Haven't got all the vel. data...called due to darkness.
Have figured out a couple of things by squirting out 20oz. of gas today. Luckly, have a digital scale that is supose to be 1/10th oz. accurate and will go up to 10 pounds. An empty QB 79, with my scope and mounts, will runs 6 lbs. 3.7oz. and an empty AR2078,with my scope, mounts, adjustable recoil pad ruls 9lbs 8.6oz. Side note: that's heavier than that AR2078 feels.
Tank to tube:
Tank to gas tube bulking isn't all that easy. Guess I wasn't as much of a record keeper the first time (20years ago), inattentive, or not as picky about results.
Unless there is a good bit of temp. difference between tank and rifle, the co2 just doesn't want to flow well.
Given a 10 - 15 degree difference, get a good fill. ( 1 to .9 oz. / 25-28gr.). That's a minimal increase from two cartridges (24gr.). Could freeze the gun and get in much more, but unless you shoot a good bit before the gun warms up, risk blowing the seals when that over load of gas warms up. As you won't have a freezer handy in the woods, a short fill that is vented (or shot rapidly until empty) will cool the rifle...it's wasteful of co2.
When tank and gun at the same temperature, get a poor one. Out in the field, they're going to be the same temperature. This will get something between .6 and .7 oz. / 17 to 20gr.. As you'd expect, the shot count is lower than with cartridges.
Haven't got all the data, but its looking like the rifle picked up a bit of speed...not a whole bunch...was shooting 14.3gr. at 670fps, seems to be averaging 682fps bulked.
(See note on wasted gas)
Remote line:
The shot count is as high as the bottle you hook up. Rather than wasting the gas in the line by venting it at the end of a shoot, shutting off the tank valve early, shooting until the gas inside the gun and line is used, then disconnecting works well. Pretty large volume of gas; enough for 4-6 good full power shots (depending on the gun's speed) and a progressing of decreasing vel. shots.
IF there is any vel. difference, it will take a lot of shots to find it...probably average within 5 fps of the average on cartridges.
Two problems:
1. You're tied to the gun by a line, so it won't be my favorite hunting system. Will work fine shooting for fun from one spot.
2. Need to take care and cheack all the connections and o-rings for leaks.
Attached bulk tank:
Get a QB 79. Not wtwo ways about it, that's as simple as it's ever going to get...just pick a bottle weight and diameter you can live with.
Have conversion caps for the QB78 that do work, but there is a real limit to how much weight you want to hang on them. With the QB79, that weight is closer to the center of gravity...with a long gas tubed QB78, that weight really gets to the balance. IF you are set on the idea, then will need to get thin tanks (which won't hold all that much CO2).
Other than being self-contained and looking better than a remote, doesn't seem to be much diffeernce in performance. WILL be a difference when the valve sucks in liquid co2, but that's true for all co2 systems...it's just that a bottle parallel with the barrel tends to let liquid into the valve often.
Wasted gas:
Surprisingly, you don't waste all that much once you trace down any leaks in the system. With a short "stub" tube from bottle valve to rifle, there is little to vent to clear a 2" long line. Of coures, if you forget to check the QD connection and it pops off, you'll wate a good bit before you can shut the tank valve. IF the 0-ring in the QD needs changing or is a bit too thin, will have to change it.
Filling from a long remote line, then venting the line, wastes a considerable amount of gas.
Using co2 to cool the rifle in order to get a max. fill wastes a good bit of gas...wasting .4oz. of gas to get a 1oz. fill doesn't seem to make gas-sense when you can get two .7oz. fills without cooling.
COSTS:
Figured this out using my local prices and the consuption of gas from a standard QB (which is somthing between .45 and .5gr. of gs per shot). Also figured you had a bulk-ready rifle and didn't include the cost of the rifle or getting it bulk ready (as it would be the same for each type of bulking).
Figuring the start up costs for each.
Base line would be cartridges. My local price is just under $16 for 40 12gr. cartridges (which is cheap). At that rate, gas-cost is about $23 for 1000shots.
Bulk fill from a big tank is cheapest by a mile. 1000shots would cost $3.80 in gas. Would take something between 10,500 to 11,000 shots to pay for start up costs. This is based on buying a new 15 pound beverage tank...can rent a full sized tank or buy used and lower the cost.
Bulk filling from paintball tanks filled at a paintball shop (using my local one for pricing). Works out to $6.25 per 1000 shots. Start up costs is much lower, so by 3,500 shots, have paid for the equipment.
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What I wanted was the longest string of "sweet spot" shots for range use...for me, that's working out to paintball tanks and remote lines. For hunting, will probably switch back to standard 12gr. cartridges and just carry a 1/2 dosen spares. In truth, I've never had more than 20-30shots at squirrels per hunt and bulking the tube would work for that...so I might just tube-bulk, and carry a few cartridges along with the standard end cap when out tree squirrel hunting.
