Can anyone tell me at what overall lengths the 7mm WSM will touch the lands in a SAAMI chamber with any bullet they are loading?

I have a Sako 75 currently chambered in 300 WSM and I'm considering rebarrelling to 7mm WSM. The Sako mag box is 2.925 inside. I'm hoping I can get near the lands with something like the 160 Accubond or the 150 Ballistic Tip and still fit the mag box.

http://www.saami.org/PubResour...20Short%20Magnum.pdf

this might help.
I don't remember what oal I was running in mine when I had it but it was pretty normal the 139gr hornady was pretty close to the cannelure.

Thanks Lamar.

I've looked at that before. My reamer is saami spec.

It's hard to calculate exactly where a particular bullet will touch the lands until you chamber a barrel.

It depends a lot on the bullet. Something like a 180 berger hybrid is about 0.160" longer than a 180 smk when they're both sitting at the lands. Here are some lengths I've measured:

2.780" 180gr berger hybrid
2.730" 180gr berger vld
2.705" 175gr SMK
2.620" 180gr SMK
2.695" 162gr hornady match

This won't match your reamer, but you can compare the bullets against each other.

quote:

Originally posted by jpl:
It depends a lot on the bullet. Something like a 180 berger hybrid is about 0.160" longer than a 180 smk when they're both sitting at the lands. Here are some lengths I've measured:

2.780" 180gr berger hybrid
2.730" 180gr berger vld
2.705" 175gr SMK
2.620" 180gr SMK
2.695" 162gr hornady match

This won't match your reamer, but you can compare the bullets against each other.

That's the kind of info I am looking for, thanks.

Looks like I will be able to seat anything I will shoot near the lands and still fit the box assuming your chamber was cut with a SAAMI spec reamer.

No, those numbers are not for a 7WSM. My point was just that the bullet makes a big difference and those numbers could be used to compare different 7mm bullets.

Fitting a magazine and seating out to the lands could be an issue with the 7WSM. Also, I haven't seen brass or factory ammo available for quite some time. Do you already have brass, dies, etc? One possibility would be to run the reamer in short and use 270 or 300 WSM brass that's necked up/down and trimmed. This gets you about 0.040" I think, uses your existing reamer, and if you already have dies you can shorten them in a lathe pretty easily. This gets you more mag length and addresses the brass availability. You could also do a 7mm-300 WSM wildcat, which is pretty similar but retains the brass length. Then there's the 7 RSAUM. You'd need a reamer, dies, etc. for these options, but it keeps the magnum bolt face. The past few years I've been running a 7WSSM in competition. This is roughly equivalent to a 284 Win but uses the same bolt and magazines I also use for the WSM version. Here is some info on that:

http://forums.accuratereloadin...6521043/m/7191005091

The magazines I use allow 2.965" (from memory), so it seems your magazine is shorter.

You could cut a stub gage with your reamer and measure a variety of bullets to see what you'll get.

as far as the length or jump to the lands goes you look at length to the ogive and not to the tip.
the tip tells you your oal for fitting into the magazine.
measuring to the ogive from the base gives you the distance from the bolt to that datum point.

all of those above will be pretty much the same oal to fit the magazine but they will all have a different jump to the lands because of the shape/length of the nose. [7s/9s/11s etc]

quote:

Originally posted by Lamar:

all of those above will be pretty much the same oal to fit the magazine but they will all have a different jump to the lands because of the shape/length of the nose. [7s/9s/11s etc]

?? The different lengths are because of the different nose shapes. Do you mean that a magazine puts an upper limit on OAL? This seems obvious. Measuring ogive with some sort of device will get you closer (depending on the device), but a stub gage cut with the reamer you intend to use (or already have used) will tell you exactly where a particular bullet will sit relative to the lands. This measurement will match the barrel cut with the reamer until the lands erode with use. This is how I got the numbers I posted. I just cut a scrap of aluminum with the reamer and mill a little window in the side to see the neck/throat. Here is what I'm talking about: