12-10-2023, 02:25 AM
Supposedly there is a concern with loads where if the bullet protrudes too far inside the case causes something called a "donut" reducing brass life. Ive never encountered it so I cant say for sure.
I do know less case volume reduces velocity potential, and can increase pressure. Ideally, I try to choose bullets that dont protrude past the case shoulder for any caliber. The Grendel is a short case already, and if your loading to fit an AR magazine you don't have many options to seat a bullet longer than saami max. If you want to use a heavier bullet its a trade off with lower velocity. If a bolt gun, having a smith throat the freebore longer I think would get some great velocity out the Grendel with the longer bullets.
I don't know how to literally measure compression, but I have a trick that lets me seat my longer bullet without compressing the load. Keep in mind that you might not actually be compressing, but rather displacing the powder around the base of the bullet. There are some tricks to helping compress powder before seating. Long powder funnels help compact the powder as its poured in. Ive never used one so cant say how well. Vibration is what works really well for me. The bullet I'm loading is just a bit longer than I would prefer (1.135" long) and just barely protrudes past the lower shoulder jct, before I seat the bullet I hold it against a hand engraver which vibrates the powder compressing it. A .257cal bullet barely slips in a sized grendel case neck and I can watch it move down by about .1" as it vibrates (this is probably the only way to measure powder compression, before and after vibration). After that, the 6.5 bullet seats in without any compressing that I can "feel" when seating. It only takes about 5 seconds to vibrate the powder that way. If you don't have a hand engraver, you can repeatedly tap the case for a while and get the same effect, it just takes too long to be practical.
I do know less case volume reduces velocity potential, and can increase pressure. Ideally, I try to choose bullets that dont protrude past the case shoulder for any caliber. The Grendel is a short case already, and if your loading to fit an AR magazine you don't have many options to seat a bullet longer than saami max. If you want to use a heavier bullet its a trade off with lower velocity. If a bolt gun, having a smith throat the freebore longer I think would get some great velocity out the Grendel with the longer bullets.
I don't know how to literally measure compression, but I have a trick that lets me seat my longer bullet without compressing the load. Keep in mind that you might not actually be compressing, but rather displacing the powder around the base of the bullet. There are some tricks to helping compress powder before seating. Long powder funnels help compact the powder as its poured in. Ive never used one so cant say how well. Vibration is what works really well for me. The bullet I'm loading is just a bit longer than I would prefer (1.135" long) and just barely protrudes past the lower shoulder jct, before I seat the bullet I hold it against a hand engraver which vibrates the powder compressing it. A .257cal bullet barely slips in a sized grendel case neck and I can watch it move down by about .1" as it vibrates (this is probably the only way to measure powder compression, before and after vibration). After that, the 6.5 bullet seats in without any compressing that I can "feel" when seating. It only takes about 5 seconds to vibrate the powder that way. If you don't have a hand engraver, you can repeatedly tap the case for a while and get the same effect, it just takes too long to be practical.