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Posted: 3/25/2010 2:21:27 PM EDT
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I decided to load up some prvi 62 gr, ss-109's today using AA-2230 powder, LC brass and cci 450 primers,
fired with open sights at 80 yards. 2.2630 OAL. The loads were five each of the following weights with results: 1) 24.4 grains - 2-1/2" group 2) 24.7 grains - 1-1/4" group, (best one) 3) 25.0 grains - 4.0" group, shot high, blew out 1 primer 4) 25.3 grains - 4-1/2" group, shot higher, blew out 2 primers The difference in accuracy going from load 2 to 3 was drastic. 25 grains was obviously getting too hot! Is it normal for there to be such a difference in accuracy with just .3 grains of powder difference in 5.56? |
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Quoted: I decided to load up some prvi 62 gr, ss-109's today using AA-2230 powder, LC brass and cci 450 primers, fired with open sights at 80 yards. 2.2630 OAL. The loads were five each of the following weights with results: 1) 24.4 grains - 2-1/2" group 2) 24.7 grains - 1-1/4" group, (best one) 3) 25.0 grains - 4.0" group, shot high, blew out 1 primer 4) 25.3 grains - 4-1/2" group, shot higher, blew out 2 primers The difference in accuracy going from load 2 to 3 was drastic. 25 grains was obviously getting too hot! Is it normal for there to be such a difference in accuracy with just .3 grains of powder difference in 5.56? I think the real question is how accurate YOU are with open sights at 80 yards. Are you an accurate enough shooter with this setup to tell if one is better than the next? I use a 1-9 scope on my AR at 100 yards at a benchrest to work up accuracy loads. 4" groups is par for the course with open sights for me... the 1-1/4" group with open sights at that range seems pretty dang good - the question is whether it's repeatable or just a lucky group? And I probably would have skipped shooting the 25.3 grain rounds after blowing out a primer... Is the primer pocket too loose, or are there signs of high pressure or something wrong with the gun? I'd diagnose this before shooting more... ETA: to answer your question, I've seen some fairly broad differences on certain loads with just 0.2 grains difference in charge depending on the bullet & load. Heck, I've got one sitting on my wall showing trickled charges with a 4-1/2" group with 24.6 grains of N140 & Hornady 68 Grain HPBT, then a 1.2" group just after it with 24.8 grains of N140... so, yeah... |
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Quoted:
I decided to load up some prvi 62 gr, ss-109's today using AA-2230 powder, LC brass and cci 450 primers, fired with open sights at 80 yards. 2.2630 OAL. The loads were five each of the following weights with results: 1) 24.4 grains - 2-1/2" group 2) 24.7 grains - 1-1/4" group, (best one) 3) 25.0 grains - 4.0" group, shot high, blew out 1 primer 4) 25.3 grains - 4-1/2" group, shot higher, blew out 2 primers The difference in accuracy going from load 2 to 3 was drastic. 25 grains was obviously getting too hot! Is it normal for there to be such a difference in accuracy with just .3 grains of powder difference in 5.56? Yes when you are near a max load. With 62 gr SS-109's and AA-2230, 24.5 grs is my load. 25 was too hot in my AR, so I backed off 1/2 gr and all is good. I'm using LC brass and Win SR primers. Good luck |
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Oh wow, my loads were conservative!
I hate goign to the range with family because i only got to test one powder charge. Using LC 07 brass, CCI military primer and 23.6gr of AA2230 I was getting 4 rounds within an inch, but then my fifth round was far off. Now my barrel is rated 2-2.5MOA, but i was trying out a new two stage trigger and I was honestly shooting sometimes when i wasnt exacly expecting it so either the fifth shots were the ammo, or just me. I want to go much higher though because i want to raise the velocity a bit, unfortunetly every local place is old out of AA2230. |
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Quoted: Quoted: I decided to load up some prvi 62 gr, ss-109's today using AA-2230 powder, LC brass and cci 450 primers, fired with open sights at 80 yards. 2.2630 OAL. The loads were five each of the following weights with results: 1) 24.4 grains - 2-1/2" group 2) 24.7 grains - 1-1/4" group, (best one) 3) 25.0 grains - 4.0" group, shot high, blew out 1 primer 4) 25.3 grains - 4-1/2" group, shot higher, blew out 2 primers The difference in accuracy going from load 2 to 3 was drastic. 25 grains was obviously getting too hot! Is it normal for there to be such a difference in accuracy with just .3 grains of powder difference in 5.56? Yes when you are near a max load. With 62 gr SS-109's and AA-2230, 24.5 grs is my load. 25 was too hot in my AR, so I backed off 1/2 gr and all is good. I'm using LC brass and Win SR primers. Good luck same load i use, i have thousands of these loaded..very consistent and great groups for a mil projectile! |
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I think the real question is how accurate YOU are with open sights at 80 yards. Are you an accurate enough shooter with this setup to tell if one is better than the next? I use a 1-9 scope on my AR at 100 yards at a benchrest to work up accuracy loads. 4" groups is par for the course with open sights for me... the 1-1/4" group with open sights at that range seems pretty dang good - the question is whether it's repeatable or just a lucky group? And I probably would have skipped shooting the 25.3 grain rounds after blowing out a primer... Is the primer pocket too loose, or are there signs of high pressure or something wrong with the gun? I'd diagnose this before shooting more... ETA: to answer your question, I've seen some fairly broad differences on certain loads with just 0.2 grains difference in charge depending on the bullet & load. Heck, I've got one sitting on my wall showing trickled charges with a 4-1/2" group with 24.6 grains of N140 & Hornady 68 Grain HPBT, then a 1.2" group just after it with 24.8 grains of N140... so, yeah... [/quote] I agree I probably should not have fired the 25.3 gr. loads! The primer pockets were all uniformed and the primers had a nice, tight fit. At 80 yds. I have my good days and my not so good days with accuracy but this time I took my time and was calm. One of these days I'll get a scope but I want to take a highpower class and be as familiar as possible with good 'ol irons for now. The barrel is a 20" 1/9 twist chrome lined Model 1 Sales. I've loaded AA2230 with Win. SR primers and the CCI 400's. They seemed to shoot a bit more sooty than the CCI 450's. |
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Quoted:
I have a number of loads with the same bullet and case specs but instead of AA-2230 I'm using H335 (25.0 gn). Anyone know which powder burns hotter? This kinda has me a bit concerned as that I haven't tried 'em out yet. With 62 gr SS-109's I use 25.0 grs H-335 also. I got pressure signs at 25.5 grs and droped the load a half grain. LC brass, Win SR primers. I seat bullets to mid cannelure and lightly crimp with a Lee FCD. I have no idea which powder burns hotter. That's something I would never worry about with this load. |
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