Thank you to our advertisers!







Author Topic: HP .22 design/build  (Read 10187 times - 1 votes) 
)

Offline rsterne

  • Member 2000+fps Club
  • Bob and Lloyd
  • GTA Senior Contributor
  • *****
  • Posts: 25334
  • GTA Forums Person of the Year 2017
  • Real Name: Bob
Re: HP .22 design/build
« Reply #320 on: March 24, 2021, 12:57:09 AM »
Pretty amazing how the FPE drops when the majority of the mass is the air, isn't it?....  ::)

Bob
  • 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).

Offline Scotchmo

  • GTA Senior Contributor
  • ******
  • Posts: 2104
  • Real Name: Scott Hull
Re: HP .22 design/build
« Reply #321 on: March 24, 2021, 01:09:05 AM »
Pretty amazing how the FPE drops when the majority of the mass is the air, isn't it?....  ::)

Bob

Until you calculate the air mass. The total kinetic energy (fpe) is mostly there with most of it in the air molecules, and the remainder in the much lower mass projectile.

It does make one realize why you get quickly diminishing returns when you get past the mid 900's fps. Most of the potential doesn't end up in the projectile.
  • Los Osos, California

Offline rsterne

  • Member 2000+fps Club
  • Bob and Lloyd
  • GTA Senior Contributor
  • *****
  • Posts: 25334
  • GTA Forums Person of the Year 2017
  • Real Name: Bob
Re: HP .22 design/build
« Reply #322 on: March 24, 2021, 02:16:13 AM »
Yep, one of the primary reasons I tune in the mid 900's (the other being less wind drift).... In addition, the huge drag increase above 1000 fps means than not only do you waste air to get there, the slug loses a lot of that hard earned velocity and energy in the first few yards.... Pretty much 3 strikes and you're out in the Transonic region....  ::)

Bob
  • 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).

Offline Scotchmo

  • GTA Senior Contributor
  • ******
  • Posts: 2104
  • Real Name: Scott Hull
Re: HP .22 design/build
« Reply #323 on: March 24, 2021, 10:47:57 PM »
I got a chance to get to the range today with my new Labradar and newly cast Arsenal 257420 slugs. I took 50 shots with the unsorted slugs. I had some consistency issues in these first batches but I am getting better with the casting process. I wanted a good baseline in this trip and I got that. The first three shots were not picked up by the Labradar so I went into the menu and changed the sensitivity from 5 down to 1. It picked up every shot after that. But I only got 21 recorded before the battery warnings started. The Labrader uses up the AA batteries quickly. I have an 8000mah rechargeable/solar lithium pack coming in but now I suspect that I might want something larger for longer sessions.





Some of the slugs were a not 100% filled and were unsorted, so that could have affected consistency/accuracy/BC values a little. Left example had poor fill. right example was good:


The Labradar worked well as I figured it out. I used the Labradar iphone app to control/arm it remotely so that was convenient. I had it set to record velocities at muzzle, 10yd, 25yd, 50yd, 75yd, and 100yd. It picked up all 21/21 shots at 10yd, 25yd and 50yd. It got flaky past 50yds. Some gave 0 and some were obviously wrong. It got maybe 14/21 good readings at 75 yds, and maybe 9/21 at 100yds.

The data file show the first three shots as 34gr but that was before I input the correct 70.5gr for projectile mass. If I throw out the fastest and slowest shots, I get 19 shots averaging 952fps, with an SD of 6.75fps. The BC was disappointing as the few shots that were the best were only 0.110, and some were under 0.07. But I still have not cut a barrel lead-in and slugs were forced in with some shaving in the process. I will do the lead-in now that I have my slug mold. Maybe it will be a little better after that.

Labradar Data file downloaded from sim card:


I'm trying to use better gauges these days to get better pressure readings. The regulator is set to 2100-2200psi into a 225cc plenum. I'm finding that charging the bottle past 4000psi does not seem to get me as many extra shots as expected. So I charged the 2000cc bottle to 3540psi and after 50 shots was at 2990psi. Using the Sikes airgun calculator, I get 1.53 FPE/cu-in per shot. That seems high for a 140+fpe airgun, but it does have a 36" barrel and I'm testing in the optimal pressure ranges. My spread sheet shows that I should get about 194 shots at 142fpe on a full 4300psi. That agrees closely with the sikes calculator.

I was not all that careful on accuracy. I shot two groups with most of the shots within a 2moa circle at 100 meters. It was windy:


Results are:

I'm happy with the Labradar. ++
I'm not happy with the BC of the 257420 slugs so far (BC=0.11). --
I'm surprised at the efficiency and high shot count (easily 100+ shots@140+fpe). +++
I'm OK with the initial accuracy (2moa @100m). +
« Last Edit: March 24, 2021, 10:56:58 PM by Scotchmo »
  • Los Osos, California

Offline rsterne

  • Member 2000+fps Club
  • Bob and Lloyd
  • GTA Senior Contributor
  • *****
  • Posts: 25334
  • GTA Forums Person of the Year 2017
  • Real Name: Bob
Re: HP .22 design/build
« Reply #324 on: March 25, 2021, 02:05:03 AM »
I don't know what range you used to calculate the BC from the LabRadar data, but the 100 yd. data is very poor, and even the 75 yd. data has some questionable velocities.... As you said, maybe only 2/3rd of the 75 yd. data usable.... What do you get for the BC if you average the MV and the 50 yd. data (throwing out questionable data from shots 9 & 16)?....

The VanDerWaals effect will not give you the extra shot count above 4000 psi that you would expect using Boyle's Law.... The higher you go above 3000 psi, the fewer extra shots you get for each 100 psi....

Bob
« Last Edit: March 25, 2021, 02:07:17 AM by rsterne »
  • 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).

Offline Scotchmo

  • GTA Senior Contributor
  • ******
  • Posts: 2104
  • Real Name: Scott Hull
Re: HP .22 design/build
« Reply #325 on: March 25, 2021, 03:34:04 AM »
I don't know what range you used to calculate the BC from the LabRadar data, but the 100 yd. data is very poor, and even the 75 yd. data has some questionable velocities.... As you said, maybe only 2/3rd of the 75 yd. data usable.... What do you get for the BC if you average the MV and the 50 yd. data (throwing out questionable data from shots 9 & 16)?....

The VanDerWaals effect will not give you the extra shot count above 4000 psi that you would expect using Boyle's Law.... The higher you go above 3000 psi, the fewer extra shots you get for each 100 psi....

Bob

I used the best performers to calculate the 0.11 BC (shot #17 for instance). I'll see if I can add BC calcs to the spreadsheet so I don't need to manually calculate each. But I know it would be way less than 0.11 for this string. The Labradar manual says the estimates for maximum range are:
.223 (5.56mm), 40-60yds
.308 (7.72mm), 80-100yds
.355 (9mm), 100-130yds

My guess is that the .257 with a .22 diameter base would be close to the .223 ability to register. And the reading out to 50yds all look good. I'd say that all the readings that I highlighted in green were good. Those highlighted in yellow might be questionable but potentially usable, and those highlighted in red look wrong since they don't follow a logical trend-line:



That VanDerWaals effect made me rethink the need to fill any of my tanks to 4500psi, and now maybe even keep under 4000psi.
« Last Edit: March 25, 2021, 03:41:42 AM by Scotchmo »
  • Los Osos, California

Offline sb327

  • Expert
  • *****
  • Posts: 1015
  • yes
  • Real Name: David
Re: HP .22 design/build
« Reply #326 on: March 25, 2021, 09:59:37 AM »
The difference in fill out on those slugs looks like the difference between a pressure pour and a regular pour.

Not sure what method you used or if you may have been experimenting to see what works best.

Your castings are looking really nice. What temp do you use to burnout the pla?

Dave

  • USA, OK, Stigler
Dave

Offline rsterne

  • Member 2000+fps Club
  • Bob and Lloyd
  • GTA Senior Contributor
  • *****
  • Posts: 25334
  • GTA Forums Person of the Year 2017
  • Real Name: Bob
Re: HP .22 design/build
« Reply #327 on: March 25, 2021, 01:10:33 PM »
Quote
The difference in fill out on those slugs looks like the difference between a pressure pour and a regular pour.

or not letting the sprue cool long enough, or the lead not hot enough, or the mold not hot enough, or the sprue plate not hot enough....

I still get a few like that, notably the first couple of pours when the mold is coming up to temp (and yes, I use a hot-plate to preheat it).... I count to 5 after the sprue pool solidifies before cutting the sprue, to set a regular rythym.... If I am still seeing bases like that, I increase the heat of the melt....

HINT:  Bottom pour pots like the 10 lb. Lee can have the spout MUCH colder than the melt, which means the first cavity you fill can look like that, even when everything SHOULD be working OK.... I lift the handle to "squirt" out a bit of lead before filling the first cavity on each pour to eliminate that problem.... You end up with a pile of lead pretty quickly, which I just push off to the side to add back into the melt along with the sprues and any cast-off bullets when the pot is getting low.... Obviously do this carefully, to avoid splashing yourself with molten lead....

Bob
« Last Edit: March 25, 2021, 01:15:26 PM by rsterne »
  • 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).

Offline Scotchmo

  • GTA Senior Contributor
  • ******
  • Posts: 2104
  • Real Name: Scott Hull
Re: HP .22 design/build
« Reply #328 on: March 25, 2021, 03:34:04 PM »
I use the basic Lee 90021 pot that is rated for 4 pounds of metal and a Lee ladle. I originally ordered a 4 cavity mold as I suspected that 5 cavity would be at the limit of what the ladle can easily handle. I switched the order to 5 cavity as I can always upgrade the pot and ladle at a later time. I run the pot at about the 8.5 setting. I preheat the aluminum mold by setting it across the pot opening. I hold the mold handle and tip it slightly down. I dip the ladle. A full pot makes it easier to get a full charge in the ladle. I move the ladle down above the mold as I pour attempting to fill equally and fully. If I overfill the first cavities too much, I run low by the 5th cavity. The 5th cavity is the one that gets the most fill errors. Even the 4th once in awhile. and sometimes the early cavities if I move over them too fast. When I concentrate on the work and get into a rhythm, they all come out of the mold fully formed. A good portion of the lead ends up as a continuous sprue cap. I dump that on the work bench after swinging the sprue cutter. After I get several sprue caps on the bench, I use needle nose pliers and sink them back in the pot.

https://leeprecision.com/lead-ladle.html

https://leeprecision.com/precision-melter.html
« Last Edit: March 25, 2021, 03:42:42 PM by Scotchmo »
  • Los Osos, California

Offline Scotchmo

  • GTA Senior Contributor
  • ******
  • Posts: 2104
  • Real Name: Scott Hull
Re: HP .22 design/build
« Reply #329 on: March 25, 2021, 04:06:41 PM »
... What temp do you use to burnout the pla?


My casting buddy informed me that the investment plaster is cured for 4 hours at 1400 F as recommended by plaster mfg. The PLA burns out during that process. Not sure at what point the PLA is completely eliminated.

Besides PLA, he has done burn out of resin (photo-polymer) printed patterns, and it takes the full 4 hours.
  • Los Osos, California

Offline sb327

  • Expert
  • *****
  • Posts: 1015
  • yes
  • Real Name: David
Re: HP .22 design/build
« Reply #330 on: March 25, 2021, 10:41:34 PM »
Thanks for that info Scott. Much appreciated. My little kiln can handle that without issue. (Outside, I would have to guess it smokes quite a bit)

Dave
  • USA, OK, Stigler
Dave

Offline rsterne

  • Member 2000+fps Club
  • Bob and Lloyd
  • GTA Senior Contributor
  • *****
  • Posts: 25334
  • GTA Forums Person of the Year 2017
  • Real Name: Bob
Re: HP .22 design/build
« Reply #331 on: March 26, 2021, 02:04:02 AM »
I question the 50 yard data on shots 9 & 16 in particular, they are way too low to fit with the trend of the others, IMO....whereas the 25 yd. data for those two shots is OK.... The rest I would just average the MV and 50 yd. velocity and use the averages to calculate the BC.... BTW, don't fall for the "simple" BC calculations on some of the airgun websites.... Use ChairGun (G1), Strelok (G1), or the BC (G1) calculator on the JBM website.... Any time you find a "simple equation" to calculate the BC it undoubtedly uses a constant drag model (usually Cd = 0.20 or 0.22) and they do NOT work in the Transonic (they ignore the huge drag increase there).... You have to calculate the actual Cd for your projectile at your average Mach number, using the delta distance and delta velocity, and the mass and cross sectional area of your slug (complex in itself, and watch your units), and then correct for your local atmospheric conditions.... Then divide that into the Cd of the G1 model for your average Mach number.... and then multiply by the SD to get the BC (G1)....

Bob
« Last Edit: March 26, 2021, 02:06:35 AM by rsterne »
  • 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).

Offline Scotchmo

  • GTA Senior Contributor
  • ******
  • Posts: 2104
  • Real Name: Scott Hull
Re: HP .22 design/build
« Reply #332 on: March 26, 2021, 05:29:12 PM »
I reran the BC data for some of the shots using the ChairGun G1 and it does not look as bad as I had originally thought. The individual trend lines of shots 9 and 16 look valid, but the BC is low when compared to the others. I finally cut a lead-in on the barrel and will retest later to see if I get more consistency. And after that, test at different muzzle velocities.

I also did a very light polish on the inside of the barrel and then pushed some slugs through. Not bad, but It looks like it might benefit from a heavier polish.
« Last Edit: March 26, 2021, 06:09:44 PM by Scotchmo »
  • Los Osos, California

Offline mackeral5

  • GTA Senior Contributor
  • ******
  • Posts: 2958
  • yes
  • Real Name: Mike D
Re: HP .22 design/build
« Reply #333 on: March 26, 2021, 08:32:55 PM »
Scott-  Of all of my TJ's barrels, for some reason the 2 that I've had in .257 1:14 have been the roughest I have seen.   Don't be afraid to get aggressive with it.  I made a lead lap, then fire lapped, then polished with JB's and Mother's  my most recent one and it is still so tight it prefers .256 slugs.  After all of that the bore still shows inclusions when viewed with a borescope, but engraving on slugs is like a mirror...  My .300, .357, and .457 TJ's all cleaned up much better than I could get my 25-20 liners.....
  • Lake Harding AL

Offline Scotchmo

  • GTA Senior Contributor
  • ******
  • Posts: 2104
  • Real Name: Scott Hull
Re: HP .22 design/build
« Reply #334 on: March 26, 2021, 09:53:47 PM »
Scott-  Of all of my TJ's barrels, for some reason the 2 that I've had in .257 1:14 have been the roughest I have seen.   Don't be afraid to get aggressive with it.  I made a lead lap, then fire lapped, then polished with JB's and Mother's  my most recent one and it is still so tight it prefers .256 slugs.  After all of that the bore still shows inclusions when viewed with a borescope, but engraving on slugs is like a mirror...  My .300, .357, and .457 TJ's all cleaned up much better than I could get my 25-20 liners.....

I remember reading that in your posts. I'll shoot it this way first. It is a little tight. The bore is a go with a 0.249" pin gauge, and no-go with a 0.250" pin. The slug dia measures 0.2555"-0.2565" before pushing/sizing. After a push through, slug shows a max of 0.2555". I'd like to eliminate any burrs on the bore and groove. The dimensions show that there is a little meat that I can remove from the lands and still be in tolerance. And when I decide to get more aggressive, I'll take it slow. Too much lead-in or crowning can be fixed, but too much lapping and of the bore, well - you just live with it or replace the barrel. Fortunately, the barrel is easy to remove, so I won't mind lapping/testing in small stages.

Note: First, I'll check my lead-in and crown as closely as possible to make sure the burrs are not from there.
« Last Edit: March 26, 2021, 09:58:16 PM by Scotchmo »
  • Los Osos, California

Offline rkr

  • GTA Senior Contributor
  • ******
  • Posts: 4077
Re: HP .22 design/build
« Reply #335 on: March 30, 2021, 02:03:48 AM »
I like that 2000cc bottle, how much does it weight? Those bullets look like the BT version of 257420, in my gun they group best at slightly lower velocity (920ish fps). We measured them at 0.17-0.18 BC with Timo's labradar.
  • Finland
Huub Viking Mk2 .177/.22 bullpup - grab'n go gun
BSA Scorpion SE .177 - 12 fpe UK model
BSA Scorpion .25 - 100M BR gun at 60 fpe
BSA Scorpion .224 - 100M BR gun at 100 fpe
Evanix Blizzard .257/.357 - 160/230 fpe
Exanix Sniper X2 .357/.45 - 210/270 fpe silhouette gun
Drozd Blackbird HPA - 1200 rpm full auto fun gun / meat grinder
Evanix AR6 carbine/pistol
+ a couple of springers

Offline Scotchmo

  • GTA Senior Contributor
  • ******
  • Posts: 2104
  • Real Name: Scott Hull
Re: HP .22 design/build
« Reply #336 on: March 30, 2021, 08:51:19 PM »
I like that 2000cc bottle, how much does it weight? Those bullets look like the BT version of 257420, in my gun they group best at slightly lower velocity (920ish fps). We measured them at 0.17-0.18 BC with Timo's labradar.

The bottle weighs 3.3 lbs. empty. With a regulator/valve installed and 3000psi of air, it weighs 4.8 lbs.

My Arsenal slug mold is the boat tail version of the 257420. In my first tests at 950fps, I got 0.152 as the best BC. I plan on testing it next with the adjustable regulator at various velocities. Probably from 900-1020fps. With the latest capacitor discharge circuit, the single 4700uf capacitor is limiting me to about 2500psi with voltage maxed out (63v). If I run the Cothran valve too close to the edge, velocities get inconsistent.  Running at 2300psi-2400psi gives me about 1020fps (160fpe) and a little leeway on the hammer strike.
  • Los Osos, California

Offline Scotchmo

  • GTA Senior Contributor
  • ******
  • Posts: 2104
  • Real Name: Scott Hull
Re: HP .22 design/build
« Reply #337 on: April 01, 2021, 02:41:29 PM »
I've made over a dozen breeches for this project. Only 5 or 6 actually got tested. The first two that I tested were plastic and they actually worked well enough. The last three were cast aluminum. It was a progression with many design changes early on. The last several have had no design changes. The only differences in those last three cast breeches was the casting quality. This last aluminum breech could be better cosmetically, but it filled out out fairly well so I decided to paint it flat black and call it done.

This breech is very specific to the Benjamin Armada. There is no cocking mechanism as the gun has an electronic hammer. The current design is ambidextrous (swap out left or right projectile shuttle). Integrated 20moa, 2.5" high, 34mm scope mounts. Barrels is clamped in place and is quick/easy to swap by via four socket head screws. Barrel prep is easy as there are no ports in the barrel.
« Last Edit: April 01, 2021, 02:51:40 PM by Scotchmo »
  • Los Osos, California

Offline Motorhead

  • Field Target Shooter .... Stand em up Shoot em down
  • GTA Senior Contributor
  • ******
  • Posts: 16781
  • 2019 Hall Of Fame Recipient
  • Real Name: Scott
Re: HP .22 design/build
« Reply #338 on: April 01, 2021, 06:32:53 PM »
Just WOW .... Always thinking outside the box.
  • Northern California ... Old Hangtown
** Home of MOTORHEADS AG Tuning Services **
   ** West Coast Dealer for THOMAS AIR **
    * PM me for further contact & tuning info.

       Sacramento Valley Field Target Club
#https://sites.google.com/site/sacvalleyairgunclub/