300 PRC or 30 Sherman mag

[VLD Pilot]

Ya, know what you mean, I'm building a hot 25 cal to run supressed for mule deer and pronghorn, they are much nicer for sure. But the last several elk our group have taken have been 703, 713, 816, 710, 840, 860, 873, 963, 1002.......so I prefer to use my .338 for them, and they are also quite a ways up in the back country, so light weight helps, so a brake is the best option in this unique circumstance of a light rifle in a large caliber ha ha

I'm not sure if my 25-284 is classified as hot as there are many bigger cartridges bigger but hot enough from me running the 135 Berger's at 3130 from a 24" barrel. It's going out to Wyoming on a Mulie/goat hunt this September. Can't wait.

 

[VLD Pilot]

No that is retumbo. I love N570 just to hard to get and keep around. At one point I had 4 diff. Rifles running it and it dried up and Kaiser Sose on me again so I just quit using it amazingly fast velocities with N570

How does Retumbo compare to N570 velocity wise. Obviously accuracy is important and ultimately will be the deciding factor but I have N570, H1000, Retumbo and RL33 to try

 

[jpndave]

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

But as @codyadams said above the increased pressure is still there! Unless you are talking a few fps the minimal capacity increase gives. The tough brass, reduced taper and 40° shoulder hide pressure signs but it is still there. Arguably it's still safe (or maybe even safer than Hornady brass/SAAMI chamber) but the chamber/throat/barrel are still seeing the increased pressure.

The 300 PRC is already an "improved" design with minimal taper and 30° shoulder. The SM is "more improved". The difference between 300 PRC & 30 SM is MUCH less that 280 to 280 AI.

If you run the same Lapua brass in a 300 PRC w/Alex Wheeler's reamer and the 30 SM to the same pressure or even the same pressure signs they are going to be a lot closer - meaning only small gains w/the 30 SM over 300 PRC vs large gains compared to stock SAAMI chamber Hornady brass to pressure signs.

 

[VLD Pilot]

But as @codyadams said above the increased pressure is still there! Unless you are talking a few fps the minimal capacity increase gives. The tough brass, reduced taper and 40° shoulder hide pressure signs but it is still there. Arguably it's still safe (or maybe even safer than Hornady brass/SAAMI chamber) but the chamber/throat/barrel are still seeing the increased pressure.

The 300 PRC is already an "improved" design with minimal taper and 30° shoulder. The SM is "more improved". The difference between 300 PRC & 30 SM is MUCH less that 280 to 280 AI.

If you run the same Lapua brass in a 300 PRC w/Alex Wheeler's reamer and the 30 SM to the same pressure or even the same pressure signs they are going to be a lot closer - meaning only small gains w/the 30 SM over 300 PRC vs large gains stock SAAMI chamber Hornady brass.

Yes I'm only talking about hitting that 3000 fps mark with the 225s. Should be an easy accomplishment in the improved version.

 

[VLD Pilot]

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

No if I were looking for that, I'd go with the 30/338 Lapua improved. Just trying to keep pressure down from the PRC standard cartridge while trying to hit that 3000k velocity. Seems to be the speed I prefer with all my ideal bullet weight for cartridge combos

 

[snox801]

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

I never thought of forming bars as a downside. Simply because your barrel gains speed as it's broke in. So I spend the break in periods getting to know the rifle and fire form.
No real loss for me. Then I get to my final load work. But correct nothing magic with it it's just an improved

 

[snox801]

How does Retumbo compare to N570 velocity wise. Obviously accuracy is important and ultimately will be the deciding factor but I have N570, H1000, Retumbo and RL33 to try

Rl33 may be the ticket if you can get enough in the case. It shines in similar cases I have. Not sure why but it has surprised me more than once

 

[VLD Pilot]

I never thought of forming bars as a downside. Simply because your barrel gains speed as it's broke in. So I spend the break in periods getting to know the rifle and fire form.
No real loss for me. Then I get to my final load work. But correct nothing magic with it it's just an improved

The best part of that scenario is 300 PRC ammo will shoot very well in the 30SM so it's not really like your fireforming as a step. Your using the load for a purpose other than that. Hunting maybe or shooting steel for fun not just burning up powder and bullets to form brass

 

[VLD Pilot]

Took me a few wildcats to figure that out. Now I don't even think about the cartridge that I built the rifle for. I use the ammo I'm fireforming for use as a hunting rifle or target rifle and do drop data on it for that use. Once all the brass is formed, I then start over. The rifle/cartridge gets full use thru it's entire life.

 

[snox801]

Took me a few wildcats to figure that out. Now I don't even think about the cartridge that I built the rifle for. I use the ammo I'm fireforming for use as a hunting rifle or target rifle and do drop data on it for that use. Once all the brass is formed, I then start over. The rifle/cartridge gets full use thru it's entire life.

That's exactly what I do a lot of times. PRC ammo shoots great out of mine plenty accurate for hunting.

 

[MallardAddict]

No if I were looking for that, I'd go with the 30/338 Lapua improved. Just trying to keep pressure down from the PRC standard cartridge while trying to hit that 3000k velocity. Seems to be the speed I prefer with all my ideal bullet weight for cartridge combos

As several others have already stated the increased capacity of the SM is NOT enough to equal out the higher velocity being made at significantly lower pressure.

Physics and ballistics just don't work that way as velocity in equals bullet weights always equals either more powder or more pressure. The SM is a gain in powder of about 1.5% yet it gets 100+ fps more velocity which can only mean it runs at higher pressure.

No established pressure testing for the SM but it's likely safe to do as people are doing assuming quality actions and brass and a lick of sense/ caution when loading but the claims of less pressure are pure BS!

The easiest way to a low pressure 225 load at 3k fps is to use a RUM or Norma/NMI.

 

[bigngreen]

You can mask some signs of bolt thrust but the expansion of the case head is the same for the parent case and anything based of that case at the same pressure, if your paying attention you'll load the them to the same pressure range, run a Pressure Trace and you'll see pressure is pressure you can alter time.

The 30 SM predates the 300 PRC, 30 Nosler and ADG.

 

[VLD Pilot]

As several others have already stated the increased capacity of the SM is NOT enough to equal out the higher velocity being made at significantly lower pressure.

Physics and ballistics just don't work that way as velocity in equals bullet weights always equals either more powder or more pressure. The SM is a gain in powder of about 1.5% yet it gets 100+ fps more velocity which can only mean it runs at higher pressure.

No established pressure testing for the SM but it's likely safe to do as people are doing assuming quality actions and brass and a lick of sense/ caution when loading but the claims of less pressure are pure BS!

The easiest way to a low pressure 225 load at 3k fps is to use a RUM or Norma/NMI.

Ok forget pressure. Sure it's there without a doubt. But just the 3 extra grains of powder will get me to 3000 EVEN at the same pressure the 300PRC would without compressing and causing more pressure that's not needed with the SM. Is the extra 3 grain necessary in reality, probably not. 2925 vs 3000. I mean it's more of a number I'm trying to get to easier than the actual difference between those to velocities in performance.

 

[VLD Pilot]

As several others have already stated the increased capacity of the SM is NOT enough to equal out the higher velocity being made at significantly lower pressure.

Physics and ballistics just don't work that way as velocity in equals bullet weights always equals either more powder or more pressure. The SM is a gain in powder of about 1.5% yet it gets 100+ fps more velocity which can only mean it runs at higher pressure.

No established pressure testing for the SM but it's likely safe to do as people are doing assuming quality actions and brass and a lick of sense/ caution when loading but the claims of less pressure are pure BS!

The easiest way to a low pressure 225 load at 3k fps is to use a RUM or Norma/NMI.

Considering I want to 300 PRC, the easiest way to get to that speed I wanted was just to add another two to three inches to my barrel length. Hindsight.