Ok I braved the cold weather and headed out to the range to do a magazine accuracy comparison. I'm posting a 3x5. My results are surprising and CONFIRM that if the rounds are not loaded perfectly, accuracy goes to hell. Why?.... I found an issue with my BETA PITA Sled.
Excuse list: Its COLD, 39 degrees, and I was literally being buried in 5.56 and 7.62 casings by 2 guys shooting to the left of me. I didn't mind it, but it threw a few of my shots off.
50 yd, FIRST TIME using Eley Edge in the rifle, and it LOVED it. First 5 test shots off target were 1 ragged whole. Which I lol'ed and thought, well that will be the best group of the day since its not on the target I want to take a pic of!
Broken down by rows:
Row 1 = 15 rnd stock mag
Row 2 - 10 round clear mag
Row 3 - BETA PITA sled
Let me discuss each row after you see the pic. Each of the circles are 1 inch diameter. (Just trace a $0.25 piece. They are .995 of an inch. Cheap way to test!)
Row 1 - accuracy improved..... as the magazine emptied! Less tension on the rounds as they are fed. Target 1/3 is 5 rounds!
Row 2 - most consistant. Flyers were me. I ONLY loaded 5 at a time in the magazine. Less tension.
Row 3 - WTF?! How is the sled this far off? It took me a bit but I figured it out.
I had SEVERE feed issues with the sled. It made no sense. Keep in mind this is a beta one. When I inserted it I made sure it was far up and clicked. It was seated tight. 2 reasons this result was so bad. First was after the initial shot, the sled was infinitesimally dipping down in the front. Each follow up shot was worse, until I had major feed issues. (Like ejecting when pushing the bolt forward!) It wasn't until the very last target 3/3 that I figured it out. This is because of a burr I have on the front pin of my BETA PITA sled. I'm going to file it down and test again. There is no doubt in my mind the sled should be the most accurate.
Secondly, due to trying to figure out the problem, almost every one of the shots in Row 3 were cold bore. It was 39 degrees with a bit of wind. It didn't take long for the barrel to cool. Also I was REALLY cold by the time I got to row 3. It was almost 2 hours. (Testing, people chit chatting, range going cold for people to put up targets, etc) and I was fighting some shivers.
What do I think this proves:
I believe these results only strengthen the belief that if the rounds are not fed perfectly, the accuracy will be off. When looksing at the rounds that failed to feed right on the sled they were nicked. When looking at the rounds with teh highest tension that cause rough feeding and nicks, they were the worst performing. Looking at the mag with the least wiggle, and only 5 rounds for less tension, the results were much better.
I would REALLY love to see someone else with a 10 rnd mag and a sled do this same test!