My .257 Condor Build
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My .257 Condor Build
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Topic: My .257 Condor Build (Read 11328 times))
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
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Real Name: Bob
Re: My .257 Condor Build
«
Reply #80 on:
February 09, 2020, 07:24:21 PM »
Yeah, I've never heard of an unvented reg. that works long term.... They need a constant pressure as a reference standard....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #81 on:
March 06, 2020, 05:03:07 PM »
I have spent the last month nursing my dog Molly back to health after her knee surgery.... I am happy to report she is recovering well.... During that time I received a .25 cal Condor valve from Doug Noble (dyotat100) and installed it in a 250 bar (3625 psi) 500 cc bottle that I had lying around.... I did not take it apart, but I did notice that
the valve spring is just enough to hold the poppet closed for filling
, compared to a very stiff spring in a stock Condor valve.... The strong spring is not required because Doug's valve has a larger stem, but the same size top hat OD (necessary to fit the .25 cal breech)…. so it doesn't have any tendency to "blow open" like a stock valve does.... This means that a heavier hammer and stronger hammer spring are required to allow even the 3000 psi fill of a stock Condor, let alone more pressure for increased performance....
I wanted to find out what Doug's valve could do without upgrading the hammer and spring, and I finally got some time today to do some testing.... After a few shots to find the appropriate fill pressures, I shot two strings, one from a 2400 psi fill with some 59.6 gr. slugs, and the other from 2700 psi with slugs that weighed 82.5 gr.... Here are the results....
The FPE levels were significantly greater than stock, and slightly higher than my modified Condor valve with the angled ports in the stem.... but occurred at MUCH lower pressures, showing just how much better Doug's valve breathes.... It does, however, require a lot higher power wheel setting to reach those power levels, even at the reduced pressure.... in fact to get a string starting at 2700 psi required the PW to be maxed out.... There is no doubt that once I fit a heavier hammer and the stronger spring that Doug sent there is much greater FPE lurking inside....
The valve delivers a very nice bell-curve, with 9 shots within a 4% ES for both strings.... The average was 115 FPE with the light slugs and 135 FPE with the heavy ones, but the peak power was delivered at only 2200 psi with the 59.6 gr. and a peak of 140 FPE at just 2400 psi with the 82.5 gr.... My modified Condor valve peaked at 138 FPE at 3000 psi with the 82.5 gr. (and no bell-curve)...
After a few years watching Doug's expertise with the Air Force guns, I didn't see any sense in trying to reinvent the wheel.... I am delighted with the performance of his valve, and have no doubt that with just a hammer and spring change you could tether a .257 Condor at 3000 psi or less and shoot 70-85 gr. slugs as fast as necessary.... Using the extra power available with the change to a 3600 psi bottle will just be the icing on the cake, allowing even heavier slugs to be used, up to the limit of what will work in this 14" twist barrel....
Bob
«
Last Edit: April 02, 2021, 08:09:22 PM by rsterne
»
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #82 on:
March 07, 2020, 07:56:26 PM »
I installed Doug's hammer spring today, with the stock hammer.... I know Doug recommends a heavier hammer, but I wanted to see what would happen, and what fill pressure was possible with just the spring change.... The spring is about 10 lbs/in instead of about 4 lbs/in for the stock spring, but it is more than 1/4" shorter....
I started with the power wheel at the minimum setting (1), and filled to 2700 psi and tried the 82.5 gr. bullets I used for yesterday's test.... The velocity jumped to 891 fps, with the second shot slower.... Filled to 2820 psi (what my SCBA tank had in it) I got a 7 shot string, starting at 911, a second shot of 914, and then a decline down to 868 fps at 2400 psi, giving 7 shots averaging 147 FPE.... This compared to the stock spring at PW = 14 (maximum) yesterday, which gave me 9 shots from 2660 psi down to 2120 averaging 135 FPE.... So, Doug's spring at the lowest power wheel setting would allow a higher fill pressure than the stock spring at the highest PW setting.... It was, of course, harder to cock.... I tried various PW settings with the 82.5 gr. bullet at 2820 psi, and the velocity peaked at 931 fps (159 FPE) at PW=4, and then declined after that.... I assume the hammer was bouncing off the Delrin spacer under the top hat on Doug's valve when I cranked the PW over 4 at 2800 psi....
I then got out some 92.6 gr. Lyman 257464 RN bullets, to see what would happen with a heavier weight and more pressure (my other SCBA tank was full)…. The gun was even harder to cock at PW=6 (although certainly OK), so I started there at 3100 psi, and got a first shot of 922 fps (174 FPE), and then 910 for the second shot.... This means that even with the stock hammer, Doug's spring will allow a higher fill than that.... I tried PW=4 at 3000 psi (910 fps, followed by 898), and then dialed the PW back to 2, refilled to 3000 psi, and shot an 8 shot string which started at 858 fps, peaked at 880, and then fell back to 845 fps (a 4% ES), leaving 2420 psi in the 500 cc bottle.... That 8 shots averaged 154 FPE from a 3000 psi fill, with an efficiency of 1.01 FPE/CI....
So, Doug's spring, installed with the stock hammer, can easily allow a 3000 psi fill at near minimum spring preload.... In fact, with a lighter bullet, like the 257420, even with the PW set to minimum you may not be able fill to 3000 if you want a bell-curve, although I didn't try that.... If you want to shoot 70-75 gr. bullets, you may not need to change the hammer, and just use Doug's .25 cal valve and his hammer spring.... It may even be possible to shoot 80-90 gr. bullets with a 3600 psi fill with the stock hammer, but you will have to crank up the power wheel, and the gun will be getting hard to cock.... In that case, a heavier hammer will allow you to reduce the PW setting, which is the route Doug recommends.... Again, I never tried over 3100 psi today....
I'm very pleased with Doug's valve and hammer spring.... I have already seen 170 FPE at 3000 psi, even without a hammer change....
Bob
«
Last Edit: March 09, 2020, 05:52:08 PM by rsterne
»
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #83 on:
March 08, 2020, 06:03:35 PM »
Today I increased the pressure to 3600 psi to see how Doug's Valve and Spring worked with the stock hammer.... I did the testing with the 92.6 gr. Lyman 257464 RN bullet, which is about as heavy as you can go with the 14" twist barrel.... First I tried numerous power wheel settings, with the following results....
As you can see, the results show a similar pattern to a stock Condor.... Once you get to maximum power, increasing the PW setting causes the top hat to bounce off the Delrin stop on the valve stem, and that bounce reduces the dwell and therefore the FPE.... The velocity peaked at PW = 10 at 969 fps (193 FPE)…. My "lofty goal" calculation for 3600 psi in a .257 with a 26" barrel is 202 FPE, so that gets to within 4.5%, which is pretty good.... I backed off the PW to 8, and started a string from 3600 psi.... It was 950, 958, 946, 938 and 920 before it dropped more than 4% from the peak, so I reduced the PW setting to 7 and shot two strings, both from a 3600 psi fill.... They are shown below in red.... all strings with a 92.6 gr. bullet....
You will note that the velocity of the first shot varied, and they were either side of the 925 fps I got when I tested the velocity a PW = 7 above.... This means that I need just a whisker more hammer spring preload ( PW = 7.3? ) for a 3600 psi fill, to avoid those large swings on the first shot.... I ran out of bullets, but it is pretty obvious from the 2 strings that with a little fine tuning I can get 7 solid shots within an ES of less than 3%.... The average over the 15 shots of those two strings was 938 fpe (181 FPE) at 1.15 FPE/CI.... I am very pleased with that efficiency at this power level.... especially considering the Condor does not have a stellar reputation for efficiency....
Although Doug told me that I should make a heavier hammer, I seriously doubt that would actually give an increase in power, because the hammer is already bouncing off the valve, and more than likely it would drop the efficiency.... It certainly would reduce the cocking effort by allowing me to use a lower PW setting, but on the other hand it would likely mean that I would not be able to reduce the PW far enough to shoot a lighter bullet, such as the 257420, without having the velocity pushing over 1000 fps (or having a declining shot string)…. If you look at the black line on the chart above, you can see what happens with an 82.5 gr. bullet with a 3000 psi fill at PW = 2.... That setting would push the 257420 into the mid 900s, so Doug's spring, with the stock hammer, gives me a nice adjustment range between the minimum PW setting and PW = 8 to handle all weights of bullets and pressures up to 3600 psi.... I think I'll stay right where I am for now, as I don't think a heavy hammer would buy me any more FPE with this 26" barrel....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
MJP
Member 4400+Fpe Club
GTA Senior Contributor
Posts: 2136
I'll make it real. For me.
Real Name: Marko
Re: My .257 Condor Build
«
Reply #84 on:
March 09, 2020, 01:33:48 AM »
Nice testing and thoroughly analyzed as always.
Shot any groups?
This is a good indication of the work Doug has done developing the valves. You can take anyone else's condor valve and you won't see performance nearly as good as this.
Even my own valves lack the consistency of the shot string, but that is not my goal.
Others try to copy Dougs work, and that tells a lot.
Marko
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Finland
Impossible just takes a little bit longer to achieve.
If an engineer is not presented with a suitable problem, they will create their own!
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #85 on:
March 09, 2020, 01:38:46 PM »
I agree, Doug really knows what he is doing on the Air Force PCPs.... and it is because people try and copy him that I have refrained from giving details of the internals.... As always, no groups, and they are unlikely to occur until next year after we close the Motel.... Actually this winter I didn't get a lot of shop time because I have been concentrating on nursing my dog, Molly, back to health after her knee surgery.... She is doing well, but still months from full recovery....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #86 on:
March 11, 2020, 04:08:15 PM »
Today I double-checked the power wheel settting to confirm that maximum FPE occurred at PW = 10 wth a 3600 psi fill.... I tested it with bullet weights of 62 gr. and 105 gr., and that was the case with both weights.... I used that setting and tethered the gun at 3600 psi to find the velocity of every possible pellet and bullet I had in .257 cal.... The pellets I used were .25 cal, but the skirts were 0.257" or so, and I was confident that at 3600 psi they would blow out to seal just fine, and that proved correct.... Here is a chart showing the maximum velocity and FPE I am getting at 3600 psi with my .257 Condor with Doug's valve and spring....
Those below 42 gr. were pellets.... Note that this gun will push the 25.4 gr. JSB Kings at 1420 fps.... All the pellets were supersonic, I just did this out of curiousity…. Also note that the heaviest three bullets were too long to stabilize, and were tumbling by the time they hit the backstop, which was only 6 yards behind the Chrony….
…. This leaves a usable range of bullet weights from 58-93 gr., which produce between 160-190 FPE, with the heavier bullets having more energy, as expected.... The NOE 73.9 gr. boattail version of the 257420 shot at 1041 fps (and the HP at 1051), which may or may not be usable.... but if I have to slow it down it is a simple matter to dial back the power wheel, and/or drop the pressure a bit.... The shortened HP version, at 58.3 gr., was just supersonic (1124 fps) at PW = 10 and 3600 psi.... but if I want to use those I can easily drop the pressure down to 3000 psi and back off the power wheel accordingly.... The gun is capable of hitting the high 900s with an 85 gr. bullet, and could be backed off a bit to save air....
One other thing I determined is that PW = 8 looks like the perfect setting for tethering 80-90 gr. bullets at 3500-3600 psi, the gun shoots a 4-shot string starting from 3600 within a 2% ES, getting over 1.0 FPE/CI at that setting.... At 3500 psi and PW = 8 it is right at the top of the bell-curve.... All in all, it looks like this gun will make a very capable varmint and target rifle.... providing the accuracy matches the power....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #87 on:
March 12, 2020, 08:32:59 PM »
I have always been curious about how the diameter you size a bullet to effects the velocity.... so today I used the Condor and 3 different bullet weights, and tried every size from 0.251" to 0.259", shot 3 shots with each bullet and determined the average velocity.... I then plotted that vs. the diameter....
The highest velocity was at 0.257", which corresponds to the groove diameter of the barrel.... There was essentially no difference between 0.256" and 0.258", both being within 1-2 fps.... With the heaviest bullet, even sizing to 0.255" or 0.259" really didn't make more than 2-3 fps difference in the velocity, but with the lightest bullet both were down about 5-6 fps (still pretty much lost in the ES)…. Where a bit of blowby became obvious in reducing the velocity was at 0.254" and smaller.... The velocity loss was more pronounced with the lighter bullet, which likely has something to do with the relationship between mass and bore friction compared to the heavier one....
I have seen similar results to this before, but this is the first time I actually set out to find out how much blowby affected velocity.... and the answer is not much.... Basically all you need to worry about when trying different sizing is the accuracy.... Anywhere from 0.002" smaller to 0.002" larger than the bore makes virtually no difference to the velocity.... Even 0.003" under only looses 1-2%....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
dyotat100
Expert
Posts: 1095
Re: My .257 Condor Build
«
Reply #88 on:
March 19, 2020, 01:36:11 PM »
Thanks for taking the time to run it through its paces. Glad to see your happy with it. There is a reason for running the heavier hammer besides preload. I will try with and without on a gun I will have here soon.
I normally shoot teathered. I have setup guns to do 5-7 shots for customers.
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rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #89 on:
March 19, 2020, 01:47:31 PM »
Yep, 5-7 shots is easily obtainable by just backing off the PW a turn or two from maximum power.... The difference between a really tight 4 shot string ideal for tethering and a 7 shot string with a 3-4% ES is only 1 turn on the PW with the stock hammer and your spring.... The thing I like about using the stock hammer is that it is easier to dial down for lighter bullets or lower pressure that it would be with a heavier hammer.... I think it just gives more flexibility in the .257, although it is a bit harder to cock than it would be with a heavier hammer....
I am delighted with the valve and spring, Doug.... My compliments....
Bob
«
Last Edit: March 19, 2020, 01:50:08 PM by rsterne
»
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
Jim Holmgren
Plinker
Posts: 155
yes
Real Name: Jim
Re: My .257 Condor Build
«
Reply #90 on:
September 24, 2020, 12:47:40 PM »
I read through this thread today and have some questions.
BTW I love reading these project threads and how you describe your work and thoughts, many thanks it's appreciated!
The picture on the first page helps me to understand this valve greatly.
I find it weird that the condor valve doesn't have any reference to atmospheric pressure in closing the same way as a conventional valve has with it's valve stem.
But if I understand right Dougs valve does have a closing pressure? But not all of them has it as it depends on the caliber?
I understand that you don't want to give details of someones else valve, but could you or Doug make a drawing of the principles on how it works, like the first drawing you made?
I guess the valve stem is bigger then the breech in OD of Dougs valve?
There was also some talking about a "blodnob" valve, I searched of it but didn't find much info.
It's like a normal AF valve but with the poppet at the end of the valve body instead of inside it? Maybe someone could make a simple drawing of that one too?
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rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #91 on:
September 24, 2020, 01:58:31 PM »
Jim, although the AF valves do not have atmospheric pressure as a reference, there is a pressure differential across the top hat, or can be depending on the diameter.... That is explained in Reply #12.... This pressure differential tends to hold the valve OPEN, leading to more dwell for a given hammer strike.... The valve is closed by the valve spring, and the air rushing out past the poppet.... Additionally, although the area doesn't change, if you bevel the entrance to the hole through the stem, instead of having a simple cross hole as in the stock valve, since the air can pass more easily from behind the poppet into the stem, there is less drag, which also reduces the closing force.... That is why when I angled and enlarged those holes, in Reply #61, I lost closing force, as explained in Reply #63.... and ended up with no tuning range....
Doug's valve has a similar streamlining of the ports leading into the stem, and the stem is a larger OD.... Since the top hat is the same OD (it must be to fit inside the barrel), this reduces the area shown in red in #12 (the differential) opening the valve, but there is a small loss in closing force due to the tapered ports.... Doug's valve compensates for the reduced
closing
"blow open"
force by using a
stiffer
weaker
valve spring, and you must run a stronger hammer spring (and usually a heavier hammer) to aid in opening the valve because of the lower differential.... His valve operates in the same manner, but the
heavier
different
springs on both ends (valve and hammer) give you back the tunability lost by the increases in flow inherent in his design....
HTHs....
Bob
«
Last Edit: April 02, 2021, 08:07:39 PM by rsterne
»
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
Jim Holmgren
Plinker
Posts: 155
yes
Real Name: Jim
Re: My .257 Condor Build
«
Reply #92 on:
September 24, 2020, 02:37:42 PM »
Ok that clears it up a bit, thanks!
Seems very tricky to get right and to tune, I think I prefer the conventional setup, seems more sensible haha.
But it's a quite slim/streamlined the inline type of design I must say.
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rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #93 on:
September 24, 2020, 03:18:34 PM »
Definitely flows a bit better.... I think you can use about 10% lower pressure than a conventional valve.... comparing Doug's to a good flowing conventional valve with as smooth as possible 180 deg. turn.... There is still the restriction caused by the air flowing around the poppet and "slaloming" through the ports between it and the stem.... They are best described as an "axial flow" valve, as they are definitely not "straight through"....
Bob
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Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
Hobbyman2007
N.U.A.H. Expert
GTA Senior Contributor
Posts: 3011
yes
Real Name: Denis
Re: My .257 Condor Build
«
Reply #94 on:
September 28, 2020, 08:59:57 AM »
Excellent reporting as usual Bob. Now this has got me thinking , do I really need a .257 Texan?
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Dowling,Ontario, Canada
I like air guns ,and they like me
Voltar1
Plinker
Posts: 299
yes
Re: My .257 Condor Build
«
Reply #95 on:
December 14, 2021, 12:12:44 PM »
Hi Bob, late to this party. Looks to be a fun journey you are on. Are you still shooting the 257? Wondering what weight hammer you settled on?
Be well eh
Walter
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Rocky Mtn House, Alberta
Walter
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #96 on:
December 14, 2021, 09:58:18 PM »
I ended up using a stock hammer and Doug's hammer spring.... Best to you this Christmas....
Bob
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Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
Voltar1
Plinker
Posts: 299
yes
Re: My .257 Condor Build
«
Reply #97 on:
December 15, 2021, 01:38:50 PM »
Merry Christmas to you and yours Bob.
Would you happen to have the weight of that stock hammer?
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Rocky Mtn House, Alberta
Walter
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26958
GTA Forums Person of the Year 2017
Real Name: Bob
Re: My .257 Condor Build
«
Reply #98 on:
December 16, 2021, 01:04:57 AM »
Sorry, I don't....
Bob
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Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
quyang
Shooter
Posts: 8
yes
Real Name: li
Re: My .257 Condor Build
«
Reply #99 on:
January 18, 2022, 05:53:14 AM »
I found you again BOB. I read your article carefully. Your time to acquire this toy is too short, so you don't have a very deep understanding of this type of PCP. The biggest problem with such PCP is structural strength and rigidity. A secondary issue is tightness. by improving these issues. This type of PCP has enormous potential.
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CHINA, Hulunbiur
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My .257 Condor Build