Deep Throat

[ekp]

I have collected and shoot a lot of Post War customs on 98 actions. They have all been originally re-barreled and stocked. No cut downs. I have found one common problem. The throat on these rifles are rather deep. I have had them borescoped and there is no problem with the barrels themselves.

My .270 built by WA Sukalle needs the bullet seated 115 thousands of the lands to function in the magazine. How much can I gain by having the magazine milled out?

 

[ekp]

I have collected and shoot a lot of Post War customs on 98 actions. They have all been originally re-barreled and stocked. No cut downs. I have found one common problem. The throat on these rifles are rather deep. I have had them borescoped and there is no problem with the barrels themselves.

My .270 built by WA Sukalle needs the bullet seated 115 thousands of the lands to function in the magazine. How much can I gain by having the magazine milled out?

I guess I may be answering my own thread. After doing some research I believe I would be better served with a bullet with a tangent ogive. Is this true and if so does anyone have a recommendation for a bullet? I have found that Hornady's Interlock seem to seat further out in my 30-06 mauser custom then other bullets.

 

[JerrySharrett]

As to throat depth, bullet jump, and accuracy, you'll just have to try it. Some barrel/bullet/load combinations shoot well jumping. Probably has more to do with how the bullet is "presented" to the throat. i.e. If the case neck clearance is within about 0.0015" or so and the bullet is seated straight, this allows the bullet to start down the barrel without any significant in-bore yaw, everything should work out ok. Bullets that start out with a lot of yaw have a problem going to sleep and one main problem here is that a bullet that is not asleep has more trouble bucking the wind than a bullet that is asleep on exit.

And, if the bullet is of a design, like a long round nose that has a lot of bearing surface, the bullet will straighten itself more in the barrel than something like a VLD that has more overhang than bearing surface.

IMO!!

 

[sbindy]

How well does the rifle shoot now? IMO, if the chamber is concentric with the bore, it may not be worth it to do a bunch of modifications just to get the bullets closer to the lands.

I would just take the bullets it likes and seat them out to where they are .010 off the rifling and see if it does like them closer. If not, then you aren't out of anything but some bullets and your time.

Another option would be to try the Sierra .30cal 165gr BTHP Gamekings in the .30-06, or the 140gr BTHP Gameking in the .270. These bullets easily reach the rifling in most rifles, and are ridiculously accurate for a hunting bullet.

 

[ekp]

How well does the rifle shoot now? IMO, if the chamber is concentric with the bore, it may not be worth it to do a bunch of modifications just to get the bullets closer to the lands.

I would just take the bullets it likes and seat them out to where they are .010 off the rifling and see if it does like them closer. If not, then you aren't out of anything but some bullets and your time.

Another option would be to try the Sierra .30cal 165gr BTHP Gamekings in the .30-06, or the 140gr BTHP Gameking in the .270. These bullets easily reach the rifling in most rifles, and are ridiculously accurate for a hunting bullet.

Would not a flat base bullet with a tangent ogive give more a bearing surface and allow me to seat closer to the lands?

 

[sbindy]

A Flat base bullet would, but a Tangent Ogive bullet such as the Hornady, or a VLD style bullet, Not necessarily. The Tangent Ogive places the diameter of the bullet that will engage the rifling farther back than the same bullet weight with a Secant Ogive. This all gets a little cloudy when you add in one of the Polymer tipped bullets, as even with a Secant Ogive, they have even more jump than just a regular Hornady Interlock bullet.

 

[ekp]

A Flat base bullet would, but a Tangent Ogive bullet such as the Hornady, or a VLD style bullet, Not necessarily. The Tangent Ogive places the diameter of the bullet that will engage the rifling farther back than the same bullet weight with a Secant Ogive. This all gets a little cloudy when you add in one of the Polymer tipped bullets, as even with a Secant Ogive, they have even more jump than just a regular Hornady Interlock bullet.

I was under the impression that all flat based bullets were tangent and boat tail were secant ogive. Apparently I am mistaken. So does the tangent ogive give more a bearing surface and bullet jump as well. What would be the best combination of bearing surface with less bullet jump in a bullet. Do you have an example of such? How do Berger's stack up in this regard?