Re-barreling a 700SA to 7-08??

[ImBillT]

Why are you against it?

Against excess twist?

Jackets that are concentric enough not to suffer accuracy losses in tight twist barrels are mostly used in match bullets, and even they can loose accuracy if the twist is too tight. If the bullet is stabile, I’m not aware of any advantages going any tighter on twist except perhaps through the transonic range. Regardless of range concerns, I’m not aware of a bullet that needs a tight twist that will also perform well at such low impact velocities. If a 9” twist will stabilize a 195gr EOL, what advantage do you expect to get from using a 7.5” twist?

Thin jacketed bullets will blow up mid flight with excess RPM. Going with a tighter twist than necessary limits what bullets can you use on the might end, again with no advantage on the top end. By all means, use the twist required to shoot the bullet that you want to shoot. Going with faster or slower twists come with advantages and disadvantages, but when you not longer get any advantage by going tighter, why do it? It does come with disadvantages.

 

[tzone]

But then a loaded round won’t fit in the magazine unless you have done some serious work.

The 700 has the biggest mag box of the SA's I believe. If you want more than that, you're going to have to get into some serious cash as you say or get AR style detachable mag. Which isn't a bad option, but I don't think it's what he wants for this gun.

Against excess twist?

yes

 

[ImBillT]

The 700 has the biggest mag box of the SA's I believe. If you want more than that, you're going to have to get into some serious cash as you say or get AR style detachable mag. Which isn't a bad option, but I don't think it's what he wants for this gun.

yes

That’s exactly why I didn’t recommend lengthening the throat. Lengthening the throat will just make it so that you can’t reach the lands while seating to mag depth.

An out of the box 700 S/A does not have the longest box available without going to a L/A. A factory 700 S/A is usually considered to allow seating depths of 2.80”, but getting away with up to 2.84” is not that uncommon. A) You don’t have to modify a 700 S/A receiver in any way, or use one of the extended boxes to get up to 2.950”. Any bottom metal that will accept AICS magazines will accept an Accurate Mag that can be loaded to 2.950”. If you inlet an ADL stock yourself, you can get MagPul bottom metal for $85, and use Accurate Mags for $55 each. You can get PT&G M5 style bottom metal that will accept the same magazines for $100 if you have a stock that is inlet for M5 or if you can inlet it yourself. So $140-$155 and some stock work will get you a detachable mag setup that will go up to 2.950” with no action modification. B) Most, if not all, of the clones are setup from the factory for at least a 3.100” extended magazine boxes, and I think some can handle even longer. You can get a Christensen action, stainless and Cerakoted, with bottom metal, TriggerTech trigger, one-piece bolt, and already including an extended box for $850-950. You can get a stainless Stiller without the trigger or box for $750. I don’t recommend opening up a Remington and installing the extended boxes, because after you pay for the mill work and the extended box and follower, you’re in it for almost as much as going with a clone, but your action, bolt and trigger aren’t as good, so if you’re using a Remington instead of a clone, I recommend just planning to keep your COAL at 2.80” for a factory box, or 2.950” for a detachable. C) I don’t think that a Sako L-57 and L-579 are considered short actions, but they are pretty darn small, and have substantially longer magazines than 2.80”. C) I believe that M48s and M98s Are considered to be medium length actions, even though an M48 is pretty short, and again, both allow quite a bit longer seating than 2.80”.

All of that is exactly why I wouldn’t recommend using a longer than SAAMI throat for a 7-08 in a 700 S/A. If you’re loading to magazine length, then lengthening the throat will just move your lands farther away. With heavy bullets, you won’t be able to reach the lands at mag length anyway, why move them even farther away? I wasn’t recommending doing any modification, using another action, or even going to detachable mags. I was recommending leaving the throat right where SAAMI specs put it. If you’re loaded to mag length in a 700 S/A, lengthening the throat isn’t doing anything for you.

Excess twist? It can lead to midair blowups, decreased accuracy(especially with non-match grade bullets), increased fowling, and Barnes testing even indicated decreased penetration with identical impact velocity. Use the twist required for your bullet AND conditions. Any more twist than that is a waste, and could come with downsides. There isn’t a 7mm cup and core hunting bullet from a mainstream manufacturer that requires more than a 9” twist under most western hunting conditions(most of your sea level hunting out west isn’t super cold, and most of your super cold hunting is done quite a bit above sea level. AK is probably an exception). 8.5”or 8” would more than cover your butt for freezing temps at sea level. Unless you’re planning to use a really long mono, why would you need to go any tighter than that?

 

[cahunter805]

The 700 has the biggest mag box of the SA's I believe. If you want more than that, you're going to have to get into some serious cash as you say or get AR style detachable mag. Which isn't a bad option, but I don't think it's what he wants for this gun.

yes

Winchester M70 SA have a mag box of 3.1” and is exactly why I used one to build my 6.5SAUM. Feeds awesome since it was a WSM action to begin.