Advice: Lead alloy and bhn

[462]

Lamar and Ian: voted "most likely to double" by ASBC seven years in a row.

The Doublemint Twins.

If I ever topped 1900 fps it was not to purposely go fast.

After selling all the old Mausers, the Krag, the Enfields and the K-31s, the 03A3 is the sole bolt action that sees cast bullets. Lyman's 311284 and 18.0-grains of 2400 and the RCBS 30-180-SP with either 13.5-grains of Unique or 20.0-grains of 2400 are its accuracy loads.

Thank you, sirs!

 

[fiver]

you got it right Bret.
remember the fast powder speed of red-dot and the like are gonna work much differently than the slower pistol powders like 2400.
the fast ones are a straight up peak and then a straight down again line.
you can mess with the slower ones because they have to climb to get there, so manipulating how long it takes doesn't mess with it's pressure peak except for the engraving spike.[or the removal of it]
it does bing and bang on the bullet a bit differently though.

it works the same way with faster and medium rifle powders too.
it's like you started over again a little further down the line.
but sometimes it's a necessity to make those slower rifle powders work just a bit harder at the start to get anything near a decent burn.
can't always do it [like in a semi auto] but in a bolt gun it's worth the effort if your gonna flirt with the far/far side of 2K speeds.

 

[Bret4207]

Thanks. I'm pretty much done with the far, far side of 2K, but right around there up to 2200-ish is still in play. With the slower powders I've found crimp can help and seating the nose out into contact is usually a bonus. Doesn't always work though, even if it seems like it should. Some combinations seem to like a little jump, figuring that out is part of why I'm bald.

 

[L Ross]

Thanks. I'm pretty much done with the far, far side of 2K, but right around there up to 2200-ish is still in play. With the slower powders I've found crimp can help and seating the nose out into contact is usually a bonus. Doesn't always work though, even if it seems like it should. Some combinations seem to like a little jump, figuring that out is part of why I'm bald.

The other reason is your Mom's Dad was bald. Oh, and the raging testosterone levels.

 

[Bret4207]

Actually, my mothers father had a full head of jet black hair into his mid 80's!!! But her mothers brother was bald like me.

 

[Bass Ackward]

Wow! Thanks. This is the best discussion I have read in a long time. I was actually impressed with the knowledge of some folks that have tended to keep their answers short and not too detailed. I …. don’t agree with everything but it does offer in-sites to what you do / believe and positions you have taken in the past. It’s amazing how we can believe some of the same things and say (argue) it from completely different perspectives. As complex as the topic is, it’s still over simplified because bore diameter (caliber) and gun dimensions can change a lot of what is required in THAT gun. It’s why I like 44 caliber, especially over 45. 44 is the only bore / groove that matches 22 caliber if you ratio it out for rifling height to bore diameter (drive area) and broadens what you can get by (away) with in you mix. If you can’t win fair in life, cheat.

 

[popper]

Military testing hardness of 9mm (Pb and Sb only)shows Vickers hardness of 7.5 and pure lead is 4. Lead is softened by RATE of applied force (i.e. initial pressure). Deformation becomes linear about 35k psi at room temp (knee of curve). 800 psi @ 260F. Frictional strain is very low as is the deformation i.e. it moves rather than deform and movement is small. The higher 300K deg temp in 0.2 millisecond stress rate makes the surface of Pb/Sb alloy act much like putty! The bulk of the bullet doesn't soften as much. SB/Pb is a mixture, not an 'alloy'. So, yes, a jacket helps a lot. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7287887/ Details here.
We say Sn/Sb (an alloy) helps as it prevents Pb from breaking apart when the stress is too high. I guess we would call that 'toughness'. Adding Cu does both, increases BHN and 'toughness'.
My Cu enhanced alloy did 2150 and MOA @ 100 - a plain base PC'd. 145 gr. I'm inclined to think it was the gas port in the AR that created base cutting and the apparent impact 'ring' on the target. I have a GC version that doesn't have that problem.

 

[Ian]

Popper, the gas port does nick the bases, I have proof from many recovered flat-base bullets from my BLK. The metal from the nick is what condenses on the bolt tail in these situations, not from any other part of the bullet. The ring pattern doesn't show up until long past the sonic barrier, through, as you experienced.

 

[Ian]

Wow! Thanks. This is the best discussion I have read in a long time. I was actually impressed with the knowledge of some folks that have tended to keep their answers short and not too detailed. I …. don’t agree with everything but it does offer in-sites to what you do / believe and positions you have taken in the past. It’s amazing how we can believe some of the same things and say (argue) it from completely different perspectives. As complex as the topic is, it’s still over simplified because bore diameter (caliber) and gun dimensions can change a lot of what is required in THAT gun. It’s why I like 44 caliber, especially over 45. 44 is the only bore / groove that matches 22 caliber if you ratio it out for rifling height to bore diameter (drive area) and broadens what you can get by (away) with in you mix. If you can’t win fair in life, cheat.

Bass, you should hang around more, your perspective on these things and many others is missed.