My crew recently switched from a pneumatic caulking gun to an M12 battery-powered model from Milwaukee. The pneumatic worked just fine but I thought it would be more convenient not to be tethered to a hose.
I also liked the idea of being able to use the same gun with same with different size cartridges. The M12 gun is sold in three configurations: for 10-ounce tubes, quart-size tubes, and with an enclosed aluminum barrel for sausage tubes. The motor, handle, and battery are the same for all. Adaptor kits allow the operator to buy one model and change to other types of tubes by swapping out the drive rod and carriage (the part that holds the tube). The changeover is easy; the carriage threads onto the motor and the drive rod slides in from the back. This was handy for us because we use 10-ounce tubes for caulking trim and siding, and quart tubes for gluing down subflooring.
The cordless caulking gun did a stellar job. Near the back of the housing is a dial that allows the operator to control the speed at which the tool dispenses material. There are six different settings, which can be changed to suit the temperature of the material and the speed at which you plan to apply it. When you release the trigger, the motor retracts the rod about 1/4 inch so the gun stops dispensing material. We found that in warm weather you will still get some ooze out, but no more than from a manual glue gun.
The quart-size M12 tool (2444-21) weighs 5.5 pounds with battery so it's slightly heavier than the pneumatic we used before. For us, the extra weight was a small price to pay for avoiding the use of a hose. The kit version of this tool can be purchased online for about $160 and includes one battery, a charger, and gun. According to the manufacture, you can apply up to 150 10-ounce tubes of caulk per charge. Most of our work is framing so we mostly use quart tubes of subfloor adhesive. The one time we kept track, the battery gauge said we used half a charge to apply a full box (12 quart tubes) of glue.
We normally caulk siding with 10-ounce tubes in a manual gun so doing it with a battery-powered tool took some getting used to. For caulking we found it best to set the dial to 2 or 3 so that the caulk came out slow enough not to make a mess. There is, however, a downside to using this slower speed. When you release the trigger the drive rod and piston back off; when you squeeze it again it takes a few seconds for them to re-engage and start pushing out caulk. This was never a problem with subfloor glue because we apply it at high speed. I don't consider this to be a big deal but it needs to be mentioned.
For applying caulk the M12 gun works best on longer runs – ones you would not be able to do with a single squeeze of a manual gun. It does not do a better job than a manual gun but it's far more comfortable to use. We didn't keep close track of it but I'd say it took about half a charge to dispense two cases (24 tubes total) of caulk.
I like everything about this tool except the nylon drive rod. The manufacturer says it will be durable and it feels like it would be, but I'm not keen on hanging the tool from the hook on the end of it. It's probably just force of habit; I'm used to drive rods being made out of metal.
After using the M12 Caulk and Adhesive Gun I wouldn't hesitate to recommend it to other carpenters. It speeds up the work and is more flexible than a pneumatic because the same gun can be adapted to different size tubes.