HyperSnyper
01-18-2002, 03:13 PM
This is a thread I got off the Warpig Forums (http://www.warpig.com/forums/tech/misc/messages/1011048500237.shtml). The poster did testing on numerous guns to dispel the Open vs Close Bolt Markers, and came to the conclusion that it is actually the recoil that affect accuracy.
Here goes:
<B>
Posted by Sgt "Lucky13" Sheehan on January 14, 2002 at 17:48:33:
I've been out of loop on the whole debate for the last 5 months with the military and all, but me and some of my boys ran our own bench tests with a Spyder, Mini-Mag, STO, and an on-loan Shocker SF. Being Dye Boomstick lovers, we had 14 and 12 inch barrels mounted on each, and Uniregs across the board. Brand new Marballizer paint for all, and our markers ready to compare, with two closed bolt and two open.
Bolting a Vise onto a metal table and securing it with a big daddy load of sandbags to keep it stable (overkill to say the least), we had our bench mount for the markers, and locked each one down and zeroed in various dot sights to the center of a test 3 times 5 shot grouping from each marker in turn, and then range tested them from 15, 30 and 45 meter survey points, with a solid wooden 6x6 target board.
The results concurred with Warpigs comparison, in that there was very little difference in grouping in lateral windage shifts (indoor building) and range trajectory was almost identical except where low pressure allowed a straighter power curve during the last 5 meters of each parabola on the Spider and the Shocker. Bear in mind these markers had identical barrels, paint, regulator and fps settings, and all were bench zeroed to the sights and shot while locked down at the various ranges (45 meter shots were extremely random and difficult to set, with a 12 degree loft set on each with the Vise lock)
Surprisingly, the Spyder had a better grouping than the Mag and Cocker, with the Shocker coming in 1st with a good lead in grouping tightness.
SO WHY IS IT HARDER TO HIT WITH AN OPEN BOLT IN PRACTICE(in common opinion)?!?
Flabbergasted I unstrapped the last marker and took some pot shots at the board again, still zeroed to my specs, with all 4 markers. SURPRISE!!
The reason for lost range and accuracy made itself apparent as my assistant observed as I shot from an unsupported standing position. Still zeroed and using Breath, Trigger and Sight Picture control according to standards with each marker, he noted that the Blow Forward designs DIP THE BARREL when fired.
In Military firearms this has the exact same effect. A closed bolt fires the second you squeeze the trigger because the round is already in the pipe and the only thing to do is discharge it, such as with an M-4 and M-16, thus the round leaves the barrel before the recoil can kick the tube up. A M249 SAW however, while using the exact same round and almost identical ballistics, is Open Bolt in that once you pull the trigger the whole bolt carraige assembly slams forward and THEN the round discharges, giving it FORWARD recoil and dropping the barrel, and it's notorious for being innacurate on the first round.
The exact same thing happened while free-hand sharpshooting the Mag and Spyder against the Cocker and Shocker. The mechanical inertia of the bolt ramming into the breach drops the barrel enought to lower your aim point and the trajectory of the ball before it leaves the barrel, what we call Rock and Roll along the GT(Gun to Target) line. The Closed Bolt systems had no real mechanical motion slamming the chassis around, and the gas had expanded with the ball out of the barrel long before the bolt went to the rear for a new round, keeping the firing plane level and stable.
Our findings? On a technical level, there is no ballistic difference between open and closed, but in real world practice, GT deviation really does affect windage and range. Unless you have hands like a vise, you will probably be affected by blow forward rock and roll. Mike's Minimag was significantly less harsh in than the moving(slamming) mechanical parts were lighter and smoother than the Spyders stock internals, which had more mass and a more violent blow forward. The ballistics may be the same when perfectly stable, but a guy running and gunning before he gets bunkered is not a stable platform. Low recoil blow/friction blow forward systems aren't really that bad at all, and can be compensated for easily by bench zeroing a sight and then modifying the zero to compensate the barrel drop at a range you find you typically play at, such as 15 meters, because of parallax. Remember a 2degree barrel drop at 10 feet means little difference, but the GT modifier multiplies that variance the further you get out QUICKLY.
Just our findings, we could be nuts =)
</B>
This was a topic I was always trying to get people at the Spyder Forums to believe in the Spyder Owners forums before I got my Mag. Not that many people believed me. This is the other counter part to LP Spyders. The LP air flow isnt any better than HP air flow. But by cutting the pressure from 800 output to 300 output, in addition to changing the drive springs to weaker ones, to cut recoil down more than half.
The same can be seen in the Mag. If the bolt, which is the only moving assembly in the Mag, is lightened significantly, which is well accomplished with the SuperBolt, then our Gun-to-Target deviation (Mil Jargon I guess) will be completely eliminated.
We may have the advantage even over the other high end electros since our Mags only moving assembly is the Bolt. While most electros still use an electronic 3 way to force a hammer and Bolt forward (more heavier? I have to do more research).
So the conclusion.
Tom, PLEASE PLEASE PLEASE dont give up on the Super Bolt. It will be a complete revoltion to the Mag community, and will heighten our markers over others.
-Hyper
(P.S. Tom, My own thoughts about the cracking Superbolts, could it be from a misaligned barrel due to the "twist-n-locl system. Yous have to admit, no matter how well the machining is done on the barrel, there are only 2 orings stablizing the barrel in place, while more barrels have a more stable fit through metal to metal threading. Just Mu own opinions. Either way, I will be buying a Superbolt very soon once I get my paycheck)
Here goes:
<B>
Posted by Sgt "Lucky13" Sheehan on January 14, 2002 at 17:48:33:
I've been out of loop on the whole debate for the last 5 months with the military and all, but me and some of my boys ran our own bench tests with a Spyder, Mini-Mag, STO, and an on-loan Shocker SF. Being Dye Boomstick lovers, we had 14 and 12 inch barrels mounted on each, and Uniregs across the board. Brand new Marballizer paint for all, and our markers ready to compare, with two closed bolt and two open.
Bolting a Vise onto a metal table and securing it with a big daddy load of sandbags to keep it stable (overkill to say the least), we had our bench mount for the markers, and locked each one down and zeroed in various dot sights to the center of a test 3 times 5 shot grouping from each marker in turn, and then range tested them from 15, 30 and 45 meter survey points, with a solid wooden 6x6 target board.
The results concurred with Warpigs comparison, in that there was very little difference in grouping in lateral windage shifts (indoor building) and range trajectory was almost identical except where low pressure allowed a straighter power curve during the last 5 meters of each parabola on the Spider and the Shocker. Bear in mind these markers had identical barrels, paint, regulator and fps settings, and all were bench zeroed to the sights and shot while locked down at the various ranges (45 meter shots were extremely random and difficult to set, with a 12 degree loft set on each with the Vise lock)
Surprisingly, the Spyder had a better grouping than the Mag and Cocker, with the Shocker coming in 1st with a good lead in grouping tightness.
SO WHY IS IT HARDER TO HIT WITH AN OPEN BOLT IN PRACTICE(in common opinion)?!?
Flabbergasted I unstrapped the last marker and took some pot shots at the board again, still zeroed to my specs, with all 4 markers. SURPRISE!!
The reason for lost range and accuracy made itself apparent as my assistant observed as I shot from an unsupported standing position. Still zeroed and using Breath, Trigger and Sight Picture control according to standards with each marker, he noted that the Blow Forward designs DIP THE BARREL when fired.
In Military firearms this has the exact same effect. A closed bolt fires the second you squeeze the trigger because the round is already in the pipe and the only thing to do is discharge it, such as with an M-4 and M-16, thus the round leaves the barrel before the recoil can kick the tube up. A M249 SAW however, while using the exact same round and almost identical ballistics, is Open Bolt in that once you pull the trigger the whole bolt carraige assembly slams forward and THEN the round discharges, giving it FORWARD recoil and dropping the barrel, and it's notorious for being innacurate on the first round.
The exact same thing happened while free-hand sharpshooting the Mag and Spyder against the Cocker and Shocker. The mechanical inertia of the bolt ramming into the breach drops the barrel enought to lower your aim point and the trajectory of the ball before it leaves the barrel, what we call Rock and Roll along the GT(Gun to Target) line. The Closed Bolt systems had no real mechanical motion slamming the chassis around, and the gas had expanded with the ball out of the barrel long before the bolt went to the rear for a new round, keeping the firing plane level and stable.
Our findings? On a technical level, there is no ballistic difference between open and closed, but in real world practice, GT deviation really does affect windage and range. Unless you have hands like a vise, you will probably be affected by blow forward rock and roll. Mike's Minimag was significantly less harsh in than the moving(slamming) mechanical parts were lighter and smoother than the Spyders stock internals, which had more mass and a more violent blow forward. The ballistics may be the same when perfectly stable, but a guy running and gunning before he gets bunkered is not a stable platform. Low recoil blow/friction blow forward systems aren't really that bad at all, and can be compensated for easily by bench zeroing a sight and then modifying the zero to compensate the barrel drop at a range you find you typically play at, such as 15 meters, because of parallax. Remember a 2degree barrel drop at 10 feet means little difference, but the GT modifier multiplies that variance the further you get out QUICKLY.
Just our findings, we could be nuts =)
</B>
This was a topic I was always trying to get people at the Spyder Forums to believe in the Spyder Owners forums before I got my Mag. Not that many people believed me. This is the other counter part to LP Spyders. The LP air flow isnt any better than HP air flow. But by cutting the pressure from 800 output to 300 output, in addition to changing the drive springs to weaker ones, to cut recoil down more than half.
The same can be seen in the Mag. If the bolt, which is the only moving assembly in the Mag, is lightened significantly, which is well accomplished with the SuperBolt, then our Gun-to-Target deviation (Mil Jargon I guess) will be completely eliminated.
We may have the advantage even over the other high end electros since our Mags only moving assembly is the Bolt. While most electros still use an electronic 3 way to force a hammer and Bolt forward (more heavier? I have to do more research).
So the conclusion.
Tom, PLEASE PLEASE PLEASE dont give up on the Super Bolt. It will be a complete revoltion to the Mag community, and will heighten our markers over others.
-Hyper
(P.S. Tom, My own thoughts about the cracking Superbolts, could it be from a misaligned barrel due to the "twist-n-locl system. Yous have to admit, no matter how well the machining is done on the barrel, there are only 2 orings stablizing the barrel in place, while more barrels have a more stable fit through metal to metal threading. Just Mu own opinions. Either way, I will be buying a Superbolt very soon once I get my paycheck)