300 PRC or 30 Sherman mag

[Alex Wheeler]

.260 is a minimum to keep a 230 from pushing through the bushing line on the neck and messing with your neck tension. The 245 will need more. Now thats not to say you cant shoot it in a .260. So long as there is no contact with a doughnut in the neck it will be fine, you just will not be able to work with your neck tension much.

 

[highdrum]

Has anyone had a chance to compare the bearing surface length on 245's and 230's?
If .260 is enough that the 245 isn't stuffed down too far I may just go with that

245 has 0.100" more bearing. 0.529 vs 0.633, the 245 is a massive freaking bullet, considering the 300 berger is 0.556.

 

[VLD Pilot]

Not true
Run the numbers.
A 245 at 2800 has 200 more ft lbs and .5 minutes less drift in a 10 mph cross wind than a 215 at 3000 fps or a 230 at 2900.
Not a huge difference but its certainly there, plus the extra mass from a 245 should knock elk down with authority!

Old thread I know but you wouldn't need to worry about settling on 2800 fps with the 30SM and 245s. I think getting 2950-3000 is pretty common with it.

 

[adk hunter]

So in other words, isn't the 30 Sherman Mag to the 300 PRC what the .280AI is to the .280?
The .280AI is well worth it

 

[VLD Pilot]

So in other words, isn't the 30 Sherman Mag to the 300 PRC what the .280AI is to the .280?
The .280AI is well worth it

I've heard 75-150 fps

 

[7.62 Gunner]

I've heard 75-150 fps

My personal experience was 50 fps over the prc
It's only a 1 grain h20 increase and the laws of physics apply

 

[VLD Pilot]

My personal experience was 50 fps over the prc
It's only a 1 grain h20 increase and the laws of physics apply

Wish I could get more consistent numbers. Many say 75-150 others say hardly any difference. I'm only going with a 30SM so I can reasonably get 3K with 225s and no pressure issues. I felt like with a 26" barrel and the 300PRC, I'd have to step on it too hard to make 3000. Kinda want a medium load to achieve that speed. Guess I'll have to get my own experience with the cartridge and post my results.

 

[codyadams]

Wish I could get more consistent numbers. Many say 75-150 others say hardly any difference. I'm only going with a 30SM so I can reasonably get 3K with 225s and no pressure issues. I felt like with a 26" barrel and the 300PRC, I'd have to step on it too hard to make 3000. Kinda want a medium load to achieve that speed. Guess I'll have to get my own experience with the cartridge and post my results.

Reason is going to be tough brass and a case design that is good at disguising pressure signs. Tough quality brass such as Peterson, ADG and some others won't necessarily kill primer pockets running at 70k psi consistently, these companies have tested this, and the 40° shoulder does a good job reducing bolt thrust, therfore not showing ejector marks until higher pressure. So, no pressure signs, and primer pockets hold up just fine, so you run your loads at higher pressure and get more velocity, so that is how you end up with 75-100 fps more velocity with only a small increase in powder.

Now, I'm not saying this is necessarily a bad thing, if your brass is holding up fine, and your not having heavy bolt lift or showing ejector marks, then what is the downside of running 70k psi on a reciever that can handle it without breaking a sweat? There really isn't one, so therefore you are capable of getting more performance.

However, here is what I have found in my personal experience running several AI and Sherman cases vs. standard cases. I'll use the 7mm rem mag as my first example. Using ADG brass in a remington action, there is a pretty wide margin of pressure between initial pressure signs, such as slight increase in bolt lift and onset of ejector marks, and loosing primer pockets. Enough so, that if you run your load right at the beginning or a little below these initial signs of pressure, such as only getting a very faint ejector mark, primer pockets have lasted at least 8-9 fireings so far on one particular rifle, on what I would consider pretty hot, or top end load. But when you redesign the case to that of an ackley improved or Sherman type design, it seems to narrow that margin. Your initial pressure signs seem to come at a higher pressure range, and you really need to watch. In a 7 Sherman max on a Defiance anTI, I had a load that just shot phenomenal, however it was right at pressure signs. I wouldn't get bolt lift, but I had a shadow of the ejector every time. Not a shiny mark, but one that if you had it in the light right, you would see it. After 3 fireings of this load, the primer pockets were gone. I would consider it very similar pressure signs to the 7mm rem mag load, but obviously higher pressure. I had a similar experience with Norma brass in a .270 Sherman, and my .260 AI with Lapua brass.

So essentially, if you are careful, you can ride that line of having your brass last, while still getting a significant boost in performance, as long as you have somewhat of a margin away from pressure signs. Where, at least with good quality brass, I have found in a standard case you can get away with faint pressure signs. That is just what I have observed in 5 Sherman rifles and 2 AI rifles, vs standard cartridges I loaded for. Honestly anymore, I try to run all my rifles at least 1 grain below pressure signs, case capacity dependant, I usually get better consistency anyway, and I dont need to worry about beating up brass. If I need more performance, I'll just go with a larger chambering.

Sorry about the novel, didn't intend to run on like that.....

 

[VLD Pilot]

Reason is going to be tough brass and a case design that is good at disguising pressure signs. Tough quality brass such as Peterson, ADG and some others won't necessarily kill primer pockets running at 70k psi consistently, these companies have tested this, and the 40° shoulder does a good job reducing bolt thrust, therfore not showing ejector marks until higher pressure. So, no pressure signs, and primer pockets hold up just fine, so you run your loads at higher pressure and get more velocity, so that is how you end up with 75-100 fps more velocity with only a small increase in powder.

Now, I'm not saying this is necessarily a bad thing, if your brass is holding up fine, and your not having heavy bolt lift or showing ejector marks, then what is the downside of running 70k psi on a reciever that can handle it without breaking a sweat? There really isn't one, so therefore you are capable of getting more performance.

However, here is what I have found in my personal experience running several AI and Sherman cases vs. standard cases. I'll use the 7mm rem mag as my first example. Using ADG brass in a remington action, there is a pretty wide margin of pressure between initial pressure signs, such as slight increase in bolt lift and onset of ejector marks, and loosing primer pockets. Enough so, that if you run your load right at the beginning or a little below these initial signs of pressure, such as only getting a very faint ejector mark, primer pockets have lasted at least 8-9 fireings so far on one particular rifle, on what I would consider pretty hot, or top end load. But when you redesign the case to that of an ackley improved or Sherman type design, it seems to narrow that margin. Your initial pressure signs seem to come at a higher pressure range, and you really need to watch. In a 7 Sherman max on a Defiance anTI, I had a load that just shot phenomenal, however it was right at pressure signs. I wouldn't get bolt lift, but I had a shadow of the ejector every time. Not a shiny mark, but one that if you had it in the light right, you would see it. After 3 fireings of this load, the primer pockets were gone. I would consider it very similar pressure signs to the 7mm rem mag load. I had a similar experience with Norma brass in a .270 Sherman, and my .260 AI with Lapua brass.

So essentially, if you are careful, you can ride that line of having your brass last, while still getting a significant boost in performance, as long as you have somewhat of a margin away from pressure signs. Where, at least with good quality brass, I have found in a standard case you can get away with faint pressure signs. That is just what I have observed in 5 Sherman rifles and 2 AI rifles, vs standard cartridges I loaded for. Honestly anymore, I try to run all my rifles at least 1 grain below pressure signs, case capacity dependant, I usually get better consistency anyway, and I dont need to worry about beating up brass. If I need more performance, I'll just go with a larger chambering.

Sorry about the novel, didn't intend to run on like that.....

Nothing I'll ever need to worry about. Not planning on running hot loads. Lapua brass medium loads. Just looking for a bit better than the PRC gives with less pressure. I think I can get it that way. Sounds like you certainly have to experience based on your Novel. Appreciate that info. John

 

[CA48]

My experiences pretty much mirror Codys when it comes to my personal wildcats, AI and 3 Sherman cartridges I have loaded for. That was a good explanation. I think you can expect to easily run 75-100 fps over a standard 300 PRC all things being equal when you add 3.5grs of case capacity, reduce case taper, and add a 40* shoulder. I've loaded for a lot of 300 PRC's 24-26" barrels and they shot best with n565 and h-1000 at 2850-2950 with 205 bergers. I could have and did run some faster but that's where they shot best most of the time. And I would would not run a customer rifle at the top end anyway. My personal 30 Sherman Mag shoots best at 2950 with 215s and n570 out of a 20" barrel if that tells you anything even though it's not a direct comparison. Although I think mine will not be the norm but on the higher end for velocity and I am running a warm load. But for educational purposes I've added 0.6gr to my load and still got 10 plus firings out of a case with some slight ej shadows.

 

[VLD Pilot]

My experiences pretty much mirror Codys when it comes to my personal wildcats, AI and 3 Sherman cartridges I have loaded for. That was a good explanation. I think you can expect to easily run 75-100 fps over a standard 300 PRC all things being equal when you add 3.5grs of case capacity, reduce case taper, and add a 40* shoulder. I've loaded for a lot of 300 PRC's 24-26" barrels and they shot best with n565 and h-1000 at 2850-2950 with 205 bergers. I could have and did run some faster but that's where they shot best most of the time. And I would would not run a customer rifle at the top end anyway. My personal 30 Sherman Mag shoots best at 2950 with 215s and n570 out of a 20" barrel if that tells you anything even though it's not a direct comparison. Although I think mine will not be the norm but on the higher end for velocity and I am running a warm load. But for educational purposes I've added 0.6gr to my load and still got 10 plus firings out of a case with some slight ej shadows.

Pretty impressive from a 20" bbl. Good to hear about case life tho as well.

 

[elkaholic]

I have 8 firings and still going on my brass with a 245 at 3000' with a 28" barrel.

Pretty impressive from a 20" bbl. Good to hear about case life tho as well.

 

[7.62 Gunner]

Wish I could get more consistent numbers. Many say 75-150 others say hardly any difference. I'm only going with a 30SM so I can reasonably get 3K with 225s and no pressure issues. I felt like with a 26" barrel and the 300PRC, I'd have to step on it too hard to make 3000. Kinda want a medium load to achieve that speed. Guess I'll have to get my own experience with the cartridge and post my results.

Yeah there's no downside to the 30 sm if preformed brass is available, it wasn't when I had mine and I wasn't enamored enough with it to justify the extra time and expenses of fireforming so I went 30 Nos.
Just don't go into it expecting magical performance and you won't be disappointed

 

[VLD Pilot]

I have 8 firings and still going on my brass with a 245 at 3000' with a 28" barrel.

Good news for sure. Especially considering I'm not shooting 245s and that 3000 fps number is what I'm looking for with 225s. Should work out pretty well.