I just reread you 1st post. Could you describe the "broken" spring. Was it the factory one? Was it actually in 2 pieces?
I have installed several hornet kits now. I have not perfected the SGS seal sizing. I can get them close. Snap on a Vortek 26mm moly seal next time and enjoy 680-720 fps with the Hornet kit. I use his cold tar mainly on his tight kits also.Jason G
I installed a Hornet kit in my HW85. It took me two tries, but it's shooting 14.3 gr CPUM in the 680- 685 fps range. I didn't do a huge shot string, but IIRC, my velocity spread was in the single digits.So I vote for taking another stab at sizing your seal.I chucked the piston rod in the drill press and held a piece of sandpaper against the side of the seal. I used a steel rule behind the sandpaper to be sure I didn't round over the front lip of the seal.Also, did you reduce the size of the wiper band on the rear of the seal?
Quote from: bhh on April 20, 2017, 11:23:20 PMI installed a Hornet kit in my HW85. It took me two tries, but it's shooting 14.3 gr CPUM in the 680- 685 fps range. I didn't do a huge shot string, but IIRC, my velocity spread was in the single digits.So I vote for taking another stab at sizing your seal.I chucked the piston rod in the drill press and held a piece of sandpaper against the side of the seal. I used a steel rule behind the sandpaper to be sure I didn't round over the front lip of the seal.Also, did you reduce the size of the wiper band on the rear of the seal?No. I did nothing to the seal other than put in on the piston. It seems there are two schools of thought on design. The factory seals have a thicker ring at the leading edge, while these seals have the back lip enlarged, I guess that is the 'wiper band' you are referring to. I think I"m going to put the factory seal back in just for yucks and see what my numbers are. I want to try to isolate the source of the inconsistent velocity drop. Spring or seal?
I've never heard of lubing piston seals. That's going to lead to a lot of dieseling, I think. The inside of the piston should be lubed enough just from the grease/tar that's on the spring to dampen vibration.While you have it apart Michael, you may want to also fine sand the ends of the spring. I understand that if they are not square and smoothly-finished, it leads to vibration. (the buzzing you describe at the end of the shot cycle)
An overly tight seal won't really cause a wide shot-to-shot velocity spread. A tight seal might cause velocity to drop steadily when shooting several shots in succession, however. I've seen it in my guns, most likely heat related.The .22 caliber Weihrauchs tend to have bores that are on the larger side, and this can cause pellet fitment issues. The H&N FTT in 5.53 and larger are usually a good choice, but keep in mind that these can vary from tin to tin in size by a good bit. If each and every pellet doesn't fit snug in the breech, that could be your problem. Also if you have shot it enough to break a spring, it's probably about time for a new breech seal. Cheap to replace, and it's not a bad idea to keep a spare on hand. Concerning the chrony, if it's one of those green fold up jobs, beware of that thing. I've had one for years and they can be very picky and erratic with lighting. Make sure that the lighting is good enough that you aren't getting any error messages. And also be sure to rest the rifle on bags to keep it shooting at roughly the same place over the sensors each time. On mine, varying the height of the shot over the sensors can cause erratic readings, although it will give a reading every time. Found this out while working on some regulated PCP rifles. The ARH are good seals when used properly. Most times they will need sizing to be "right". He explains all this on his website in the item description. But a seal that is too tight will almost always perform better than one that is too loose.IMO I believe your problem is pellet, breech seal, or chrony related in that order. Check all of these things before tearing the rifle down again to mess with the seal. Why do the most labor intensive thing first? Hey, I'm lazy Hope you get it sorted out. It's surely something simple. Just keep us posted and take it one step at a time.