SDR21 question

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zach12
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Sun Nov 09, 2008 9:55 am

i bought SDR21 from a supply shop. i checked it and it said... 1 1/2" crestline SDR21. i dropped a golfball in it and it rolled down the barrel. is it supposted to do that? or does it have a firm fit?
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FishBoy
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Sun Nov 09, 2008 10:25 am

a golfball is pretty solid (not soft & squishy), so it probably shouldn't be too tight. Also, I'm pretty sure it is supposed to fit just lose enough to roll down the barrel (@ least with sdr 21). The most important thing is that it doesn't have lots of space around it when it's in the barrel.
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frankrede
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Sun Nov 09, 2008 10:57 am

Its not supposed to fit tight....
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starman
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Sun Nov 09, 2008 11:30 am

The majority of golf balls will roll in loosely but with very little slop. However, I've found a few balls (5 or 6 out of dozens) that were too large and thus too tight to use.

Therefore the SDR21 is such a good fit that the high end of golf ball size tolerance isn't usable.
EphOph
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Mon Nov 10, 2008 11:06 pm

About a month ago, I found two golf balls in my backyard, and they differ in diameter by about 1/8". I won't be able to test their fit in SDR-21 until next week, but I'm assuming that one of them will fit very poorly. I suppose that different manufacturers produce balls of slightly different size. This isn't the first time I've heard of golf balls not fitting properly in SDR-21. Try some different ones and see what you get.
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jook13
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Mon Nov 10, 2008 11:21 pm

I made a golfball launcher a few months ago and I remember taking a golfball to a local plumbing shop. I tried the ball in a piece of sdr 21 and it seemed a bit loose, but still fit well enough for me to decide to buy it. When I got home, I started to sleeve the sdr 21 inside a piece of schedule 80 2 inch (took A LOT of effort and lube). after I finished that process I put a golfball in my newly made barrel and it seemed to fit a lot more snug. Just to a point where I can push it down the pipe with a slight amount of effort.

As a side note, it seems to shoot better when the ball is tighter and tougher to push down the barrel. I am not sure if this is due to the fact that it is a combustion or not, but I am guessing that it is.
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MrCrowley
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Mon Nov 10, 2008 11:53 pm

jook13 wrote: As a side note, it seems to shoot better when the ball is tighter and tougher to push down the barrel. I am not sure if this is due to the fact that it is a combustion or not, but I am guessing that it is.
If the projectile is tighter, the cannon builds up more pressure behind the projectile, more pressure = more force = more power.

Regardless if it was combustion or pneumatic, it would improve performance slightly.
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