#11
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My .20-.223AI is about a duplicate and I run the BR-4 with H4895/39 gr. BK's and RL17/55 gr. Berger. I use the 7 1/2 in larger capacity SR primer cases. I will be loyal to the 7 1/2's because when I couldn't get the others Big Green always had primers on the shelf! German Salazar did some testing of primers in a clear tube and the 7 1/2's looked like a blow torch! High brisance may be an understatement!
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"That which does not destroy me, has made a huge tactical error" |
#12
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Considering the current cost of BR-4 primers, I would develop my load around the 7 1/2 primers. Unless you have a full custom benchrest 204 Ruger I really doubt you will see an accuracy difference.
The chart that Chickenthief posted has always been my guide for primers when it comes to cup thickness, but that chart is going on 20 years old. I have to wonder if the data on it is still valid. |
#13
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The BR4's and 450's shoot to the same poi in my 17 Remington, and I really can't tell and difference in accuracy. Larry
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A gun is just like a parachute, if you really need one, nothing else will do. |
#14
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#15
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Pahoghunter, I have not checked the distance off the lands, because in the CZ 527, the limiting factor is the magazine length. Instead of playing with seating depth, I have had to work with powder type and load volume. First I tried IMR 4895 at various load densities, finally settling on 28.5gr, (I went up to as high as 29gr in testing) however I was unhappy with the flier percentage. I decided to try the H335 as that gives decent velocity with lower load density, and finally settled on 26.5 gr as that was giving me the most consistent grouping over 10 shot strings. .204 is a real barrel heating cartridge so I shoot two shots and then allow for cooling before going on with two more etc. If I go with more than two or three shots, accuracy immediately begins to suffer. Also, on the advice of a board member here, I wipe every 20th shot for copper fouling, and that really helps keep the accuracy dialed. The 39 blitz king suffers badly from wind drift. I was out yesterday testing and the wind was switchy, my hold off at 300 yards, was 1.5moa to drop into zero. My vertical though was .75 moa except for the occasional high flier, which was 1 shot out of 10, and was almost always the 3rd shot of a string (I am learning to adjust for the rifles tendency to shoot high as it heat up) I have never posted a picture here, but I will try to get some pics up of my targets so you can dissect the groups and see what I'm talking about here.
Regards, B |
#16
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204r
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#17
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