codyadams
Well-Known Member
Those were into ballistic gel.Thanks thats great to see they expand well below 1700 fps, what did you shoot them into for your test?
Those were into ballistic gel.Thanks thats great to see they expand well below 1700 fps, what did you shoot them into for your test?
They recommend a minimum of a 10 twist, not a big difference but obviously enough, plus if it's a button rifled barrel, there is the possibility of the twist being slightly off one way or another. Not as likely with a single point cut. I have heard of people with button rifled barrels being off by a half inch or more! I prefer to go even tighter than the minimum, went with a 7.5 twist in my wife's Sherman max to make sure it will work with the monos I plan on running in it.I bought some 178's for this past season elk hunting. Loaded in my 10.25 twist 300 WSM and no go keyholes,at 100.
My "10-twist" Lilja button rifled barrel turned out to be a 10.55 twist. I only order cut rifled barrels, after that realization.They recommend a minimum of a 10 twist, not a big difference but obviously enough, plus if it a button rifles barrel, there is the possibility of the twist being slightly off one way or another. Not as likely with a single point cut. I have heard of people with button rifled barrels being off by a half inch or more! I prefer to go even tighter than the minimum, went with a 7.5 twist in my wife's Sherman max to make sure it will work with the monos I plan on running in it.
Do you have a method to trigger a LabRadar at 800yds, to catch the bullet velocity down range? I didn't know that type of down range bullet velocity measurement was possible with a LabRadar...I do plan on experimenting in the future, by putting a lab radar behind a steel target at range, say 800 yards, and fire shots past it to get a reading at range, in conjunction with recorded muzzle velocities of the same shots to get a 100% accurate bc calculated by velocities at different ranges.
I would think if an air rifle will trigger the labradar with the external mic, that the hypersonic crack of the bullet would do it as well. My plan was to have a target made with a 6x6 cutout in the middle, and large enough to protect the radar from misses, and shoot through the hole to record velocities. I haven't tried it so not certain it would work, but in theory I think it would.....Do you have a method to trigger a LabRadar at 800yds, to catch the bullet velocity down range? I didn't know that type of down range bullet velocity measurement was possible with a LabRadar...
Ya, I hope it would work, I have had hypersonic bullets fly pretty close past me, and I know without a doubt it's louder than my moderated pcp rifle, so I THINK the external mic trigger would work......Well let me know if it works Cody. When I purchased my LabRadar, I talked to one of their sales reps and he told me it wasn't possible to record down range velocities. But that's been maybe 3 yrs ago. So if it is possible, I'd like to do that also.
Even with out collecting down range velocity, I do calculate a bullet BC values over the first 80-100yds of bullet travel with my LabRadar. Just involves some time with my ballistics software. Some trial and error on BC values until I arrive at a BC that matches the velocity decay over the first 80-100yds. Sometimes I'll record velocity all the way out to 100yds,which is nice. But I generally catch bullet velocities over the first 80yds. If I shoot 3, 4, or 5 bullets, I'll average their velocity at 0, 20, 40, 60, 80, 100yds. And then tweak the input BC value with my ColdBore 1.0 ballistic program until I get a good velocity match at those yardages. It's pretty darn close. Gives a high end BC value because I'm determining the BC at the bullets highest velocity from my rifle. And we know bullet BC value decreases as velocity decreases at longer ranges.
I have a triplicate optical chronograph setup, and have used it to collect bullet velocity at 1000yds. Two Oehlers and One PACT chronograph set up on a single skyscreen rail. I protected the skylights with an AR500 steel plate. Had to have good conditions to place the bullets over the skyscreens at 1000yds. The AR500 plate kept me from destroying my 7 skylights on a few errant shots. I'd receive 4 separate velocity recordings using that setup (2 from the Oehler 35P), so I had high confidence in the values when all recorded velocities were in agreement. But the LabRadar would be much simpler (more forgiving on bullet placement) if it could triggered "on" by the sonic crack of the rifle bullet.
How have you found the Cayuga projos relative to the Badlands Gen II for pressuring up? I run the 7mm 150 Badlands Gen 2's at 3,711 fps. Could I expect the Cayuga 151's come out about the same?Ran a bc test on the 127 .270 Cayuga, not with a lab radar, just the ol shoot and see method. Zeroed at 100, shot at 300, 510, and 896. Didn't take pics of the 300 yard group, it was exactly POA and that close really doesn't interest me. Here is the 510 and 896 yard groups.
The 4 darker impacts are 510, the far left impact was due to the 10ish mph wind (gusting from 5 to 12 mph) dropping off significantly. Then the three lighter impacts were at 896. I was going to run it out to 1200+ yards, but ran out of light. For reference, the black dot is the bottom of a spray paint can.
Out to this range, the G7 bc Josh states of .245 is shaking out very close. 25" barrel running supressed, Arken EP-4 optic.