Altitude sickness cured in Albuquerque... a B-30 saga (Graphic)

Altitude sickness cured in Albuquerque... a B-30 saga (Graphic)

Joined: April 2nd, 2005, 6:57 am

November 12th, 2010, 7:59 pm #1

Anyone want to guess what this is?



Years ago I ordered a B-30 .22 from Xisico, my first magnum springer.
After unboxing it I cocked and loaded a pellet and fired it point blank into a pine 2x4. The pellet literally bounced off pine and that was my introduction to the wonderful world of Chinese airgun-smithing

Before long, I had everything apart and found the problem: the breach end of the barrel had not been pulled far enough into the receiver loading zone with the breech nut tightened as far as it would go, so the end of the compression cylinder was hitting against the receiver with a metallic "click" before contact was made between the barrel and breech seal - my first (and one of many) clearly identified manufacturing defect! Since I did not want to pull the barrel out of the receiver tube, I simply took about .080" off the breech end of the compression cylinder on my mill, put the rifle back together and went merrily on my way.

Over time, I discovered the honorable Jim Macarri and his universe of superb airgun products and ordered a tune kit with a FAC spring and a Tesla seal for high power. After making my own scope riser and installing a decent scope,



the B-30 was one of my most accurate and hard hitting guns - which made me a reasonably happy camper... until my Chrony arrived in the mail

That was when I learned the sad story about spinger altitude sickness. You see, all springers use ambient air to push their pellets down the barrel, and can only take so big a gulp of it when cocked. Here in Albuquerque, the atmosphere is less dense - and the result is that unless a springer is designed to take a bigger gulp of air, it will shoot anywhere from 2 to 3 percent slower per 1000 ft of altitude. For me, that's a whopping 15% slower pellet velocity than at sea level!

So if you can shoot your B-30 .22 in Phoenix (1,100 ft.) with a 14.3 gr CPH at 730fps, then I should be getting a whimpy 630fps with the same pellet in the same gun. Maybe you are cheering because my pellets no longer bounce off pine boards, but I once again was in a fuming muddle

Time to fire up the mill and lathe in the barn and make me a honking big gulp cylinder for my B-30.
So I bored out my compression cylinder - Boy that thing is made from tough stuff - lots of chrome in that alloy. The chips were deep purple and hard as diamonds.



and I decided to make a custom 1.024" piston seal to go with it, so I sliced up the stock seal and scanned it into photoshop



... took measurements, and made a larger OD 3D model of it



and then tried making one out of teflon on my cnc mill



which didn't work because teflon distorts permanently under high shear and bending loads

By now I was tired and disappointed, so I relaxed by fixing and shooting my B-40 .22 which is a whole 'nuther saga...

Until a great guy named Walter Glover told me about a nifty seal that you can buy at the Parker Store called a PolyPak seal. In this case is was a standard seal, part no. P4615A90 made from Molythane (who ever thought of combining molybdenum in the urethane??)

So I fired up the lathe and made a custom stroked piston for my oversize cylinder with a groove at the top specially made for the 1.000" Polypak seal. And it turned out well. The stock piston weighs 295 grams, and the custom piston weighs 320 grams.



My B-30 now shoots:

CPHP 14.3 gr @ 750 fps = 17.87 ftlbs
RWS Superdomes 14.2 gr @ 740 fps = 17.27 ftlbs
Dynamic Sn2 air bullets 12.85 gr @ 795 fps = 18.04 ftlbs!

The shot cycle is slightly improved which is interesting, the velocities are at least as consistent as my Vortek powered B-40, and I am sure that I can get it to group well with the right pellet and holding style.



Tom









Last edited by kestreltom on November 12th, 2010, 8:42 pm, edited 1 time in total.
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Joined: October 2nd, 2009, 10:15 pm

November 12th, 2010, 9:46 pm #2

1 WOW!
2 Will you adopt me?
3 When are you making this for the B40
4 and can I buy one
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Joined: April 2nd, 2005, 6:57 am

November 13th, 2010, 1:50 am #3

Thank you sir!

LOL! the house is full of family right now, so not considering additions... but thanks for asking!

I made that custom piston as a sort of challenge to see if I could do it on my lathe, but it took too long to ever consider making one for money - I'm sorry. A stroker piston for the B-40 sounds nice, but if you can already get close to 15 ftlbs with the Vortek kit you have already won the game AFAIK.

If the B-40 piston can be taken apart by removing a pin that allows you to separate the head from the cylinder, then it might be possible to make a custom retrofit head. I can't remember if the B-40 piston comes apart.

Tom
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Joined: October 25th, 2002, 3:46 pm

November 13th, 2010, 7:57 pm #4

Anyone want to guess what this is?



Years ago I ordered a B-30 .22 from Xisico, my first magnum springer.
After unboxing it I cocked and loaded a pellet and fired it point blank into a pine 2x4. The pellet literally bounced off pine and that was my introduction to the wonderful world of Chinese airgun-smithing

Before long, I had everything apart and found the problem: the breach end of the barrel had not been pulled far enough into the receiver loading zone with the breech nut tightened as far as it would go, so the end of the compression cylinder was hitting against the receiver with a metallic "click" before contact was made between the barrel and breech seal - my first (and one of many) clearly identified manufacturing defect! Since I did not want to pull the barrel out of the receiver tube, I simply took about .080" off the breech end of the compression cylinder on my mill, put the rifle back together and went merrily on my way.

Over time, I discovered the honorable Jim Macarri and his universe of superb airgun products and ordered a tune kit with a FAC spring and a Tesla seal for high power. After making my own scope riser and installing a decent scope,



the B-30 was one of my most accurate and hard hitting guns - which made me a reasonably happy camper... until my Chrony arrived in the mail

That was when I learned the sad story about spinger altitude sickness. You see, all springers use ambient air to push their pellets down the barrel, and can only take so big a gulp of it when cocked. Here in Albuquerque, the atmosphere is less dense - and the result is that unless a springer is designed to take a bigger gulp of air, it will shoot anywhere from 2 to 3 percent slower per 1000 ft of altitude. For me, that's a whopping 15% slower pellet velocity than at sea level!

So if you can shoot your B-30 .22 in Phoenix (1,100 ft.) with a 14.3 gr CPH at 730fps, then I should be getting a whimpy 630fps with the same pellet in the same gun. Maybe you are cheering because my pellets no longer bounce off pine boards, but I once again was in a fuming muddle

Time to fire up the mill and lathe in the barn and make me a honking big gulp cylinder for my B-30.
So I bored out my compression cylinder - Boy that thing is made from tough stuff - lots of chrome in that alloy. The chips were deep purple and hard as diamonds.



and I decided to make a custom 1.024" piston seal to go with it, so I sliced up the stock seal and scanned it into photoshop



... took measurements, and made a larger OD 3D model of it



and then tried making one out of teflon on my cnc mill



which didn't work because teflon distorts permanently under high shear and bending loads

By now I was tired and disappointed, so I relaxed by fixing and shooting my B-40 .22 which is a whole 'nuther saga...

Until a great guy named Walter Glover told me about a nifty seal that you can buy at the Parker Store called a PolyPak seal. In this case is was a standard seal, part no. P4615A90 made from Molythane (who ever thought of combining molybdenum in the urethane??)

So I fired up the lathe and made a custom stroked piston for my oversize cylinder with a groove at the top specially made for the 1.000" Polypak seal. And it turned out well. The stock piston weighs 295 grams, and the custom piston weighs 320 grams.



My B-30 now shoots:

CPHP 14.3 gr @ 750 fps = 17.87 ftlbs
RWS Superdomes 14.2 gr @ 740 fps = 17.27 ftlbs
Dynamic Sn2 air bullets 12.85 gr @ 795 fps = 18.04 ftlbs!

The shot cycle is slightly improved which is interesting, the velocities are at least as consistent as my Vortek powered B-40, and I am sure that I can get it to group well with the right pellet and holding style.



Tom








wow, nice job there!

Would love to know how you bored out the compression cylinder!

Walter....
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Joined: October 2nd, 2009, 10:15 pm

November 13th, 2010, 8:55 pm #5

Anyone want to guess what this is?



Years ago I ordered a B-30 .22 from Xisico, my first magnum springer.
After unboxing it I cocked and loaded a pellet and fired it point blank into a pine 2x4. The pellet literally bounced off pine and that was my introduction to the wonderful world of Chinese airgun-smithing

Before long, I had everything apart and found the problem: the breach end of the barrel had not been pulled far enough into the receiver loading zone with the breech nut tightened as far as it would go, so the end of the compression cylinder was hitting against the receiver with a metallic "click" before contact was made between the barrel and breech seal - my first (and one of many) clearly identified manufacturing defect! Since I did not want to pull the barrel out of the receiver tube, I simply took about .080" off the breech end of the compression cylinder on my mill, put the rifle back together and went merrily on my way.

Over time, I discovered the honorable Jim Macarri and his universe of superb airgun products and ordered a tune kit with a FAC spring and a Tesla seal for high power. After making my own scope riser and installing a decent scope,



the B-30 was one of my most accurate and hard hitting guns - which made me a reasonably happy camper... until my Chrony arrived in the mail

That was when I learned the sad story about spinger altitude sickness. You see, all springers use ambient air to push their pellets down the barrel, and can only take so big a gulp of it when cocked. Here in Albuquerque, the atmosphere is less dense - and the result is that unless a springer is designed to take a bigger gulp of air, it will shoot anywhere from 2 to 3 percent slower per 1000 ft of altitude. For me, that's a whopping 15% slower pellet velocity than at sea level!

So if you can shoot your B-30 .22 in Phoenix (1,100 ft.) with a 14.3 gr CPH at 730fps, then I should be getting a whimpy 630fps with the same pellet in the same gun. Maybe you are cheering because my pellets no longer bounce off pine boards, but I once again was in a fuming muddle

Time to fire up the mill and lathe in the barn and make me a honking big gulp cylinder for my B-30.
So I bored out my compression cylinder - Boy that thing is made from tough stuff - lots of chrome in that alloy. The chips were deep purple and hard as diamonds.



and I decided to make a custom 1.024" piston seal to go with it, so I sliced up the stock seal and scanned it into photoshop



... took measurements, and made a larger OD 3D model of it



and then tried making one out of teflon on my cnc mill



which didn't work because teflon distorts permanently under high shear and bending loads

By now I was tired and disappointed, so I relaxed by fixing and shooting my B-40 .22 which is a whole 'nuther saga...

Until a great guy named Walter Glover told me about a nifty seal that you can buy at the Parker Store called a PolyPak seal. In this case is was a standard seal, part no. P4615A90 made from Molythane (who ever thought of combining molybdenum in the urethane??)

So I fired up the lathe and made a custom stroked piston for my oversize cylinder with a groove at the top specially made for the 1.000" Polypak seal. And it turned out well. The stock piston weighs 295 grams, and the custom piston weighs 320 grams.



My B-30 now shoots:

CPHP 14.3 gr @ 750 fps = 17.87 ftlbs
RWS Superdomes 14.2 gr @ 740 fps = 17.27 ftlbs
Dynamic Sn2 air bullets 12.85 gr @ 795 fps = 18.04 ftlbs!

The shot cycle is slightly improved which is interesting, the velocities are at least as consistent as my Vortek powered B-40, and I am sure that I can get it to group well with the right pellet and holding style.



Tom








What kind of power is it going to have at lower altitudes? Will it be pushing 14 grain pellets at 900 fps? I think we have a new magnum standard then.
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Joined: April 2nd, 2005, 6:57 am

November 13th, 2010, 10:47 pm #6

wow, nice job there!

Would love to know how you bored out the compression cylinder!

Walter....
with the CC in the vise in a custom holding fixture, and a boring head in the spindle. I used the longest of my 3/4" carbide tipped boring bars. I think I used around 500 rpm at a 2 ipm feedrate and took several cuts of maybe .005" - .008" depth.

btw. Sorry about the too-hard urethane thumbs
I did manage to make a nice shim for my B-40 breech seal out of that stuff. Machines nicely, but not very flexible.

Tom
Last edited by kestreltom on November 13th, 2010, 11:13 pm, edited 1 time in total.
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Joined: April 2nd, 2005, 6:57 am

November 13th, 2010, 11:35 pm #7

What kind of power is it going to have at lower altitudes? Will it be pushing 14 grain pellets at 900 fps? I think we have a new magnum standard then.
I think my B-30HA (high altitude) might hit 19 or 20 ftlbs at lower levels, but not much more. I think it will run out of spring power before it reaches the power levels you mention - so a monster spring would be needed, but I bet accuracy would deteriorate. What I essentially did was to provide an adequate air cushion to transmit the spring's power to the pellet at altitude.
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Joined: October 2nd, 2009, 10:15 pm

November 14th, 2010, 2:12 am #8

Did you know that on the AA TX and PS they adjusted the length of the piston rod to gain or subtract power? So making the stem stick out farther would reduce the power and shorter would increase it. Maybe something else you might want to tinker with.
If I had your tools I would make my own compression chamber and piston sets for the B30 and B40 one for 12fpe and one for whatever i could get out of it. My B30 does ok for my altitude but would love to see around 700+ numbers.
Keep up the good work.
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Joined: April 2nd, 2005, 6:57 am

November 14th, 2010, 6:06 am #9

Wow - learn'n something new every day!
That's nice. By shortening the stem you add stroke and spring preload. Very nice.
Maybe a stem with a threaded stub and a corresponding threaded bore in the piston head?

Mike, I heard you say you were up around 7000 feet. Where exactly are you (Colorado?)?

Tom
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Joined: October 2nd, 2009, 10:15 pm

November 14th, 2010, 7:32 am #10

I'm in Big Bear Ca. That info was relayed to me by Tom Gore from Vortek. One of the things he had me check when I started running into troubles.
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