cooper t bolt - Page 3

VM-onster · 02-21-2008, 05:01 PM

Hey no prob bud, so do you have the stock bolt now? Have you cupped it? I found this to be better for me than a flat front. I think directions are on evil eds website... It makes the ball sit better and pushed equally. try it if u have a dremel, very easy...

DRAGON · 02-22-2008, 11:34 AM

yea that was the first thing i did when i first found the empire 5 or 6 years ago,
this is the best site for vm stuff

dragon

Anonymous Coward · 02-22-2008, 03:06 PM

I got the ACP under shot bolt today. Now I have never handled the Cooper-T better bolt for the VM-68, but I did have a Cooper-T better bolt for the sniper. If the Cooper-T VM-68 bolt is similar to the Cooper-T sniper bolt, then the ACP design is furthest from.

Like I said I just got it in the mail and it will be awhile before I get a chance to shoot it. My backyard is small. No really small. So maybe proof (or lack of) is in actually using it. The bolt design isn't anything like Cooper-T's design. Chauncey's design used a bottom cut channel that ran the length from the port exhaust to the front of the bolt. So all the gas is channeled to the bottom of the ball. Hence a reduction of FPS as the flow is channeled specifically at the bootom of the bolt. The ACP took their standard open faced bolt, cut to oring grooves around the valve port, and then removed 1/5 of the bottom section of the open face. It's basically an opened faced bolt with a wide cut down the bottom center.

Think of the letter 'C' and that's the face of it. The only thing I can think of for the reason for this design is it still has the bolt velocity screw inside of it. But in a backspin application there are other ways to limit flow on the VM.

This might have been poorly researched on their part. And what's sad is this bolt is well machined. The face is nicely rounded to cup the ball, the port is angled for flow simular to AKA and Mad designed in high flow and zero flash. It's a quality piece in the hand. But I wonder if they actually tried this out?

I already have a ACP open faced delrin bolt and love it And my experience with other backspin bolts tells me this isn't going to give me the results I expect. But I'll still have to give it a try. I might fill this one with epoxy and cut a channel like Chauncey's original design if things aren't working as expected. Or design a plug insert for the bolt.

Who knows maybe I'll eat crow once I run it through some. But experience with this tells me otherwise.

HP_Lovecraft · 02-22-2008, 03:29 PM

I remember the website for the Undershot bolt specifically stated that the bolt did not give the paintball enough backspin to generate enough "magnus force" to offset gravity.

Instead, they claimed higher accuracy because of centrifical force. Some made up concept like "Linear Rifling", as opposed to "Axial Rifling".

I did once have a CooperT bolt for a snipe. It looked exactly like the VM bolt, except it was black. Just a tiny hole at the base of the boltface. I had some luck a while ago converting other bolts to work like the CooperT, but its a bit tricky:

Anonymous Coward · 02-22-2008, 06:04 PM

That's what I'm talking about. The ACP bolt's walls is slightly thinner. Did you use a longer screw or attach a rod to the set screw? Secondly, did you cut the section between the port and the lower channel?

HP_Lovecraft · 02-23-2008, 08:22 AM

This is what I did: (note, this is for an inline blowback, not a VM68).

I know, not very pretty. I was trying to emulate the CooperT effect by focusing the blast to the base of the paintball.

It does not seem to work as well as the CooperT, and I think it is the SHAPE of the CooperT bolt face. The CooperT is curved to match the shape of the paintball. This way the blast is DIRECTLY focused onto the rear, causing the backspin.

My version above is a more traditional bolt face. So much of the blast probobly gets dispersed, and I'm sure does not create as much backspin.

Consider the bolt "rimfire" PGP. I'm sure this is where Chauncey got the idea. The original PGP had a primitive bolt, where the valve emptied directly into the firing chamber, bypassing the bolt. You would think this would create some sort of backspin, or forespin, but it doesnt. That blast much need very specific focusing.

nick

DRAGON · 02-26-2008, 05:06 PM

thanx for the pics nick
and anonymous let us know how it goes when you do get it going

dragon

02-22-2008, 03:29 PM	#24 (permalink)
HP_Lovecraft Resident Old Fart Join Date: Aug 2006 Location: Southern Maine Posts: 2,462	I remember the website for the Undershot bolt specifically stated that the bolt did not give the paintball enough backspin to generate enough "magnus force" to offset gravity. Instead, they claimed higher accuracy because of centrifical force. Some made up concept like "Linear Rifling", as opposed to "Axial Rifling". I did once have a CooperT bolt for a snipe. It looked exactly like the VM bolt, except it was black. Just a tiny hole at the base of the boltface. I had some luck a while ago converting other bolts to work like the CooperT, but its a bit tricky: __________________ www.montneel.com My Myspace nonsense "the evidence strongly suggests that neither Billy nor Adam (Smart Parts) could have invented the electronic paintgun" -Garr M. King, U.S. Judge

02-23-2008, 08:22 AM	#26 (permalink)
HP_Lovecraft Resident Old Fart Join Date: Aug 2006 Location: Southern Maine Posts: 2,462	This is what I did: (note, this is for an inline blowback, not a VM68). I know, not very pretty. I was trying to emulate the CooperT effect by focusing the blast to the base of the paintball. It does not seem to work as well as the CooperT, and I think it is the SHAPE of the CooperT bolt face. The CooperT is curved to match the shape of the paintball. This way the blast is DIRECTLY focused onto the rear, causing the backspin. My version above is a more traditional bolt face. So much of the blast probobly gets dispersed, and I'm sure does not create as much backspin. Consider the bolt "rimfire" PGP. I'm sure this is where Chauncey got the idea. The original PGP had a primitive bolt, where the valve emptied directly into the firing chamber, bypassing the bolt. You would think this would create some sort of backspin, or forespin, but it doesnt. That blast much need very specific focusing. nick __________________ www.montneel.com My Myspace nonsense "the evidence strongly suggests that neither Billy nor Adam (Smart Parts) could have invented the electronic paintgun" -Garr M. King, U.S. Judge

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02-21-2008, 05:01 PM	#21 (permalink)
VM-onster Active Member Join Date: Dec 2007 Posts: 242	Hey no prob bud, so do you have the stock bolt now? Have you cupped it? I found this to be better for me than a flat front. I think directions are on evil eds website... It makes the ball sit better and pushed equally. try it if u have a dremel, very easy...

02-22-2008, 11:34 AM	#22 (permalink)
DRAGON Newbie Join Date: Apr 2007 Location: ontario Posts: 20	yea that was the first thing i did when i first found the empire 5 or 6 years ago, this is the best site for vm stuff dragon

02-22-2008, 03:06 PM	#23 (permalink)
Anonymous Coward Active Member Join Date: Jul 2007 Posts: 153	I got the ACP under shot bolt today. Now I have never handled the Cooper-T better bolt for the VM-68, but I did have a Cooper-T better bolt for the sniper. If the Cooper-T VM-68 bolt is similar to the Cooper-T sniper bolt, then the ACP design is furthest from. Like I said I just got it in the mail and it will be awhile before I get a chance to shoot it. My backyard is small. No really small. So maybe proof (or lack of) is in actually using it. The bolt design isn't anything like Cooper-T's design. Chauncey's design used a bottom cut channel that ran the length from the port exhaust to the front of the bolt. So all the gas is channeled to the bottom of the ball. Hence a reduction of FPS as the flow is channeled specifically at the bootom of the bolt. The ACP took their standard open faced bolt, cut to oring grooves around the valve port, and then removed 1/5 of the bottom section of the open face. It's basically an opened faced bolt with a wide cut down the bottom center. Think of the letter 'C' and that's the face of it. The only thing I can think of for the reason for this design is it still has the bolt velocity screw inside of it. But in a backspin application there are other ways to limit flow on the VM. This might have been poorly researched on their part. And what's sad is this bolt is well machined. The face is nicely rounded to cup the ball, the port is angled for flow simular to AKA and Mad designed in high flow and zero flash. It's a quality piece in the hand. But I wonder if they actually tried this out? I already have a ACP open faced delrin bolt and love it And my experience with other backspin bolts tells me this isn't going to give me the results I expect. But I'll still have to give it a try. I might fill this one with epoxy and cut a channel like Chauncey's original design if things aren't working as expected. Or design a plug insert for the bolt. Who knows maybe I'll eat crow once I run it through some. But experience with this tells me otherwise.

02-22-2008, 06:04 PM	#25 (permalink)
Anonymous Coward Active Member Join Date: Jul 2007 Posts: 153	That's what I'm talking about. The ACP bolt's walls is slightly thinner. Did you use a longer screw or attach a rod to the set screw? Secondly, did you cut the section between the port and the lower channel?

02-26-2008, 05:06 PM	#27 (permalink)
DRAGON Newbie Join Date: Apr 2007 Location: ontario Posts: 20	thanx for the pics nick and anonymous let us know how it goes when you do get it going dragon