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Flat base vs boat tail pressures

3K views 9 replies 9 participants last post by  Don Fischer 
#1 ·
In general does a flat base bullet produce more pressure than a boat tail if using the same charge?
 
#2 ·
I wouldn't know, never thought about it. I've loaded both to the exact same specs and never seen any differences.
 
#4 ·
I've read that the effect of boat tails doesn't show till way down range. Read also that a lot of bench rest shooter's figured it out and went back to flat base bullet's. The only advantage I've ever seen in boat tails is that they are some what easier to start in the case when hand loading.
 
#5 ·
I don't know definitively but suspect that if anything the boat tail may have a lower pressure simply because there should be slightly less bearing surface as compared to a flat base. Whatever the difference might be, it has to be miniscule.

As Don mentioned they are assuredly easier to start in the case and the advantageous effects of boat tails are not evident until greater distances are approached. There is one more caveat. Years ago the general consensus was that boat tails were harder on bores than flat base bullets. Someone, somewhere, sometime did an extremely long series of tests and learned that boat tails are actually easier on a rifle bore than flat base. As always my memory is suspect but I don't believe there was any measurable difference until something over 3000 rounds. So, for most of us, that is a moot point, but nonetheless, it does exist.
 
#6 ·
Boat tails IMO are marginally easier to load, especially if you aren't belling your cases out very much.

From a fluid flow stand point, the boat tail will glide smoother. Have a flat stopped end in the back, you'll get a lot of turbulent fluid flow in the back of the bullet. Have a tapered end with smaller flat, you'll drastically reduce the fluid flow and potential drag on the bullet. However I can say, with something this small and with this much acceleration, you really wont see much if any difference at all.

Source: I'm an engineer :cool:
 
#7 ·
When I was shooting 6MM bench rest, I saw no difference between the two other than the BT was easier to reload. I seem to recall it was also easier to get a touch more run out on flat based bullets , or maybe it was just me. I don't know if a barrel lasts any long using flat based bullets or boat tail. When I was shooting there was a fair bit of debate as to which was better. It looks like that same debate is still going on 30 years later.
 
#9 ·
What we need is a side by side test (same load for boat tail and flat base) shot over a chrony. I wouldn't think there would be a difference, but maybe the boat tail, weight for weight would have less bearing surface than a flat base and have lower pressure (but that's just a WAG, from thinkin', may or may not apply in real life!:rolleyes:).
 
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