No BS - 300 PRC vs 300 NM

[ZAR LRH]

I think most of us would agree that part of the 300 PRC success to date can be attributed to some very good and sometimes misleading marketing.

I've experienced some phenomenal performance (accuracy and low ES) with a improved version of the 300 NM, but a straight NM can make things a lot easier for me and going the PRC even more so.

Any real world experience on how the NM and PRC compare in reality with regards to easy tuning, accuracy, velocity and low ES with heavier bullets?

 

[Reload10]

I'm sure someone has data to back this statement up: Shorter and fatter powder columns seem easier to tune in my opinion and seem to have a large node with low ES.

Friend of mine shot the standard 300 NM for the military and had bolt thrust issues. Insane accuracy but had terrible pressure signs. I think there's a reason you went with the NM improved version

 

[Edd]

I think most of us would agree that part of the 300 PRC success to date can be attributed to some very good and sometimes misleading marketing.

I've experienced some phenomenal performance (accuracy and low ES) with a improved version of the 300 NM, but a straight NM can make things a lot easier for me and going the PRC even more so.

Any real world experience on how the NM and PRC compare in reality with regards to easy tuning, accuracy, velocity and low ES with heavier bullets?

This is from Google, there is more.

• As far back as 1946, gun writers and experts already concluded case shape had no effect on velocity or pressure.
• No matter how a case is shaped, if it is measured against one of the same caliber and capacity, it will have near identical internal ballistics.
• Col. G.O. Ashley did a load of range work comparing the .257 Ackley and a wildcat of the same caliber called the .25x60mm C.A. to support the conclusion case shape has little to no effect on ballistic performance.
• Despite this evidence, there are still wildcatters and manufacturers who claim to have innovative case designs and promise the moon when it comes to performance.
• Ackley himself acknowledged the limitations of cartridge design, saying: "There is no evidence which substantiates the claim that one cartridge design is more accurate than another."

 

[Deleted member 103481]

There is never evidence of anything until there is

 

[ZAR LRH]

@Reload10 , I agree that there is enough supporting evidence to support my and your theory about the shorter fatter powder columns. Personally, I think there is a reason why f class shooters prefer rounds like the WSM, RSAUM and 284 Win and why the Dasher and BR cartridges do so well. This however doesn't mean that one isn't able to "tune" other cartridges to the same accuracy, but in my opinion the window is smaller. How much? Well that is why I'm asking the question about the PRC.

@Edd thanks for sharing. I think the "near identical" do point to the influence of case design, but I agree that is potentially marginal. I still have to prove it, but I think there is a optimum shoulder angle (I think between 30*-35*) that will provide a little more performance for the same internal cases capacity and it is roughly based on the theory of friction loss for contractions when designing flow in pipes. I'm not discarding Col. Ashley's finding, but would like to see a comparison between two cartridges that differ more is shape, but with the same internal volume.

 

[Westernhuntr]

I think most of us would agree that part of the 300 PRC success to date can be attributed to some very good and sometimes misleading marketing.

I've experienced some phenomenal performance (accuracy and low ES) with a improved version of the 300 NM, but a straight NM can make things a lot easier for me and going the PRC even more so.

Any real world experience on how the NM and PRC compare in reality with regards to easy tuning, accuracy, velocity and low ES with heavier bullets?

I was really underwhelmed with my 300 NM.
I had a hard time getting it to shoot, and kept getting random pressure issues with otherwise normal loads.
Maybe it was a barrel issue in all fairness

It took 10-12 grains of powder to get 50 fps over my 300 prc, and case growth was ridiculous.

 

[Alex Wheeler]

All of the big 30s have a pretty long powder column. The short and fat thing is often repeated, but your not shooting the difference in a hunting rifle. Its really more about capacity than short and fat. A WSM will out agg any of the bigger magnums. As you go more overbore, you are giving up some amount of accuracy. Its been proven over many times in competition. The 300 Norma improved is one of my favorite cartridges. I like the design, capacity, and lapua brass. But it has some down sides. You do need custom dies, not an issue if you smith has this worked out. At least in my opinion, you want an action designed to handle the increased bolt thrust of the larger case, not just a standard action weakened by going to a .750 bolt. Your married to only a few chamberings with the lapua bolt face as well. I dont like the standard 300 Norma shoulder angle, Im not a fan of trimming brass every firing. For most practical purposes, the 300 PRC, 30 Nosler, or 30-28 Nosler will do everything you need for 215-230 grain bullets and is better suited for the majority of actions out there. Dont fall into the accuracy marketing. Not many I am aware of have built these bigger cases on Benchrest type platforms. I have, and they all shoot about the same, excellent. One is not easier to tune either. Now you many get a good or bad barrel that tuned very easy or fought you, but it is not because of the case. If someone wants to build a top notch rifle I usually recommend my Norma Imp. chamber, but if your looking for a little less expensive action, and factory dies, and dont need that little extra case capacity, then the 30-28 Nosler, 30 Nos, 300 PRC with ADG brass is a great choice.

 

[rustyshackleford]

I'm sure someone has data to back this statement up: Shorter and fatter powder columns seem easier to tune in my opinion and seem to have a large node with low ES.

Friend of mine shot the standard 300 NM for the military and had bolt thrust issues. Insane accuracy but had terrible pressure signs. I think there's a reason you went with the NM improved version

What exactly are the signs of bolt thrust issues? I've never heard of this but I shoot pretty vanilla cartridges.

 

[Pro2A]

This is from Google, there is more.

• As far back as 1946, gun writers and experts already concluded case shape had no effect on velocity or pressure.
• No matter how a case is shaped, if it is measured against one of the same caliber and capacity, it will have near identical internal ballistics.
• Col. G.O. Ashley did a load of range work comparing the .257 Ackley and a wildcat of the same caliber called the .25x60mm C.A. to support the conclusion case shape has little to no effect on ballistic performance.
• Despite this evidence, there are still wildcatters and manufacturers who claim to have innovative case designs and promise the moon when it comes to performance.
• Ackley himself acknowledged the limitations of cartridge design, saying: "There is no evidence which substantiates the claim that one cartridge design is more accurate than another."

So why upgrade to an Ackley version of a standard cartridge? I have never shot Ackley cartridges, but the above points seem to negate going to Ackley or other version upgrade.

 

[redleg1013]

Mic McPherson has shown otherwise.

 

[AlphaDogs]

Handloader killer the powder column myth with the side by side test of 300 WSM and 300 H&H. Different shapes, same performance. Some AIs hold enough powder to make more fps and one helps with the donut (243). Case shape is right up there with the Weatherby radius shoulder on the BS meter.

The British knew that feeding was more important than anything. Have owned a pile of 300/375 H&Hs. Never a failure to feed or eject. That can't be said of the short fatties.

 

[Edd]

... That can't be said of the short fatties.

It can't be said of the 06 length AI's either.

 

[Edd]

So why upgrade to an Ackley version of a standard cartridge?

With the choices of brass there is today, the best reason is probably because it's fun.

I don't like most of the Ackley's, I think they are ugly. I like cases with about .012" per inch taper and 30° shoulders

 

[Capt RB]

So why upgrade to an Ackley version of a standard cartridge? I have never shot Ackley cartridges, but the above points seem to negate going to Ackley or other version upgrade.

The stability of the brass is why I shoot an Ackley. In the 243ai or 6mmai, my father and I throw out our brass before we need to trim it after fire forming it. The straight 243 with what I hunt with I need to trim it back 2-3 times before tossing it at the same or 1 less cycle rate.