Reply To: Mac 1 USFT ???
Learning is just one more great thing you can do with airguns. You wont find a diagram, not that many made and really not needed. Any Field Target near you? If so someone will have one you can look at. You might try surfing for the Simple Simon- the firsat 7-8 that LD made- which became the USFT when timmy started making them for sale.
Leonardj ( maybe on the Canadian forum) made a copy, the pictures seem to be gone though. You could ( hehehe ) join LD’s private pay top play forum, might be some information there.
Really if you looked at one in person, every part is viewable, except the check valve and valve stem head. 3,000psi burst disc, thought I should correct that.
The low pressure thing is no dofferent than other pressures, some ole principals apply. The big difference is a much ( MUCH)_ lighter hammer and the dwell achived . Balancing the psi/hammer/springs principal is the same ideas You could have fun tuning any rifle you might own to low psi if you had a scuba tank that was down to say 1,500psi and tethering to it, HUGE volume low pressure.
A QB78 ( converted to HPA with a ninja tank) using 1,100 psi, with the tank tuned off will give you two shots at 12fpe, it was more fun than it sounds like playing with it.
You might in fact enjoy tinkering with a QB78/79, totally different design that the USFT but still the same theorys apply.
The USFT model that got 60+ shots per fill had a HUGE airtube , you could drop a few 500cc airtubes inside it. To get more power and keep the total fps spread reasonable a regulated HPA tank was needed, thus the newer ones with the ninja tank.
Really want to get into the USFT that Red one might be for sale – it is not mine but I do know where it lives.
Keep us posted as you move through this exploring lower psi thing.