Bullet Obturation--Jim Boatright
- Thread starter THEIS
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elkaholic
Well-Known Member
Whew!! Pretty interesting read although some was whizzing over my head!
I thought it was interesting that button rifled barrels expand less than cut rifled. That should create some interesting discussion about which is better
I thought it was interesting that button rifled barrels expand less than cut rifled. That should create some interesting discussion about which is better
Theis,
Thank you for posting the article. I really appreciated the read. I can see that I'll be plugging in a few of my rifles specifications into the provided formulas! Interior ballistics certainly is quite a mixture of variables that all play out in a few milli-seconds. Sometimes I'm surprised at the commonality of rigs and loads that are able to yield SD < 10fps. It certainly speaks to the absolute precision and QC of barrel makers and gunsmiths! It is an exciting time to be involved in shooting and reloading!
Thank you for posting the article. I really appreciated the read. I can see that I'll be plugging in a few of my rifles specifications into the provided formulas! Interior ballistics certainly is quite a mixture of variables that all play out in a few milli-seconds. Sometimes I'm surprised at the commonality of rigs and loads that are able to yield SD < 10fps. It certainly speaks to the absolute precision and QC of barrel makers and gunsmiths! It is an exciting time to be involved in shooting and reloading!
HARPERC
Well-Known Member
Talk about being dumped in the deep end of the pool! I did manage to dog paddle myself to the safety of the side.
Read it. The copper bullet portion of the paper seems like it is leaning towards someone's design with drilled bases. Is there someone making this style of copper bullets?
In my estimation paper explains why some barrels would work with the original X bullets and some wouldn't. What isn't addressed is the gilding metal bullets like the E tip. That would most likely require another paper.
Found it most interesting the button rifled barrels are prestressed and had less yield. Now wondering if a heat treatment of a special alloy steel would also yield less expansion of barrel OD allowing better obturation too. Is this the next level of perfection the cut rifling manufacturers could venture into?
Interesting read.
In my estimation paper explains why some barrels would work with the original X bullets and some wouldn't. What isn't addressed is the gilding metal bullets like the E tip. That would most likely require another paper.
Found it most interesting the button rifled barrels are prestressed and had less yield. Now wondering if a heat treatment of a special alloy steel would also yield less expansion of barrel OD allowing better obturation too. Is this the next level of perfection the cut rifling manufacturers could venture into?
Interesting read.
Varminator 911
Well-Known Member
The drilled base fits in with my vision for the future of mono metal bullets. Maximize the form factor and hold down the weight to allow higher velocity. Do this in the larger calibers because that's where there's room to further increase twist rates. A 7 twist 338-375 maybe even 416 would allow a very long sleek bullet. A G7 of 0.4+ should be possible at 3500+ fps. Those large caliper bullets are killers.
Instead of shooting a 300 grain 338 shoot a 240-300 gn 375-416 at 500 fps higher velocity.
Instead of shooting a 300 grain 338 shoot a 240-300 gn 375-416 at 500 fps higher velocity.
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bigngreen
Well-Known Member
Nice to see the math put to what many have known through trial and error.
bodean87
Active Member
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- Feb 6, 2011
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Cavity back bullets are making a design similar to that. If I recall correctly the bc was a about average. 30 cal 168 tipped .540
