When I made my deliberately too long rounds, I did them in .005 increments. I did three of each and found the rifling contact only occurred (with this particular bullet) when the measured oal was 1.175. Given that my round length variation did not exceed .008 at the worst extreme, setting 1.165 as the absolute max seemed reasonable.
So you've insured the bullet is not into the rifling by pure mathematical means. That is commendable and a VERY workable solution. Most people don't think like that, that's why I checked. They think like, "I'm not touching, therefore I'm safe." Manufacturing tolerances never enter their mind.
But, in point of fact, my accuracy suffers more with greater oal, so I will run a batch at 3.7 gr of Titegroup at shorter lengths and test those with a chrono and for accuracy, and dummy loads for magazine function. Looking at what I've done so far, I think mysweet spot for IDPA ammo will be around 1.125 with 3.6-3.7 of TG for a 124gr HBRN Berry bullet.
Depending upon your bullet ogive shape, bullets set to a longer OAL can be knocked off center as the slide
slams the bullet up the feed ramp. I used to load 9 longer (1.150-1.160), but now like you, I'm starting to recess them back into the case another .030". This does improve the accuracy.
This is a good move on your part.... just don't get carried away! My minimum as a "rule of thumb" is now 1.010".
Question: What's best way to recognize or ensure you don't compress powder? I moved to Titegroup from Unique for that reason as I started shortening and going up in bullet weight (length)...
Use the depth gauge (as in the photo) built into your caliper and measure from the case mouth down to the powder level. Then take your OAL, the case length, and the bullet length and you can calculate how far below the case mouth the bullet's base is sitting. Compare that inset distance to the measured powder height.
TiteGroup is so dense, that you're not likely to get anywhere near it unless you go to 147gr.
