Ogive and 150 grain 30 cal bullets. Opinions wanted.

kidthatsirish

Can anyone reccomend a 150 grain (or very close) 308 type projectile that has a max bearing surface or tangent (I think) ogive.

A hunting bullet would be a plus!

JustC

I would go as far as to say that a flat base projectile (which are most often hunting projectiles as well) would be your best bet for maximizing the bearing surface length. Since boat tails are a function of the overall weight of the projectile, as are the noses, both the nose length and boat tail length will dictate the length that the bearing surface can be, and still add up to a desired projectile weight. Longer nose and tail dictate a shorter bearing surface. Eliminate the boat tail, and you are left with a longer bearing surface ( if the nose length on each projectile was held constant).

Consider this,...if you wish to really maximize the bearing surface length, try a flat base, round nose, hunting bullet. If not, Both Remington and Winchester manufacture a .308" 150gr flat base, PSP hunting projectile.

as far as the ogive, a tangent ogive is the more radial transition from nose angle to bearing surface compared to a secant ogive which is the more angular transition seen with long range, ELD, Target, etc etc projectiles. The tangent ogive is the one you see most often with commercially available hunting bullets, balistic tips, etc etc. You will find a secant on projectiles such as the Berger VLD, Hornady ELD and ELDX, A-Max etc. These type long range, Very Low Drag style projectiles, with secant ogives present a longer nose profile to achieve the transition to the bearing surface of the projectile, and therefore will have shorter bearing surfaces than those with tangent ogives and nose profiles.

http://bulletin.accurateshooter.com/2007/07/283/

JustC

so I just broke out the ogive measuring tools and measured the bearing surfaces of a winchester 150gr PSP, flat base VS that of a Hornady 168gr BT HP target bullet.

The bearing surface on the 150gr PSP measured .495" VS .386" on that of the 168gr HP BT projectile. Thus, even though the 168gr projectile weighs more and is longer, the longer nose profile with sharper ogive and the existence of a boat tail, effectively reduced the length of the bearing surface VS that of a projectile weighing 18gr less, and being shorter. The shorter nose and flat base allow for a longer bearing surface on the 150gr projectile. The bearing surface is the largest diameter portion of the projectile, therefore for each .001" of bearing surface, that will have a greater percentage of overall projectile weight than .001" of nose or tail length, since they are not at full diameter, and each .001" will weight less than .001" of bearing surface.

I did measure the bearing surface of both a 150 remington PSP FB and the Winchester 150 PSP FB. The remington BS came in at .480" vs the winchester BS at .495". If you sit them side by side, you will notice the remington being slightly shorter (1.037") since it has a shorter/fatter nose profile which equates to more weight per .001" of nose length VS the winchester which was (1.105") due to a longer, sleeker nose profile which equated to less weight per .001" of nose profile.

Sooooo, all that being said, the one thing I can say for sure is that between the remington and winchester 150gr, flat base, tangent ogive, soft point hunting bullets, is that the bearing surface on the winchester is .015" longer.

kidthatsirish

So the everything the two of you have said supports my results this far with the flat base bullets shooting more accurately out of my Springfield 2 groove. Of the hornady and winchester ammo I have tried the winchester grouped tighter despite it's much higher velocities.

Now that I am reloading for it in earnest I think I am going to stick to the flat base bullets. I very well may try a round nose soft point 150 grain pill and try to push it around 2700fps.

kidthatsirish

Ever had luck with the 150 grain soft round nose from hornady?

JustC

I must admit I have never used or reloaded a round nose projectile due simply to the fact that my passion/interest was always firmly planted in the long range discipline. I have been on a bit of a break for the past few years (health issues) and am slowly regaining the fever of loading and testing at distance.

I believe that the 03a3 barrels were 1:10 twist, so you should be just fine in experimenting with most everything up to a certain weight.

charliemeyer007

I'm fond of the Secant ogive Hornady uses myself. I like that 165 ish BT myself best in the -06. It does pay to explore to find what the rifle likes.