Just finished some load development with a 260 and a 270. The large rifle primers in the 260 has a 50-80 FPS difference and the same for the 270 but using a large magnum primer. The faster velocities were with the federal 210m and 215m.
I have noticed this a constant trend.
Anyone seen the same occurance or even tested their same loads over the chronograph with different primers.
The brass appeared to be in good working pressure limits
260 123sst lapua brass 22” barrel adi 2209 44 gr and 2900fps
270 145 eldx Norma brass 20” barrel adi 2209 54.3gr and 2840 FPS
I have noticed the same with the 300 wm and 338 lapua
I’m pretty keen to see how that 145eldx goes on game I shot it out to 720m on steel today and i had to true the BC up a little to get it right as things were flatter than the geo ballistics showed. it seemed a lot more consistent than the 150sst at that range. I put a couple into dirt at 420 and 720 while getting it doped so I will go and retrieve some bullets to see what they opened up like and will post them later. I have also run some actual dope with the 129 Barnes lrx at that range too and was a good flier.
Hope some of this helps anyone looking into these two relatively new projectiles as there is not much out there on them.
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