There is a 0.9 ounce difference in weight between the Triple-K magazine (right) and a genuine Beretta (left) magazine for a Beretta M1951.
Loaded that is 0.3 lb. (Triple-K) vs 0.4 lb. (Beretta).
The Beretta magazine seems to work slightly better. It's worked for a whole box without failures. The Triple-K has a failure to extract about once a box.
Not sure why the magazine affects extraction, but it's real with this pistol.
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ReplyDeleteYour experience is far from unique and not reserved solely for this one firearm. Years ago I picked up a well worn Star B in 9mm with 3 included magazines. Ran out to the range to test it. The gun jammed every 3rd or 4th round with all 3 magazines. Frustrating as heck examined the mechanism inside. The extractor was new and all the parts pretty good in terms of functioning without much side to side wiggle, the gun had been serviced somewhat before being sold off by whatever military or police armory had it. Went and found a brand new Mecgar magazine for the unit. Day and night, the new magazine worked flawlessly. This led me to do what you show in the picture, put old next to new, load both up and take a close look. Turns out the original magazines had worn out/widened the lip on either side, allowing the 9mm round to randomly point upwards far more than what the new magazine allowed. I tried fiddling with one old one to make the lip a bit narrower, but that did not work, simply jammed the round more often. Lesson learned, metal forming and precise angles are important for magazines, in some more critical than others. It is a great "truck" gun, cheap and functional now.
ReplyDeleteOG Star B 9x19mm magazines are designed to work with steel cased WW2 German ammunition. Brass cases are too slippy and you get jams.
DeleteMecgar's replacement corrects this.
Something is rubbing during the recoil/extraction cycle. The loss of energy reduces the slide travel velocity and distance, increasing the probability of extraction failure.
ReplyDeleteLittle differences add up to big changes in probability. I am guessing that the round stands taller in the feed lips, and the slide is dragging on the top round.
The frustrating thing is how inconsistent it is. I should be more precise in saying it happens, on average, every 50 rounds with the Triple-K magazine. I can shoot 300 rounds no problem then have a series of failures all in a row. Then I can have a single failure, clear, and nothing for a long time.
DeleteIf nothing else, it's great for malfunction drills.
The round in the Triple-K does look to sit higher. Critical dimension would be magazine catch surface to top of round. Spring tension may increase drag on the slide. Load 1 or 2 rounds in each mag, place them "head to head" and press together, see which one yields first. Try ammo with a little greater power.
ReplyDeleteThe feed lip contour looks subtly different. Have you tried swapping the speing and/or follower between the two mags (assuming they are compatble). One of the other of those two things are likely to be the difference if it isn't the feed lips.
ReplyDelete