6.5 saum question

[Highvoltage]

Just got my 6.5 saum back built on a long tikka action. I don't know the free bore but it seems like a mile. My question is I started seating 147 eldms with a 50 thou. Jump and I'm at 3.050". Do those of you who utilize the long actions take full advantage of all the free bore? The bullets looks goofy sitting that far out but I've measured and the boat tail is below the neck junction. I could go out farther yet if I need to. Let me know your thoughts. Thanks in advance and best wishes.

This is a brand new unfired gun.

 

[Mikecr]

The boat tail through neck-shoulder junction doesn't hurt anything. It's seated bullet bearing that you need to be aware of.
There is no advantage to a particular free bore length that I know of, other than allowing bullets seated deep enough, but not too deep.

 

[ARlife4me]

The boat tail through neck-shoulder junction doesn't hurt anything. It's seated bullet bearing that you need to be aware of.
There is no advantage to a particular free bore length that I know of, other than allowing bullets seated deep enough, but not too deep.

What he said^^^^^^^^^

 

[ARlife4me]

If you don't have an excessively long barrel, there really isn't any advantage for seating longer than specs. Going longer barrels with longer coal can give that extra powder room for more gas volume to push the bullet. I like the ability of seating all of boat tail in shoulder with bearing surface making 100% neck contact.

 

[Highvoltage]

I messaged the barrel manufacturer who did the chamber job and he said they went with .081 free bore but after running my oal length gage in there it seems like a lot. I started all my loads at 50 thou off so that will be my "jam" and I'm going to work in from there. Hopefully I can get something that likes the jump. Thanks again.

 

[Weaver93]

Depending on projectile ogive design there can be more length in front of the bearing surface on one than other projectiles. I believe the 147 ELD-M in 6.5 has a pretty high BC so it probably fits that category. If you seated a Sierra and that ELD-M to the same BTO you would see your OAL difference due to the design of the projectiles.

Some projectiles are not very sensitive to jump and can run well with a stretch to the lands others, like some Berger projectiles are really sensitive. I say this and should say that jump sensitivity is relative since what does not matter to me would give a bench rest guy a heart attack! Most of those guys jam everything into the lands. .050" off is nowhere near a jam, but it doesn't mean they won't shoot good there. Use a comparator to measure and you will see what difference ogive design makes. Staying away from compressing you powder will help with pressures and keep your brass running longer too.

Effects of Cartridge Over All Length (COAL) and Cartridge Base To Ogive (CBTO) - Part 2

The first half of this article focused on the importance of COAL in terms of SAAMI standards, magazine lengths, etc. There is another measure of length for loaded ammunition which is highly important to precision.

bergerbullets.com

 

[QuietTexan]

Do those of you who utilize the long actions take full advantage of all the free bore? The bullets looks goofy sitting that far out but I've measured and the boat tail is below the neck junction.

Oh yeah, 100%. My 300 RUM is almost at 4.000" COL running long Berger VLDs, used to look really goofy to me compared to the stuffed factory spec loads. Newer case designs are meant to have a lot of bullet out of the case, that's a big part of why a 300 PRC can run with larger case capacity rounds - there's less bullet inside the case taking up space. If the boat tail is below the case/neck junction when you find your jam then start way out at 0.010" off without any concerns. I bought my last target action in a long specifically planning on a SAUM.

 

[RockyMtnMT]

Seat them to what I call "That looks good", and run them. My guess it they will shoot well. Just call that your longest oal and if you have to adjust seating depth then work them deeper. There should be a sweet spot.

 

[Highvoltage]

Thanks for all the responses! I'll double check all may measurements and let them fly.

 

[Rosebud]

Just got my 6.5 saum back built on a long tikka action. I don't know the free bore but it seems like a mile. My question is I started seating 147 eldms with a 50 thou. Jump and I'm at 3.050". Do those of you who utilize the long actions take full advantage of all the free bore? The bullets looks goofy sitting that far out but I've measured and the boat tail is below the neck junction. I could go out farther yet if I need to. Let me know your thoughts. Thanks in advance and best wishes.

This is a brand new unfired gun.

Room for more powder!

 

[XLR Industries]

I talked with Rich Sherman and he said he always likes to have the bullet diameter seated into the neck. Personally, I always try to put the boat tail to ojive conjunction at the shoulder neck conjunction. That is what I was taught early on and it has always worked pretty well for me!

 

[Mikecr]

I talked with Rich Sherman and he said he always likes to have the bullet diameter seated into the neck. Personally, I always try to put the boat tail to ojive conjunction at the shoulder neck conjunction. That is what I was taught early on and it has always worked pretty well for me!

I think you mean base-bearing junction above neck-shoulder junction.
And this seating depth is often less than cal diameter. Many necks are very long.

 

[XLR Industries]

Yessir boat tail to the bearing surface I apologize! Been saying that wrong my whole life lol.

 

[Mike D Texas]

Just got my 6.5 saum back built on a long tikka action. I don't know the free bore but it seems like a mile. My question is I started seating 147 eldms with a 50 thou. Jump and I'm at 3.050". Do those of you who utilize the long actions take full advantage of all the free bore? The bullets looks goofy sitting that far out but I've measured and the boat tail is below the neck junction. I could go out farther yet if I need to. Let me know your thoughts. Thanks in advance and best wishes.

This is a brand new unfired gun.

I think SAAMI length cartridges look goofy with the bullet stuffed way down in the case.

On the left is my 264 Win Mag Improved throated for 156 Bergers to be seated at the neck shoulder junction. On the right is a SAAMI length one.