7mm SAUM SAAMI ???

[bobinpa]

But min SAAMI freebore is .090 like previously mentioned.

Ok.... I'm not sure I understand. I looked at a SAAMI print yesterday on their website and I come up with .2177". Am I reading it wrong?
Here is a link to the SAAMI page and the print is on page 45;

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

 

[Sandstorm]

Looks like .090 free bore per SAAMI spec, Sir
But like Ned mentioned see if you can verify yourself.

 

[WSnyder]

Ok.... I'm not sure I understand. I looked at a SAAMI print yesterday on their website and I come up with .2177". Am I reading it wrong?

Yes you are reading it wrong. Freebore as previously stated is .090".
The correct numbers to determine the FB are: 2.1532-2.0632=.0900

 

[WSnyder]

In the common use term "freebore" is generally referred to as the parallel/cylindrical portion of the throat just ahead of the neck throat transition so in this case it would be .090". Same as a common JGS print using the U and V dimensions. Pretty much everyone refers to a JGS U&V as "freebore" no?

You are correct in my mixup between throat and of lead. I'll fix it. He was using 2.3709-2.1532=.2177 which is not the "freebore".

 

[Edd]

Ok.... I'm not sure I understand. I looked at a SAAMI print yesterday on their website and I come up with .2177". Am I reading it wrong?
Here is a link to the SAAMI page and the print is on page 45;

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

.2177" is the length of the angled part of the throat.

The SAAMI print shows the throat angle to be 1 degree. The SAAMI print shows the freebore to have a diameter of .2846" and a length of .090". It also shows a .277" barrel bore diameter.

.2177" is the distance it takes a 1° angle to go from the freebore diameter to the bore diameter. This is calculated on one side of the throat.

 

[bobinpa]

I apologize for causing such a debate however I am grateful for the knowledge. I'm no gunsmith or rifle builder but I thought that I could figure out a print.... After the education that you guys gave me, I see there is more than just the freebore involved in determining what bullet should work in a given chamber. If I understand what has been explained, the freebore and throat are 2 different areas and both combined determine how far out of a case a bullet can be seated. Please correct me if I am wrong because I like to learn....

For the record, I did commit to buying the rifle, although I haven't seen it yet in person yet. Should have it in the next couple of days...

 

[Ned Ludd]

I was wrong. Freebore as listed in the SAAMI drawing is .090" as several people have correctly stated. I apologize for the error and have removed my previous posts. I modified the correct 7 RSAUM SAAMI chamber drawing below for clarification. Again, sorry for the confusion, Bob.

 

[davidjoe]

Here’s two spec reamers.

My GS does not like my solid pilot reamers, but I can say without reservation that SAMMI spec reamers, I have barrels in use from both of my saum reamers, without additional throating, will allow any match bullet to be seated without bolt lug grind.

Regardless of what the SAMMI print looks like, I can seat, if desired, so as to expose a very significant amount of body, with no issues. It is not necessary to seat below the donut to do so either, although I shoot some bullets that group best with that much jump.



I have a 7mm unithroater but those need to be used sparingly if ever. Guys need to realize that throating out a barrel does what shooting string fire is already going to do - lengthen the throat sooner toward the point of gas blow by and inaccuracy.

I will personally reserve my unithroater for a barrel with a tighter bore that develops high pressure.

 

[bobinpa]

Well I picked it up last night, which is good! The down side is that I don't have and can't find any brass for it ANYWHERE! I have plenty of stuff for the rifles I shoot but I don't have any 7mm or 300 SAUM brass. Sadly, it looks like this one will be sitting in the safe for a while until I stumble on some brass. Do any of you guys know where I might have some luck?

 

[WSnyder]

RSUAM brass has been really hard to get for a long time even way before this current crunch. You might watch GA Precision to see if they ever restock 6.5 GAP 4S brass. If they do or if you find someone else selling it you can use it and just neck it up. I sold off all of my surplus 6.5 GAP brass a year or so ago.

Also: ADG has made 6.5 SAUM (6.5 GAP) brass so you could watch for it somewhere too.

 

[davidjoe]

Well I picked it up last night, which is good! The down side is that I don't have and can't find any brass for it ANYWHERE! I have plenty of stuff for the rifles I shoot but I don't have any 7mm or 300 SAUM brass. Sadly, it looks like this one will be sitting in the safe for a while until I stumble on some brass. Do any of you guys know where I might have some luck?

Brother, we (especially me) have been talking about that very issue on here for several years. I have a thread about even starting up with 8 x 1:8 barrels chambered for the 300 WM to use in F-Class, because the brass situation was more frustrating than I could stand.

 

[dthomas]

Just keep looking, eventually youll come across some. Maybe contact adg and ask when they will make another run.

 

[davidjoe]

I have to ask this now, I’m afraid, but you’re aware that Berger 180 hybrid bullets are, and will probably from now on, be hard to source, right?

 

[bobinpa]

I have to ask this now, I’m afraid, but you’re aware that Berger 180 hybrid bullets are, and will probably from now on, be hard to source, right?

Yes, I know. I was able to find some 175 gr Elite Hunters. Not exactly what I wanted but close. I don't shoot competitively.... mostly score or ground hog matches so I am hopeful that the 175s will be accurate.

 

[davidjoe]

Yes, I know. I was able to find some 175 gr Elite Hunters. Not exactly what I wanted but close. I don't shoot competitively.... mostly score or ground hog matches so I am hopeful that the 175s will be accurate.

You’ll be in good shape, then. The bullet crunch is really only on about one or maybe two 7mm bullets the F-Open guys shoot.

Like DThomas says, ADG puts out good saum brass. I believe a few high volume guys have recently switched calibers so you’ll have a good chance to stock up, but when you see it, grab what you’ll need because they really only cycle through calibers a time or two a year.

 

[bobinpa]

How popular is 180 gr Lapua Scenar? Anyone have any experience with them in this cartridge?

 

[Sandstorm]

They have used a lot of them in England from folks ive talked to.. I dont know how poular
they still are however. The 183 SMK's will also work.

 

[davidjoe]

How popular is 180 gr Lapua Scenar? Anyone have any experience with them in this cartridge?

I have shot them in a SAUM. They are exceptionally uniform bullets that shoot very small groups and do not need one of the faster twist barrels. The Scenar is one of the bullets either a Saum or .284 could excel with. They are a waterline wonder on calmer days. They do require a bit more wind reading skill and do not have a tip that is conducive to repointing.

You could say of them that on a calmer day where wind skills can steer them, they would contend to win against about anyone, and they have zero true flyers in any given box.