I posed this same question on another forum as it seems different folks frequent different forums. Please accept my preemptive apology if that is poor forum etiquette.
I bought a green laminate HW77k from Krale about 18 months ago. After shooting it for about 8 months and getting really fed up with poor accuracy I tore into it and found all kinds of problems-melted piston seal, broken spring, really tight first inch of the barrel. Well I resolved all of those issues and got it shooting about 760fps with 8.64gr H&N FTT. That was with a OEM replacement spring from Pyramyd Air and one of Maccaris blue "bullet seals." That settled into 750fps over the course of a couple thousand pellets and held at that speed. I think that is just a hair less than 11fpe. Since that corrective action about a year ago, the gun has been quite accurate but very hold sensitive (that sounds like counter intuitive-it is CAPABLE of great accuracy IF I do everything just right).
I had tried one of Maccaris yellow, parachute-type seals when I first opened it up. I found an fps spread of about 50 with that yellow seal. When investigating the large fps spread, I found that the yellow seal had gas channels melted into it. I concluded that the exaggerated lips of the parachute seal were acting like a squeegee and pushing all the lube in front of the seal and then it was detonating. I went with the bullet seal after that and had much more consistent fps numbers and learned tonight that it's not melting the face of the seal like it had with the parachute seal it came with from the factory and the yellow Maccari parachute seal I had initially tried.
Fast forward to this evening. It has always bugged me that it was a couple fpe weaker than I thought it should be, as I ordered a FAC gun (non-12fpe). I'm not a big number chaser but I do sometimes use this gun to shoot field target and thought a couple more fpe would net me a flatter shooting gun. I finally decided to open it back up and put a new spring in and see how the piston seal looked. Pyramyd Air spring was fine, maybe 1/4inch shorter than the new Vortek spring I put in this evening. The piston seal was also still in great shape but while I had it open, I decided to size it since it was still fitting really tight and I wondered if the too-tight piston seal was maybe robbing me of those couple extra fpe. I had expected it to "wear-in" more than it had. So, I changed two variables: I put in the new Vortek spring, and re-sized the same blue Maccari piston seal that I'd put in a year ago.
Got it all put back together and put a few through the chronograph. I just knew I was gonna be in the 850-860fps range.......nope. End result of all of that-760fps average over 20 shots. Which I strongly expect to settle into about 750fps over the course of the next couple thousand shots. So, I changed multiple variables and got right back where I started-about 11fpe.
That lead me to my title question: Does anyone know how HW limits their 12fpe guns to non-FAC levels? I'm wondering if it is via reduced transfer port diameter or reduced compression chamber size or something that can't be undone with a new, more powerful spring. That would explain why I cant get past 11fpe. It would also explain why the gun is hold sensitive as I would think it "oversprung" with a transfer port (or reduced comp tube or ?) that simply cant handle all the air coming at it.
I just checked my order confirmation email from Vortek (to make sure I'd ordered a OEM power spring) and this is what I just put in the gun:
HW 97 OEM Replacement Spring
Product Code: V10-810125-31
Price: $18.90
Nicely fits the HW/Beeman HW97/77 and Clone airgun guides for OEM+ power.
(On the plus side: all my trajectory data should still be applicable if I leave it as-is
I bought a green laminate HW77k from Krale about 18 months ago. After shooting it for about 8 months and getting really fed up with poor accuracy I tore into it and found all kinds of problems-melted piston seal, broken spring, really tight first inch of the barrel. Well I resolved all of those issues and got it shooting about 760fps with 8.64gr H&N FTT. That was with a OEM replacement spring from Pyramyd Air and one of Maccaris blue "bullet seals." That settled into 750fps over the course of a couple thousand pellets and held at that speed. I think that is just a hair less than 11fpe. Since that corrective action about a year ago, the gun has been quite accurate but very hold sensitive (that sounds like counter intuitive-it is CAPABLE of great accuracy IF I do everything just right).
I had tried one of Maccaris yellow, parachute-type seals when I first opened it up. I found an fps spread of about 50 with that yellow seal. When investigating the large fps spread, I found that the yellow seal had gas channels melted into it. I concluded that the exaggerated lips of the parachute seal were acting like a squeegee and pushing all the lube in front of the seal and then it was detonating. I went with the bullet seal after that and had much more consistent fps numbers and learned tonight that it's not melting the face of the seal like it had with the parachute seal it came with from the factory and the yellow Maccari parachute seal I had initially tried.
Fast forward to this evening. It has always bugged me that it was a couple fpe weaker than I thought it should be, as I ordered a FAC gun (non-12fpe). I'm not a big number chaser but I do sometimes use this gun to shoot field target and thought a couple more fpe would net me a flatter shooting gun. I finally decided to open it back up and put a new spring in and see how the piston seal looked. Pyramyd Air spring was fine, maybe 1/4inch shorter than the new Vortek spring I put in this evening. The piston seal was also still in great shape but while I had it open, I decided to size it since it was still fitting really tight and I wondered if the too-tight piston seal was maybe robbing me of those couple extra fpe. I had expected it to "wear-in" more than it had. So, I changed two variables: I put in the new Vortek spring, and re-sized the same blue Maccari piston seal that I'd put in a year ago.
Got it all put back together and put a few through the chronograph. I just knew I was gonna be in the 850-860fps range.......nope. End result of all of that-760fps average over 20 shots. Which I strongly expect to settle into about 750fps over the course of the next couple thousand shots. So, I changed multiple variables and got right back where I started-about 11fpe.
That lead me to my title question: Does anyone know how HW limits their 12fpe guns to non-FAC levels? I'm wondering if it is via reduced transfer port diameter or reduced compression chamber size or something that can't be undone with a new, more powerful spring. That would explain why I cant get past 11fpe. It would also explain why the gun is hold sensitive as I would think it "oversprung" with a transfer port (or reduced comp tube or ?) that simply cant handle all the air coming at it.
I just checked my order confirmation email from Vortek (to make sure I'd ordered a OEM power spring) and this is what I just put in the gun:
HW 97 OEM Replacement Spring
Product Code: V10-810125-31
Price: $18.90
Nicely fits the HW/Beeman HW97/77 and Clone airgun guides for OEM+ power.
(On the plus side: all my trajectory data should still be applicable if I leave it as-is