Given the gun is a QE, make note of how far back you can cut that shroud, before the big end interferes with the cylinder. If you do that, you likely won't be able to unscrew the cylinder without removing the shroud. That is, if there is even enough room there to cut it back. You could probably just machine back the last 1/2" of the barrel and get results, but you'd need to go a full inch to make sure you got all the choke out.
Quote from: Rallyshark on July 23, 2020, 01:00:03 AMGiven the gun is a QE, make note of how far back you can cut that shroud, before the big end interferes with the cylinder. If you do that, you likely won't be able to unscrew the cylinder without removing the shroud. That is, if there is even enough room there to cut it back. You could probably just machine back the last 1/2" of the barrel and get results, but you'd need to go a full inch to make sure you got all the choke out. I have read your reply a few times and it has only just sunk in what you mean. I didn't even think about the moderator/air cylinder clearance. Hmm so I'd either have to go with the original barrel looking crappy without the shroud, get a slug barrel machined to take the shroud or a slug barrel with threads for an after market moderator.
Quote from: Reidy on July 25, 2020, 09:29:02 PMQuote from: Rallyshark on July 23, 2020, 01:00:03 AMGiven the gun is a QE, make note of how far back you can cut that shroud, before the big end interferes with the cylinder. If you do that, you likely won't be able to unscrew the cylinder without removing the shroud. That is, if there is even enough room there to cut it back. You could probably just machine back the last 1/2" of the barrel and get results, but you'd need to go a full inch to make sure you got all the choke out. I have read your reply a few times and it has only just sunk in what you mean. I didn't even think about the moderator/air cylinder clearance. Hmm so I'd either have to go with the original barrel looking crappy without the shroud, get a slug barrel machined to take the shroud or a slug barrel with threads for an after market moderator.You have few options on how to do this really. First, I think you should remove the QE and see how far the barrel itself actually goes past the cylinder. You may not have enough room, even without the QE, unfortunately. If that's the case, you can completely scrap the modifying the factory barrel idea all together. That would leave you with the option 2, getting another barrel machined(more $$). Option 3 is order some slug sample packs, so you can test various slugs and see how they do with the barrel as is. I think some people have had decent results with slugs and the factory barrels. Option 3 would be the most cost effective option by far, and you don't know until you try. The FX hybrid slugs may be worth a try as well, since they are essentially hollow and will deal with the choke better than some other slugs.
Saludos. Es mejor idea cambiar por un cañón nuevo sin choke,que eliminar el tramo final del choke Por otro lado si lo que desea es tirar puntas(slug) y no pellets.,sólo necesita subcalibrar las puntas y comprobar con quémedida su cañón estrangulado consigue los mejores grupos. Mi Bt65 custom, con cañón original estrangulado, consigue buenos grupos con puntas a .252 .Y también con un cañón LW sin choke con el mismo subcalibre. Lo importante es conseguir un velocidad de la punta en salida de 270 m xsg o cerca.Y para eso se necesita modificaciones de puerto de transferencia,muelle más duro y peso de martillo mayor.
my guess would be not enough hammer spring or heavy enough hammer to drive the valve open. 180 bar is around 2610 psi. that's asking for a lot. especially with only a 200 bar fill which is 2900 psi. you only have 20 bar or 290 psi for shots. which wouldn't be very many.granted this is only a .22 cal, but still there is only so much that you can get. If you're about maxed out on the hammer spring. then you need to do something different to get velocity up and maintain shot count.if it were me i'd start by dropping the reg pressure, and backing the hammer spring back off. then work back up to you max FPS. I don't have this particular airgun. just my gauntlet .25 cal. and been playing with different settings on it. With my barrel port opened and factory valve with aftermarket poppet, i found my best speed at 1700 psi, pushing 25.4 gr to 885 FPS. i was running the jsar super tune kit but my hammer spring had collapsed on me in a quest for HIGH FPS trying with 2000 psi.You may have even possibly collapsed your hammer spring. this would be why your FPS has dropped off. I found that if i go for more reg pressure then my velocity start to drop off quickly. the more your reg pressure increases the more hammer spring you need.
ahh. now i'm starting to understand. It has been my understanding based off a lot of marauder/ qb78/79 builds that when changing from unregulated to regulated, one tends to not get the expected performance of the unregulated setup. i'd have to look into how the setup is with the bt65, but if it is a drop in regulator that goes into the tube, then i would say your losing available plenum space. plenum size is a key factor. And you definitely seemed to follow logic on increasing reg set point. which would be an attempt to overcome the small plenum size. which from my understanding would require at least a 10% increase in reg set point. but once you near the less than one-half CC per FPE, then you're in rough shape. For example my gauntlet has 24 CC of plenum and without valve mods i can just barely get over 50 FPE. hence the less than one-half CC per FPE. my regulator is outside and at the end of the tube with a 380 cc bottle. now take a tube of unregulated gun and add regulator inside the tube, then plenum area gets smaller as well as CC of available high pressure air.
Nice. That was about to be my next line of thinking. Something restricting flow. Since everything else was checking out as normal.