3000fps out of 20”bbl?

[muzzlebrake]

Getting as close to 100% case fill and as close to 100% ignition and 100% burn
Before that bullet exits the barrel is the whole key. Doing all that with the highest chamber pressure the barrel can stand and the highest pressure the case can stand is the trick. Some of these new powders are pretty good at getting higher velocities than we reloaders were used to back when. The CFE powders and StaBall and a few of the extreme propellants are interesting and more data is coming out now. Takes some work but that's the fun of it.
Almost all of these modern wildcat bench cartridges are in the short magnum design category for a reason. More efficient powder burn. I suspect that choosing a bullet of the weight you want and the shortest bearing surface on the lands is going to be the fastest MV. May not be the most accurate long range as the BC is not going to be as high as the longer surface bullets like Berger and the ELD's. I always got higher velocities with the Moly coated Nosler ballistic silvertips. Thick heavy base and shorter bearing surface. And then there's the Barnes bullets with all those grooves reducing bearing surface. They are generally even faster for me than Noslers.

[trophy8]

Don’t be so sure. I showed you the chrono reading of my all factory 20” 308 with 168ABLR.


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Sketchy *** powder load. I loaded those crazy things. Powder crunches harder than your old knees

[canny]

Can you post up that load and speeds? 7saw with 160s is struggling to get 2900 out of a 26" tube.

Here it is, now take into consideration a few things. First this was with a 120g bullet and a 24” barrel (it’s now been cut to 20”). As you can see I was getting mid 3200 FPS before any pressure signs. I was getting right around 3300+ when I started to see extractor marks. I have no doubt that with this load and the now 20” barrel that I can still be in the 3100s which would put a 140g at around 3000fps or a little over.

Disclaimer: This load was developed very carefully for my specific gun and as always you should do your own development and not rely on this information.


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[bbqfan5909]

Understand your math with losing 50fps per inch of barrel. But, you may have a lot of unburnt powder, coming in considerably under the 3k mark. Wouldn’t doubt your having to find a new powder to hit that 3k.

Here it is, now take into consideration a few things. First this was with a 120g bullet and a 24” barrel (it’s now been cut to 20”). As you can see I was getting mid 3200 FPS before any pressure signs. I was getting right around 3300+ when I started to see extractor marks. I have no doubt that with this load and the now 20” barrel that I can still be in the 3100s which would put a 140g at around 3000fps or a little over.

Disclaimer: This load was developed very carefully for my specific gun and as always you should do your own development and not rely on this information.


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[canny]

Understand your math with losing 50fps per inch of barrel. But, you may have a lot of unburnt powder, coming in considerably under the 3k mark. Wouldn’t doubt your having to find a new powder to hit that 3k.

We will see, I have some H4350 and RL17 on hand to try if needed, and also the 50fps is just a general average there are several other variables that influence that. I figure this configuration around the 35fps/inch.


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[Slick8]

I know it's not 3k fps, but I really like the idea of the 7 SAUM pushing 180's around the 2,800 fps range in short barrel rigs. They'll hang with the energy of the faster 140s for the first couple hundred yards, then surpass them as range increases. They also buy you some forgiveness in the wind, which is never a bad thing. Its just hard to find a more versatile combo in the 20"-22" range that packs that much punch but maintains it's "shootability" and manners.

This is what I built this year.

I'm running 2775 with minimal load development for 180s over H1k. Ran it to 2825 with no pressure signs but at 100% case capacity. I'm sure there's more speed with other powders but I'm a hodgedon extreme lover.

Next to no recoil and very easy to tune is a great combo. Took my first deer with it last week, a wt doe at 450.

I'd say 140-150s would hit 3k but wouldn't gain much over the 180s other than being flatter to 300.

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[Silentnight]

This is what I built this year.

I'm running 2775 with minimal load development for 180s over H1k. Ran it to 2825 with no pressure signs but at 100% case capacity. I'm sure there's more speed with other powders but I'm a hodgedon extreme lover.

Next to no recoil and very easy to tune is a great combo. Took my first deer with it last week, a wt doe at 450.

I'd say 140-150s would hit 3k but wouldn't gain much over the 180s other than being flatter to 300.

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What barrel length?
Did you build on a long or short action?

[canny]

Understand your math with losing 50fps per inch of barrel. But, you may have a lot of unburnt powder, coming in considerably under the 3k mark. Wouldn’t doubt your having to find a new powder to hit that 3k.

Wanted to follow up. I was able to run some rounds through the Lab Radar yesterday. These were the 120g Nosler BTs based on my previous data, just now coming from the 20” barrel. The MV did drop but still came in with an average of 3120fps. So I lost about 120fps going to the shorter tube.

The ES is high which could be a result from unburned powder but I am happy with the velocity.


The gun will still shoot…




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[bbqfan5909]

Moving quick brother, looks like you will be hitting on the lower node to get the ES down?

Wanted to follow up. I was able to run some rounds through the Lab Radar yesterday. These were the 120g Nosler BTs based on my previous data, just now coming from the 20” barrel. The MV did drop but still came in with an average of 3120fps. So I lost about 120fps going to the shorter tube.

The ES is high which could be a result from unburned powder but I am happy with the velocity.


The gun will still shoot…




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[canny]

3000fps out of 20”bbl?

Moving quick brother, looks like you will be hitting on the lower node to get the ES down?

This was not a ladder test, just sighting in the rifle to hunt with.

I think the node could be right around this mark. I had the following velocities to get this average

3119
3102
3119
3126
3143
3119

4 of 6 were within 7fps. Will need some further investigation.

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[Mike D]

If you pick your powder and bullet combo correctly you shouldn’t have a problem reaching your goal.

I have a 6.5x47 Lapua with a 22” barrel shooting 129 grain Accubond long range bullets at 2922 fps and it’s a dream to shoot.


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[ColinR]

I know it's not 3k fps, but I really like the idea of the 7 SAUM pushing 180's around the 2,800 fps range in short barrel rigs. They'll hang with the energy of the faster 140s for the first couple hundred yards, then surpass them as range increases. They also buy you some forgiveness in the wind, which is never a bad thing. Its just hard to find a more versatile combo in the 20"-22" range that packs that much punch but maintains it's "shootability" and manners.

Thinking this is my next build. Gonna send you a pm tomorrow with some questions on action length and freebore.

[sectxag06]

6.5 Sherman short, 3000fps with a 20’ barrel
Or
7 SAUM seems to have a reputation for not giving up too much velocity out of short barrels, and is easy to hand load for.

This. Go with one of the Sherman wildcats or the 6.5 GAP 4S.

[ultrastealth]

Or you can wait for Sig's .277 Fury, which at this point seems to have been nothing but a marketing ploy.

[freerhunter16]

I ended up ordering a 7 SPRC from McWhorter with their custom load development for 180 VLDs. With their load, they are claiming I should see ~2900 fps out of a 22” bbl with the 180s.

After going back and forth between different options a million times, I decided to listen to the folks that know more than me and landed on 2900 fps with a 180 instead of trying to reach 3000+ with a lighter bullet.