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spudtech rifled barrel tests
indoor range: 50 feet
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The first test was conducted at our indoor range at a distance of 50 feet from target to muzzle. The target was a large sheet of paper which would record the shots as holes. A plastic splash guard was set up to contain some of the mess. The launcher used was our L1, 2600cc chamber with direct propane and dual spark. The fuel mix for all of the tests was 37 PSI using a 41cc meter pipe giving a calculated mix of 4% propane to air.
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The combustion chamber was attached to Hollywood style "shorty" C-stands using mafer clamps. The stands were weighted down with sandbags and fitted with nonskid feet. A third stand secured the barrel near the muzzle allowing quick barrel changes. This setup did not move at all, the laser sight came up in the same spot after each shot and after each barrel change. A high speed video did reveal a slight flexing of the stands and the barrel.
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The ammo for this test was hand selected Russet and Baby Red potatoes. 6 shots of each were fired through the rifled and smooth bore barrels. The Red potatoes created a slug 1.75" thick and the Russet slugs were about 2" thick. The slug cutter used works great but the speed and simplicity of the breech barrel knife on the SpudTech barrel was the clear winner.
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The thinner profile of our modified barrel knife created tight fitting, cylindrical and unfractured slugs. Everything was in place to begin shooting.
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Our test bed was set up at a 50' distance and sighted in using the laser and by looking through the barrel from the rear. The chamber was vented after each shot by removing the barrel and end cap. A roll up door is open behind the camera provided fresh air. Just a couple shots indoors can bring carbon monoxide to dangerous levels. Always shoot in a well ventilated area.
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The propane pressure was monitored on every shot although it didn't move. It stayed at a constant 37 PSI throughout the tests. Here the gas pressure is being checked by the flame of a lighter. This shows either confidence in design and construction or a total lack of common sense.
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The tests proceeded smoothly and trouble free. Every shot fired strong without a single misfire. For each shot, the fuel pressure was allowed to equalize inside the meter pipe then the supply valve was closed. The feed valve was opened then closed to charge the chamber. A delay of 5 seconds allowed the propane to mix with the air before the trigger was pulled. The launcher was held in place with one hand on the trigger grip and the other holding the barrel near the muzzle. This test took about 2 hours to complete and through it all the band practicing downstairs played Ace of Spades over and over and over and...
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Both barrels performed well at the 50' distance. The widest spacing is shots #4 and #6 at 24 inches using Russets in the smooth bore barrel. The rifled barrel scored 2 direct hits and a tight grouping using the Baby Red's. Most of the slugs stayed together in the air although a few broke up leaving small secondary holes in the target. There's no need to plot or graph this target, the results are pretty clear. They both work good at 50 feet. The advantage goes to the rifled barrel for its' tight grouping with the Baby Reds. The rifled shots also seemed quieter in the air with less tumble or spiraling. The outdoor tests at 150' would paint a better picture of the rifled barrel performance. We cleaned up the mess and packed it in for the night.
If you like to gamble, I tell you I'm your man,
You win some, lose some, all the same to me,
The pleasure is to play, makes no difference what you say,
I don't share your greed, the only card I need is
The Ace Of Spades
Motorhead, 1980
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