7 SAUM in Rem 700 LA free bore help

[NW_Hunter]

Disclaimer: This is my first attempt at putting together a custom rifle

I'm trying to plan my hunting rifle build. Was going to go 28 Nosler but after running into issues with COAL and mag length I opted to ditch that idea, as I don't dislike my current stock setup and I'm trying to save money for a comp rifle build.

I'm looking to into building a 7 SAUM using my long action. My max COAL for my mag is 3.5" so plenty of room to throat long. I want to run Berger Hunter 180 VLDs. I'm trying to determine optimal free bore. I'm still trying to get set up with my reloading equipment so loading a dummy round and having a reamer cut based off said dummy round isn't really an option for me right now.

Looking to see what others with similar build are running for free bore.

Is there a way to determine optimal free bore without loading a dummy round?

Thanks in advance. Been reading threads on here and learning tons! Looking forward to the continued education!

 

[wvlapua]

.188 freebore is perfect imo. Anymore than that, 180 class bullets won't reach the lans with caliber diameter still seated in the neck.

 

[NW_Hunter]

.188 is one spec I've read, another was .250 I believe. Where does the boat tail end up in the case with .188 freebore?

 

[NW_Hunter]

Went back and revisited those other threads.

From what others have said .188 free bore is good for hybrid 180 class bullets. But others are recommending more free bore for high BC vld projectiles. What's your experience with the vlds in 7 saum?

 

[Edds]

If I was ordering a reamer for a 180 VLD and if I wanted it to touch the lands, I wound order one with .140" freebore.

 

[Barney88PDC]

I literally did exactly what you want to do for the exact bullet. A 0.180" freebore will put the base of the bearing surface at the neck shoulder junction, exactly where you want it.

https://www.snipershide.com/shooting/threads/7saum-build-ritten-precision-updated.125705/

Let me save you some frustration and jam the bullets a bit or they will likely not want to shoot well.

 

[NW_Hunter]

Thanks for the link to your write up, very informative. Jamming the vlds into the lands is something I'd like to avoid on a hunting rifle as I hunt with one in the chamber and will load/unload that round dozens of times throughout the elk season. My 7mm rem mag seemed to shoot the 168 berger vld decent (with a questionable barrel) with a a short jump to the lands, hoping to do the same with this 7 SAUM

 

[Deadman Pointers]

@NW_Hunter What is your rationale behind the 180 VLD? I am in an identical situation trying to decide between a LA 7saum and 28 Nosler to throw the heavy skinny Bergers at elk.

 

[Lynn Jr]

The Berger VLD bullets like to be jammed hard into the lands and jumped a long way.
The gold standard is to put the bearing surface/boattail junction and put it 0.050 in front of the neck/shoulder junction to keep it away from the donut at the neck/shoulder area.
As you don't want to jam hunting rounds I would go with more freebore not less.

 

[Barney88PDC]

Knowing what I know now.......

The 7 SAUM is a FANTASTIC caliber. However, if you want to run heavier than a 168 class bullet I would not go short action. You already stated going long so that's good. Well if you are going to go long then why not put more powder in the chamber and get the bullet going even faster. So if I have to rebarrel I will use my long action to its potential and go with something with more powder. Either a 7LRM or a 28 Nosler if I had to pick one today. Try to source brass before you commit to 7SAUM as when I looked a few months ago I could not find any. The 7LRM was designed for a 180 so with the bullet seated properly it's getting the full potential of the action but where you would want the bullet in the case. I just have not had good success with Hornady brass in a 6.5SAUM so I'm leery of it in a magnum, it worked fine for a 6mm Creedmoor. If I went 28 Nosler, which is what I'd probably do, I'd run the 195 Berger EOL (after making sure it would fit in the mag, otherwise it's a 180 hybrid). And if you want to save some headache if you go 7SAUM doing load development just use the 180 Hybrid, the animals can't tell the difference, trust me, despite what the internet tells you.

 

[NW_Hunter]

@NW_Hunter What is your rationale behind the 180 VLD? I am in an identical situation trying to decide between a LA 7saum and 28 Nosler to throw the heavy skinny Bergers at elk.

From everything I've read the Berger vld seems to be one of the best hunting bullets available. I have no personal experience with it but have decided to run them based off their ballistics and reviews. As far as the 180 I'm following advice I got from a friend, whos opinion I value.

I really wanted to run the 28 nosler myself but I ran into mag length issues and I'm not willing to replace/rework my stock again too remedy the issue. This rifle will be primarily a dedicated hunter and I'm really itching to very into PRS so once this build is finished I'll be looking to build a comp rifle.

 

[NW_Hunter]

The Berger VLD bullets like to be jammed hard into the lands and jumped a long way.
The gold standard is to put the bearing surface/boattail junction and put it 0.050 in front of the neck/shoulder junction to keep it away from the donut at the neck/shoulder area.
As you don't want to jam hunting rounds I would go with more freebore not less.

Yes, I'm aware of the issue of not wanting to jam hunting rounds. I've read the berger article about tunning the vld round when jamming isn't an option. My back up plan is to run the Berger 175 elite hunter if I can't get the vld to shoot well.

I've got recommendations to run anywhere from .180 to .220 free bore. .220 freebore aligns pretty close to @Barney88PDC said if you add dinner freebore to keep the bullet away from the donut area.

I'm new to reloading can you explain why you want to be off the donut area, and is this really an issue if I use an expander bushing to resize the neck from the inside?

I think I'm going to contact PTG and get their run down on how to make this calculation mathematically since I'm not geared up to load a dummy round at this time (still collecting gear).

 

[NW_Hunter]

Knowing what I know now.......

The 7 SAUM is a FANTASTIC caliber. However, if you want to run heavier than a 168 class bullet I would not go short action. You already stated going long so that's good. Well if you are going to go long then why not put more powder in the chamber and get the bullet going even faster. So if I have to rebarrel I will use my long action to its potential and go with something with more powder. Either a 7LRM or a 28 Nosler if I had to pick one today. Try to source brass before you commit to 7SAUM as when I looked a few months ago I could not find any. The 7LRM was designed for a 180 so with the bullet seated properly it's getting the full potential of the action but where you would want the bullet in the case. I just have not had good success with Hornady brass in a 6.5SAUM so I'm leery of it in a magnum, it worked fine for a 6mm Creedmoor. If I went 28 Nosler, which is what I'd probably do, I'd run the 195 Berger EOL (after making sure it would fit in the mag, otherwise it's a 180 hybrid). And if you want to save some headache if you go 7SAUM doing load development just use the 180 Hybrid, the animals can't tell the difference, trust me, despite what the internet tells you.

I did want to go 28 nosler initially, but it's not going to work because of mag length. I really don't want to replace/rework my stock so I opted to go to something else. I haven't even considered the 7 LRM, but it's something to look into.

Good point in trying to source brass first.

My back up plan if I can't get the 180 vld to shoot is to go with the 175 elite hunter which is a hybrid design. And yes I realize the animal can't tell the difference it's more me chasing the numbers, something I have a bad habit of doing.

 

[NW_Hunter]

Need to look into more yet but my first concern with 7lrm is coal. I was pretty close to max coal with my 7mmRM with berger 168 vld. The 7lrm being of same case length I'm not sure I'd be able to run the 180s

 

[Lynn Jr]

Yes, I'm aware of the issue of not wanting to jam hunting rounds. I've read the berger article about tunning the vld round when jamming isn't an option. My back up plan is to run the Berger 175 elite hunter if I can't get the vld to shoot well.

I've got recommendations to run anywhere from .180 to .220 free bore. .220 freebore aligns pretty close to @Barney88PDC said if you add dinner freebore to keep the bullet away from the donut area.

I'm new to reloading can you explain why you want to be off the donut area, and is this really an issue if I use an expander bushing to resize the neck from the inside?

I think I'm going to contact PTG and get their run down on how to make this calculation mathematically since I'm not geared up to load a dummy round at this time (still collecting gear).

You want to keep the bullet in front of the donut area because it is an inconsistent restriction. The brass varies too much so tension and seating depth are both affected.

Some shooters will buy the K-M carbide neck cutter just so they can remove it. Picture shows the cutting flutes.

Before ordering a reamer I would get a single piece of brass and the bullet you plan on shooting just to make sure your magazine can handle the length.