Caribou Gear

New 300 Sherman build

Pressure...

I am using Federal 215m which are inherently soft. I don’t have any flattening just a minor crater at those loads. I consider these at pressure when the edges flatten and I get a swipe.

Rich’s original testing back in 2010 with different brass has the 180 up to 3150 FPS in Winchester brass. Albeit, most of his accuracy came with 190’s at 3050fps.
 
H4831sc was a little slow. It pushed the 180 Partition to 2943fps.

63g of RL16 ran it up to 3073 but I had a minor swipe mark. So it probably maxes out around 62.5g and 3050.

Off to the store for some IMR 4831 and maybe some N550 if they have it.
 
Spent some time this week playing with different powders. I really wanted RL26 to work but with a 180g it is just too light of a bullet in this cartridge. A 200g Accubond ended up @ 2920 FPS.

IMR 4831 did ok but hit pressure too soon for my targeted velocity goals.

RL16 showed promise at 3073 but had a large ES that I didn’t like.

Finally, I tried H4350. To my surprise it clobbered the competition. It is pushing a 181g Hammer at 3111 FPS. Primers are still rounded and show no sign of pressure in my rifle. I’m excited to take it out to shoot some groups later this week.
 
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Impressive performance. I had never heard of this round before either.
 
Impressive performance. I had never heard of this round before either.

I hadn’t either until last fall. I went searching for something to replace my 7 Mag. On a different forum I read about it and starting asking questions. I wanted a cartridge that wasn’t the run of the mill, pushed a 180g over 3000fps, and had a standard bolt face. The 300 Sherman checked all the boxes.

Pretty happy with it so far. Looking forward to hunting with it this fall.
 
It’s a 30-06 on steroids. The shoulder is bumped out further from the Ackley version and it uses the 270 parent case to have a longer neck. 280AI brass is 90% formed and works the best. After fire forming it will add another 2-3 grains.

View attachment 146225

Hello,

I have .30 Gibbs, which is similar to the 300 Sherman except for a 35-degree shoulder and shorter.

.30 Gibbs loaded with Berger 190 VLDs.jpg
.30 GIBBS fire-forming progress.jpg

I started with .35 Whelen brass to establish the false shoulder, so I do COW method forming.

On my first load (not looking for any accuracy, but it is well under 1 MOA) with RL-17 57g, 190 Berger VLD, I was getting 2806 FPS ES=15 SD=6 out of my Kimber 84L Hunter with 24" barrel. It still has more for more powder. I was playing around with powders that I already have open. I have some Peterson .280 Rem brass to try and form. Also, have .30 Gibbs brass inbound from Qual Cart. I will be loading the Berger 205s next but will eventually settle in the 180g range since my goal is for <yard deer/elk set-up

Looking forward to some performance sharing loads.

Cheers!

Ed
 
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Hello,

I have .30 Gibbs, which is similar to the 300 Sherman except for a 35-degree shoulder and shorter.

View attachment 166348
View attachment 166347

I started with .35 Whelen brass to establish the false shoulder, so I do COW method forming.

On my first load (not looking for any accuracy, but it is well under 1 MOA) with RL-17 57g, 190 Berger VLD, I was getting 2806 FPS ES=15 SD=6 out of my Kimber 84L Hunter with 24" barrel. It still has more for more powder. I was playing around with powders that I already have open. I have some Peterson .280 Rem brass to try and form. Also, have .30 Gibbs brass inbound from Qual Cart. I will be loading the Berger 205s next but will eventually settle in the 180g range since my goal is for <yard deer/elk set-up

Looking forward to some performance sharing loads.

Cheers!

Ed
With the short necks on the Gibbs are you getting an enough neck tension to keep the hammer securely in place? I’m guessing you have to crimp them.

I gave up on HH in my 260 Ackley because I couldn’t keep them in place even with a crimp. They have just about as short of a neck.
 
With the short necks on the Gibbs are you getting an enough neck tension to keep the hammer securely in place? I’m guessing you have to crimp them.

I gave up on HH in my 260 Ackley because I couldn’t keep them in place even with a crimp. They have just about as short of a neck.
I've only loaded 190 Berger thus far; no HH yet.
 
Good afternoon all, sorry to bring up an old thread, I've been lurking for a while and have been considering a very similar build (will likely be a couple year project given the current inventory/lead times to get parts).

I am trying to decide between a 30-06 AI, 30x280AI, or 300 Sherman. The only real reason the 30-06AI is in the running is for the ability to use factory ammo in a pinch and seems to be the easiest to fireform cases. I have had a hard time finding data on either the 30x280AI or the 300 Sherman but they seem pretty close.

Addicting, are you still sticking with the 181 HH's or have you tried any others given that the hammers seem to like as much velocity as you can give them. How are you forming your brass? Can you fireform by basically loading a 30x280AI and the shooting like you would a standard/factory 30-06 in a 30-06Ai chamber or do you need to use COW or hydro form.

Also, have you compared the difference in case capacity between the 280AI brass and the formed 300 Sherman brass? just trying to figure out if the extra forming steps are worth it over the 30x280AI.

thanks in advance.

-Matt
 
Good afternoon all, sorry to bring up an old thread, I've been lurking for a while and have been considering a very similar build (will likely be a couple year project given the current inventory/lead times to get parts).

I am trying to decide between a 30-06 AI, 30x280AI, or 300 Sherman. The only real reason the 30-06AI is in the running is for the ability to use factory ammo in a pinch and seems to be the easiest to fireform cases. I have had a hard time finding data on either the 30x280AI or the 300 Sherman but they seem pretty close.

Addicting, are you still sticking with the 181 HH's or have you tried any others given that the hammers seem to like as much velocity as you can give them. How are you forming your brass? Can you fireform by basically loading a 30x280AI and the shooting like you would a standard/factory 30-06 in a 30-06Ai chamber or do you need to use COW or hydro form.

Also, have you compared the difference in case capacity between the 280AI brass and the formed 300 Sherman brass? just trying to figure out if the extra forming steps are worth it over the 30x280AI.

thanks in advance.

-Matt
A 30-280ai is the same as a 30-06ai except the neck is a little longer on 270/280 brass. Any 30-06ai reamer you find will have enough neck to accommodate the 270/280 brass.

As for the 300 Sherman. I can’t say I recommend it over the AI for what you gain. The lack of components and cost simply are not worth the advantage.

I have used 280ai brass and it works great at first but you will only get 2-3 firings out of it before you start getting case head separation. Fire forming from 270/280 brass is better because it takes brass from the neck verses the body. I have 10+ firings on RWS 270 brass.

If I had to do it over again, I would have mine reamed out to 30 Sherman Mag which is a AI version of the 300 PRC case. Headstamp Brass is readily available and the capacity is there if you want to run them hard. But you can load them down in the same range as the 30-06ai or 300 Sherman without issue.
 
Addicting, are you still sticking with the 181 HH's or have you tried any others given that the hammers seem to like as much velocity as you can give them. How are you forming your brass? Can you fireform by basically loading a 30x280AI and the shooting like you would a standard/factory 30-06 in a 30-06Ai chamber or do you need to use COW or hydro form.
COW was a PIA for this brass as you have to take it out to 8mm then back to .308. Case necks can only stretch so far before you start loosing them to cracked necks. At .308 I lost a few, going to 8mm cost me more. It simply is Not worth it.

I have shot 3 elk with the 181HH. I am selling what I have left as I don’t think I can push them fast enough. 3030fps seems fast but necropies tell the whole story. I don’t feel the bullet is fast enough to open fast enough, I feel it is opening 8-10” past where it should. The pair of lungs below show what I’m talking about. Bullet went right to left in the pic. I will either go back to 180 Accubonds at 3100 or drop down to the 160 class mono to get the speed up.
 

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A 30-280ai is the same as a 30-06ai except the neck is a little longer on 270/280 brass. Any 30-06ai reamer you find will have enough neck to accommodate the 270/280 brass.
So I was looking at the Nosler Load Data, they have case dimensions for both the 280AI and the 30-06AI. The Case body of the 280AI is 0.097 longer than the 30-06AI. Doing some basic calculations the 30-06AI has approximately 4% gain in case capacity and the 30x280AI should have about 8% over the standard 30-06.
 
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