reading through the thread posted. that guy has done alot of major mods to the bt65. unless yours is setup the exact same, i doubt you'd hit his numbers. He's got a custom end on the tube, plus its opened up wider than the factory. then the lightened hammer, enlarged transfer ports, custom poppet and poppet seat. I'm sure you could get close to what his is, but it would take a lot of finesse and tweaking to get there.Unless of course i miss where your was modded similarly and i may be off course in my thinking.Thats awesome that you got a new barrel in route. I hope it performs well for you. I had to do the same with my gauntlet. Had a bad spot towards the muzzle and affected groups.
So, good news. Hatsan are sending me a new barrel!
Quote from: Reidy on August 19, 2020, 07:26:01 PMSo, good news. Hatsan are sending me a new barrel!That's great! Hatsan is usually pretty good about that stuff, unless somebody did something silly to the gun. I see the thread you were talking about, and I actually commented in it,lol! After adjustment, he was getting 24 shots around 45 fpe. The big difference with his is that it's unregulated, so the power is a lot easier to make. I'm sure your gun could get very close to that too unregulated. Especially, with no bad o-rings or ports out of alignment. If you want to stay regulated, I'd recommend ordering a .25 plenum from Huma. That is, if you have a Huma reg? Actually, if you have Huma reg, you could order the .25 plenum and the XXL(carnivore) plenum to play with, since they aren't that expensive. So yeah, I think you'll be able to get close to your goals pretty easily, one way or the other. As a side note, I just ordered a BT65 cylinder and a Huma Carnivore reg(BIG plenum) to play with on one my project guns It's a learning process, and it will all click together after you get some more tinkering time with the gun I think. If you get around to going through all the porting and valve, you'll beat your goal. That's down the road though, after you get that accuracy you're after. You're certainly on the right track. Sometimes that track isn't as straight as we'd like though,lol.
I understand it can be frustrating sometimes when things don't do what you think they should. I do still think your gun is perfectly capable of that shot string. Let us know when you get the new barrel in, and we can start from scratch on that tuning. I'm saying wait for the new barrel, because I want you to separate the upper breech assembly from the trigger tube while installing the barrel. That way you can visually see through the breech port to the barrel port and get the alignment spot on. That may be a good time to go ahead and open up the barrel port slightly and clean it up, along with the hole in the breech, transfer, and cylinder carrier(part the valve cylinder screws into). Those little things will help a lot, and they are pretty easy to do with just basic tools. Especially, since you'll already have that stuff apart to do it. That will help a good bit with or without the reg. The valve breathes well enough that the porting is your restriction at the moment. If you got really froggy, and went after the valve too, you could make that gun a real fire breather
Well, the good news is that my 'new' barrel arrived. Here's to hoping it isn't from a rifle that was returned due to poor accuracy. Also, I was not asked to return my original one. So I'll be trying out recessing the crown to remove the choke. And if I make a pig's ear of it I can just remove the moderator threads to give it a regular crown then rethread it for a regular air rifle moderator. Or I could get a QE shroud and shorten it to fit the shorter barrel. The bad news is that my coolant pump for the compressor stopped working so I can't recharge my rifle to try it out until the replacement arrives.
Just be careful not to use screws that are too long. You don't want them going in too far where they can obstruct airflow, or even hit the valve pin. I usually grind the screws down below the channel with the a dremel cutting disc after I put them in the valve. Then I use the JB Weld on top.
You can adjust the alignment a little bit by loosening the screws that hold the cylinder carrier(brass cylinder that the valve screws into on the gun) in place, and moving it fore or aft and re-tightening the screws. That will change your alignment a little, and may get one of the holes to line up better.
I'm also thinking that I'll make valve hole 3/16" to match the transfer ports. I'm thinking that a smaller hole opening into a bigger hole then going back into a smaller hole is going to be less efficient than one bigger hole closing into a smaller hole.
Quote from: Reidy on August 29, 2020, 07:10:33 PMI'm also thinking that I'll make valve hole 3/16" to match the transfer ports. I'm thinking that a smaller hole opening into a bigger hole then going back into a smaller hole is going to be less efficient than one bigger hole closing into a smaller hole.You are correct there! Actually, you may want to go ahead and slightly elongate/clean up the barrel port to match the transfer port. The porting is only as good as the smallest opening. I do usually thin the probe on the sides that sit over the barrel port, but leave the tip close to regular size, so there are no pellet seating issues on ammo with a deep skirt. If you were looking at the probe where it sits over the port it would be similar to )(, but not quite that drastic. You could open the valve hole up to around .2 ish to give you a little wiggle room on alignment. That would have no negative effect.