SpudFiles

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A little ID sanding and UHMW bushings will make this a beautiful golf ball barrel insert that will slide right into the existing barrel. Resultant video to follow and I won't be coming back without my sonic boom. 3X, MAPP and o2 with 200psi burst disc should do it. If it doesn't, 250psi burst disc and 3.5x will.

Sounds promising.

Chrony it! (Or else we cannot be sure that it really happened...)

Sorry to pee in your cornflakes, but that ID sanding is going to be at best, a nightmare.
Getting a pipe from 1.634" to a consistent 1.682" (at minimum, if you want reasonably free moving balls*) is going to be hard.

I know that Hal off UKSGC used a motorcycle cylinder hone (used for increasing cylinder bore) to try and change a pipe's ID, but it didn't exactly work out great.

*Cue JSR

Sorry to pee in your cornflakes, but that ID sanding is going to be at best, a nightmare.
Getting a pipe from 1.634" to a consistent 1.682" (at minimum, if you want reasonably free moving balls*) is going to be hard.

I dunno I think it could be done, the key here is very accurate machines and a slow err insertion rate (by that I mean how fast the pipe is fed into the machine) into the boring machine so its the same id in all places. The only problem I see is getting a 1.682'' drill bit thing*. Although it could be cnc milled although it would be cheaper by just buying a proper barrel.

*Sorry for all the non technical names of parts

This is the one I originally saw, but couldn't find it for some reason when I made this post.

http://www.mcmaster.com/#89965k77/=1ztcug

.002" is much easier than 1/16"

You might try this http://www.mcmaster.com/#4561t513/=1zxhox as an alternative. D_hall has used the stainless version of this and seemed pretty happy with the results.

BTW, here's another gratuitous SS flyby for your entertainment...

[youtube][/youtube]

I don't think I could ever get tired of those videos.

starman wrote:You might try this http://www.mcmaster.com/#4561t513/=1zxhox as an alternative. D_hall has used the stainless version of this and seemed pretty happy with the results.

BTW, here's another gratuitous SS flyby for your entertainment...

[youtube][/youtube]

That WOULD be great, but the ID of my barrel is 1.87"

Well I shot some golf balls at 3X in the desert and the shots got a lot louder, but I have no idea how fast they were going. It was really strange to watch the balls fly in a straight line far across a valley into the side of another rocky hill. They went straight but seemed to float slowly across the distance. It was crazy. I didn't use my tubing insert as I haven't finished sanding the inside as it really is a pain in the ass as several people here warned it would be. What I need is a cylinder hone that is driven by a hand drill. That will get it handled. I'll update again later with a chrony reading when I get one.

Moonbogg wrote:... I'll update again later with a chrony reading when I get one.

In the absense of the chrony just fire more or less straight up and time how long it takes from firing until the round hits the ground. The Cd of golfballs is well known and it should be possible to calculate a reasonably accurate muzzle velocity from the hang time.

Careful the round doesn't hit you on the way down.

you can use a laptop and a measuring tape. I got some foreign software off a forum that did it for me, but simply recording it, then zooming way up in audacity ad measuring miliseconds between firing peak and hitting a nice hard backstop and ofc dividing by the distance.

Moonbogg wrote:Well I shot some golf balls at 3X in the desert and the shots got a lot louder, but I have no idea how fast they were going. It was really strange to watch the balls fly in a straight line far across a valley into the side of another rocky hill.

If you haven't crossed the supersonic threshold, you are getting darned close to it. HGDT predicts supersonic + with a configuration like yours at 3x.

starman wrote:

Moonbogg wrote:Well I shot some golf balls at 3X in the desert and the shots got a lot louder, but I have no idea how fast they were going. It was really strange to watch the balls fly in a straight line far across a valley into the side of another rocky hill.

If you haven't crossed the supersonic threshold, you are getting darned close to it. HGDT predicts supersonic + with a configuration like yours at 3x.

Right, thats why I have chosen to persue it because HGDT predicts its capable. I even switched to MAPP for a little boost. So i'll keep at it and possibly try the laptop sound card method. Shooting straight up would be fun as always, but i'd have to find a bridge or something to park my car under and hide myself as well

Ragnarok wrote:Sorry to pee in your cornflakes, but that ID sanding is going to be at best, a nightmare.
Getting a pipe from 1.634" to a consistent 1.682" (at minimum, if you want reasonably free moving balls*) is going to be hard.

I know that Hal off UKSGC used a motorcycle cylinder hone (used for increasing cylinder bore) to try and change a pipe's ID, but it didn't exactly work out great.

*Cue JSR

Why hone it. For the change needed a tapered piston (Mandril) can be made and driven through with a hammer and rod to mandril form it slightly larger. Heat softened PVC could then be placed on the outside if you wish to sleeve it inside PVC.

Moonbogg wrote:Shooting straight up would be fun as always, but i'd have to find a bridge or something to park my car under and hide myself as well

Maybe not required much as you think. It's going to go up a whole lot faster than it comes back down. The terminal velocity for a falling golf ball is only around 70 mph....not that I would want to get hit by that but a hard hat and a basic golf umbrella will pretty much protect you. Keeping the dent from the top of your car will be a little more challenging....