Lots to learn when installing new seals? some of you guy's out there do not have the knowledge of us old guy's, their maybe other issues with power from your HW you don't want to hear!
Quote from: Jim-in-UK on June 16, 2022, 08:47:48 AMOne further point, Ron, is that the factory export spring rate is circa 55 lbf/in, against yours nearer 63 lbf/in, so the force driving recoil acceleration will be less, and I believe it's the initial recoil acceleration, and consequent rifle rotation around the centre of gravity, that's opening the breech.It may be that the spring you are using is just over the limit of the breech locking capability.Other than your last sentence I'm afraid I don't understand what you're explaining.I sanded 0.002" off the breech seal and the lock up feels much more positive with no flex. This along with oiling the latch and snugging the pivot tension a tad made some difference. Still the POI would stay pretty good a while and then go away so I switched to solid mounted Hawke Vantage scope and the groups immediately improved. Often one hole (at ten yards) so I reinstalled Dampa mounted Airmax and the vertical dispersion returned. To diagnose the scope and mount I then installed the Airmax on the Vantages Sportsmatch rings. The Airmax printed as good as the Vantage in solid rings. It seems the Dampa mount wasn't returning to zero all the time.After burning through almost 500 JSB 13.73 Exacts today I switched to testing with H&N FTT 11.42. After 10 or 15 conditioning shots the FTTs printed single round hole groups for 60-70 rounds with the solid mounted Airmax. I switched back to JSBs and the first two groups were single round hole the opened up to ragged holes. It might have been a leading thing or I was simply fatigued after wrenching on, cocking and shooting this thing for 6 hours. I locktited the screws and put it aside until tomorrow.As much as I like the gun to prefer the heavier JSBs, the efficiency and accuracy says it prefers the lighter H&Ns.Thanks for your help. While no one thing seemed to cure the gun today, I can tell you your suggestion about the breech seal made a noticeable difference. Thank you.
One further point, Ron, is that the factory export spring rate is circa 55 lbf/in, against yours nearer 63 lbf/in, so the force driving recoil acceleration will be less, and I believe it's the initial recoil acceleration, and consequent rifle rotation around the centre of gravity, that's opening the breech.It may be that the spring you are using is just over the limit of the breech locking capability.
I'm sorry you feel that way? not my intent, information you post makes my wheels spin, to help you figure out what's going on with your rifle, Myself having been inside more HW rifles then I can count and having work done on them by people who have tools like SUNNEN Honing machines {ETC} I have a vast knowledge far beyond basic tuning, the information you have posted about your experiences with this R1 is nothing more then a basic tune up, IMO if your seals are not robbing your power you my have an out of round compression tube and no tune in the world will fix that! The tube has to be fixed, unfortunately HW's are known for having out of round tubes from time to time, and a lower power rifle with all you have done to this R1 is a good indicator,
Quote from: Bayman on June 16, 2022, 06:55:04 PMQuote from: Jim-in-UK on June 16, 2022, 08:47:48 AMOne further point, Ron, is that the factory export spring rate is circa 55 lbf/in, against yours nearer 63 lbf/in, so the force driving recoil acceleration will be less, and I believe it's the initial recoil acceleration, and consequent rifle rotation around the centre of gravity, that's opening the breech.It may be that the spring you are using is just over the limit of the breech locking capability.Other than your last sentence I'm afraid I don't understand what you're explaining.I sanded 0.002" off the breech seal and the lock up feels much more positive with no flex. This along with oiling the latch and snugging the pivot tension a tad made some difference. Still the POI would stay pretty good a while and then go away so I switched to solid mounted Hawke Vantage scope and the groups immediately improved. Often one hole (at ten yards) so I reinstalled Dampa mounted Airmax and the vertical dispersion returned. To diagnose the scope and mount I then installed the Airmax on the Vantages Sportsmatch rings. The Airmax printed as good as the Vantage in solid rings. It seems the Dampa mount wasn't returning to zero all the time.After burning through almost 500 JSB 13.73 Exacts today I switched to testing with H&N FTT 11.42. After 10 or 15 conditioning shots the FTTs printed single round hole groups for 60-70 rounds with the solid mounted Airmax. I switched back to JSBs and the first two groups were single round hole the opened up to ragged holes. It might have been a leading thing or I was simply fatigued after wrenching on, cocking and shooting this thing for 6 hours. I locktited the screws and put it aside until tomorrow.As much as I like the gun to prefer the heavier JSBs, the efficiency and accuracy says it prefers the lighter H&Ns.Thanks for your help. While no one thing seemed to cure the gun today, I can tell you your suggestion about the breech seal made a noticeable difference. Thank you.Well done on getting it sorted, Ron.To explain my first paragraph. When a springer is shot, the recoiling rifle wants to rotate about its centre of gravity, which is under the axis of the cylinder. The butt wants to fall, the muzzle to rise, and the greater the force the spring places on the piston and rifle at piston release, the fiercer the snap from a stationary barrel to one that's rising, and this places a strain on the barrel latching mechanism.One way to reduce the tendency for the rifle to rotate is to put a heavy scope on it, which raises the centre of gravity nearer the axis of the cylinder. Using a Dampa mount isolates the rifle from the mass of the scope at the very start of recoil, whereas the Sportsmatch mount is a direct connection between the mass of the scope (mainly the glass) and the rifle. I wholeheartedly agree with your last sentence. When diagnosing any issue, be it the IC engine, human disease or a spring/piston airgun, it's tempting to look for a single cause, when often there will be two or more contributory factors at work.
Trying to come back to the main principle of the thread, perhaps it is important to remember the different OBJECTIVE of both kit makers.JM is all about smoothness of shot cycle, consistency, and accuracyVortek sells on power and Silence of the shot cycle.So, it is understandable that the basic "philosophies" of spring design differ.JM's springs can usually be spaced up if you want/need more power. It's part of their design intent because you can find the power spacers in JM's website.Vortek decided to go to the stepped top-hat route and that is interesting because it allows increased pre-load without altering the masses at play.As long as we keep the perspective that it is not an "apples to apples" comparison, I think the discussion is providing valuable information and is being very useful.Thanks!HM
Quote from: Bayman on June 14, 2022, 08:46:36 PMAs for selling my R1, I'll probably hang on to it now that I put another new 20 caliber barrel on it. If I feel I want more power from it I will just put back the 29 coil 0.865"x 0.148" Vortek spring. It was making 18-19 fpe before I switched to 27 coil spring and then the JM kit. Or I'll just convert it 22. I have too much time and money tied up in it to let it go now. Besides it's still a cool gun.Hi Ron,Can you remember how much preload the 29 coil Vortek spring had when making 18 - 19 ft. lb. in the R1?Just trying to get a handle on the energy efficiency of what we in the UK call FAC rifles.Thanks,Jim
As for selling my R1, I'll probably hang on to it now that I put another new 20 caliber barrel on it. If I feel I want more power from it I will just put back the 29 coil 0.865"x 0.148" Vortek spring. It was making 18-19 fpe before I switched to 27 coil spring and then the JM kit. Or I'll just convert it 22. I have too much time and money tied up in it to let it go now. Besides it's still a cool gun.
Jim I just realized that I totally goofed in measuring preload lengths. I measured from the end of the compression tube to the end of the springs. This is ok as a side by side spring comparison but it doesn't represent the true preload length. It doesn't account for the amount the trigger block threads into the compression tube. A weak guess for that would be about a half inch. I'll get the exact amount next time I open the gun. I have a feeling it will be soon. I'm probably going to cut the 29 coil spring or shim the 27 coil a tad. I'd like to find a happy medium of power and accuracy.Thanks again for the help. Sorry about providing you bad preload measurements. Be wellRon
Quote from: Bayman on June 17, 2022, 07:25:14 PMJim I just realized that I totally goofed in measuring preload lengths. I measured from the end of the compression tube to the end of the springs. This is ok as a side by side spring comparison but it doesn't represent the true preload length. It doesn't account for the amount the trigger block threads into the compression tube. A weak guess for that would be about a half inch. I'll get the exact amount next time I open the gun. I have a feeling it will be soon. I'm probably going to cut the 29 coil spring or shim the 27 coil a tad. I'd like to find a happy medium of power and accuracy.Thanks again for the help. Sorry about providing you bad preload measurements. Be wellRonHi Ron. Thanks for the correction, and don't give goofing a second thought - we all do it from time to time!I remember the HW trigger block thread at nearer an inch, but to compromise, if it's 20mm then the force acting on the piston at the point of release is near 1,500N, or 337 lbf, which will give blistering recoil acceleration. The energy efficiency drops to 30%, which is not good news, as a lot of the lost energy drives piston bounce and hence recoil surge.Reducing the spring by one coil wold raise its rate from 11.1 to 11.5 N/mm, but the reduced preload would reduce the force acting on the piston to nearer 320 lbf. What we don't know is what effect that might have on energy efficiency.Thanks for the update.Jim
Ron are you using a Macarri piston seal or Vortek? I recently went through down on power issue with a Macarri kit for my R10. The piston seal was snug so I sanded it on the lathe. Made little difference. I believe it was Kirk who suggested I try a Vortek seal and DO NOT size it. Made a big difference in power and open my eyes to Vortek seals. I know this doesn't address the spring differences, but for me the issue of down on power was a piston seal.
Hector thanks for trying to get things back on track. The thread has gotten very deep into some technical topics I never understood and find quite interesting. It's also been a place where some people have come to aire their biases and ego. I'm not interested in either.To get back on topic, it was suggested earlier that spacers could be added to JM kit to pick up the power. This is true but there's only so much you can do with spacers. In this application I seriously doubt there's enough room for spacers to make up the difference in power between the two kits. The spring is simply weaker. Keeping this fair and current, the Vortek stepped tophat was pretty much a gimmick. It's not used on the Hw80 full power kit. It was used on the Weihrauch 25 & 26mm kits. I have installed a bunch of these kits and I've never seen more than 15 fps difference between the high and low tophat settings . It's usually ten fps. I've discussed this with Tom at Vortek. I haven't seen a stepped tophat from him in months. He may have abandon the concept.Thank you for adding your knowledge to the thread and being a gentleman.Be wellRon
Quote from: Bayman on June 17, 2022, 02:40:23 PMHector thanks for trying to get things back on track. The thread has gotten very deep into some technical topics I never understood and find quite interesting. It's also been a place where some people have come to aire their biases and ego. I'm not interested in either.To get back on topic, it was suggested earlier that spacers could be added to JM kit to pick up the power. This is true but there's only so much you can do with spacers. In this application I seriously doubt there's enough room for spacers to make up the difference in power between the two kits. The spring is simply weaker. Keeping this fair and current, the Vortek stepped tophat was pretty much a gimmick. It's not used on the Hw80 full power kit. It was used on the Weihrauch 25 & 26mm kits. I have installed a bunch of these kits and I've never seen more than 15 fps difference between the high and low tophat settings . It's usually ten fps. I've discussed this with Tom at Vortek. I haven't seen a stepped tophat from him in months. He may have abandon the concept.Thank you for adding your knowledge to the thread and being a gentleman.Be wellRonRon;I do agree that you can only do so much with spacers.But I have found that, in a properly sprung system, a LITTLE spacing can make a rather large difference.I don't have data about JM or Vortek springs, having dropped their use some time ago in search of utmost log term consistency, but using a Titan XS #1 (0.127" WD, 0.827" OD, 31 coils in 11") as an example on an LGV that is using an OEM piston and seal, a 0.160" spacer at the rear, increases ME by a bit over 1/2 ft-lb. from slightly under 12 ft-lbs to over 12 ft-lbs Do bear in mind that it is less than 1 W.D. and yet the difference in ME is a full 5%By the same token, increasing the spacing to 0.195" produced nearly no difference, and at 0.275" the rifle would not cock/latch. Which would seem to indicate that the LGV had "maxed out" its internal capacity. In yet another instance, a D54 with an ORing sealed piston and a Titan XS #4 spring (0.142" WD, 0.890" OD, 28 coils in 9.9"), originally tuned for the 8.49 grain pellets was yielding 8.7 ft-lbs with the H&N's BFT (9.57's), but a spacer of 0.320" made the energy jump to 12.11 ft-lbs, that is 3.4 ft-lbs, or 39% of energy gain from a relatively thick spacer, but perfectly doable in most large formats. Dropped down to a 0.200" spacer and the output became 11.7 ft-lbs, which is perfect for WFTF level shooting. Again, showing the higher versatility of larger compression chambers.I have found this seemingly inconsistent/irrational behaviour almost across all the calibers/energy levels, which means that some testing may be beneficial in most cases; so I have made sets of 5 calibrated spacers that allow me to go from 0.0400" to 0.430" and they are a useful tool to decide where to trim a spring or how to make a top-hat. ;-)Spacing (front and rear) and weighing of the piston/front end of the spring are just tools in the tuner's toolbox.And, as fickle and variable as airguns are, it is interesting to leave no stone unturned, sometimes you may find that the stone is a geode ;-) !Keep well and shoot straight!HM