300 Norma mag. VS 300 PRC
- Thread starter Ranger188
- Start date
Most guys shooting 245s in ELR Light are single-feeding the rounds even with a mag feed rifle.
Alex Wheeler
Site $$ Sponsor
What were the base numbers on the dies? The .200" in this case means nothing. Its solid brass. You need to measure up around .350" where they actually expand to see how much they size.
moondog
Gold $$ Contributor
I was assuming Alex was talking about the Berger 230s.
wi50
Silver $$ Contributor
The base in his die is .0016 smaller than mine. What's it? I don't have the dies here to measure today, I sent mine back so he can use it. We were shooting together roughly 6-7 weeks ago and I had brought my size die, he brought the "bad one" well the second bad one at that point after the first go around blaming the bottom chamifer. We have a press at the that range. I brought some measuring tools, micrometer, snap gauge and some die wax so we could fire a few cases from different guns, measuring dies, size cases and size some brass from each to compare. The new die measures small. It sizes .0016 smaller than mine. Shaves the brass and quite hard on the press handle to operate....like at the point of going to pull the rim off the case when trying to get the case retracted. I just sent my die with so he could size his batch of brass as I just don't need it for the short future.
A few guys I shoot with, build for have gotten dies previously, all worked out. But this last one, two strikes so far. I gotta do another 300nmi for a friend but I figured I'd order a die, check it then chamber the barrels or I got someone waiting with a rifle and no die, but for the last say 2 months they been out of stock.
So where's the problem, I have Peterson and lapua brass. Reamer from jgs. The normally stocked 35 degree aw version. It all sizes and works perfectly. The last two dies have been the problem.
As I said before, its not my problem to figure out. Somewhere something got changed in how they're making the die. The first problem die was simply exchanged for another, which was also bad. Currently out of stock so, hopefully rhe next ones work.
As far as the original posters question, 300 prc vs the .300 nmi. 600 yds to a mile. The prc is sure easy. No forming, a little better component availability. Reloading dies that work. Mines sure been the easy way.
A few guys I shoot with, build for have gotten dies previously, all worked out. But this last one, two strikes so far. I gotta do another 300nmi for a friend but I figured I'd order a die, check it then chamber the barrels or I got someone waiting with a rifle and no die, but for the last say 2 months they been out of stock.
So where's the problem, I have Peterson and lapua brass. Reamer from jgs. The normally stocked 35 degree aw version. It all sizes and works perfectly. The last two dies have been the problem.
As I said before, its not my problem to figure out. Somewhere something got changed in how they're making the die. The first problem die was simply exchanged for another, which was also bad. Currently out of stock so, hopefully rhe next ones work.
As far as the original posters question, 300 prc vs the .300 nmi. 600 yds to a mile. The prc is sure easy. No forming, a little better component availability. Reloading dies that work. Mines sure been the easy way.
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Ledd Slinger
Silver $$ Contributor
I still wouldn’t be considering a RUM with 245s and im sure you won’t find it much on ELR competition lines either.
If a person wanted a big fast single shot 30 cal for ELR, then i would look into the 300 Lapua Improved, but the 300 NMI will do most everything a person can expect to get from the 30 cal bullets at ELR without having horrible barrel life.
Ledd Slinger
Silver $$ Contributor
Thats Hornady quality control at its best! Lol! I have an early 35 AW NMI die from them that works well tho
I had a Redding die in 6.5x47L do the same thing as you described. Had a small base with a sharp edge that shaved the brass bad. Hard to de-burr hardened steel cleanly, so had to send it back to Redding for a replacement.
The Norma definitely fits those long bullets really well in a magazine.
My 300RUM based 338 has a 4.31 coal.
Alex Wheeler
Site $$ Sponsor
Its not my problem to figure out either, I have never made a penny off giving away my intellectual property. But here I am trying to help figure it out anyways
Ledd Slinger
Silver $$ Contributor
No telling how many dies they cut with the same reamer before changing it out. Maybe they reground the FL sizing reamer too many times or a new replacement reamer is out of spec ???Its not my problem to figure out either, I have never made a penny off giving away my intellectual property. But here I am trying to help figure it out anyways
Agreed about the 300 rum but i'm talking in general, Every match i've been too around 90%+ of the guys are single feeding their rifles including the light guns. I'm also not a fan of the rebated rim on the RUM.
long40shot
Gold $$ Contributor
I'm really in enjoying my PRC. Still working up loads, but like Alex pointed out in an older thread, fired brass gains more than you would think in the 300prc. Here a picture of my before and after. New on the right, once fired on the left.
Matt
Attachments
You should do a case capacity test with water to see how much the fired case grew.
Ledd Slinger
Silver $$ Contributor
There’s definitely some room for an improvement design on the 300 PRC as well if a person wanted to push the envelope with it. Would not have considered that option when there was only Hornady brass, but now that there is Lapua and ADG brass available, it might be worth toying with a little bit.
With only my shoulder slightly farther forward on my 338-375 Ruger design, i gain 4gr of capacity with a fired PRC case against a virgin case. The virgin case was also necked up to 338 cal to compare apples to apples
With only my shoulder slightly farther forward on my 338-375 Ruger design, i gain 4gr of capacity with a fired PRC case against a virgin case. The virgin case was also necked up to 338 cal to compare apples to apples
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30 Sherman could be alot of fun too.
I single feed 99% of my ELR stuff.
I ran error budgets for the 2 cartridges the OP currently shoots and the PRC. I thought the results were interesting so I'm going to over share.
There is fairly broad agreement at this point, and it's straightforward to demonstrate, that the error budget for ELR includes Dispersion, velocity spread, BC spread, and uncertainty in the aiming point. For my personal Rubik's Cube, the other 2 sides are conditions and spotting equipment.
These plots are produced by importing 3 range cards for each cartridge from AB Analytics into Excel. The range cards are for the baseline, -100 fps, -10% BC. The differences between the range cards are scaled for the assumed velocity and bc spreads. Each of the first 3 error budget components are rolled into a RMS estimate. 4X the SD is used to estimate ES. This is a model I use to prioritize effort, it doesn't "prove" anything.
QL was used to estimate the performance of 3 cartridges. I assumed they all used a 30" barrel that's readily available from Barrel Brokers.
The first was the 300 NMI with a 245 hybrid. I assumed N570, a midlife start pressure, and added powder until the model reached 72,000 psi. The pressure level was selected because it's what the model gives for internet loads "with no pressure signs". The predicted velocity was 3150 fps. For the error budget, it was assumed the gun would put 20 shots into 0.75".
The second was the 300 PRC with a 230 ATip. With H1000, the same start pressure as the NMI, and 67,000 psi peak pressure, the prediction was 2950 fps. This is the modeled peak pressure I run my guns at. Lapua and boutique brass will take more but my experience has been much above this degrades bullet performance. The accuracy of this gun was also assumed to be 0.75" for 20 shots.
The third was the 300 WSM with a 220 hybrid. H4831SC, 67,000 psi peak pressure, 2825 fps. The accuracy was assumed to be 0.5" for 20 shots.
20 fps velocity spread for 20 shots was the base assumption. This can be reached by advanced hobbiests. It's pretty much trading the SD of commercial match ammo for the ES. At this level, velocity spread won't be your biggest problem.
For the NMI, the error budget looks like:
RMS calculations are intended to estimate what is likely to happen when multiple effects are contributing to an outcome. The point of this discussion is to illustrate how different components take their turn dominating the problem.
If you'd like to confirm or track BC spread, that 2000 - 2500 yards range is a good place to select bullets and retire barrels. The idea that bullets won't take the pressure your brass will can also be tested out here. The shallower the backstop, the greater the illusion that the vertical spread is smaller than it actually is becomes. Conditions are a problem as well. Initially, it'll take a truing conditions kind of day to suck it up and retire a barrel. After seeing the results of a few barrel replacements, it'll get easier to justify. Having a second gun that you regard as subordinate to use for comparison also helps see when it's time to freshen up the hot rod.
Zooming in the NMI to 1600 yards:
At 1600 yards, the shortest path to more hits might still look like improving the precision. The reality is all 3 contributors are about the same size and the other 2 will keep the vertical spread up. If there are 3 contributors to spread and they're all the same size, the RMS estimate will be 1.7 instead of 3. If one of those contributors completely goes away, the RMS estimate will drop to 1.4.
Comparing the other 2 cartridges to the NMI:
The relatively small differences probably were not intuitive to most. From this perspective, more velocity and higher BC only shorten the TOF. That's important, but it's not as strong an influence as shot to shot variations. This is what the 7 saum guys are up to. It has a little more performance than the 300 WSM, but the real point is for hobby use the 300 WSM works fine.
Zooming down to 1600 yards, the assumed better accuracy of the 300 WSM lets it hold its own to 1200 yards.
So far, the 300 NMI is still "better", even at just 1600 yards. The next issue is the BC variation isn't just the bullet. The barrel is a contributor and becomes the dominant contributor as it ages.
For the high pressure double base powder fueled NMI, 2%, 3%, 4% BC spread could be 150 rounds, 300 rounds, 400 rounds. My straight 300 Norma went 550 rounds before flunking the 2300 yard test. Only the first 250 rounds used double base powder. The rest were Retumbo. Plotting a NMI with some wear against the other cartridges:
The other cartridges will also wear and restore the hierarchy, but it'll be a slower process.
If you don't worry about what's going on beyond 2000 yards, the hot rod barrel will be useful for more rounds. If a smart alec with a short 7mm gives you a hard time at the range, this is how they're doing it.
There is fairly broad agreement at this point, and it's straightforward to demonstrate, that the error budget for ELR includes Dispersion, velocity spread, BC spread, and uncertainty in the aiming point. For my personal Rubik's Cube, the other 2 sides are conditions and spotting equipment.
These plots are produced by importing 3 range cards for each cartridge from AB Analytics into Excel. The range cards are for the baseline, -100 fps, -10% BC. The differences between the range cards are scaled for the assumed velocity and bc spreads. Each of the first 3 error budget components are rolled into a RMS estimate. 4X the SD is used to estimate ES. This is a model I use to prioritize effort, it doesn't "prove" anything.
QL was used to estimate the performance of 3 cartridges. I assumed they all used a 30" barrel that's readily available from Barrel Brokers.
The first was the 300 NMI with a 245 hybrid. I assumed N570, a midlife start pressure, and added powder until the model reached 72,000 psi. The pressure level was selected because it's what the model gives for internet loads "with no pressure signs". The predicted velocity was 3150 fps. For the error budget, it was assumed the gun would put 20 shots into 0.75".
The second was the 300 PRC with a 230 ATip. With H1000, the same start pressure as the NMI, and 67,000 psi peak pressure, the prediction was 2950 fps. This is the modeled peak pressure I run my guns at. Lapua and boutique brass will take more but my experience has been much above this degrades bullet performance. The accuracy of this gun was also assumed to be 0.75" for 20 shots.
The third was the 300 WSM with a 220 hybrid. H4831SC, 67,000 psi peak pressure, 2825 fps. The accuracy was assumed to be 0.5" for 20 shots.
20 fps velocity spread for 20 shots was the base assumption. This can be reached by advanced hobbiests. It's pretty much trading the SD of commercial match ammo for the ES. At this level, velocity spread won't be your biggest problem.
For the NMI, the error budget looks like:
RMS calculations are intended to estimate what is likely to happen when multiple effects are contributing to an outcome. The point of this discussion is to illustrate how different components take their turn dominating the problem.
If you'd like to confirm or track BC spread, that 2000 - 2500 yards range is a good place to select bullets and retire barrels. The idea that bullets won't take the pressure your brass will can also be tested out here. The shallower the backstop, the greater the illusion that the vertical spread is smaller than it actually is becomes. Conditions are a problem as well. Initially, it'll take a truing conditions kind of day to suck it up and retire a barrel. After seeing the results of a few barrel replacements, it'll get easier to justify. Having a second gun that you regard as subordinate to use for comparison also helps see when it's time to freshen up the hot rod.
Zooming in the NMI to 1600 yards:
At 1600 yards, the shortest path to more hits might still look like improving the precision. The reality is all 3 contributors are about the same size and the other 2 will keep the vertical spread up. If there are 3 contributors to spread and they're all the same size, the RMS estimate will be 1.7 instead of 3. If one of those contributors completely goes away, the RMS estimate will drop to 1.4.
Comparing the other 2 cartridges to the NMI:
The relatively small differences probably were not intuitive to most. From this perspective, more velocity and higher BC only shorten the TOF. That's important, but it's not as strong an influence as shot to shot variations. This is what the 7 saum guys are up to. It has a little more performance than the 300 WSM, but the real point is for hobby use the 300 WSM works fine.
Zooming down to 1600 yards, the assumed better accuracy of the 300 WSM lets it hold its own to 1200 yards.
So far, the 300 NMI is still "better", even at just 1600 yards. The next issue is the BC variation isn't just the bullet. The barrel is a contributor and becomes the dominant contributor as it ages.
For the high pressure double base powder fueled NMI, 2%, 3%, 4% BC spread could be 150 rounds, 300 rounds, 400 rounds. My straight 300 Norma went 550 rounds before flunking the 2300 yard test. Only the first 250 rounds used double base powder. The rest were Retumbo. Plotting a NMI with some wear against the other cartridges:
The other cartridges will also wear and restore the hierarchy, but it'll be a slower process.
If you don't worry about what's going on beyond 2000 yards, the hot rod barrel will be useful for more rounds. If a smart alec with a short 7mm gives you a hard time at the range, this is how they're doing it.
Someone will ask, so here's the wind:
Again, bigger is better but not by as much as most expect.
My take on wind is it's on you and the best thing to do about it is shoot faster / keep track of more than just your last shot.
I used 2 mph because you need to practice staying on top of the wind to this level to have much success. Like loading 20 fps ES ammo, it'll take some practice. This is the change in wind between shots, not the first guess.
Again, bigger is better but not by as much as most expect.
My take on wind is it's on you and the best thing to do about it is shoot faster / keep track of more than just your last shot.
I used 2 mph because you need to practice staying on top of the wind to this level to have much success. Like loading 20 fps ES ammo, it'll take some practice. This is the change in wind between shots, not the first guess.
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