Boattail bullets -- how great are they?

[Montana Pete]

I tend to use both boattail and flat base bullets. It is hard not to, since so many bullets identified as "match" or "competition" happen to be boattails.

I did some reading on boattail bullet design-- here's one article that is pretty good.

http://www.swage.com/ftp/rbt.pdf

One factor often overlooked when discussing any supposed advantages of boattail design is -- this design imparts greatest benefit when the bullet drops to subsonic speeds.

I am shooting a 22-250 and putting bullets out at over 3500 fps. My bullets would have to be WAY downrange to drop to subsonic speed. Although there is some limited value even at supersonic speed, apparently. But at supersonic speed, the shockwave at the bullet's nose causes slow-down much moreso than the bullet's base. Thus at supersonic speed the design of the bullet's ogive is more critical for sustaining velocity than is base shape.

Another consideration is -- are some of these so-called boattails really boattails at all? I notice the very slight tuck at the base of some bullets called by some bullet makers as a boattail. The article quoted above says the bullet's taper at the tail should be roughly one caliber in length. Some of the fast .224 bullets have little better than a rounded base corner -- even though called boattails.

Lastly, I have read that many benchrest shooters prefer flatbase bullets, for whatever reason. Is this true?

One possible advantage to boattails not yet mentioned -- the rebated base may prevent scratching or marring of the important bottom edges of the bullet during the reloading process.

Any comments on boattail bullets would be appreciated.

 

[j mckinnie]

they

shoot is all

 

[HovisKM]

Pete,

As I understand it, what you may be missing is something that has nothing to do with ballistics but has everything to do with concentricity where the bullet rides the rifling. I had a couple of well known bullet makers tell me the resurgance of BT's in short range BR has more to do with the quality of the jackets than anything else. Assuming the bullet maker is doing everything right and the dies are equal, the more varitation in the bullet jacket walls usually equals more variation in the base of the cup. If you are running close to the top end tolerances of jackets, when you make a flat base bullet, around the bottom of the cup is where the power ring is and this will creat more off center CG. However, with BT bullets, you move where the bullet rides the lands/grooves at further up the jacket, thus the bottom of the cup has less effect on the final product.

I know that is probably hard to follow. I'm no bullet maker and just don't know the bullet lingo well enough to convey what I have been told by a few. Also, they maybe wrong anyway.

I hope Bart and some other top bullet makers/die makers (calling George...hint..hint) will chime in and give worthy opinions, as mine should be taken just as "food for thought".

Hovis

 

[Larry Elliott]

Boattail bullets show their greatest trajectory advantages at longer ranges, but the boattail needs to be long and shallow to offer much advantage from what I've read. The bullets designed for long range shooting usually have long 9° boattails to offer the most streamlined tail to the bullet. Long range shooters also uniform and/or point their bullets to close the open hollow points to increase their BC's.

If the case mouth is properly chamfered it shouldn't scratch or scrape the shank of the bullet on seating. Boattails ease the bullet into the case mouth, but that's like inserting a tapered pin into a hole. If bullets are being scratched or scraped when they're seated a VLD or K&M inside chamfering tool will alleviate that, but even a standard Wilson style tool should give a smooth chamfer if any sort of care is taken.