Discussion in 'Air Guns' started by cobalt327, Jul 17, 2016.
In reference to “Geo”s comment on hopup. Like to hear more as he works on this mod. I really think spinning the bb will be the answer for anyone looking for range and accuracy using a smooth bore BB gun. The airsoft people has proven this technology and uses it in all their better equipment.
I’m in the process of experimenting with the old screw in shot tubes in old Daisy’s
I’m “redneck” tech, using rat tails files, pencil ✏️ erasers and epoxy to form the device. Should be ready to launch next week.
I doubt anyone here will discount redneck engineering as a way to reach a goal.lol In fact, that's how this thread began: cheap BB gun, hack saw a preload spacer and use a hand drill to bore out the air tube, and the rest is history, as they say. So go for it!!
And let us know how it works!
I’m very interested as well. This topic is making think about pulling out my airsoft “rifle” and do a bit of work really figuring out how it works. It certainly has range, power, and accuracy.
Hello all. First post here. Just a thanks to cobault and every one else.with your help have gotten 3guns working! a1105,,102,,and a 499b.looking to do some hot rodding in future. I started this thread 3 years ago,can't believe it was still here! my posts will be short and poorly written,as I am on a tablet that really ticks me off. good shooting all........BB
bb nels, thank you for making it back to our thread- my first gun was a 102 and I've also owned an 1105 and 499b so we have that in common already! Please don't hesitate to ask if you have any questions about your hotrodding.
Colbalt, are the RR and the mod 25 springs interchangeable? Put one of your HP springs in a 102. A worn out 102. Got another 50 FPS. Like to put one in my 25.
The new production model 25 uses a shorter spring with less rate than even the stock RR, so my spring will be too much for it. I never tried it, but a shortened RR spring might work in the new style 25 though. The older 25s use a stronger and longer spring, and a RR spring might work in one of them- but whether an increase in MV would result, and how much the increase would be, if any, I don't know. A HP spring may be too much but if I had the specs of the stock spring I could say for sure if the HP spring would be a good replacement.
MODEL 25 2016:
Wire 0.087”, 5.85” free length
MODEL 1938B 2016:
Wire 0.0905”- 0.091”, 7” free length
Your 102 sounds like it might need resealing. If you know whether it uses a 7/8" or a 13/16" seals, let me know and I'll see if I have one that'll fit.
Dave, it’s also good to make sure of the condition of the air tube. They can be restricted on the end due to being peened nearly shut. That is often a result of having bb’s stuck in the tube and repeatedly trying to fire it. I’ve taken apart at least 2 1938b’s that had the shot tube length almost full of bb’s and dirt. Air tubes were in very bad condition.
Not saying yours is that way, but any amount of air tube restriction results in mv decrease.
Newer/ more powerful springs such as Cobalts always benefit from opened up air tubes. The new style seemless tubes can be drilled out to 1/8”. They old style seemed tubes are a crap shoot. 3/32” is about it, the seem makes the drill wander.
Then a bit of work on the port also helps with the air flow.
Ok guys, thx for the inf again. I don’t plan to rebuild the old 102. Used it to learn disassembly etc. and try the new HP spring. I also cut a notch in the top of shot tube and glued a pencil eraser in it. Attempting to create a hopup. Placed it 2 1/2” in front of bb to avoid air tube strikes. And best I can measure, bb has .010/.015” engagement with the rubber.
So I changed two elements——without a baseline. Other than the increase in velocity from the spring, but not sure what if anything was changed by the piece of “rubber”.
Bbs are flying straight out to 30 yds. —-left to right. Don’t know if any flight elevations (bb carry) was altered , shame on me—- no baseline.
Think next experiment will be with the new RR, have the Lasso mount and a good scope on it. as weather allows, will shoot targets at 25/30 yds with original gun. Then repeat with Cobalts HP spring Then add the hopup mod. And maybe then can judge any advantage the device may add.
No suggestions but I like what you're doing and will be watching.
hello cobault just a quick question,, what are the specs on your custom spring? and what are its best applications? just finished reading 32 pages all over again,, and now I got big pics bb
It's made to replace the stock spring used in a large number of Plymouth made and Rodgers made Daisy lever action BB guns. It's not recommended for the 25 or 1894. If you have a specific gun in mind that you want to use it in, you can ask here or send me a PM and I'll tell you if it's a good fit or not.
Decided to pull the shot tube, RR carbine (China), and attempt installing a “hopup” device. Got the front sight pug out, and noticed how far “off center” the chamfer to the bore was. Is this common, or have I got a line reject ??
I know how important the crown is on a “firearm” and would assume the same on any “gun”.
Anyone have experience with this issue ??
I'll inspect some shot tubes I have here and will get back to you about the off center bore. The crown is important, just as you suspected. Maybe not as critical as with a powder burner, but it still needs to be right IMHO. I recrowned a 105B that came to me in an airgun lot off eBay, it looked all chewed up like the muzzle had been ground into concrete. Shot okay for MV but accuracy was non existent. Recrowned it using a brass screw and valve grinding compound and the accuracy did improve markedly, so it is a 'thing'.
Okay, the new 1938B tubes I have are the seamless tubing type and the bores look centered. The crowns are present, although as can be seen there's definitely room for improvement. The shot tube shown on the far left of the group photo and also shown alone came from a gun that was very accurate.
May mean nothing but the know-to-be-accurate tube, while not perfect, looks to have a better crown than the new unknown accuracy tubes...
I believe it is an exponential relationship with velocity.
The slower your projectile the less it should matter.
I'm not a real physicist anyway, so you shouldn't take my ramblings as the truth (!), but I'm guessing turbulence is going to be the same as the oft-quoted rule among aviation nerds... "drag increases as the square of the airspeed", which I may be misquoting anyway.
Short answer... Yes, your crown matters (but not as much as if your projectile was going seven times as fast)!
Daisy stockmaker par excellence Shane has messaged me about an electroless nickel plating kit from Caswell, possibly one that is within reach of the home hobbyist. Nickel won't be as durable as hard chrome but still may be durable enough, and could be reapplied as needed. I'll look into it and report back. If anyone is acquainted with this, feel free to chime in!
Along about the time this thread was started I decided that my ideal BB gun was going to be a Daisy lever action repeater that would shoot 400 fps and do it as accurately as possible. Little did I realize what a tall order that really was! It has taken most of three years and a lot of help, but my dream is now a reality: My #1 Red Ryder is now shooting 420 fps and can put 10 shots inside 1.23" at 10 yards using Daisy zinc BBs from WM (and this will improve, no doubt about it). I am happier than I can put into words!! I received a lot of help from hinz57 and he will be the first to point out this has been a community project- so thank you one and all. Without the help of everyone here, this would not have been possible.
My gun as it is currently configured is using one of hinz57's custom 499 shot tube and a precisely bored front sight/barrel plug that fits the 499 tube like a glove. Along with that it’s using his custom air tube and my HP spring. The stock trigger has a lighter pull, the blade reshaped and smoothed and the anti beartrap has been removed. The plunger tube and piston are stock 1938B parts.
The stock is from my good buddy Shane, who doesn’t post here but he does stop by to see what’s new, so thanks again Shane, you’re “one of the guys” whether you post or not. And I would encourage anyone who wants a truly awesome maple stock, or a refinished and/or modified factory stock to give him a shout. PM me for contact details or you can reach him through his eBay store, Rest-O-Mod.
I recently installed a 3/4” tube Weaver C4 4x scope, it was popular in the ‘50s and ‘60s with rimfire shooters. It has a tip-off Weaver mount that attaches to the Lasso scope rail I got from PA. There are much better scopes and I even own some but I like the look of the Weaver, plus it’s light. But I’m not used to using a scope; in fact the three groups I shot using the Weaver on my gun are my first. I shot the groups sitting, forearm rested and the buttstock shouldered. The third group was my best and that makes me confident the groups will improve with practice. Besides getting used to the scope I need to try different ways of holding it while shooting with the forearm rested.
While this is a big milestone for me, it in no way marks the end of anything- there are still a LOT of good things yet to come, so stay tuned!
Congratulations! beautiful looking gun.
Thank you very much. I hope and pray things start to go better very soon on your end.
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