Recommend 7mm-300wm or 7mm Valkyrie

[BigSwede]

That sounds like a good plan. I am starting plans with my local smith and we are both excited to put things together

 

[BigSwede]

If I do want some bullet flexibility is there a better/best chamber setup or should I commit to setting it up for my intended Berger 180's.

 

[Broz]

I would set it up for a 180 and use an 8 twist. The 180's have shot great for us from an 8 twist and when the 195's become available you will be set.

Jeff

 

[BigSwede]

5 or 6 groover to minimize stress on the jacket?

 

[Broz]

5 or 6 groover to minimize stress on the jacket?

Have used both 5C / 5R and Hart 6 groves. I guess I favor the Harts.

Jeff

 

[Slaysesh]

Have used both 5C / 5R and Hart 6 groves. I guess I favor the Harts.

Jeff

What makes you favor the hart barrel?

 

[Broz]

What makes you favor the hart barrel?

Well, They seem to shoot very very well and when chambering they machine up smooth as silk.

Jeff

 

[fmajor]

I would set it up for a 180 and use an 8 twist. The 180's have shot great for us from an 8 twist and when the 195's become available you will be set.

Jeff

I'm not wanting to derail the thread and I hope my question is in keeping with the topic, but I notice a lot of anticipation for the Berger 7mm 195gr bullet.

Why?

Aside from obviously increasing BC - could there be any unforeseen drawbacks to such a long projectile?

I was reading somewhere here (I recall Kirby Allen was a participant in the thread among other experienced shooters) about extensive testing with super heavy .30 cal bullets - 240gr (iirc).

The problem encountered by Kirby and the fella who owned some precision bullet company was that the bullets were so long - too long - that the jacket/core was engaging the lands before the bullet cleared the case. This caused the bullet jacket/core to twist; deforming and ultimately destroying the projectile rendering it useless.

Could this be something that limits the 195gr 7mm bullet?

At what ratio is caliber to projectile length (as a necessary means to achieve weight) in order to maximize BC reached?

Again, apologies if this is too far off-topic.....

 

[Broz]

Based from what I have seen and tested in 30's going from a 210 VLD to a 215 Hybrid and the 230 Hybrid, as well as what I know about the difference in nose design , specifically the "hollow point" I have few worries. The Reamer design will take care of the problems you describe as far as having way too much bullet seated in the case. The ration of bullet leaving the case and when it contacts the lands is a reamer issue.

Jeff

 

[fmajor]

Based from what I have seen and tested in 30's going from a 210 VLD to a 215 Hybrid and the 230 Hybrid, as well as what I know about the difference in nose design , specifically the "hollow point" I have few worries. The Reamer design will take care of the problems you describe as far as having way too much bullet seated in the case. The ration of bullet leaving the case and when it contacts the lands is a reamer issue.

Jeff

Thanks Jeff -

This is very interesting stuff!!! Probably deserves a thread of it's own - seems to be lots of very specific information beyond discussing the larger, more powerful case 7mm's...

OP, sorry to derail/distract from a great discussion of the larger-case 7mm's.

 

[Edd]

I was reading somewhere here (I recall Kirby Allen was a participant in the thread among other experienced shooters) about extensive testing with super heavy .30 cal bullets - 240gr (iirc).

The problem encountered by Kirby and the fella who owned some precision bullet company was that the bullets were so long - too long - that the jacket/core was engaging the lands before the bullet cleared the case. This caused the bullet jacket/core to twist; deforming and ultimately destroying the projectile rendering it useless.

Could this be something that limits the 195gr 7mm bullet?

Why is contacting the lands before clearing the case an issue? Doesn't this situation exist in many, maybe most, cartridges?

The published specs on the 195gr bullet shows a shorter bearing surface than some lighter weight 7mm bullets.

I have some 130 gr 6.5mm bullets that have a bearing surface almost .100" longer than the 195gr 7mm bullet.

 

[fmajor]

Why is contacting the lands before clearing the case an issue? Doesn't this situation exist in many, maybe most, cartridges?

The published specs on the 195gr bullet shows a shorter bearing surface than some lighter weight 7mm bullets.

I have some 130 gr 6.5mm bullets that have a bearing surface almost .100" longer than the 195gr 7mm bullet.

I can't remember the exact details of the research. The participants in the discussion (Kirby Allen and others) experienced something to do with the bullet deformation due to excessive length. I believe it was because the bullet began spinning in the barrel before leaving the case neck.

They had done extensive testing on heavy(240grs iirc)/high BC .30 cal bullets, but I cannot recall the complete causality for their findings.