Rebated Boattails

[AWLEAPHART]

Has anyone on the site compaired rebated boattail to the norml boattail. I was reading on the Corbin (swaging bullets) site and started wondering. Does anyone sell rebated boattail bullets in 7mm. There is no BC info so you dont know what kind of BC you can get of of making the bullets your self.I was looking at the overall cost to buy the dies to make the bullets but is it worth the cost? Thanks

 

[Steve Blair]

Some folks think that they have a slight sealing advantage over conventional boattails and are easier to form. It also seems likely that they have more base turbulence (drag) than a conventional boattail.

 

[Laurie]

As Sleepygator says, they're much easier to form accurately than a conventional tapered boat-tail, hence Corbin producing his dies for them. Corbin also makes great claims for them, but most ballisticians don't believe they are ballistically superior.

The only large manufacturer which still makes rebated BT bullets is Lapua which has been making this type since before WW2. All of its models are either 0.308" calibre or the slightly larger East European / Scandinavian 7.62mm (0.310") the latter for 7.62X53R which is the traditional 20th century military cartridge in Finland like your .30-06 or our (British) 0.303".

The 185gn Lapua D46 has a tremendous reputation and is still available here in the UK. The bullet was originally developed in 185 and 200gn forms for Finnish 7.62X54R machine-guns. Many countries had adopted BT bullets after the Germans showed the way in WW1 (to increase extreme range for MG Battalion concentrated barrage-fire, up to 5,000 metres possible with the right ammo), but a tapered boattail design bullet caused terrible barrel erosion with the steels then available giving unacceptably short barrel life. The D-series rebated bullets were found to give acceptable life, good range and accuracy.

They are FMJs of course, not HPBT Match designs with a flat solid jacket base. So they have a small depression in the base and exposed lead, albeit smaller than in a conventional BT or flat-base FMJ. This is generally regarded as a BAD THING in accuracy terms as the powder gasses can affect bullet flight as they overtake it at the muzzle by catching on the depressed base. Lapua says not in this design, and their reputation is very good - but is that just a matter of inherited reputation from the days when conventional HPBTM bullets weren't nearly as good as now?

I did read a range-test years ago by an American LR prone shooter (back in the days when the .300 Magnums were king) which said that D46s beat the pants off Sierra MKs in long-range grouping and elevation control ............... for 19 out of every 20 shots. But, whatever they did, the testers couldn't eliminate the 5% flier factor. So, make of that what you will.

There will be specialist small-scale bullet suppliers that produce rebated base BT bullets - we have one in the UK that I know of - presumably using Corbin dies.

If you want to see an image of the D46 (and the Lapua B-series 'Lock-Base' FMJs), I will be putting one in Part 4 of my series on handloading .308W in the February issue of the free online magazine

http://www.targetshooter.co.uk/

that goes live on Feb 1st. I can't send it to you or post it here now, as I've yet to write the feature and take the pics!

Regards,

Laurie,
York, England

 

[AWLEAPHART]

Thats a lot of info. Thanks alot.

 

[spclark]

There's a Canadian outfit that puts out a line of rebated bullets in diameters from 6mm up thru 50BMG:

http://matrixballistics.com/products.html