Ok...so it shot well in load development and practice over the winter, but now it's warm out, they're not shooting well, and it's the bullet's fault?
I don't know whether it is the bullet's fault or not. The shooting friend who is paying for the bullets is unwilling to buy another box of 186 Juggs and has bought a box of 185 TMKs to work with. They suspected irregularities in the bullet tips to be a source of trouble and were convinced that bullets with more regular tips shot better.
With the care we took adjusting powder charge and OAL in the initial development, and the choice of a Hodgdon Extreme powder, I would not have expected temperature changes from the 50s to the 80s to change the accuracy or velocity significantly.
One also cannot rule out shooter error, but since I am not personally the shooter, that issue is hard to gauge. I am supporting a shooting friend the best I can. But since it's not my money, the final say in component choices is not mine. The friend is a pretty good shooter, and their scores have dropped significantly from last season shooting this bullet.
Added to that, you have no idea if or how the velocity might have changed as the temp increased?
Hodgdon makes very specific claims for their Extreme powders, do you have a good reason to doubt their claims? I've seen temperature sensitivity in the RL series, but not in the Extreme series other than this possible case.
I hate to tell you but your luck with the 175 TMKs isn't likely to be any better if that's the level of attention you give to your loads. Velocity measurement as temps rise during spring/summer is an absolute must if you do load the initial load development during the colder months.
A LabRadar was ordered last fall, promised imminently throughout the winter, and finally arrived in May. I understand the importance of velocity measurements, but we weren't willing to spring for something to replace our older optical chronographs (which became unreliable) while waiting for the LabRadar. When the LabRadar finally arrived, we were able to successfully chronograph a number of 30 caliber bullets, including AMAX, VMAX, Barnes, Ballistic Tip, etc., but the LabRadar failed to read with a dozen or so shots with the 185 Jugg.
With Extreme powders, my reloads have managed to win a lot of matches, including some national matches, without always measuring velocity. So while velocity measurements can certainly help, they are not essential to success, and one can move forward productively when equipment or other circumstances prevent velocity measurements.
You're certainly welcome to try the TMK, but I think you'd be far better off properly adjusting your load with the Jugs as opposed to going to a totally new bullet.
Confidence is a big part of shooting success. It may not be completely justified rationally, but if the shooter has lost confidence in the bullet, it is likely time to change. The plastic tipped TMKs were compelling due to the tip variations noticed in the Juggs. Having been reloading for 20 years, I am also of the view that a new bullet can be more likely to succeed once a given bullet has performed well in load testing and practice but poorly in the field.
For starters, the TMK is a secant ogive bullet. They are reputed to be rather finicky with regard to seating depth. You may not even be be able to seat them properly/optimally in a chamber throated long enough for the Jugs. That's a lot of time and effort if it turns out you can't.
We've had success with a lot of secant ogive bullets without getting them into the lands. Consistent 0.5 MOA is all we are looking for.
If you have acquired a bad opinion of the Jugs and simply don't want to stay with them, I'd suggest trying the 185 Hybrids rather than a 175 gr bullet, especially as your chamber was cut for the Juggernauts. The Hybrids are only about .010" longer in the bearing surface than the Jugs, and have a slightly higher BC. Both are significantly longer in the bearing surface than the TMK.
That's something to keep in mind if the TMKs don't work out. But given the difficulties finding Berger bullets consistency, the observed issues with the tip, and the extra cost of the Bergers, it wouldn't surprise me if something else like the AMAX was next in line to try.
I have a high opinion of the Jugs, another shooter in our group has had great success with shooting them very fast well off the lands. But I've also experienced the fact that not every rifle likes every bullet.
I've recently been shooting the 185 Hybrids in a rifle chambered with .180" freebore using H4895/Palma brass/small rifle primers and so far the load is working very well. This load is centered on an OBT node (node 4, 30" barrel) and is giving me ~ 2775 fps. The 185 Hybrids are seated at ~.010" off the lands and the COAL is 3.064".
Frankly, the .180 freebore is quite a bit more than is necessary, I wasn't paying as close attention to the 185 Hybrid dimensions as I should have been when I had Kiff work up the reamer. However, it's working just fine. The .168" freebore PTG reamer designed for the Jugs would work very well. You could load them easily with even less freebore than that and still keep the boattail/bearing surface junction above the neck/shoulder junction. However, H4895 will push the pressure up there in order to hit OBT node 4, so IMO, Palma brass is a no-brainer.
Lots of practical advice and good information there, thanks.
Load specifics really are meaningless without knowing your chamber specs, case volume, etc.
More information is always better than less. The manuals have loads for generic or different bullets of that weight loaded to the SAAMI OAL spec. QL gives some info for that specific bullet and different OALs. More data for that bullet and powder would not be a perfect recipe, but it would be more information close to what we are trying to do.
But you should be looking for somewhere in the neighborhood of 2750-2775 fps with H4895 and a 185 gr bullet. According to Quickload, this will give pressures in 61-62K psi range, so standard brass may not hold up so well. With sufficient freebore, somewhere in between 43 and 44 gr of H4895 is where you'd likely end up with a 185 gr bullet, probably closer to the low end than to 44 gr. But again, your chamber and case volume will dictate the correct charge weight. I wouldn't suggest starting out any higher than 43 gr (or slightly less). I have used both Varget and H4895 with the Juggernauts, and now H4895 with the 185 Hybrids. H4895 will usually give you about 25-30 fps greater velocity at the OBT node, with comparable ES/SD and precision in my hands. But the pressure may be just a tick higher with H4895. Either one seems to work very well with bullets in that weight range out of 30" barrels.
Having had high pressure issues before and short case life, odds are we're not going to chase the 4th OBT node and settle for a velocity closer to the 5th, letting group size rather than barrel time tell us what the rifle likes. However, since QL suggests we might get to 44 grains of H4895 with the 175TMK, we might go that high and see what happens. It would be nice to have feedback from someone who has worked with the 175 TMK and H4895.
Thanks for the feedback.
