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MAC1 USFT Analysis/Overview
- Thread starter Franklink
- Start date
I remember Mac1 is down for a bit operation ? i don't remember .
I have USFT #233 , fantastic shooter . The red one on the Classified for about an hour before i bought it .
I have USFT #233 , fantastic shooter . The red one on the Classified for about an hour before i bought it .
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I don’t know how I missed this thread turning into 13 pages. I must have been shooting my USFT.
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Traded out the barrels to see how @SAZs barrel compares to mine.
Measurement wise, the OD of his is about 0.005" bigger, and that required opening up the ID of a spare moderator adaptor a bit to work. Got it installed now though and took a few shots yesterday evening.
I don't get this gun out often enough! Every time I shoot it after it's sat for a while it makes me smile.
Measurement wise, the OD of his is about 0.005" bigger, and that required opening up the ID of a spare moderator adaptor a bit to work. Got it installed now though and took a few shots yesterday evening.
I don't get this gun out often enough! Every time I shoot it after it's sat for a while it makes me smile.
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I've had some learning experiences with this stinker barrel in the last few days.
I first installed it on my USFT to shoot it as-is, for a baseline. Easy peasy on a USFT, two Phillips screws to remove the wood block under the gun, then loosen the four breech bolts that go all the way through the baseplate, air tube, and breech block. The two on the side of the slit in the breech need loosened the most. Slide out my barrel, slide in Larry's barrel, tighten everything back up.
Larry had done some extensive indexing tests and documented them all, right on the barrel. His "witness" attachments can be seen in the above photo. With his prior testing, I was able to get the impact point within 4, 1/8moa clicks on the horizontal turret and within 5 clicks on the vertical, from the scope zero with my barrel. I'll deal with the slightly higher impact point, and run with the 4 horizontal clicks while I test this barrel, to aide in getting back to good with my own barrel when this experiment is over.
In the first shooting session I saw exactly what Larry described: couple good shots going going into nearly the same hole, then a couple flyers spraying around erratically, then another couple good shots.
Decided to pull the barrel for closer inspection. Pellets pushed through felt good, no catchy grabby mixed with loose, just a little bit of resistance felt through the entire length. It seems to have the typical Lothar tight spot at the breech end, although not as bad as some. And the good here was that the pellet doesn't free fall after that initial tight spot. And then it has a choke at the normal 3/4-1" in from the muzzle. Choke isn't overly aggressive. It felt quite similar to how pellets pushed through my 1:36 barrel feel, which made me optimistic for this project.
Inspection of the crown showed that it was slightly off-center. Bore itself seems centered to the blank, but the angle of the crown was deeper on one side. I decided this would be the first thing to try: new crown. I consulted @Arzrover and he had a great suggestion on how to remove the old crown while keeping everything square. Followed his recommendation and got down to virgin bore, ie took off about 1/8" of barrel to omit the offset crown.
The recrown was accomplished with the brass screw trick, although it is only a very minimal bevel.
Pushed a bunch more pellets through my magic barrel and this stinker bareel and compared them. Pushed to the choke and then back out the breech end, also all the way through, etc. Concluded that with my barrel the heads only slightly contact the grooves, leaving a defined edge on the widest part of the head of the pellet, but with Larry's barrel there was a wide ring of contact visible on the head of the pellet, ie even the rifling grooves were displacing lead. Conclusion there was that Larry's barrel was slightly tighter than mine. Got his permission to open it up with some lapping compound and then did so, also focusing on that tight spot at the breech. After that process pellets pushed through both barrels look very similar.
Reinstalled in the gun and shot these 24, 10 shot groups; 15 @ 30 yards and 9 @ 55 yards. The number next to the group is the order in which they were shot. Rings are 1".
These were taken from a bumbag, not a bench, so there is some human error in there. Also moved a few clicks here and there between groups. Also, shot the 240+ shots in less than an hour. I was really cranking them off at times. When I'd slow down and really focus id have a pretty tight group. I star'd the best ten shot groups, #10 @ 30 yards measured 3/8" CTC and # 9 @ 55 yards measured 13/16."
The seeming "flyers" correlate pretty well with pulled shots.
I've been trying to get my 80cf SCUBA down low enough to empty it and do an inspection, so I had it sitting next to me to refill every 40-45 shots. USFT uses such little air though that I'm still up around 2400psi, having started at a smidge over 2500 before these 250ish shots. Guess that mean I need to shoot some more.
I'm glad this little project came up. I was recently eye balling a really good deal in the classifieds but getting the USFT out and shooting it made me realize I've already got too many amazing guns that I still really enjoy and that I don't have time to shoot. Last thing I need is another one!
Awesome gun, these USFTs. Sublime trigger. Quite literally built to shoot from a bumbag. Chill shot cycle. Easy as pie to swap barrels when the need arises. Just overall high level of performance that makes me smile when I shoot it.
So what's next with Larry's barrel? Well I feel like it's competitive now. I sure would not have tried to shoot it in a match with how it shot before. I think there might be some gains in accuracy from a different batch....these today were 7th run of this die. And I was using a 3d printed moderator that hasn't fully earned my trust. So I think I'll try some other pellet batches and a different moderator and see how it shoots. I'm seriously considering running my USFT with Larry's barrel at the next Airgunners of AZ match 9 days from now. And I want to shoot it on a windy day to get a feel for how wind resistant pellets fired from it are, a comparison to what I call my "magic" barrel of the same specs.
I first installed it on my USFT to shoot it as-is, for a baseline. Easy peasy on a USFT, two Phillips screws to remove the wood block under the gun, then loosen the four breech bolts that go all the way through the baseplate, air tube, and breech block. The two on the side of the slit in the breech need loosened the most. Slide out my barrel, slide in Larry's barrel, tighten everything back up.
Larry had done some extensive indexing tests and documented them all, right on the barrel. His "witness" attachments can be seen in the above photo. With his prior testing, I was able to get the impact point within 4, 1/8moa clicks on the horizontal turret and within 5 clicks on the vertical, from the scope zero with my barrel. I'll deal with the slightly higher impact point, and run with the 4 horizontal clicks while I test this barrel, to aide in getting back to good with my own barrel when this experiment is over.
In the first shooting session I saw exactly what Larry described: couple good shots going going into nearly the same hole, then a couple flyers spraying around erratically, then another couple good shots.
Decided to pull the barrel for closer inspection. Pellets pushed through felt good, no catchy grabby mixed with loose, just a little bit of resistance felt through the entire length. It seems to have the typical Lothar tight spot at the breech end, although not as bad as some. And the good here was that the pellet doesn't free fall after that initial tight spot. And then it has a choke at the normal 3/4-1" in from the muzzle. Choke isn't overly aggressive. It felt quite similar to how pellets pushed through my 1:36 barrel feel, which made me optimistic for this project.
Inspection of the crown showed that it was slightly off-center. Bore itself seems centered to the blank, but the angle of the crown was deeper on one side. I decided this would be the first thing to try: new crown. I consulted @Arzrover and he had a great suggestion on how to remove the old crown while keeping everything square. Followed his recommendation and got down to virgin bore, ie took off about 1/8" of barrel to omit the offset crown.
The recrown was accomplished with the brass screw trick, although it is only a very minimal bevel.
Pushed a bunch more pellets through my magic barrel and this stinker bareel and compared them. Pushed to the choke and then back out the breech end, also all the way through, etc. Concluded that with my barrel the heads only slightly contact the grooves, leaving a defined edge on the widest part of the head of the pellet, but with Larry's barrel there was a wide ring of contact visible on the head of the pellet, ie even the rifling grooves were displacing lead. Conclusion there was that Larry's barrel was slightly tighter than mine. Got his permission to open it up with some lapping compound and then did so, also focusing on that tight spot at the breech. After that process pellets pushed through both barrels look very similar.
Reinstalled in the gun and shot these 24, 10 shot groups; 15 @ 30 yards and 9 @ 55 yards. The number next to the group is the order in which they were shot. Rings are 1".
These were taken from a bumbag, not a bench, so there is some human error in there. Also moved a few clicks here and there between groups. Also, shot the 240+ shots in less than an hour. I was really cranking them off at times. When I'd slow down and really focus id have a pretty tight group. I star'd the best ten shot groups, #10 @ 30 yards measured 3/8" CTC and # 9 @ 55 yards measured 13/16."
The seeming "flyers" correlate pretty well with pulled shots.
I've been trying to get my 80cf SCUBA down low enough to empty it and do an inspection, so I had it sitting next to me to refill every 40-45 shots. USFT uses such little air though that I'm still up around 2400psi, having started at a smidge over 2500 before these 250ish shots. Guess that mean I need to shoot some more.
I'm glad this little project came up. I was recently eye balling a really good deal in the classifieds but getting the USFT out and shooting it made me realize I've already got too many amazing guns that I still really enjoy and that I don't have time to shoot. Last thing I need is another one!
Awesome gun, these USFTs. Sublime trigger. Quite literally built to shoot from a bumbag. Chill shot cycle. Easy as pie to swap barrels when the need arises. Just overall high level of performance that makes me smile when I shoot it.
So what's next with Larry's barrel? Well I feel like it's competitive now. I sure would not have tried to shoot it in a match with how it shot before. I think there might be some gains in accuracy from a different batch....these today were 7th run of this die. And I was using a 3d printed moderator that hasn't fully earned my trust. So I think I'll try some other pellet batches and a different moderator and see how it shoots. I'm seriously considering running my USFT with Larry's barrel at the next Airgunners of AZ match 9 days from now. And I want to shoot it on a windy day to get a feel for how wind resistant pellets fired from it are, a comparison to what I call my "magic" barrel of the same specs.
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Had another session with the stinker barrel....and it's still a stinker barrel.
Was really hoping that not shooting as fast would eliminate that random flyer, but it remains, even when REALLY concentrating. Not very often, occasionally it'll even shoot ten in a row without a flyer, but eventually one is coming. And they're not horrible, even the flyer is still pretty close to aim point, but it's certainly not in the 1/4 to 3/8" cluster that the rest of the group is landing in.
Also, the flyer incidence seemed worse on this second session when it was more windy. Dunno if the wind is the issue or what.
In short, the stinker barrel will shoot ten shot groups into 5/8" @ 30 yards, and 1.25" @55, which is good, but not great.
I put my magic barrel back on there after running another couple hundred through the stinker and there'a just no contest. Magic barrel puts em all into 3/8" @ 30 yards, from a bumbag, in the wind. So magic barrel is back on the USFT and it's "whole" again.
I've really enjoyed shooting the USFT in these 400-500 shots over the last couple days, and I'm leaning heavy towards shooting it next weekend at the monthly ft match. And I'm even considering shooting without the knee riser that I have historically always used.
Edit: just shot another half a tin and nope, gonna stick with the high knee riser. I like how much weight it saves by shooting without it, and I'm just a smidge more stable without it, but my neck sure gets stiff getting into position without that tall knee riser.
Edit#2: Figure I've shot close to a tin and a half (500ct) out of the USFT in the last three days and man I sure love this gun. For all the reasons listed in the last 12 pages, but at the top right now is air usage. I'm gonna have to burn through a sizable chunk of a sleeve of pellets before I get the air in this 80cf SCUBA down to my fill pressure of 1500psi on the USFT! I thought a little revisit of the USFT would be a good way to get that tank empty for inspection, but looks like it's gonna need a BIG revisit of the USFT to get there, lol. This gun sure makes a good argument for the guy who might want to simplify and get rid of compressors and lots of the paraphernalia that seems to pile up for an airgun nut. Could downsize considerably, while keeping a high level of precision, AND not have to take the huge step down in performance by becoming a primary springer shooter.
Was really hoping that not shooting as fast would eliminate that random flyer, but it remains, even when REALLY concentrating. Not very often, occasionally it'll even shoot ten in a row without a flyer, but eventually one is coming. And they're not horrible, even the flyer is still pretty close to aim point, but it's certainly not in the 1/4 to 3/8" cluster that the rest of the group is landing in.
Also, the flyer incidence seemed worse on this second session when it was more windy. Dunno if the wind is the issue or what.
In short, the stinker barrel will shoot ten shot groups into 5/8" @ 30 yards, and 1.25" @55, which is good, but not great.
I put my magic barrel back on there after running another couple hundred through the stinker and there'a just no contest. Magic barrel puts em all into 3/8" @ 30 yards, from a bumbag, in the wind. So magic barrel is back on the USFT and it's "whole" again.
I've really enjoyed shooting the USFT in these 400-500 shots over the last couple days, and I'm leaning heavy towards shooting it next weekend at the monthly ft match. And I'm even considering shooting without the knee riser that I have historically always used.
Edit: just shot another half a tin and nope, gonna stick with the high knee riser. I like how much weight it saves by shooting without it, and I'm just a smidge more stable without it, but my neck sure gets stiff getting into position without that tall knee riser.
Edit#2: Figure I've shot close to a tin and a half (500ct) out of the USFT in the last three days and man I sure love this gun. For all the reasons listed in the last 12 pages, but at the top right now is air usage. I'm gonna have to burn through a sizable chunk of a sleeve of pellets before I get the air in this 80cf SCUBA down to my fill pressure of 1500psi on the USFT! I thought a little revisit of the USFT would be a good way to get that tank empty for inspection, but looks like it's gonna need a BIG revisit of the USFT to get there, lol. This gun sure makes a good argument for the guy who might want to simplify and get rid of compressors and lots of the paraphernalia that seems to pile up for an airgun nut. Could downsize considerably, while keeping a high level of precision, AND not have to take the huge step down in performance by becoming a primary springer shooter.
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@Franklink,
I didn't see the last couple of your posts till just a few minutes ago. Excellent writeup like always.
I have to say again how much I appreciate all the work you've put in on the "stinker" barrel for me.
I wish there had been a better outcome but like we discussed "not every barrel comes off the top shelf".
Unfortunately, it behaved just as badly for you as it was doing for me.
Thank You !
I didn't see the last couple of your posts till just a few minutes ago. Excellent writeup like always.
I have to say again how much I appreciate all the work you've put in on the "stinker" barrel for me.
I wish there had been a better outcome but like we discussed "not every barrel comes off the top shelf".
Unfortunately, it behaved just as badly for you as it was doing for me.
Thank You !
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Well considering how I shoot the stinker barrel maybe magic for me@Franklink,
I didn't see the last couple of your posts till just a few minutes ago. Excellent writeup like always.
I have to say again how much I appreciate all the work you've put in on the "stinker" barrel for me.
I wish there had been a better outcome but like we discussed "not every barrel comes off the top shelf".
Unfortunately, it behaved just as badly for you as it was doing for me.
Thank You !
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Sounds like you're softening me up for a trade or ????Well considering how I shoot the stinker barrel maybe magic for me
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I too have a barrel that used to be a stinker but no longer is, after work done by @nervoustrig.
It is a .20 caliber LW chrome moly, 23 inch length. I shoot it in an unregulated USFT. I shoot USARB heavy varmint benchrest (25 meters, 20 FPE max), where the central bull is 2 mm wide. To score all tens on a card, the centers of all shots need to be within 3.84 mm of the center of the bull, i.e., need a 25 shot CTC of 7.69 mm (about 0.3 inches). To score an “X”, the center of the shot needs to be within 1.84 mm of the center of the bull. (A .22 scoring plug is used).
Before nervoustrig’s work, the barrel would periodically send a pellet 5 to 8 mm (about 0.2 to 0.3 inches) off of my POA, giving me a 9 or 8 score for the shot, even in windless conditions and with no changes or mistakes by me.
The barrel felt to me like it had a very tight choke. A pellet pushed through had moderate resistance at the leade, followed by quite loose but variable resistance until it reached the choke, then required a lot of force to get through the muzzle.
Nervoustrig found the choke was somewhat heavy at 2 thousandths of an inch. He found some fairly pronounced radial marks and a constriction at the breech end and along the bore. He did a cast lapping of the barrel, with special emphasis on easing the transition into the choke and giving the choke a more favorable surface finish that is not as prone to leading up. He also put on a fresh crown.
When I got the barrel back, pushing a pellet through was amazing. A little tightness at the leade, then butter smooth, consistent resistance through the bore, and what felt like a very gradual build of resistance and less overall resistance at the choke. Pellets had more distinct, clean rifling marks on them compared to pre-work pulled pellets.
However, my initial results with the new barrel were not fully encouraging. The good news was that I no longer got the stray flier. But my average spreads were worse than before. After lots of experimenting, I found I needed to stop regularly cleaning the barrel with WD-40. After a WD-40 cleaning, I needed well over 100 shots before the groupings would tighten nicely. Even after using dry patches, I needed 30+ shots before I could expect good groups. (Before the barrel work, I needed to clean with WD-40 after every 50-80 shots to avoid increasing spreads. And spreads did not worsen after such cleanings). I still need to lube pellets before putting them into the barrel to avoid lead build-up that I get if I don’t lube pellets. And after about 100-150 shots, I’ll pull a dry patch to avoid risking an increase in spreads.
Along with a bunch of other modifications (that I’ll detail in a different post), I can regularly shoot 15 shot CTCs of 6.5 mm or less in windless conditions with a properly set up gun. This enables scores of 248 to 250 on our benchrest cards.
So I suspect you were on the right track in reworking the stinker barrel. Maybe more work is needed. Or maybe other aspects of shooting with that barrel, e.g., cleaning regimen, have to be changed. And I learned that each barrel is different and I have to find out what it needs to perform its best.
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