Comments by "" (@neutronalchemist3241) on "Ladislav Findorak's Prototype Lever-Delayed PDW" video.

The AA-52 is the French GPMG since 1952.
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Actually the bolt starts moving the same moment the round is fired, otherwise there would be NOTHING pushing the bolt carrier. The lever only forces the bolt carrier to accelerate faster than the bolt, so exchanging mass (that would be required in a simple blowback) for speed (to accelerate a mass at double the speed, you need four times the energy).
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@atomicsmith the only mechanical advantage created by the lever is that the carrier has to move at a faster pace than the bolt, so exchanging mass for speed. The ratio of the pace is decided by the ratio of the leverage. Actually the weight of the bolt carrier is a MAJOR factor in those designs (see for example that of the FAMAS, that's all but "negligible") because the lighter the carrier, the higher the leverage ratio needed to obtain a safe enough locking, but the higher the leverage ratio, the narrower the difference from too early and too late opening. That's why the AA52 is the appreciated and trouble-free French GPMG since 1952 (because a 10kg GPMG can have a quite hefty bolt, that doesn't need so much leverage ratio to delay it's opening) while the FAMAS, that had more stringent weight requirements had a troubled development process (the F1 couldn't even safely fire NATO standard munitions).
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@atomicsmith It's not a mith, it's how physics works. What you call "mechanical disadvantage" is only the mechanical disadvantage of moving a mass. No mass, no disadvantage. The "mass of at least 20lbs to adequately slow a 5.56 casing down" is out of this world. A VERY SAFE formula to calculate blowback bolts weight is to assume a 4m/s bolt velocity is safe, then the required bolt mass is: bolt mass in pounds = 1.09×10-5 * bullet mass in grains * bullet velocity in fps * (diameter of bolt face / diameter of bullet base). According to this formula, .223 Rem requires a 7 pounds bolt. In reality this formula is well known to give bolt masses that are far too high and become exceedingly higher as the power of the round increases. IE, according to this formula, 1.7 pound is required for 9mm Parabellum and 2.3 pounds for .45 ACP. Reality is that it requires a minumum of just 10 ounces for 9mm and 12 ounces for .45 ACP. The reason you don't see direct blowback in rifle calibers is that the mass required is is just too large, but it doesn't come even close to the mass you think is required. The lever of the FAMAS is roughly 3 o 1, thats also the limit where a lever delayed blowback stop working because the difference between too little and too much delay becomes too narrow. The spring rate is static, it doesn't change with acceleration. That's why it's not even considered when calculating the bolt's mass.
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@atomicsmith To accelerate a mass at double the speed in the same time you don't need double the energy, but four times the energy. To triple the speed you need nine times the energy.
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@atomicsmith Sorry, but 7lb bolt / 3 (leverage factor) / 3 (reduction factor based on other calibers, since 10 ounces compared to 1.7 lbs and 12 ounces compared to 2.3 lbs are about 1/3. Let's ignore the fact that the results of the formula are increasingly off as the power of the rounds increase) is 0.78 pounds, not 1.45. You have also to subtract from the 7lbs the weight of the bolt and the weight of the delaying lever (that on average moves at the same pace of the bolt), but let's ignore that too for now. Do you think the bolt carrier on a FAMAS PLUS THE RECOIL SPRING TUBE AND CHARGING LEVER (that recoil with the bolt carrier, also half the weight of the recoil spring contained in the tube should be counted)) has a weight so much different than 0.78 pounds? I should say it's a bit more.
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