Yes, I know; Brocock makes excellent out-of-the-box pistols. However, I am neither willing to BUY one, nor do any of them fulfill all my demented air pistol desires. Also, I already had an awesome .22 Brocock Sniper XR LAMINATE mostly gathering dust, because it has been relegated to a single, specific use (35 Foot Pound class Bench-Rest Silhouette competition). Lastly, Brocock pistols all use plastic stocks.
So I decided to build my own dream air pistol!
Correction- my own dream air pistol-carbine CONVERTIBLE... with a wooden (laminate) stock.
But before butchering a perfectly good $2000 PCP rifle, believe it or not, I put not only a lot of thought into it, but a lot of fore-thought into it. Upon realizing the finished product would do about 90% of everything any sane airgunner could ask of any airgun, meaning about 50% of everything this lunatic airgunner can dream up for an airgun, out came the hack-saw and pipe cutter!
Having previously reported (on this forum) some of the gory details, this post will concentrate on the end PERFORMANCE results. More specifically, those results achieved yesterday shooting 'Black Magic' in PISTOL form.
Primary motivations for butchering a perfectly good Sniper XR Magnum rifle being to "build a BETTER mouse-trap" for Extreme Pistol Field Target competition, launch a new EXTREME Extreme Pistol Field Target competition (or class), and expand air pistol hunting horizons beyond previous bounds, the four-position, instant-power-adjusting-knob not only had MUCH to do with success, but added another, multi-layered "learning opportunity" complication to the project/process/ADVENTURE.
The Extreme Pistol Field Target power limit being 20 foot pounds, and the anticipated maximum power output of the chopped to 14.5" barrel being 26-28 foot pounds on the (highest) Power Level Four, I expected to have to do no small amount of 'tuning' to land a lower Power Level setting in the 19-20 FP range. If all went as hoped, that tuning might entail not only lowering the regulator (output) pressure, but possibly also adjusting the (factory) hammer-tension nut on the ass-end of the receiver. Such proved to be the case; but that process couldn't have gone more perfectly in my wildest dreams (which, TRUST ME, are wilder than most sane folks imagine).
One of my many quirks, foibles and idiosyncrasies being POWER-lust, I was pleasantly surprised to see the 14.5" chopped pistol barrel producing 865 FPS/30.1 foot pounds over the chronograph with my preferred 18.1 grain FX pellets. However it was no surprise to find Power Level Two not only coming closest to my 20 FP goal, but 10% above that Extreme FT goal; as hoped. And, FORE-THOUGHT.
Reducing the regulated-output pressure being part and parcel to the anticipated process, depressurizing the gun being part of that process, and a shorter/smaller-diameter chamber-bottle being another anticipated change (mostly for aesthetic purposes), thankfully I was able to effect a trade of the original 480cc bottle for the 300cc bottle seen in the third (pistol) photo above. With the smaller bottle in place but little experience adjusting regulator pressures, thankfully my guess of about a quarter-turn of the reg-adjustment screw got me exactly where I wanted to go; that being BELOW my end-goal of as close to 20 foot pounds on Power Level Two as possible. Power Level Two averaged 686 FPS and 18.9 foot pounds, to be exact. Increasing reg pressure output with the external adjusting screw presenting no danger with pressure in the bottle/gun/plenum, I crept up on my power goal quite 'gingerly'; landing at 701 FPS/19.75 foot pounds average with the 18.1 FX pellets at a regulator output pressure of 125 BAR. SUCCESS!
But... wait! What if, as anticipated, power crept up a little after a few dozen or hundred shots? Remember that fore-thought part?
Yep; that's what happened. Exactly as hoped! To exactly 710 FPS/20.3 FP after about fifty shots. Sure hope that hammer-spring power-nut works well, because MANY DON'T!
Backing off the nut had less effect than expected, but 1-1/4 counter-clockwise revolutions worked pure MAGIC! Results-
18.1 grain FX, 125 BAR reg pressure, Power Level 2, 10 shot string- Low= 701, High= 703, Extreme Spread= 2, Standard Deviation= .8, Average= 701 FPS/19.8 Foot Pounds.
18.1 grain FX, 125 BAR reg pressure, Power Level 4, 8 shot string- Low= 844, High= 849, Extreme Spread= 5, Standard Deviation= 1.7, Average= 846 FPS/28.8 Foot Pounds.
In over three decades of obsessive chronograph testing of hundreds of airguns of all kinds, the extreme spread and standard deviation in red above are the lowest I've ever seen.
Individuals with immensely more airgun regulator experience than me have shared their knowledge and advice to help guide my clumsy airgun monkeying efforts
. More specifically, one individual with immensely more airgun regulator experience than me has selflessly shared his invaluable knowledge and advice to help guide those efforts. Many reading this will recognize him.
In our conversations about airgun tuning and regulators Derrick often alludes to a 'sweet spot' balance of reg pressure and hammer-blow where regs perform best. And although I've seen glimpses of evidence confirming the reg basics he's explained, none so poignantly graphic as I stumbled into above. I can't thank you enough for sharing your knowledge, DW! Or enduring my creeping dementia
!
That said, don't expect any mercy out there on the Extreme Pistol FT course. No mercy! But I know you'd have it no other way.
With Black Magic's chopped barrel and shroud scheduled to go away for threading to reattach the shroud top-hat/moderator-attachment today, yesterday was my only opportunity for accuracy testing for a while. Of course the winds were hideous; gusting all over the place to 25-30 MPH. Nevertheless, as is my habit, I decided to quantify accuracy best as possible in the near-gale-force conditions by shooting four consecutive five-shot groups at 50 yards from stool-and-bipod field target position, followed by four more groups from sand-bagged bench-rest. It proved a most 'interesting' exercise.
Considering the wind conditions, I was (again) quite pleasantly surprised to achieve a 1.30" c-t-c average from the stool-and-bipod FT position (bottom-most four groups below). That comparing favorably to my abilities in good conditions, I took it as a good sign of the pistol's capabilities in human hands. Correction- sub-human hands!
Upon moving to the bench, it was no surprise to see my point-of-impact move up and right about 1" (top four groups below). Changes of POI are normal with any rifle or pistol from drastically different positions and rests. It was also no surprise to see the bench-rested groups' average calculate to no better than 1.07" c-t-c, given the wind conditions. More specifically, given ONE SHOT opened-up one group considerably due to a sudden, momentary lapse in gusts not noticed until that shot broke. That stated, I have no doubt Black Magic will average 3/4" c-t-c or better groups at 50 yards in still conditions; because, no doubt, the hideous winds accounted for at least .32".
However a huge surprise was the relatively small difference of only .23" between the bench-rested and FT position results. I'll explain that like this- ONE experiment should not be construed as conclusive.
Unfortunately it will be a while before the threaded barrel and shroud return to conduct more testing. Regardless, suffice to say I couldn't be happier with how this conversion has gone so far.
I really, REALLY look forward to testing at Power Level Four upon return of the threaded barrel and shroud...
WITHOUT HEARING PROTECTION! "Say what?"
So I decided to build my own dream air pistol!Correction- my own dream air pistol-carbine CONVERTIBLE... with a wooden (laminate) stock.
But before butchering a perfectly good $2000 PCP rifle, believe it or not, I put not only a lot of thought into it, but a lot of fore-thought into it. Upon realizing the finished product would do about 90% of everything any sane airgunner could ask of any airgun, meaning about 50% of everything this lunatic airgunner can dream up for an airgun, out came the hack-saw and pipe cutter!Having previously reported (on this forum) some of the gory details, this post will concentrate on the end PERFORMANCE results. More specifically, those results achieved yesterday shooting 'Black Magic' in PISTOL form.
Primary motivations for butchering a perfectly good Sniper XR Magnum rifle being to "build a BETTER mouse-trap" for Extreme Pistol Field Target competition, launch a new EXTREME Extreme Pistol Field Target competition (or class), and expand air pistol hunting horizons beyond previous bounds, the four-position, instant-power-adjusting-knob not only had MUCH to do with success, but added another, multi-layered "learning opportunity" complication to the project/process/ADVENTURE.
The Extreme Pistol Field Target power limit being 20 foot pounds, and the anticipated maximum power output of the chopped to 14.5" barrel being 26-28 foot pounds on the (highest) Power Level Four, I expected to have to do no small amount of 'tuning' to land a lower Power Level setting in the 19-20 FP range. If all went as hoped, that tuning might entail not only lowering the regulator (output) pressure, but possibly also adjusting the (factory) hammer-tension nut on the ass-end of the receiver. Such proved to be the case; but that process couldn't have gone more perfectly in my wildest dreams (which, TRUST ME, are wilder than most sane folks imagine).
One of my many quirks, foibles and idiosyncrasies being POWER-lust, I was pleasantly surprised to see the 14.5" chopped pistol barrel producing 865 FPS/30.1 foot pounds over the chronograph with my preferred 18.1 grain FX pellets. However it was no surprise to find Power Level Two not only coming closest to my 20 FP goal, but 10% above that Extreme FT goal; as hoped. And, FORE-THOUGHT.
Reducing the regulated-output pressure being part and parcel to the anticipated process, depressurizing the gun being part of that process, and a shorter/smaller-diameter chamber-bottle being another anticipated change (mostly for aesthetic purposes), thankfully I was able to effect a trade of the original 480cc bottle for the 300cc bottle seen in the third (pistol) photo above. With the smaller bottle in place but little experience adjusting regulator pressures, thankfully my guess of about a quarter-turn of the reg-adjustment screw got me exactly where I wanted to go; that being BELOW my end-goal of as close to 20 foot pounds on Power Level Two as possible. Power Level Two averaged 686 FPS and 18.9 foot pounds, to be exact. Increasing reg pressure output with the external adjusting screw presenting no danger with pressure in the bottle/gun/plenum, I crept up on my power goal quite 'gingerly'; landing at 701 FPS/19.75 foot pounds average with the 18.1 FX pellets at a regulator output pressure of 125 BAR. SUCCESS!
But... wait! What if, as anticipated, power crept up a little after a few dozen or hundred shots? Remember that fore-thought part?
Yep; that's what happened. Exactly as hoped! To exactly 710 FPS/20.3 FP after about fifty shots. Sure hope that hammer-spring power-nut works well, because MANY DON'T!
Backing off the nut had less effect than expected, but 1-1/4 counter-clockwise revolutions worked pure MAGIC! Results-
18.1 grain FX, 125 BAR reg pressure, Power Level 2, 10 shot string- Low= 701, High= 703, Extreme Spread= 2, Standard Deviation= .8, Average= 701 FPS/19.8 Foot Pounds.
18.1 grain FX, 125 BAR reg pressure, Power Level 4, 8 shot string- Low= 844, High= 849, Extreme Spread= 5, Standard Deviation= 1.7, Average= 846 FPS/28.8 Foot Pounds.
In over three decades of obsessive chronograph testing of hundreds of airguns of all kinds, the extreme spread and standard deviation in red above are the lowest I've ever seen.
Individuals with immensely more airgun regulator experience than me have shared their knowledge and advice to help guide my clumsy airgun monkeying efforts
. More specifically, one individual with immensely more airgun regulator experience than me has selflessly shared his invaluable knowledge and advice to help guide those efforts. Many reading this will recognize him.In our conversations about airgun tuning and regulators Derrick often alludes to a 'sweet spot' balance of reg pressure and hammer-blow where regs perform best. And although I've seen glimpses of evidence confirming the reg basics he's explained, none so poignantly graphic as I stumbled into above. I can't thank you enough for sharing your knowledge, DW! Or enduring my creeping dementia
!That said, don't expect any mercy out there on the Extreme Pistol FT course. No mercy! But I know you'd have it no other way.
With Black Magic's chopped barrel and shroud scheduled to go away for threading to reattach the shroud top-hat/moderator-attachment today, yesterday was my only opportunity for accuracy testing for a while. Of course the winds were hideous; gusting all over the place to 25-30 MPH. Nevertheless, as is my habit, I decided to quantify accuracy best as possible in the near-gale-force conditions by shooting four consecutive five-shot groups at 50 yards from stool-and-bipod field target position, followed by four more groups from sand-bagged bench-rest. It proved a most 'interesting' exercise.
Considering the wind conditions, I was (again) quite pleasantly surprised to achieve a 1.30" c-t-c average from the stool-and-bipod FT position (bottom-most four groups below). That comparing favorably to my abilities in good conditions, I took it as a good sign of the pistol's capabilities in human hands. Correction- sub-human hands!
Upon moving to the bench, it was no surprise to see my point-of-impact move up and right about 1" (top four groups below). Changes of POI are normal with any rifle or pistol from drastically different positions and rests. It was also no surprise to see the bench-rested groups' average calculate to no better than 1.07" c-t-c, given the wind conditions. More specifically, given ONE SHOT opened-up one group considerably due to a sudden, momentary lapse in gusts not noticed until that shot broke. That stated, I have no doubt Black Magic will average 3/4" c-t-c or better groups at 50 yards in still conditions; because, no doubt, the hideous winds accounted for at least .32".
However a huge surprise was the relatively small difference of only .23" between the bench-rested and FT position results. I'll explain that like this- ONE experiment should not be construed as conclusive.
Unfortunately it will be a while before the threaded barrel and shroud return to conduct more testing. Regardless, suffice to say I couldn't be happier with how this conversion has gone so far.
I really, REALLY look forward to testing at Power Level Four upon return of the threaded barrel and shroud...
WITHOUT HEARING PROTECTION! "Say what?"
Last edited:
