Minimag getting horrible efficiency

[Snake_is_hot]

I purchased a used Minimag off of ebay. It does not leak, and works fine for the most part, but I only get about 200-250 shots from a full 48/3000 HPA tank. Is this normal efficiency for a minimag, or is something wrong. Any idea what I can do about it?

[cyberave68]

Ok so first off mags use a bit of air. A 48cc isnt that big i think you may need a 68cc.

Do you know what the on/off is inside of the valve? if so i think that could be part of the problem. can you get a few pics of the valve and its parts so i can see. (back half of valve where the two pieces seperate) inside of both halves...

[Snake_is_hot]

Ok so first off mags use a bit of air. A 48cc isnt that big i think you may need a 68cc.

Do you know what the on/off is inside of the valve? if so i think that could be part of the problem. can you get a few pics of the valve and its parts so i can see. (back half of valve where the two pieces seperate) inside of both halves...

I'll try to get a chance to open it up soon. Do you need pictures of the valve and internals dismantled, or just the main parts exposed? What are you looking for on the on/off?

[Hobbez]

I have a classic valve with level 10. It only gets 600 out of a 68/45. So, yea, old mags can be gas hogs. Are you using a barrel with a big ol' bore on it? This new paint these days seems to be so small that if you have an older barrel, the overboring can hurt your efficiency.

[factoid]

You've got some efficiency problems. My level 10 classic mag gets around 500-600 shots from a 48/3000. That's with paint though...if you're dry firing efficiency will be a fair amount lower.

First things first whenever you buy a used mag, buy a parts kit (15 bucks on action village), and replace every o-ring and seal in the gun, unless you know for certain the previous owner has done it recently. It's a small investment that will give you basically two full rebuilds on the marker minus one or two parts.

Also do a full and thorough cleaning of the whole gun. If you've got gunk built up in your regulator that always seems to find its way into the on/off and gum that up too.

Take all the parts out of the regulator, clean them off, replace the piston o-ring, clean and re-grease the spring pack. Clean out the cavity inside the regulator with q-tips or something like that.

Make sure when you're replacing your regulator seat that you do a good cleaning of both halves of the regulator and valve internals.

Just go through the whole valve section by section replacing o-rings. The only one that's tricky is the double o-ring in the on/off. If you can't get them to stay seated inside each other don't worry about it. Just get it assembled and gas it up, the pressure will seat them.

If you don't get a marked improvement in efficiency after that start checking your airline fittings and your tank's regulator for leaks or efficiency problems.

[athomas]

Barrel length is a big part of efficiency of a mag. Use one that has a long control bore. Ideally, it should have about 10 - 11 inches of unported bore. You can use less as long as the barrel porting is small. A barrel that is too long is also a problem.

If you dry fire a lot, it will use a lot of air.

The on-off won't help efficiency. Only the barrel, velocity(pressure), and bolt spring affect efficiency in a mag. So, use the proper barrel, use a new bolt spring, and adjust the velocity to an optimum value (usually around 280 fps).

[Snake_is_hot]

You've got some efficiency problems. My level 10 classic mag gets around 500-600 shots from a 48/3000. That's with paint though...if you're dry firing efficiency will be a fair amount lower.

First things first whenever you buy a used mag, buy a parts kit (15 bucks on action village), and replace every o-ring and seal in the gun, unless you know for certain the previous owner has done it recently. It's a small investment that will give you basically two full rebuilds on the marker minus one or two parts.

Also do a full and thorough cleaning of the whole gun. If you've got gunk built up in your regulator that always seems to find its way into the on/off and gum that up too.

Take all the parts out of the regulator, clean them off, replace the piston o-ring, clean and re-grease the spring pack. Clean out the cavity inside the regulator with q-tips or something like that.

Make sure when you're replacing your regulator seat that you do a good cleaning of both halves of the regulator and valve internals.

Just go through the whole valve section by section replacing o-rings. The only one that's tricky is the double o-ring in the on/off. If you can't get them to stay seated inside each other don't worry about it. Just get it assembled and gas it up, the pressure will seat them.

If you don't get a marked improvement in efficiency after that start checking your airline fittings and your tank's regulator for leaks or efficiency problems.

I'll probably do the rebuild. I bought the kit, but nothing was leaking or sticking, so I didn't think it would be an issue yet. I replaced the fittings when I got it because a few of them did leak, but now they're all solid. Just so I know, how easy is it to damage the internals when rebuilding? I'm used to Phantoms and the like, which are pretty bullet-proof internally.

[athomas]

Mags are pretty solid. There's not much you can damage inside.

[hill160881]

Just because you cant here it does not mean it is not there. You should get 500 at best on that tank, remember that it stops shooting at around 650 to 750psi so you cant shoot as far into the tank as with a low pressure marker.

I get a hopper and 4 pods with a 68/3000(just barely). Thats like 700 rounds and your tank is 30% smaller so 700X30%=210 700-210=490

So you should get 400 to 500 rounds on that tank witha level 7(they are not the same body, barrel, valve and so on, so the difference will be big between my mag and yours, but it wont be that big of a difference in the efficiency)

I get hopper and 6 pods on a 68/45 with a level 10 on a EP ego mag.

So yes its time for a parts kit and check the length of the on off pin. People love to shorten them and screw them up. it should be .750" for a clasic valve

If you want to know a spec on the marker you should be able to find it here, or just ask in this thred

http://www.automags.org/forums/showthread.php?t=67604

[athomas]

You can get over 500 shots if the marker is set up for half decent efficiency. That being said, an average mag should get about 528 by my calculations on a 3000-48 tank. That's based on an average of 200in-lb of air per shot. That's the consumption for an average mag.

Using 200in-lb per shot:

Usable air is about 2200psi (3000-800)
48 ci: shots = (48 x 2200)/200 = 528

For a 68ci tank at 4500psi:

Usable air = 4500-800 = 3700psi
shots = (68 x 3700)/200 = 1258

For a 88-3000:
shots = (88 x 2200)/200 = 968
I actually use a tank like this and get 1150 shots.
That's actually lower than 170in-lb per shot.

[hill160881]

i got pretty close with my estimations

Nice math, where did you get the formula.

[athomas]

Its just a derived formula. We got a sample of air usage numbers from of a bunch of mags a few years ago. The general consensus indicated about 200in-lb of air usage for the average. some were a bit better, some a bit worst, but the majority was in the range of 200. 800 psi is just the typical low pressure where a mag may not work properly. The usable air is just the max air pressure of the bottle minus 800 thats unusable. Multiply the ci of the tank with the usable pressure and and you get in-lb of air available.