Red box arrived today with 153 gn Atips. Looks like a great bullet.
But: it is a very long bullet! Does it really truly stabilize out of a 1:8 twist 6.5 mm barrel? Anybody shot them out to 1000 yards yet, with no keyholing?
Only issue i have seen so far is that if you drop a loaded round on the tip, it will deform. Tip is quite soft. Handle them with care!
What speed are folks getting in a 24 or 26” barrel out of a 6.5 Creedmoor?
View attachment 7272015
Done some pressure testing with the 153 Atip bullet at 450 yards:
Happy to report that the 153 Atip stabilizes just fine out of an 8 twist 26” barrel at anything above 2400 fps (started very low and worked up). That is a pretty remarkable achievement for such a long heavy bullet. Compare that with the 150 gn Sierra SMK that requires a 7.5 twist barrel, which almost nobody is running today.
Accuracy was superb with all three powders. Groups were usually below 1.5” to 2” from a rickety table at 45 yards. Pretty sure i can do better from a more stable position. Well, maybe... ?
Tried three different powders so far, but did not reach max pressure yet, so will have to load higher. Was able to achieve higher speed than i anticipated for such a heavy bullet in the tiny 6.5 Creedmoor case: Got to 2785 fps without pressure signs, using Hodgedon Superformance, but still experimenting with different powders. [Will not use Superformance for anything but a hunting load, and was just curious what it would do. Not the ideal powder for a competition load.]
So far tried H4350, Superformance, and RL-17 and none of them reached max pressure, probably because the bullets are loaded ridiculously long, so more effective case capacity. Plan to try Varget as well and Win760.
BTW: Not recommending RL-17 because it is very temperature sensitive, just have it on hand so tried it. RL-26 might be better from a temp stability perspective.
At the upper speed range, recoil was significantly higher compared to the 140’s, it felt more like a 308. No surprise there.
Still a work-in-progress, will report more results once i have tested a few more powders.
Question: What powders have you guys tried for the 153 Atip, and which gave best accuracy and speed?