, the extreme differences in properties between the metal cylinders and synthetic seals in AG's demands a little more attention to finish.

I feel that in order for crosshatching to produce the intended result in AG's, ie, hold lubricant, the grooves do need to be substantial in relative terms, but I also know what happens when you take a synthetic rubber and rub it tightly against what amounts to a very fine file. That metal aint going to wear very much very quickly, and that synthetic is going to take a beating in comparison. In other words, I think the usual crosshatching procedure used in AG's is far less effective than it could be, and taking a lot of life out of seals and reducing potential power despite obvious gains.

To that end, I crosshatched the cylinder, then used a dowel with 800 grit sandpaper folder over enough times to produce a strong interference fit in the cylinder to smooth the crosshatching. The 800 grit is not enough to remove the cuts produced by crosshatching, but IS enough to smooth the edges while leaving the grooves, thus providing a smooth surface for the seal that wont' reduce the life of the seal prematurely or require an extended break in period.

Ahem, now then onwards and upwards, we hope.

Aside from the obvious outlined in the pics, I have even more changes in store. While I have figured out how to convert to a synthetic seal, and in the process gain a significant bit of swept volume, I can't reconcile what I see as a very inefficient piston design. It's heavy, has a lot of contacts points which in turn means increased friction and thus inefficiency, and is just all around poorly manufactured. I mean c'mon, I know it's a cheap rifle, but is sheet steel rolled into a tube really cheaper? To that end, I am considering just building a whole new piston that will have half the weight and half the friction points. We'll see how froggy I get about that one.

I have found some interesting sources for seals, http://www.theoringstore.com/index.php?main_page=index&cPath=172 and am looking at a teflon cup that will further reduce seal thickness and thus further increase stroke, and thus (whew) increase swept volume. All without making a new piston. Just getting rid of the leather seal and replacing with a synthetic gains almost half an inch, and for those of you thinking the cocking linkage will be a problem, you'd normally be right. However, this particular sad little B2 has a ton of slop in the linkage and has to travel over 1/2" before it even engages the piston slot, with a matching 1/2" at the compression area. In other words, the piston can move back almost a full 1/2" before being exposed to the slot. I can take it right to the limit, and maybe not have much room for breaking the barrel loose, but since it's such a light gun and will not require a lot of cocking force, it should not be a problem.

Getting long winded here, so I'll wrap up.

The stock will be lengthened, trigger guard customized with aluminum and flush fitted, a rubber butt pad added after lengthening, finished in a thick satin black coat after being heavily modded, and I'll use rubberized undercoat to produce a striped grip pattern on contact areas. This gun will be scoped obviously, hopefully produce high 600's if not 700 fps, and look like an evil little pellet flinger to boot.

Either that or it will end up part of a new pickup bumper once crushed and melted down at the junkyard for scrap;)
 

[supertech77]

you got some good idea's keep us posted with the out come;;

[Paul68]

Thanks. We'll see if they'e good or just half baked eh?

Guy down the road from me here runs a machine shop. Brought a couple things to him to look over, and I think I've found my go to for parts that have to be precision made to be safe. I'll be bringing some trigger diagrams for this B2 to him and see how he does.

[Paul68]

Been busy with my Storm, so the B2 has been neglected. Went out this morning and fabbed a seal until a decent one arrives in the mail. Posted this in the general forum, figured it belongs here really.

The leather seal is junk, so I made one out of garage stuff. Found a polyurethane sway bar bushing kit I had left over from a front end rebuild. These bushings are cylindrical and have a perfect diam hole through the center. I simply cut it down to a flat washer shape and sanded it flat, chucked it in a drill and ground the edge down to a slight angle and sized it to the breech, then lightly smoothed it with 800 grit. To get the "parachute" shape, I just found a socket of a diameter that would give the lip I wanted, heated it up with a torch, and pressed it in for a second. Then I just cleaned up the melted channel with a round dremel bit. Not precise machining, but it fits the chamber well and these particular polyurethane bushings are supposed to be self lubricating although they are probably too soft to expect anything more than maybe a thousand shots if that. To fit it to the piston I just used a new countersink bolt, the original seal washers, and a few small washers for spacers that fit inside the new seal to keep from overloading the seal and expanding it. The best part is that this homemade seal is 1/4 inch shorter than the original leather seal assembly, giving a slight increase in stroke and volume. By no means a professional job, but fun and cheap all the same. The seal is shiny because I have it soaking in Teflon lube to give it some time to absorb and maybe increase its longevity. It'll be wiped clean at assembly.

[Paul68]

Did a little more this afternoon.

Cut a strip of aluminum and bent it to shape using the workbench and clamps. Shaped the ends, sanded for what seemed like forerver, and put an inital polish on it. Voila, trigger gaurd takes shape. Still needs a final polish and mounting holes drilled. The mounting area on the stock will be recut and recessed in the rear so the whole gaurd sits in flush. First two pics are after rough cut and shaping. Last two are before final polish.

I've also included a pic of the stock which has been sitting for awhile in this configuration. Filled in the side grooves with wood putty, filled in all the gouges and nicks, ground down a huge hump along the top edge where the receiver rests, taped out the areas that make hand contact and sprayed em with three coats of rubberized undercoat, then put a coat of flat black enamel over it. I'm doing away with the gray pinstriping and going to give it a final coat of flat black. The whole thing will get sealed with semi-satin clearcoat. I have also cut out and formed a stock extension which will add 4 inches to the butt and which will be attached with two bolts fed through 1/2" aluminum pipe.

Gun is pretty much ready to assemble, just have to fab a couple small pieces.

 

[SAADE]

Paul68, great details and comments! I learned a lot, keep posting your progress.

Now, if we can just keep the "cross-hatch or die" tuning crowd from hijacking your thread! LOL

[thekid]

Everyone Has there own Ideas on cross hatching.
But if no one ever tried to improve things, we wouldn't be where we are today.
Congrats on the good work.
Rob

[Paul68]

Thanks. I enjoy trying my own mods to improve just about every toy I run into, whether it's a car or in this case an airgun. Great stress reliever and great way to push all the everyday hassles to the side and concentrate on one thing that's actually fun.

Used to rebuild and modify hot rods for about 10 years and got known as the go to guy for setting up carbs. Did everything from getting rid of throttle cables and fabricating mechanical throttle linkages to cutting off choke towers and porting/polishing for max air flow. Also fabbed a lot of solid engine mounts. Just a bit too expensive to do as a hobby nowadays.

Done a little more to tbe B2. Getting ready to to finish the stock extension. The pic shows the initial mockup. Cut the curved end of the stock off to produce a flat surface. The rough cut aluminum plate in the picture will be sized to the stock. Then I'll drill it for the bolts that will feed through aluminum tube. The bolts are deep countersunk to the new butt, the butt will be bolted to the aluminum plate, and the aluminum plate will then be screwed to the butt of the stock. Good bit of shaping still to do on everything, and the aluminum tubing will be polished before final assembly. Will add a little over 4 inches to the length of the stock and make it a little more comfortable to shoot offhand as well as keep with the "sniper" look I'm going for.

Trying not to rush it, but I really want to get started on another project that should tell me the best way to set up a compression tube.

[Paul68]

Inching closer to completion. I can already tell this is going to go the way of most of my other projects. The end product will be much different than the initial plans

At any rate, I have the parts for my 1051 Beeman sitting and waiting to be installed, and the seal and tophat for my Airhawk have also arrived, so the B2 will probably be a couple weeks waiting for completion. Did manage to get the tail end set up. The stock is just about done except for final finishing and tweaks to give it that sharp look. I changed out the aluminum mounting plate and went with plate steel instead for better durability. As outlined previously, the stock extension in all its sticky undercoated glory

[supertech77]

Pual68;you have done some great work here,myself i am waiting to see how the finished project turns out ,fps and smoothness,as i first said,you got some really good idea's and your post is well laid out and very informative.SO KEEP ON KEEPING ON,great job..and very creative.

[Paul68]

New trigger taking shape. Nothing really exciting. Just traced out the old onto a piece of sheet steel, cut it out with a drill and dremel, and began grinding shaping.

Tough part will be the pin hole and tab, but going slow should get the job done. After this it is put a finish on the metal and reassemble. Metal on this AG will not take a cold blue no matter what. I've done the surgical clean approach with everything from brake cleaner to alcohol, heat, smooth finish, rough finish, and it simply will not take a cold blue. Just turns a wierd looking chrome with slight bluish tint looking. I tried several applications, and the bluing never darkens. Will get painted instead.

Hope to get it done and out of the way as early as tomorrow.

[4932msmith]

Great work. I've enjoyed this post, especially the new improved seal. In regards to cold bluing I've had similar results, until I started warming the metal before applying the birchwood casey "SUPER BLUE". I've used  a heat gun and later boiling water as described by S. Dale in library section of this site. The water produced better results. I have found that the metal has to be dried and allowed to cool until warm, but not hot as the bluing will bubble up and leave a mess. This still does not work as well as hot bluing but is a big improvement over "cold" application and will get a couple of shades darker and is less likely to streak.  I look forward seeing the rest of the build.

[Paul68]

Appreciate the encouragement. Thanks. Gave bluing one more shot tonight. There was no possibility of oil residue, new bluing liquid, refinished the reciever yet again, and no dice. Same exact results. So, I broke down an put several layers of satin black on it, the barrel, and the brake, followed by four flat clear coats.

Trigger is almost done. Just need to drill the pin hole and the spring hole and do a final polish on the trigger shoe area. That will be the only part to get a real polishing since it's the only part that'll be visible. The sear-tab and reciever rest came out better than hoped. Now just to hope I get the pin hole drilled straight

 

[Paul68]

It lives!

Well, it's in one piece and it seems to work pretty decently

Tired of messing with it since I've got plenty of other things that actually deserve attention waiting to be gotten to, so I thrashed it together tonight. If I could have gotten the metal to take a blue, I might have worked harder on a tighter fit and finish.

The saying about polishing and poop is true. This is a twenty twenty gun. Looks good from twenty feet away at twenty miles an hour.

However, it actually shoots hard and fast. Only put ten shots through it. A little dieseling first few shots, nothing major.

Home made barrel brake is shimmed for a press fit. It's on, and I doubt its ever coming off.

The hand made trigger is a major step up from the old. Not much you can do to one of these, but it has no slop and breaks easily and sharply.

The spring is out of my Storm and cut down by 4 coils. I judged it just right far as size goes, and have maybe 1/16th of an inch between coils when cocked. In other words, just barely avoids binding. About two and a half inches of preload on it. Everything is smoothed and straightened inside. Added a polished washer in the piston, used my homemade seal, polished the spring guide, squared and polished the spring ends, and polished the compression chamber at high speed with 800 grit until I could detect only a shiny surface.

It goes, **THUNK**!!, and that's it. No twang, no piston slam. It's also a very fast thunk. The short stroke and stronger spring make for a very quick cycle. I should have measured the volume. Oh well.

I'll do some target shooting with it tomorrow after I clean the barrel, but dont expect much.

The barrel pivot had tons of slop. I managed to get rid of most of it, but the pivot sleeve is too big for for pivot bolt, which allows the barrel to move around on the pivot. No side to side slop anymore, but you can pull the barrel forward and push it back very hard, enough to notice the play. Also, the previous owner obviously bear-trapped themselves once or ten times. The barrel is noticeably bent upwards. Bent it back most of the way, but needs one more round of straightening. There's lots of little things I did, but I am too pooped to go into detail

All in all, a fun project. It'll be interesting to chrony it and maybe throw a poly seal in it. I'll be putting hex head bolts in everything at least, which should clean it up more and make tear downs faster and easier.

[4932msmith]

Great job on everything, trigger looks great.