Should probably go through the pile of new 1938b shot tubes. Maybe one is 0.178. If there were 2, put one in a gun. Make a “sorter” to pretest if they go through.... I bet some of the old seamed tubes are big enough....They looked very good in that regard, no more than 1, 2 tenths- about the same eccentricity as difference in diameters among those that were different. But for the most part they looked very uniform. Just a shame they weren't a smidgen smaller is all. I would also mention that none measured over 0.177".
I just took your advice and did just that, and I'm very glad I did! Turns out all the new and used 1938B shot tubes I checked WILL accept the Marksman BBs. What I found, though, is there seems to be a slight tight spot at the muzzle end of several of them, including the two that are in guns currently. This causes the BB to stop right after it enters the muzzle of the tube. I'm not going to say these tubes are choked- it may be nothing more than a slight restriction caused by a machining op. But the restriction is there, and because of an abundance of caution I did not force the BB past the point where it stopped by gravity.Should probably go through the pile of new 1938b shot tubes. Maybe one is 0.178. If there were 2, put one in a gun. Make a “sorter” to pretest if they go through.... I bet some of the old seamed tubes are big enough....
Thank you for reminding me- I have a numbered bit index here so I'll do just that if need be.#16 drill rod is 0.177”. Often just under that. When I first started this adventure, I purchased a piece to poke through the shot tubes with a bit of valve grinding compound on it to attempt a bit of polish. If you have a tight spot, you could give that a try. Maybe even just use the end of a #16 drill...
Thanks for the clarification on the 499 tube ID.I have seen some small variation in the 499b shot tubes. I would say nominally 0.176”.
The LW tube is 0.1751-2 at the breech.
There certainly could be 499 tubes + - 0.0005”from 0.176”
I now have Diana springs in hand. I plan to try to stuff one in the 499b/LW. Best chrono # thus far is 552, but just once. New spring, perfect bb, etc. 535 many times. Maybe improvement with more spring! Getting it in there will not be easy. Reliability. Who knows...
Your groups are about what I’m getting out of my 1938B at 33ft. At 25ft they tighten to around an inch. The additional 8 ft makes a big difference.Once I moved out to my normal target distances of 20-30 yards, the gun is shooting spot on for elevation and needed no windage adjustment either. My theory on why this is, is the added MV is counteracted at these somewhat extended ranges by the extra weight of the Marksman BBs. Or not. But they shoot very well and really put a wallop on the targets!
Plain and simply put, I do not like to shoot groups. I find it boring while also being somewhat stressful. I shoot for enjoyment. Target shooting for groups is not enjoyable for me and I find it a chore. Maybe it's that the targets reflect my lack of skill for bench shooting, well, not really bench shooting- more like shooting while sitting with the forend of the gun rested on a railing with a towel folded under it. I shoot standing or sitting w/o resting the gun when I plink and maybe that's what I need to try next time I shoot a group but I doubt it'll be any better that what's shown below. I will say that I honestly believe these BBs can shoot tighter groups than if using standard zinc plated Daisy BBs when shot by someone with the chops to take advantage of their potential- but I'm not that guy. Whether they're as accurate as or better than the Daisy Match Grade BBs I cannot say. The MV has been higher using the Marksman than Match Grades, for what that's worth.
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Took the 104 apart last night only to discover it already has a 1/8" air tube in it. Don't remember doing it but it's there. So not going to get 400 fps out of it, but I'm still stoked how well it's shooting just the same.That's an excellent idea about the 104 air tube!! The tube in my old 104 is no larger than 7/64" and may well be 3/32", so a 1/8" tube will definitely make a difference and could boost it to the 400 fps plateau.