antelopedundee
internet bum
Flat base or boattail? Is one better than the other for any particular use? Your pros and/or cons for each?
Bullet styles?
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antelopedundee
internet bum
I was thinking that if you have 2 different bullets of the same weight and caliber and seated to provide the same COL that will fit in a magazine, that the FB will seat deeper in the neck and provide more bullet pull and hence more uniform [and maybe higher] velocity than the BT which may or may not be a desirable advantage. Was thinking in terms of hunting rifles and not benchrest situations.
If you have problems with either and neck tension something is wrong in your sizing setup.
It is not just accuracy but drop from drag.
Boat tails reduce BC very slightly compared to flat base.
That means they hold velocity a little better.
It is not likely to be all that important until the range is 300 yards or more.
Target shooters want their bullets to stay supersonic at extended range.
Dropping below the speed of sound puts a lot of 'disturbance' on the moving bullet.
The Mach waves do not detach and go away in a uniform way, but can actually move their attachment point to the bullet as speed decreases.
This can 'push' the bullet in random ways from shot to shot and mess up accuracy.
The resulting loss of energy can affect expansion and overall damage to an animal target.
antelopedundee
internet bum
Somehow years ago I got the impression from RGR [maybe wrongly so] that FB bullets were better shooters than BTs. I don't remember exactly what it was that gave me that impression, but IIRC he preferred FB bullets. So if you have 2 bullets of the same weight and the same shape at the nose and you seat them into identically prepared cases with the same seating die, the FB bullet will have more contact with the case neck [hence a greater bullet pull, tho the neck "tension" will be the same] than will the BT bullet. Is this something that would favor using a FB bullet at "normal" hunting ranges.
FWIW, I'm not having issues with sizing. My usual approach is to deprime cases with a decapping die, neck size with NO expander ball and seat the bullet with the bullet doing the expanding. Was just wondering if more bullet pull is better than less bullet pull.
Butch Lambert
Active member
FWIW, I'm not having issues with sizing. My usual approach is to deprime cases with a decapping die, neck size with NO expander ball and seat the bullet with the bullet doing the expanding. Was just wondering if more bullet pull is better than less bullet pull.
Depends.
Depends.
antelopedundee
internet bum
I'm trying to get rid of junk that's been layin around since Christ was a kid. So last night I was loading some .25/.284 cases with some old Berger 87 grainers that have been on the shelf for 25 years. They were seated so the base was about 3/16 below the case mouth. I also have a chitload of Sierra 90 gr HPBT match bullets. Those under the same conditions won't seat deep enough to even stay in the case.
Dave Tooley
Active member
What does the target tell you?
I have been very successful shooting FB bullets in 1K BR comp.
I have been very successful shooting FB bullets in 1K BR comp.
antelopedundee
internet bum
I'm not a benchrester or target/competition shooter. I doubt that me or my rifles could tell the difference.
Here are a couple pics that illustrate the point. The rifle is a .25/.284 smithed maybe 25+ years ago. I assume it's a standard throat tho I've forgotten the details. So I loaded some .25 cal 87 grain Bergers that I've had for many years. You can see from the pic that it has a decent amount of neck contact. IIRC a rule of thumb is that bullet depth should be about equal to the bullet diameter. Not sure how far off of the lands it is.
Also tried a Sierra 90 grain HPBT and bullet seat depth is about half of the FB. I don't see how with 58 grains of IMR 4831 that situation would hold the bullet long enough to build up the pressure to even burn it efficiently. Seating it another 1/16 deeper means it has to jump a bunch to hit the lands.
Unfortunately I don't have any FB or BT bullets of the same weight from the same maker on hand, tho being a 12 twist it won't shoot heavier bullets like 117s or 120s for chit.
The last thing I need is to buy more bullets.
Here's a better example of what I mean by flat base bullets seating deeper than their BT counterparts of equivalent weight; in this case .25 cal sierra 100 grain bullets. Hopefully the seated deeper bullets will allow more consistent and uniform burning of the powder charge. The FBs are definitely seated deeper than the BTs are. No change was made to the seating stem position in the seating die.
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