7Saum velocities...need help.

[Mag_7s]

I went to the range to break in the barrel of my new 7saum. Yes I still do barrel break in, we can talk about that later and why i chooseto do it. I loaded up 20 rounds of a light charge of 58gn h1000. I knew velocity was going to be low but didn't think they would be 2550s low. I was expecting mid 2700s. Accuracy was pretty darn good for just a throw together load I had no expectations for, but velocity was pretty disappointing. Anyone have some advice here or velocities they started with and where they ended up?
Here are thr specs:
26" proof carbon
58gn h1000
175 berger hunting hybrid, ~12k from touch.
Cci250
Adg brass.
Velocity measured with Labradar.

 

[wind gypsy]

In a short action? You’re 5+ grains below where I run them in a long throated saum so I wouldn’t expect much velocity with that charge.

 

[Mag_7s]

In a short action? You’re 5+ grains below where I run them in a long throated saum so I wouldn’t expect much velocity with that charge.

Medium Antixm plus. The bullet is seated at the bottom of the bearing surface at the neck shoulder junction. I'm just afraid I have the slowest .284 barrel ever made. Can you think of anything else I may be missing?

 

[WeiserBucks]

It's no surprise that a low charge yielded low velocity on a brand new barrel. Break it in to your hearts desire and ramp up the charge accordingly. If its still slow after a real pressure test then it might be worthy of a little concern.

 

[Mag_7s]

I'll keep pushing it north, hopefully I'll see the a velocity a 7saum should be in with a 26" tube. I just hope it's not a bunk barrel.

 

[SouthPaw]

I had a 24" proof 7saum barrel that sped up a bunch between 100 and 200 rounds down the barrel.

 

[Mag_7s]

I had a 24" proof 7saum barrel that sped up a bunch between 100 and 200 rounds down the barrel.

This is encouraging, maybe I don't have a $2 hooker for a barrel. What powder are your using?

 

[Quicksilver]

Do a legit pressure workup, see where that gets you before condemning anything. Anything else is just taking shots in the dark.

 

[Mag_7s]

Do a legit pressure workup, see where that gets you before condemning anything. Anything else is just taking shots in the dark.

Good point. I just loaded half grain increments to 65gn /H1000. Hopefully it comes alive.

 

[Brucebarker024]

I’m shooting 180 hybrid targets from my 7 SAUM loaded at 2.950 COAL at 2930 from a 24 inch proof tube. I’m using 4831sc though because h1000 was about 200 fps slower with the same bullets.

 

[Mag_7s]

I do have H4831sc as a backup. Would you mind sharing your combo? I will work up to it.

 

[grfox92]

Minimum starting load for 175s is 61gr of H1000 which according to Hogdon will put you at 2658fps. You are significantly below book minimum and freaking out you have a slow barrel?

That's like building a race car and driving around in second gear and being concerned the car is slow.

Why would you have expected 2700fps being 5 grains under book minimum?

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[wind gypsy]

h4831 can work well but I would expect it to pressure out at lower velocities than h1000.

 

[Quicksilver]

H1000 is what I’d plan on committing to, but if yup don’t get the results you want then try the next candidate. This is purely from an accuracy perspective.

Don’t get so tied up on velocity as well. Obviously you want as much speed as you can, but if it find a good node that is very consistent and accurate roll with it.

My 7 saum is running h4350 at only 2760fps but routinely shoots under 1/2moa at any distance and SD/ES is always less than 10/20fps. I am going to explore a slower burning powder for more velocity, but I would hunt any animal any day of the week with the current load. Accuracy builds confidence, confidence fills tags.

 

[Mag_7s]

Minimum starting load for 175s is 61gr of H1000 which according to Hogdon will put you at 2658fps. You are significantly below book minimum and freaking out you have a slow barrel?

That's like building a race car and driving around in second gear and being concerned the car is slow.

Why would you have expected 2700fps being 5 grains under book minimum?

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Yes you are right, I put emotion before logic and testing. 2700 was a guess based on others loads and reported velocity with a 26" barrel. What are you using in your saum?

 

[grfox92]

Yes you are right, I put emotion before logic and testing. 2700 was a guess based on others loads and reported velocity with a 26" barrel. What are you using in your saum?

I don't have one but plan on putting one together. The numbers didn't look right from what I remember so I ran load data through Hogdon. I would load one at book minimum and see how close you are to Hogdon load data. That should give you a good baseline keeping on mind it will probably speed up around 150 rounds.

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[Brucebarker024]

I do have H4831sc as a backup. Would you mind sharing your combo? I will work up to it.

Adg brass
180 hybrid target
Fed 215
59.8 grains of 4831sc

I have no pressure signs with this but it is crunchy. Obviously, load at your own risk and all those other disclaimers.

 

[Mag_7s]

Adg brass
180 hybrid target
Fed 215
59.8 grains of 4831sc

I have no pressure signs with this but it is crunchy. Obviously, load at your own risk and all those other disclaimers.

Thank you for the info. I always start low and work up...I started with 58gn here for example.

 

[N2TRKYS]

I’m getting 2980fps with 160 grain Partitions out a 22” barrel.

2950fps with 160 grain Accubonds.

I’m using RL26. IMR7828SSC is the closest thing to RL26 that I found.

 

[FredIII]

It's absolutely impossible to beat IMR7828. It's the perfect powder for the 7saum as well as the 280AI from 140 to 180 grain bullets.