Quarterbore's Forums - Who Wants An EXPANDING 200-240 Grain Bullet?

Quote:

Originally Posted by Texdoug1 (Post 19589)

Do ya'll think the Corbins will feed in an AR? If so how do I place an order? I can't open the spreadsheet.

Don't see why it wouldn't. His website is confusing, so the best way is to email him. Below is his response when I did so.

Quote:

The .300 Whisper works very nicely with a round nose, hollow point bullet having a rebated boattail to reduce base drag. You can maximize the weight with the rounded nose, and the front end opens up better if it is blunt, while at subsonic speed, the ogive shape has far less effect on drop than the base design...like a car body, the biggest drag is from the turbulence left in the wake until the car gets up to 1050 feet per second at which point it generates a big shock wave that far overwhelms the base effect. Fortunately we have no supersonic cars other than driven by teenagers.

There is a good discussion of subsonic 300 bullets on www.Corbins.com/subsonic.htm

The problem with the pointy Sierras is that they were never designed for subsonic use, and are simply being sold that way as an expedient. On game, they are not nearly as effective as a rounded nose. They will have a somewhat flatter trajectory but the performance is not nearly as good on impact. The deep hollow cavity of the round nose subsonic design, with serrated jacket and a ball placed over an air cavity or a cavity filled with inert grease like swage lube, insures far better performance.

But to make the pointy Sierra, all you need is a normal 4-die set (RBTO-4-S). You can nudge it along toward the better performance end of the scale by using a SDD-1-S serrate/draw die to put little lines in the jacket to guide the expansion. You can also seat the core with a hollow point punch, which doesn't cost anything extra (we just substitute the HP core seat punch for the regular OT or open tip punch). The main issue will still be pushing all that copper down into a small impact area, where it resists expansion.

Here are the two packages, one for the Sierra match bullet as used for subsonic guns, and the other for the additional or changed items to make an actual subsonic design:

CSP-1 S-press........... $598
RBTO-4-S .308 6-S ogive rebated boattail open tip set... $906
J-30-125 bullet jackets, pk/250... $38
LW-10 lead wire, 70,000 gr, $39
PCS-1 core cutter .247 diam, $69.50
CSL-2 swage lube... $8

The above makes the Sierra style bullet but with the rebated boattail design.

To change this to the subsonic bullet, change the RBTO-4-S set to:

RBTO-4-S .308 1-E ogive HP rebated boattail open tip set... $906

And add these enhancements:

SDD-1-S 308 serrate/draw die... 259
PUNCH-SS Saber Tooth 308 CS internal punch... $120
BB-3/16 pk/1000 bullet balls for the tip... $30

D.R. Corbin, President
Corbin Mfg & Supply, Inc.
PO Box 2659, 600 Industrial Circle, White City, OR 97503

dave@corbins.com
order on-line at: www.SwageDies.com

Here is the non-googledocs version of the spreadsheet if you want it.
http://oregonshooter.com/share/218gr...per - cost.xls