What I know about the Mac1/LD guns-a lot of this is here-say so if you know otherwise, feel free to correct me.
The Mac1 USFT/Hunter gun was originally created by Larry Durham. He made one of these for himself in his garage and I was told it took lots of trial error to get to the point that he envisioned for the gun. It was so impressive that he was convinced to make seven more prototypes out of that garage. At some point, Tim McMurray, who is Mac1, worked it out with Larry to put the gun into production. This is all in California. From what I can determine, it seems like those first production guns were done sometime in the early 2000's.
I purchased a Mac1 from Tim recently. I ordered it right after Labor Day and received it about 7 weeks later. I had him set it up with a polygonal barrel in .177 and 20 fpe. I also had him machine a .22 barrel which has yet to go on the gun to be tested. My barrels are both LW barrels as Tim explained that they are the best barrels being made right now. When the Mac1/LD gun first started, HW was making good barrels and Tim used those. He also at one point was able to get a .22 two-grooved barrel that was extremely accurate (see Teds Holdover video on YouTube). He told me that company no longer makes exceptional barrels so it appears that he uses the best barrels available at a given time. I ordered mine in the upright version that he designates as a "hunter" versus his canted grip "usft" version of the gun. When I ordered it I was told it would be the #264th usft/hunter gun he has made. He seems to have a different numbering system for the hunter versus canted version because my receiver is number #165. He is calling this run the third generation. I asked him to save weight wherever he could and my barrels measure slightly under 16mm. While I have not weighed the gun, it feels like it weighs about what my laminate stocked HW77k does. When I compared my gun to a friends first gen, there have been noticeable improvements made, mostly in the amount of adjustments available on my third gen. For example, mine has an adjustable thumbrest, a more adjustable "stock," a threaded hammer to which weights can be added to increase fpe, the oring that seals the barrel is now on the swing port to eliminate the need to cut an oring groove into each barrel, and a transfer port that can be reduced/enlarged for fine-tuning of fps/fpe. Tim told me there are other less noticeable improvements like a glanded sealing system in the tube.
I was intrigued by the low fill pressure tubed version vs his higher pressure bottle guns so I had him make mine as a tube gun. I am getting 55 shots within 10fps with a fill pressure from 1600 to 1300. I have an 80cf SCUBA tank that started with 2800psi when I got the gun. I have only used the tank for the Mac1 gun and am down to a little under 2300psi. That 525ish psi from the tank has gotten me about 1200 shots out of the gun so far (I am not quite halfway into the third 500 count tin). I am quite happy with my air usage/vs number of shots I am getting as it appears that I should get about 5-8 tins of pellets from a full 3000psi fill down to 1600 in the scuba tank.
When I first got the gun I ran a few strings through it from a bench at 55 yards to minimize shooter influence on the guns accuracy. From a rest, my copy of the gun will make 1 hole groups at 55 yards in low wind situations. I was able to pull off multiple 10 shot groups that the colloquial dime would cover. Paintballs at 60 yards are not much of a challenge from a steady rest. It is much more accurate than I am.
At my first field target match with the gun I shot 85% (34/40). It was my first time shooting in the open class and therefore my first time shooting without my trusty bipod. I did not use a harness and was quite unsteady. 4 of the 6 shots I missed were my lack of a steady hold (I have some practicing to do). The other two were errors in ranging two targets due to them being set in very shady areas. In short, the misses were me, not the gun.
The open class of the recent Field Target Nationals in Arizona was won by an individual shooting a first generation Mac1 USFT. The same gun and the same shooter placed sixth in the Pro Class of the Knockdown Silo at the 2017 EBR. It should be noted that he was using a .177 caliber airgun at 20foot pounds to knock over .22 rimfire silhouettes. I was told he had to shoot some of the targets more than once because the low powered .177 would only rock the targets back into the headwind and they would settle back on their base without being completely knocked over. Most, if not everyone else in the Silo Knockdown use .22 airguns at higher fpe than the .177 USFT that took 6th.
The trigger on these guns is superb. I have shot 4 different usft/hunters and been impressed with the trigger on each of them.
My first firearm as a teenager was a single shot, break action .223 H&R Handi-Rifle. I shot many thousands of rounds through that gun. It uses an exposed hammer that must be cocked for each shot, in much the same way as the Mac1/LD guns. It just feels natural to me to load a pellet, cock the hammer, and carefully squeeze off the shot, knowing that the first shot needs to count because a second one wont be sent flying very quickly.
I have read in a few places where people have made comments like the above about the gun no longer being cutting-edge technology. I think they are alluding to the Thomas rifle or the RAW rifles. I have been around a few Thomas guns at matches and they appear to be a very similar gun, in how they function, to the Mac1. They of course cost nearly twice the amount but a good trigger, the ability to utilize LW barrel blanks, a swing-breech loading mechanism, and mostly aluminum construction seem to be shared features. As far as the RAW rifles, I know less about them but understand they use a regulator and higher fill pressure (both of which I wanted to avoid) so I went with the Mac1. I am not sure why the general consensus seems to be that Mac1 guns are no longer relevant but I think it probably has a lot to do with "newness." When it comes to vehicles for example, everybody always wants the latest greatest with the assumption that older vehicles don't have the coolest features. It seems like that is where Thomas guns are right now, everybody wants what appears to be the latest greatest. I wanted accuracy and longevity. I was able to get it for $2000 less than the Thomas and don't regret it even slightly. (Please don't take this as a bashing on the Thomas gun. It too, is a very impressive rifle made by a top-notch individual that spends an incredible amount of time on each rifle that he sends out-so I'm told. We all have choices in this hobby and I simply chose a Mac1 gun over a Thomas, that doesn't make me a bad person, a Mike Nisch hater, or a Thomas hater. It is simply what I chose to go with at this time-mostly because of the price.)
I have used the gun to pest with and have been equally impressed. I have a permission at a feedlot that deals with ground squirrels, starlings, and Eurasian Collared doves. If I set up in the right place, I can take shots at the ground squirrels and doves, with that caveat being that the doves are in a tree 65 yards away. I can knock doves out of that tree all day long with the Mac1-many of which are head shots (when they'll stop bobbing their head around long enough). In fact, two of the adult ranch hands and their kids, age 5 and 6, have been curious at what I was up to and came to check it out in two different instances. All four knocked doves out of the tree on their first shots with the rifle rested securely. The two younger boys have not shot much in their lives. One of the adults commented, "you just put the crosshairs on it and pull the trigger and it drops em every time." I agree.