Just screwing around I decide to try some 68gr .224 bullets. They are long -- close to an inch. I decided to go a tad hot on the Unique at 9.0gr with a COL of 2.25" and shot them in the Manual AR -- no sense in messing with a DI AR with that light powder charge. They shot great and figure around 2000fps. Twist rate formula says they are fine in my manual AR with the 1:7 twist barrel so I'll make up a bunch and try them at the range. My lungs kinda went south on me again so I won't see the range for another month.
Last Edit: Jun 5, 2015 10:06:28 GMT -5 by 22boomer
Finally got to the range again to test my manual .223 AR with the 1:7 twist. It was super hot and there was a 4000+ acre brush fire just south of the range -- lucky for me the wind was blowing south so no smoke to screw with my lungs. I shot .223 rounds using Unique from 6.0gr to 6.5gr with the Barnes 30gr varmint grenade and they all shot within 0.5" at 50 yards. Then I went to shooting Hornady 40gr V-max with 9.5gr of Unique and got the same accuracy. The 9.5gr of Unique probably put the velocity up around 2800fps. I had brought my chrony but with it being so hot I just wanted to check the accuracy and get the heck out of there. One bullet that was a big surprise to me was the Hornady 50gr soft point that was inexpensive but with a charge of 8.0gr of unique and another with 9.0gr of unique they both shot inside a 1/2" at the 50 yard range. there was only a slight difference in the POI. A bullet that did not want to work for me was the Berger 75gr Match Grade. I loaded 9.0gr of Unique under the Berger bullet but I guess I was not pushing the bullet fast enough and the accuracy was horrible. I don't really think I would use that weight bullet anyway but I had to try it to see what happened. They were so long I had to single load those rounds. this project was originally to try and duplicate 22 magnum or maybe do a bit better but I found that with just 6.0gr to 6.5gr of Unique with the 30gr Barnes I could easily do better and make an accurate little varmint round. The rest of the tests were more for fun than anything else although I do want to look into those Hornady 50gr soft points a little more.
I've kinda dropped the 5.7X28 FN cartridge for the time being and have gone to the 7.62X25 Tok cartridge. I did a bunch on loads using different weight bullets in both the manual Tok AR and the short gas system AR. I originally wanted some subsonic loads but because the range was so hot I didn't have a chance to use my chrony and just shot for accuracy. One of the bullets I was shooting was a 130gr cast bullet and I went down to 3.5gr of Tite Group in the manual AR but could not seem to figure where the darn bullets were going so I switched to the rounds I did for the gas system AR with 4.5gr of Tite Group behind the 130gr cast bullet -- got on the target but not good. I just can't seem to shoot cast bullets with any type of accuracy. Later on I discovered the light Tite Group loads in the manual AR were not making it to the target! The wood frame just below where the targets would be set had 30 caliber bullet holes at the exact count of rounds I shot from the manual AR -- darn, those bullets must have been moving slow -- the drop was about 1.5 feet. The manual AR is actually very accurate and the copper jacked bullet loads I did were all in nice little groups on all my targets -- this goes for the gas operated AR also. I was a bit embarrassed about the low shooting bullets and will not be doing that load again.
Last Edit: Jul 12, 2015 10:32:59 GMT -5 by 22boomer
My last session with the 300 blackouts had the same results using Sub loads and the Lee 230 5R boolits. On paper at 50, where are u at 75? Run a spreadsheet using velocity and calculating drop at 16 fps (not the actual math (s=1/2at^2), but just easy to do). At 1000 fps, a bullet will drop 16' the first second. Cast boolits are a game to itself. Again, my last 300 session, the boolits looked great, but way too soft and leaded horribly even at 1000 fps !!!!!
I got some Lapua 100gr HP bullets that I thought would be great and the calculations showed a drop at 100 yards of -0.9" at 2000fps. I did the same calculations for the Hornady 110gr V-max type bullet and came up with the same amount of drop. I would say that the Hornady bullet would make a better hunting round with that ballistic tip over the Lapua bullet since the Lapua bullet is actually listed as a target type bullet and they are more expensive. Picture below is the Lapua 100gr bullet -- it's very accurate but so is the Hornady 110gr V-max. I shoot these along with the Hornady bullets in the 7.62X25 carbine. I got some Moly coated Lapua bullets to try in my 300 Blackout. The Moly coating was done by a gun shop and is not available from Lapua as far as I know.