I had UA convert this M4 from a .22 pellet shooter to a .25 slug shooter. They installed a 700mm .25 Superior Heavy barrel/liner, and a .25 Slug Power Kit (probe, spring, hammer weight). I installed an AirMarksman Loki rail, Sportsmatch adjustable rings, Element Optics Nexus G1, Hawke Frontier Red Dot on a 45 degree offset mount (for 20y or less quick shots), a digital gauge (regulator), Impulse Air 1350, and an 580cc 300b AirMarksman bottle and valve. The goal was to make a relatively high powered (80-100 FPE) .25 caliber slug gun for hunting pest birds at the local Feed Lots.
If you're interested in learning how to tune an Impact this is a great video:
In a nutshell... I started by opening the valve return all the way. I started with the regulator about 120b and the QTS about 2. Then I gradually increased the regulator and QTS until I reached the desired velocity (actually exceeding it by 20-30 FPS), then I used the valve return knob to close the valve quicker which decreased the muzzle report, wasted air, and dropped the peak FPS by about 20 FPS. My reg is set at 155b, and the QTS about 3.5.
I was using the H&N 36g slugs for all the tuning. Once I had them "happily" shooting 1040 FPS, I cleaned the barrel using a Patchworm, and I took it outside to see how it would group at 50y.
To my surprise neither the H&N 34g, 36g, or the ZAN 35g, 37g would group above 1030 FPS. I left the reg and the QTS at 3.5 and went to work reducing the valve return. As soon as the velocity dropped to +/- 1000 FPS everything started grouping great.
By that time I had almost ran out of H&N 36g slugs so I changed to focus on the ZAN 37g slugs. They found their happy place at 990 - 1000 FPS. That gave me a solid 82 FPE with a BC of .107
I zero'd the Hawke Red-Dot for quick shots at 10-20y. I optically centered the scope, and then zero'd it at 42y using the Sportsmatch adjustable rings. I added the scope & projectile data into the Element Ballistic App and that gave me a zero hold at 30, 40, 50y, and hold-over after that.
I moved off of the bench and onto a standing tripod at 75 - 80y. I dialed the elevation turret to 1.0 and shot (2) 5 shot groups which was enough to instill confidence for the next days hunt.
I quickly connected and tested my Side-Shot scope camera
Then I pre-loaded a bunch of Stud Mag Loader magazines & Feeders, and packed up the rest of my gear.
If you're interested in seeing some Feed Lot "carnage" caught on Hi-Def scope cam video, then follow this LINK to my thread in the Hunting section
If you're interested in learning how to tune an Impact this is a great video:
In a nutshell... I started by opening the valve return all the way. I started with the regulator about 120b and the QTS about 2. Then I gradually increased the regulator and QTS until I reached the desired velocity (actually exceeding it by 20-30 FPS), then I used the valve return knob to close the valve quicker which decreased the muzzle report, wasted air, and dropped the peak FPS by about 20 FPS. My reg is set at 155b, and the QTS about 3.5.
I was using the H&N 36g slugs for all the tuning. Once I had them "happily" shooting 1040 FPS, I cleaned the barrel using a Patchworm, and I took it outside to see how it would group at 50y.
To my surprise neither the H&N 34g, 36g, or the ZAN 35g, 37g would group above 1030 FPS. I left the reg and the QTS at 3.5 and went to work reducing the valve return. As soon as the velocity dropped to +/- 1000 FPS everything started grouping great.
By that time I had almost ran out of H&N 36g slugs so I changed to focus on the ZAN 37g slugs. They found their happy place at 990 - 1000 FPS. That gave me a solid 82 FPE with a BC of .107
I zero'd the Hawke Red-Dot for quick shots at 10-20y. I optically centered the scope, and then zero'd it at 42y using the Sportsmatch adjustable rings. I added the scope & projectile data into the Element Ballistic App and that gave me a zero hold at 30, 40, 50y, and hold-over after that.
I moved off of the bench and onto a standing tripod at 75 - 80y. I dialed the elevation turret to 1.0 and shot (2) 5 shot groups which was enough to instill confidence for the next days hunt.
I quickly connected and tested my Side-Shot scope camera
Then I pre-loaded a bunch of Stud Mag Loader magazines & Feeders, and packed up the rest of my gear.
If you're interested in seeing some Feed Lot "carnage" caught on Hi-Def scope cam video, then follow this LINK to my thread in the Hunting section
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