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Posted: 1/22/2003 6:05:35 PM EDT
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I have an A1 20" that shoots fine with Q3131A, but short strokes whith .223 55gr v max loaded to 3100fps accoring to the box. any suggestions? Thaks |
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That 3100 fps is likely measured out of a 24" test barrel which would produce sinificantly higher velocities than a 20" AR barrel. If your rifle is functioning fine with Q3131A which is M193 spec, the problem is most likely the ammo. You could always cut a few coils off a spare stock spring and use that as you VMax spring. |
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DFBonnett has touched on the problem, but I will go into a little more detail. The v-max load was designed for a bolt-action rifle with a longer barrel. This means that the gunpowder used is a slower burning power than the standard powders used in an AR rifle. The slower burning powders will get the round up to speed on a longer barrel (longer burn duration), but on the short 20" barrel with the gas port inches before the muzzle, the powder has yet to achieve the need barrel pressure to action the rifle, once the bullet has passed the gas port. Due to this, the gas pulse to the bolt is very weak. The solution is to find/reload a round that uses faster burning power that will pressurize the barrel before the round reaches the gas port. As for clipping the a recoil spring, what you may solve with the short stroking, may turn into a feeding problem due to the lack of force that the return stroke may have to strip a round from the mag and lock the bolt. The correct solution is to use the correct type of gunpowders that will function in the rifle. But, if the rig is set up for long range shooting only (heaver bullets), and you need to tailor the rifle to work with the slower burning powders, then an adjustable gas tube with a oversized port would be a better solution. The needed gas pressure spike to unlock/action the bolt could be adjusted at the tube to suit the slower burning gunpowder’s, yet be closed down to allow the rifle to function with standard powders. Food for thought. |
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Quoted: Thanks for the info guys. I figured that slower powder was the problem. I had condsidered cutting the buffer spring, but was conserned about unforeseen consequences. The suggestion I offered worked for me in one rifle, a 20" with an A2 barrel of dubious provenance that was fussy about that underpowered Denel that Coles was humping a couple of years ago. Dano223 is the man when it come to this area. Therein lies your answer. |
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