Laser vs A-Tip Velocity?

[Taylorbok]

After you mentioned the Extraction groove I went and measured some against a fresh case and there was no expansion there at all.

I recognize there's tons of reason to use the Lasers but splash can be very difficult to see at this venue, and the match can basically be won inside of 2500 yards. We'll see where my distance testing shows favor but the splash off the A-tips might be beneficial.

Ya I know not to take a clean barrel out for testing or a match. I usually foul in 3-5 rounds which seems to stabilize the barrel for me.

I was actually trying to measure the temp stability of the A-tips load last week when my thermometer gun took a steaming shit and wouldn't read temps anymore. I haven't had a chance to go grab a new one yet. Maybe today. the way I do it is go to the range on about a 70* day and then heat some ammo under the truck heater, it'll get to about 100* and then drop some in a cooler with ice. works well.

I haven't had a chance to monitor cold bore velocities with the same load yet. Hopefully I will get to do a couple of those in the next few weeks.

Either way I seem to have ended up with 2 loads that I should be able to shoot well.

 

[SIDS01]

With the extractor groove, the measurements need to be the same case before and after. Even on the same case they'll need to be clocked. I align with something prominent in the headstamp like the first letter of the manufacturers symbol. The measurements require a blade micrometer with a vernier scale because you're measuring in tenth thousandths. I use 0.000_3" for fireforming improved cases and 8-10 loadings before the primer pockets go. 0.000_5" is more like 6 firings. By 0.001", not all the cases in a batch will be good for 3 firings.

As discussed before, the pressures that all occurs at varies widely with manufacturer. It'll vary by cartridge within a manufacturer as well. The case heads work harden with each shot so different pressure histories will also affect the results.

I've pretty much abandoned all that except for fireforming loads in favor of QL because I've developed ideas about what pressures jacketed bullets and different brass operate at. I also track the start pressure indicated by the current velocities as an indicator of where the barrel is in its life cycle. That also requires tracking ammo temps so it's done every trip. I have a lathe in the garage and favor solutions that use 1.25" barrel blanks I can get from Bugholes. It's just not worth it to waste a trip or components on a barrel that's seen better days. Between ammo, barrel life, gas, and a pizza on the way home, it was $200 for the trip I recorded that video on. Why waste it trying to get a couple more trips out of a $500 barrel? QL is a rabbit hole of its own and the Windows 11 install was a pita so I'm not sure it's the way to go for most.

I feel the same way about solid vs. jacketed splash. Other problems I've had with spotting on solids are whole bullets ricocheting down making it look like a hit below the target. That was more of a problem a few years ago. Hit indicators have improved significantly. Gophers are also more of a problem. Thats when one goes just below the target burrows a bit, hits something and skates across the berm above the target looking like it went a little high. You send the next couple really low and wonder why the fuck the vertical has gone to shit.

Yea, you're well down the road the right direction if you're sorting out the things that affect the actual velocity before the shots happen and figured out that a lot of matches are won on the early targets. I don't think it's any great mystery or a fad that the ATips are popular for light gun.