need autococker owner's opinions on this!

[hawpunch]

i have a turtled ebladed cocker that i want to convert into a mini. i just spoke with my cocker tech here in the islands, and he said that it would greatly drop my efficiency if i do the conversion. can any cocker owners comment on this? thanks.

jae park

[Lumberjack]

Not really. Your OP will increase slightl, so that may be why they say that. I shoot a Mini Cocker and it tends to be a gas hog at times.

[lew]

You're guns efficiency won't drop. If the gun is 2000+, the air chambers will be large enough so that the gun can operate at the same pressure as it did when it was full-size. I shoot a Mini and get over 2000 shots from and 88/45.

[FallNAngel]

i have a turtled ebladed cocker that i want to convert into a mini. i just spoke with my cocker tech here in the islands, and he said that it would greatly drop my efficiency if i do the conversion. can any cocker owners comment on this? thanks.

jae park

why it would drop your efficiency at all makes me wonder, let alone "greatly". Yeah, there's less room for post regulated air, but that doesn't mean you use more air when you fire the gun.

[VFX_Fenix]

For efficientcy at lower pressures with an AC, STAY AWAY FROM MINI!!!!!

Reason being that the extra space that's chopped of in the mini converstion serves as a volumizing chamber. Everything being equal, a shot with a higher input pressure will use a higer volume of air as opposed to a lower input pressure. Recharge is the issue here more than anything else. At high ROF's the more regulated air you have before the valve the better. This high volume of regulated air maintains certain characteristics (i.e. density and temprature) that will help with efficiency. A given chamber at some pressure also has more net energy than a smaller shamber at higher pressure.

A full sized post 2000 AC, well tuned, can achieve upwards of 2000 shots from a 68/45.
My '99 AC with stock guts/pnuems sees around 700 shots from a 47/3000 fill (not inspiring at all I know).

[hawpunch]

vfx,

i have a 2003 orracle body. how much of a drop in efficiency and rate of fire are we talking about (rough estimate)? thanks.

jae park

[personman]

Couldnt you just put one of those front block screw volumizer things to replace the front block screw on there? Would that compensate for the loss of the air chamber or whatever?

[hawpunch]

personman,

what's a front block screw volumizer? thanks.

jae park

[VFX_Fenix]

An LP Chamber would recover some lost volume due to the mini conversion. As for hard number of "how much will I loose" in terms of efficiency *shrug* this is just going from what lew posted about his AC's air usage per 88ci fill. From just raw numbers, say around a 20% (1/5) loss on shots per fill?

From what I know about AC bodies, the only thing that really changes from model to model is the exterior milling after 2000. So particular body doesn't matter so much as body year (pre/post 2000).

Low friction RAM (i.e. SMC or BelSales) combined with a good lpr and 3 way (BelSales/Freeflow/Plamer) will also help with your efficiency, though I don't know how much.

[FallNAngel]

Reason being that the extra space that's chopped of in the mini converstion serves as a volumizing chamber. Everything being equal, a shot with a higher input pressure will use a higer volume of air as opposed to a lower input pressure.

Actually, I don't believe that's true. What you're saying is that a higher input pressure uses a higher volume of air and vice versa. At a higher pressure, you'd use a *lower* volume of air.

1000psi * 1ci of air = 1000
1ci of air * 1000psi = 1000

Recharge is the issue here more than anything else.

Yes, if you're worried about dropoff, yes, recharge rate is important. Although a good reg will help this, being that 2k+ bodies have a larger valve chamber by design, dropoff shouldn't be a problem with the speeds that anyone will be legally shooting.

At high ROF's the more regulated air you have before the valve the better.

Read above.

An LP Chamber would recover some lost volume due to the mini conversion.

For the most part from what I've heard, expansion chambers are more or less worthless, even on pre-2k bodies.

As for hard number of "how much will I loose" in terms of efficiency *shrug* this is just going from what lew posted about his AC's air usage per 88ci fill. From just raw numbers, say around a 20% (1/5) loss on shots per fill?

Got a link and data to support this?

From what I know about AC bodies, the only thing that really changes from model to model is the exterior milling after 2000. So particular body doesn't matter so much as body year (pre/post 2000).

This is correct. Everything basically stayed the same except body milling.

Low friction RAM (i.e. SMC or BelSales) combined with a good lpr and 3 way (BelSales/Freeflow/Plamer) will also help with your efficiency, though I don't know how much.

Although technically you do save air with a smoother ram, I'm not sure how much it would really affect efficiency. It'd actually be an interesting task to figure out though. However, I completely fail to see how an LPR or 3-way is going to make any difference at all in efficiency.

[VFX_Fenix]

P1V1 = P2V2 a portion of the ideal gas law (PV=nRT)
Yes, however, there's a little more at work than just straight pressures and volumes. The volume of gas that's released by the valve causes a temprature shift in the pre-valve chamber (like with CO2 but not as pronounced). This changes the amount of energy that resides behind the not only by volume and pressure but temp as well. Durring the firing cycle there will be a small portion of gas that will condense as a result of this momentary loss of v/p/t. By minimizing the volume and pressure change in the chaber during firing events the decrease in temp and condensation of the gas will be lessend which helps to maintain consistant consumption of the valve during firing events. (EDIT - Can we see that if this trend continues long enough higher volumes of air with less energy per volume due to temp. will lead to the equivalent of sucking mostly low energy liquid through the valve as opposed to high energy gas which results in decreased efficiency because you're pulling more volume through the valve.)

There's also a consideration about muzzle velocity, if we want to hang on to V1P1=V2P2. Consider that the equalizing pressure for P2 is greater than the input pressure needed to fire the AC at 300fps? What if P2 (to shoot 300fps) were as much as half the pressure needed to equalize the new regulated air chamber V2 as the original chamber V1 @ P1? The end result is what shocker owners suffer from, their marker being too lp for it's own good (lp for lp's sake) and being a gas hog instead of starving their internals (increase in OP post Mini Conversion).

So let's say that Cocker A is full sized and has a pre-valve chamber volume of .785ci (2*(3.14*.25^2)) and an operating pressure of 21.77bar (~320psi). so V1P1 = 17.01

Cocker B has had the Mini conversion done to it which removes ~1.25" from the pre-valve chamber. So if we calculate V2 it comes out to 0.196 (0.5(3.14*.25^2)). So to be equal to V1P1, P2 must be 17.01/0.169 = 86.79bar (~1275.75psi), that's a HUGE increase in operating pressure to see the same 17.01 value and I'll bet that no cocker in the world will even be able to shoot at that pressure.

My 20% loss in efficiency is simply based off of two people's claims, one from this very form (lew) who claimed 2000+ shots from his mini'd cocker on an 88/45 and from Professional Paintball who claimed their Lockout could get 2000+ shots from a 68/45. The difference was a simple percentage calculation for loss.

The reason for the volume of air before the valve is to prevent shoot-down during long strings. By removing the extra volume the marker will starve unless given a higher input pressure to make up the lost volume. By removing that much volume of regulated air before the valve the Cocker must do one of two things (assuming everything stays the same) shoot hot or starve.

[personman]

personman,

what's a front block screw volumizer? thanks.

jae park

Heh. I made up that term. Check Fenix's post below mine, he links to what I was talking about. Its a volumizer LPC type thing..

Dont laugh at me because I dont know the terms for cocker crap!

[FallNAngel]

Cocker B has had the Mini conversion done to it which removes ~1.25" from the pre-valve chamber. So if we calculate V2 it comes out to 0.196 (0.5(3.14*.25^2)). So to be equal to V1P1, P2 must be 17.01/0.169 = 86.79bar (~1275.75psi), that's a HUGE increase in operating pressure to see the same 17.01 value and I'll bet that no cocker in the world will even be able to shoot at that pressure.

Yes, but that's kind of an off way to look at it. I've seen someone with a Midget cocker (a mini'd half block with the lower chamber cut flush with the back of the grip frame) and not once did I hear that he had to run at some obscene operating pressure to shoot 300.

My 20% loss in efficiency is simply based off of two people's claims, one from this very form (lew) who claimed 2000+ shots from his mini'd cocker on an 88/45 and from Professional Paintball who claimed their Lockout could get 2000+ shots from a 68/45. The difference was a simple percentage calculation for loss.

No offense, but again, this really has absolutely no basis. Did the person with the full bodied cocker have the same pneumatics, valve, valve spring, main spring, hammer, LPR pressure, paint, barrel and velocity as the mini cocker? Were they in the same geographic location? I highly doubt it. Even if they had similar parts, it doesn't mean they were tuned the same. No offense (and I know you're saying it was a guess), but going off of one instance on two separate markers doesn't show a trend to me. To me, I don't even see the whole mini vs full body in the shotcount above... I see a mini cocker that's tuned to get 1545 shots on a 68/4500 .. and that's with who knows what tuning, etc. Perhaps a simple spring change would boost up the numbers up to near 2000.

The reason for the volume of air before the valve is to prevent shoot-down during long strings. By removing the extra volume the marker will starve unless given a higher input pressure to make up the lost volume. By removing that much volume of regulated air before the valve the Cocker must do one of two things (assuming everything stays the same) shoot hot or starve.

How do you figure it has to either shoot hot or starve? I doubt all the people playing with mini cockers are either shooting hot or starving the valve of air. Look at Have Blue's reg test. I know he's said that the test doesn't quite show what you might think, but I'm looking more directly at one number. He tested an LCD Minireg on a Tribal with something like... 300psi output and 800psi input. The reg wasn't designed for that pressure range (and not for the Tribal) and performed the worst of all the regs tested. In the time frame he was working with, I don't even think it recharged fully. After that, everyone thought the reg was *horrible* and should definately be swapped out. What they didn't realize is that if the reg were to continue recharging linearly (even with it's bad recharge at the time), it could sustain a ROF somewhere around 20bps before it really started starving.

My point is, a good reg can recharge *very* quickly and I'd be very surprised if a minicocker would have trouble keeping up with the rof that someone would throw at it.

[VFX_Fenix]

Yes, but that's kind of an off way to look at it. I've seen someone with a Midget cocker (a mini'd half block with the lower chamber cut flush with the back of the grip frame) and not once did I hear that he had to run at some obscene operating pressure to shoot 300.

This isn't saying that it will need to operate at some horrendously large OP, it's saying that the energy stored in the larger air chamber would have to be roughly quadrupled to maintain the same energy. What's a midget cocker now???

No offense, but again, this really has absolutely no basis. Did the person with the full bodied cocker have the same pneumatics, valve, valve spring, main spring, hammer, LPR pressure, paint, barrel and velocity as the mini cocker? Were they in the same geographic location? I highly doubt it. Even if they had similar parts, it doesn't mean they were tuned the same. No offense (and I know you're saying it was a guess), but going off of one instance on two separate markers doesn't show a trend to me. To me, I don't even see the whole mini vs full body in the shotcount above... I see a mini cocker that's tuned to get 1545 shots on a 68/4500 .. and that's with who knows what tuning, etc. Perhaps a simple spring change would boost up the numbers up to near 2000.

I did qualify that a "well tuned AC could see 2000 shots per 68/45 fill". Most people take claims like this with a grain of salt from individuals, however from a company, they better be able to back-up their claims if someone challenges them.

How do you figure it has to either shoot hot or starve? I doubt all the people playing with mini cockers are either shooting hot or starving the valve of air. Look at Have Blue's reg test. I know he's said that the test doesn't quite show what you might think, but I'm looking more directly at one number. He tested an LCD Minireg on a Tribal with something like... 300psi output and 800psi input. The reg wasn't designed for that pressure range (and not for the Tribal) and performed the worst of all the regs tested. In the time frame he was working with, I don't even think it recharged fully. After that, everyone thought the reg was *horrible* and should definately be swapped out. What they didn't realize is that if the reg were to continue recharging linearly (even with it's bad recharge at the time), it could sustain a ROF somewhere around 20bps before it really started starving.

My point is, a good reg can recharge *very* quickly and I'd be very surprised if a minicocker would have trouble keeping up with the rof that someone would throw at it.

Counter point - Consider the volumizing chambers on Angels, if those chambers are not pressent the Angel requires a higher input pressure from the HPR (like we see in Mini Cockers) in order to achive a given ROF without volocity drop off. No matter how quickly recharging a reg is there will be a fine point where the input pressure must be increased (either to the gun through the HPR or the input pressure from the air course) or the marker will starve.

P1V1 = P2V2 a portion of the ideal gas law (PV=nRT)
Yes, however, there's a little more at work than just straight pressures and volumes. The volume of gas that's released by the valve causes a temprature shift in the pre-valve chamber (like with CO2 but not as pronounced). This changes the amount of energy that resides behind the not only by volume and pressure but temp as well. Durring the firing cycle there will be a small portion of gas that will condense as a result of this momentary loss of v/p/t. By minimizing the volume and pressure change in the chaber during firing events the decrease in temp and condensation of the gas will be lessend which helps to maintain consistant consumption of the valve during firing events. (EDIT - Can we see that if this trend continues long enough higher volumes of air with less energy per volume due to temp. will lead to the equivalent of sucking mostly low energy liquid through the valve as opposed to high energy gas which results in decreased efficiency because you're pulling more volume through the valve.)

EDIT - By gaining volume in exchange for pressure, no matter how fast your reg is, the proppellant gas will continue to cool and condense until the string ends when everything can come back to what ever ambient is. Durring the string however the cooler gas carries less energy so a higher volume of said gas is required to maintain pressure, this is where the efficiency is lost chiefly when making charge areas smaller.

[GT]

Ill add a few comments here.

The Ideal gas law assumes that your are somewhat close to atomspheric pressure and not much more. It is a poor model for how gasses behave at our higher operating pressures.

Angels with volumizers have never ever seen a performance increase, pre-speed. It was more stupid bling bling that people bought into. Secondly shoot down is most of the time caused by piss poor reg performance. I dont care how big your volumizer is if your reg sucks you are going to get shoot down, peroid. I'll even go a step further and call BS on guys who actually say that the volumizers on vikings do anything.

back on topic
Mini's: If you want a real answer I would ask BradAGD or Doc Nickel. They are one of the few guys on this board that have had a wealth of experience in working with millions of different types of cockers. I am amazed when I talk to Brad about cocker stuff and the litany of info that he knows.