I remember reading up on the legendary Quackenbush guns throughout the years. The maker was a trailblazer in the big bore market. Some day I may pick up one of those pistols that pop up every once in a while. Any other tunes that you've run with the Outlaw?Brent definitely designed this gun to run on 4500psi. I think he sized the throat a little small which contributed to excessive ES and less peak power. He was also known to run helium, so maybe helium consumption was the reason for the small throat.. By trying to tune it more conservatively, I think I'm going to be able to find a fairly economical hunting tune at 3500-3800psi and still have 3 shots above 400fpe. Then with a simple spring/hammer change go back to slinging 302gr at 920fps on a 4500psi fill. Somewhere along the way I'd like to find a 5+ shot 300fpe plinking tune with relatively flat ES.
Early on the DAQ was dumping on the second shot. Talked to Dennis and he said up the fill pressure from 3000 psi to 3300 psi and maybe a little more to see if that doesn't fix the dump. He said he tests the guns at much higher pressures, and didn't bat an eye at increasing it over specified pressure. I think I could take a little off the hammer spring and get three decent shots, and have air left over. This is why your thread is interesting to me. You are doing what I should probably do. I have varied the pressure from 3k to 3700 psi. I've had extended conversations with Mr. Hollowpoint, and Eric Henderson. Both have owned many Quackenbush's, and both told me the same thing, that the gun is built heavy duty and most of the rifles seem to have a sweet spot of 3300-3700 psi. That's 10-19% increase over what Dennis says on his website. The kick is more substantial at those higher pressures. But as Dennis says, gauges tend to not agree with each other and each gun is unique, and that's why he's okay with upping to the 10% while suggesting that a little more is ok. BB Pelletier said his .308 Outlaw liked 3200-3500 psi. I giggled with almost every shot I made on Sunday. Quote from: mackeral5 on April 28, 2020, 06:40:01 PMI remember reading up on the legendary Quackenbush guns throughout the years. The maker was a trailblazer in the big bore market. Some day I may pick up one of those pistols that pop up every once in a while. Any other tunes that you've run with the Outlaw?Brent definitely designed this gun to run on 4500psi. I think he sized the throat a little small which contributed to excessive ES and less peak power. He was also known to run helium, so maybe helium consumption was the reason for the small throat.. By trying to tune it more conservatively, I think I'm going to be able to find a fairly economical hunting tune at 3500-3800psi and still have 3 shots above 400fpe. Then with a simple spring/hammer change go back to slinging 302gr at 920fps on a 4500psi fill. Somewhere along the way I'd like to find a 5+ shot 300fpe plinking tune with relatively flat ES.
By the looks of those marks, someone could have tried polishing the barrel with a power tool, resulting in over-sizing the bore some. After the cut and re-crown to fix the barrel, you may experiment with a larger diameter, tighter fitting slug. I experimented with a smaller slug recently and got a bigger group size with a looser slug. With that spring running the first two shots being within a few fps it will make a great hunting rig when you get that barrel sorted out.
Hey my Brother, congratulations on getting an awesome Big Bore Air Rifle. I haven't read the thread yet but wanted to answer to your post. My gun was the one Brent made on the video Helium Hogs and Airguns. My gun shot awesome and very very accurate, this TJ barrels and Timny triggers are wonderful. My gun was used strictly for hunting. I used Mr. Hollow Point 280 and his new 255 that he designed especially for this gun. The purpose of the 255 is to insure complete pass thru. The 280 open up huge and usually is lodged on the opposed side of the animal stuck in the hide. My gun preformed best at 4300psi getting 980-990fps with the 280 for the first shot. Accurate out to 175 easy but kept all my kill shots under 125. I did take a few longer shots but for me the hunt is the spot and stalk!! That gun took Fallow, Axis, whitetail, mule deer, Pronghorn and several other animals. I had a very nice offer and wound up selling her. My next gun is the Extreme .408 Carbine. Best of luck and enjoy that GREAT GUN!!