That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
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That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
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Topic: That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last. (Read 1237 times))
Ribbonstone
GTA Senior Contributor
Posts: 12030
That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
«
on:
September 22, 2017, 08:51:42 PM »
Took me long enough (about a year of off and on "futzing" around, but I finally found a setting that would give me +300 foot pounds per 12gr. (+600 foot pounds for 2X12gr) in a QB.
They aren't super high power shots, and I have to "stretch" it to a 2.5% varation (from 604fps to 618fps...about 14fps over 60 shots).
The Junk=YArd Dog 5mm co2 QB.
Bits and pieces from various QB's, mostly hanging around the parts box. QB78D trigger,QB 78S tube/guts, 5mm HW barrel and modded breech/bolt slapped down on top of the tube, striker spring tweaking, mstrighter weight reduction, transfer port a bit reduced, etc.
Even though we're in the first day of fall, the temp. was a pretty steady 87F during the test...warm climated, may as well take advanatge of it while I can.
But I got to my goal: 300 foot pounds per 12gr. WITHIN a reasonable velocity varaition.
60 shots, 2 X12gram, 10 SHOT GROUPS. 11.2 foot pounds per shot, 611 fps average (604-618fps), 13.4gr. HAd to add a 6th target by hand ('casue I'm too cheap to burn another target just for one bullseye) just to be sure there were 60 shots (but there an't more than 62, as the decline in impact was quick and nasty after 60-62 shots).
So lets say it's 60 shots X 11.19 foot pounds....which is 671 foot pounds per 2X12gr. fill....or about 335 fpe per 12gr. AND at a resonably "sporting" energy level.
OK...I fialed at 12 foot pounds with 12gr. co2. Not that I couldn't get to 12 foot pounds (after all, it's not far from 11.2 foot pounds), but when I did the gas use per shot ended up well under the 300FPEper 12gr. goal.
And I do not find the .27" group average too shabby for 10-shot groups
«
Last Edit: September 22, 2017, 09:02:15 PM by Ribbonstone
»
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Louisiana
rsterne
Member 2000+fps Club
Bob and Lloyd
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Re: That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
«
Reply #1 on:
September 23, 2017, 02:19:37 AM »
Well done.... That 87*F temperature certainly helps.... but getting that FPE level with such a consistent velocity is wonderful....
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).
CraigH
GTA Senior Contributor
Posts: 3540
Real Name: Craig
Re: That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
«
Reply #2 on:
September 23, 2017, 08:33:43 AM »
A++++ Accuracy, Consistent velocity, Power level, Efficiency!
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Lone Tree, Colorado
With freedom comes a terrible responsibility
Jbutzi
Shooter
Posts: 31
yes
Real Name: Jim
Re: That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
«
Reply #3 on:
September 23, 2017, 11:13:28 AM »
Pretty impressive! Good job!
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USA Wisconsin Bristol
Ribbonstone
GTA Senior Contributor
Posts: 12030
Re: That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
«
Reply #4 on:
September 23, 2017, 11:41:52 AM »
Thanks.
87F helps for sure, it's not far from the average temp for this time of year here.
One trick about chronographing and target shooting:
Once you get it all lined up....move the target face, not the chronograph.
I'm not much for lasers on airguns, but it does make that easy. Rifle sits on the bags the same, chronograph stays the same, just the target gets shifted every set of shots.
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Louisiana
Ribbonstone
GTA Senior Contributor
Posts: 12030
Re: That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
«
Reply #5 on:
September 23, 2017, 01:47:31 PM »
Bob:
Co2 is more of a viable alternative gas the farther south you go.
Averages always hide stuff (which is why a man can drown in a pond with an average depth of 4")...but this will pretty much give you and idea:
http://www.neworleansonline.com/tools/weather2.html
I do like VISITING the frozen north...for a few days....but am hot climate guy.
«
Last Edit: September 23, 2017, 01:50:40 PM by Ribbonstone
»
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Louisiana
anti-squirrel
How'd I become a
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Posts: 9733
Wadcutter fan
Real Name: Peter
Re: That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
«
Reply #6 on:
September 23, 2017, 04:12:34 PM »
That is some seriously sweet efficiency you got there, Ribbs!
And I'll add that I wouldn't be surprised if you choice of barrel helped. I think it is possible with .22 and .177, but I always thought the .20 was just such a perfect compromise for between the 2, and it seems to line up Very Nice with a powerlet.
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Quinton Virginia
Slingshottist and antique tool junkie
EdGuns, Crosmans, and a couple big-bores from the Far East
Ribbonstone
GTA Senior Contributor
Posts: 12030
Re: That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
«
Reply #7 on:
September 23, 2017, 04:28:50 PM »
That HW barrel has always been a help...it's been on 3 different QB's. Also think you are right, it's at it's best with "middle energy" levels (something like 12-25 foot pounds)....which is an area few play in, so the 5mm gets short-changed.
Would be a good choice for a Disco.Maxi, as the energy level would be about right (as there are no good heavy weight pellet choices today)...but for a "bigger" PCP, would be a matter of down tuning to suit the pellets.
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Louisiana
oldpro
GTA
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Posts: 10981
yes
Real Name: Travis
Re: That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.
«
Reply #8 on:
September 23, 2017, 10:00:56 PM »
Fantastic!!! Thats pretty impressive. A+++
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Katy, Texas
Raptor mini 2 in .25
Huben k1 .22
LCS SK-19
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That 300 foot pounds per 12gr. thing (attention rstern)...I got there at last.