300 Win Mag v. 7mm-300 Win Mag

[jski]

Having limited experience with the 300 Win Mag, I’ve been reading about the wildcat
7mm-300 Win Mag. I’ve watch some videos showing >1 mile shots with the 7mm-300. I don’t believe that’s possible with a 300 Win Mag?

So my question is: How much does necking down to 7mm and adding a bullet with a better BC add to the 300 Win Mag range?

 

[redneck2]

I think it’s called a 7 mm Remington Magnum. I’m sure there are insignificant differences, but it should be essentially the same thing. Either way the parent case is a .375 H & H. In this instance you’d gain maybe 10 grains of powder capacity. But, shooters are sizing down due to recoil, muzzle blast, and barrel life.concerns.

Years ago Weatherby introduced the .30-378. It was the end all, be all, do all long range thumper. I worked at the LGS and knew a guy that bought one. Required a muzzle brake or shoulder surgery. He shot it until it burned out the barrel, about 800 rounds IIRC. Another in the long line of “my dogs bigger than your dog” series.

Or, just get the same thing that is already a factory round. https://en.m.wikipedia.org/wiki/7mm_Shooting_Times_Westerner

I had looked into 1,000 yard shooting. The 160ish 7mm’s have super BC’s. 162 A-Max and Berger’s have BC’s over .6

 

[jmr40]

There are several 300 magnums, not just the 300 WM. And several others have more powder capacity than the Winchester version. I'm not aware of any wildcat rounds where the 300WM is necked down to 7mm. That doesn't mean it doesn't exist. But doing that would not give you any advantage over the 7mm Remington magnum. It is possible that you've read about one of the other 300's being necked down. And the 300 WM doesn't have any problems at all shooting to a mile or even more. It, along with many other cartridges is still viable beyond 2000 yards. The biggest advantage of doing it with a 7mm is reduced recoil.

If you compare bullets with the same BC leaving the muzzle at the same velocity the trajectory is amazingly close and the velocity down range stays about the same. And the important thing is how far downrange does the bullet remain above about 1000 fps. As long as the bullet is supersonic reasonable accuracy can be expected. Once it drops below that speed bullet flight becomes unstable and accuracy is no longer possible. Going to a smaller caliber allows you to use lighter bullets to achieve the same BC. The 6.5's have become popular because they will shoot 147 gr bullets with minimal recoil and they still remain stable in flight out to the same ranges as 300 and 7mm bullets. In 7mm you have to go up to 168-175 gr bullets to get the same BC. In 30 caliber 215-230 gr to achieve the same BC. In 338 over 250 gr.

If you can get a 6.5/147, a 7mm/168, a 300/215, or a 338/250 to all leave the muzzle at about 2800 fps the down range trajectory, and the range where they drop below 1000 fps will be pretty darn close. If you can find a way to get them to leave the muzzle at 2900 fps you'll add a few yards of effective range. But just a few yards, probably less than 50-100. And at 2000+ yards another 50 yards of effective range just isn't much of an improvement.

 

[Jessesky]

Any more than say a 7mm Weatherby or 28 Nosler, the cartridge becomes grossly inefficient. This is why the 7mm rum did not take off. The expansion ratio can’t burn all that powder efficiently enough. A 200fps gain over 7mm rem mag at the cost of being one of the worst barrel lives out there.

 

[Varminterror]

The "7-300" is not the same thing as a 7mm Remington Magnum. The shoulder of the 7RM is pushed back considerably from the 300wm, while the various 7-300's are not. Since this is such a simple and intuitive wildcat, multiple versions exist. Straight neck down 7-300wm's retain the 25 degree shoulder, while the 7mm Practical blows out the shoulder to 30 degrees. The 7mm Rogue is another 7-300wm, which blows out the body taper, and pushes the shoulder angle out - of course, necking down as well.

There are also 7-300's of different flavors: The shorter version of the 7mm Mashburn is very similar to a 7-300wm, however, it uses shortened, blown out, and necked down 300 H&H cases. The Mashburn Long does not shorten the H&H case, and is considerably longer than the 7-300wm's. The 7-300 Norma obviously uses 300 Norma as the base.

Below is a 7mm Practical beside a 7mm Remington Magnum, which as stated above, is a 300win mag, necked down, and shoulder blown out to 30 degrees. The performance improvement can be perceived in seeing the cases side by side. The straight 7-300 will have a longer, steeper shoulder, while the 7mm Rogue has a similar shoulder, but visibly/noticeably straighter body.



ETA: Here's a straight 7-300, note the standard 300wm body taper and 25 degree shoulder compared to the 7mm Practical 30degree shoulder above. Also note, the downside of the long 25 degree shoulder in the 7-300wm is the incredibly short neck, a fault of it's parent, the 300wm, as well.



ETA-A: Here's a 7RM, 7 Mashburn, and 300wm. Note the body taper and shoulder position differences. If I recall correctly, Mashburn can't be made from 300wm, despite being SUPER close, as the case neck ends up short, hence starting with the 300 H&H.

 

[LoonWulf]

7mm Rogue is another 7-300wm, which blows out the body taper, and pushes the shoulder angle out - of course, necking down as well.

This is what I've considered building, tho I didn't know its name lol.

Or actually I guess what I wanted was the Practical.

I really like the STW, but even in the long 700 action, the heavy bullets are stuffed well into the case.

A blown out 300wm case, or another thought I had was the .375 Ruger, is shorter and still allows for more powder.
Long barrel and slow powder should allow for delivering a useable amount of extra velocity over the 7mag.

Course I need another magnum 700 to test this hypothesis......

 

[Varminterror]

I’ve watch some videos showing >1 mile shots with the 7mm-300. I don’t believe that’s possible with a 300 Win Mag?

Given a proper twist, a long enough barrel, a heavy enough rifle, and a heavy enough bullet with a substantial BC, they'll both still be supersonic at 2,000yrds, EASILY capable of 1 mile. In fairness, given large targets and appropriate bullets, a guy can get 6.5 creed/260/243/30-06/6 creed to a mile. They won't be supersonic, but they won't be far enough out to really kill the game. A normal 7mm Rem mag or 300win mag will get to a mile with a smile on its face.

What I CAN tell you - in ELR competition, 7mm's don't keep up with 30's, 30's don't keep up with 338's, and 338's don't really keep up with 375's and 416's. Out to 2,000, 30's and 338's will play, and fast 7mm's can almost hang, but neither 7's or 30's are good options. I run a 31" 1:9" 300wm and 33" 1:10" 300RUM to 2,000yrds, it's far easier with a 338LM.

Among the 7mm's, not just the 7-300 are in the "slightly super magnum class." 7mm RUM, STW, Dakota, etc are out there which push past the 7mm Rem Mag.

Barrel life is terrible for any of these, cartridges listed above, but it's far worse for the 7mm's than the larger calibers. Rifles don't stay happy for very long when you're pushing huge amounts of powder through tiny bores. The 7 Practical is touted to last longer than the RUM, but not as long as the 300 WM, and I'll admit, brass doesn't last long enough for me to want to do a lot of work to make brass.

 

[Varminterror]

another thought I had was the .375 Ruger, is shorter and still allows for more powder.

Better idea than a 7-300wm.

 

[LoonWulf]

Better idea than a 7-300wm.

Yeah I liked that idea better honestly, and I was really hoping Ruger would do a family of smaller bore mags bassed on the .375, but they didn't.
I've read that the .375 Ruger brass isn't consistent enough for an ELR build (again I just READ that, no experience).
For my usage it probably doesn't mater lol.

 

[Varminterror]

I've read that the .375 Ruger brass isn't consistent enough for an ELR build (again I just READ that, no experience).

There aren't many great options for the belted mags either. Norma, Hornady, and Nosler are about as good as it gets for belted mags, and you're largely stuck with Hornady for the Ruger Mags. I have a 416 Ruger, and use 300wm hornady brass for one of my 300's, and my wife uses Nosler and Norma brass for her 7mm and 338. Win brass for our WSM's, naturally, and Rem brass for my 300 RUM. I'd be lying if I said any of the Nosler, Norma, or Hornady batches were any better than the others. I weight sort, turn necks, and anneal to improve consistency a little bit, but by and large, it doesn't make a huge difference.

Something interesting to me these days is the 33 XC. Good brass is available, or could be made from good Lapua brass. But honestly, the next ELR rifle I build will be a 416, taking every advantage I can get, instead of "approaching" with a "kinda ELR rifle" in 300 or 338.

For my usage it probably doesn't mater lol.

For my abilities in ELR, it doesn't matter either. Brass is pretty low on my list of "influencers". It's cliche' to say it, but it's an entirely different game than LRP.

 

[troy fairweather]

i would like to do a 7mm canadian it fits perfect in a long action remington 700 or a 7mm-300 norma but brass for them is $$$ i like the idea of the 7mm-300wm for the small coust of brass. tho a 7rm is more then i need here in new york.

 

[js8588]

Yeah I liked that idea better honestly, and I was really hoping Ruger would do a family of smaller bore mags bassed on the .375, but they didn't.
I've read that the .375 Ruger brass isn't consistent enough for an ELR build (again I just READ that, no experience).
For my usage it probably doesn't mater lol.

Give it time. The 30 PRC is based on the 375 Ruger. 6.5 PRC already exists and 7mm will be along shortly, I'm sure.

 

[ExAgoradzo]

When I looked into the 7mm mags I came up with the 28 Nosler being the king of speed (for factory loads) but the Remington so close that (for me) the difference didn’t matter. Now, I understand that you are talking wildcats and not factory: that’s fine and I like you guys because we wouldn’t have factory loaded rounds in cool cartridges without you all... but the key question to me and has been alluded to here is what is the cost to benefit ratio? How much powder to how much gain? I’m still jonesen for a 7mm Rem Mag in a nice 26” barrel; but priorities just won’t let that happen short of someone deciding to bless me...

Thanks for letting me geek out with you guys...
Greg

 

[LoonWulf]

True, I'd actually forgotten about the 300PRC.

 

[js8588]

True, I'd actually forgotten about the 300PRC.

I've noticed we both have an affinity for oddball ballistic hipster leadslingers.

Ballistic Hipster Leadslingers...want to start a band?

 

[LoonWulf]

When I looked into the 7mm mags I came up with the 28 Nosler being the king of speed (for factory loads) but the Remington so close that (for me) the difference didn’t matter. Now, I understand that you are talking wildcats and not factory: that’s fine and I like you guys because we wouldn’t have factory loaded rounds in cool cartridges without you all... but the key question to me and has been alluded to here is what is the cost to benefit ratio? How much powder to how much gain? I’m still jonesen for a 7mm Rem Mag in a nice 26” barrel; but priorities just won’t let that happen short of someone deciding to bless me...

Thanks for letting me geek out with you guys...
Greg

73-74gr of Retumbo will give you 160 class projectile at +/-3000 from a 26" barrel.
I've tested that load over 4 7rem mags.
For reference, a 24 dosent loose alot with that load. My new RAM gets [email protected], my slowest 26 barely broke 3k, my fastest got to 3100 at 74.

One of those got rechambered to 7mm stw with no other alterations.
83gr of Retumbo (I think, it's recorded at home but I'm going from memory) delivered 3200fps from it's 26" barrel.

 

[LoonWulf]

I've noticed we both have an affinity for oddball ballistic hipster leadslingers.

Ballistic Hipster Leadslingers...want to start a band?

HAH! It would have to be an Alternative band.....

 

[troy fairweather]

u cant go wrong with the 7 rem mag ammo is cheap for normal hunting loads. a 7mm prc would be nice

 

[redneck2]

Or, there’s this...

http://bulletin.accurateshooter.com/2012/05/284-shehane-284-improved-for-long-range/

 

[Varminterror]

Or, there’s this...

http://bulletin.accurateshooter.com/2012/05/284-shehane-284-improved-for-long-range/

284 Shehane doesn’t hang with 7-300’s, let alone the other supermagnums we’re talking about here. It’s really only in the class of the straight up 7 Rem mag, and only if you’re pushing it EXTREMELY hard. I cut my first 284 Shehane 8 or 9 yrs ago at the advisement of Boyd Allen, as I was looking for something with better barrel life than the 6.5-284 I was rebarreling for the 2nd time in a single season.

As for @ExAgoradzo ’s question - what’s the cost to benefit ratio: nobody shoots ELR to save money. Period. The extra powder cost isn’t terribly significant, and really, there isn’t a huge difference in dies, bullets, barrels, or brass, not compared to the overall cost of the game in general.

But here is the reality we face: I am go the range, and going to throw over a dollar per shot down range today to develop my ELR skills (or at least try to do so). If I can spend a couple pennies more to increase my hit percentage, I will, because most often, misses don’t tell us nearly as much about our shot under the conditions we fired as a hit would. An unseen miss is a complete loss of that investment. A near miss, which hits the target at 1500yrds gives me feedback to learn. A tiny bullet which doesn’t give much splash, which goes unseen, is as bad as a miss. A light impact which doesn’t elicit much target response in mirage is as bad as a miss. So in a game where accomplishments at every 50-100yrd increment take a sizable improvement in gear or skill, making your gear more forgiving is a real advantage.

Sure, it might be like tuning a stockcar to run 2MPH faster than the field, or engineering a triathlon bike to weigh a half pound lighter, but that’s the game. Man and gear have to be at the top of their game.

Does the average Joe with his ONE rifle, who has never fired a shot past 200yrds benefit from a 7 Practical over a 7 Rem mag? Nope. Does a guy like David Tubbs benefit from running a 33XC instead of a 338LM? Yup.

 

[LoonWulf]

I'd never heard of the 33XC till this thread....
I just ran across the 37XC also, I'm liking the performance specs
350 class projectiles at 3100fps......
Makes my Ruger 270s a 2800 seem anemic

 

[someguy2800]

284 Shehane doesn’t hang with 7-300’s, let alone the other supermagnums we’re talking about here. It’s really only in the class of the straight up 7 Rem mag, and only if you’re pushing it EXTREMELY hard. I cut my first 284 Shehane 8 or 9 yrs ago at the advisement of Boyd Allen, as I was looking for something with better barrel life than the 6.5-284 I was rebarreling for the 2nd time in a single season.

As for @ExAgoradzo ’s question - what’s the cost to benefit ratio: nobody shoots ELR to save money. Period. The extra powder cost isn’t terribly significant, and really, there isn’t a huge difference in dies, bullets, barrels, or brass, not compared to the overall cost of the game in general.

But here is the reality we face: I am go the range, and going to throw over a dollar per shot down range today to develop my ELR skills (or at least try to do so). If I can spend a couple pennies more to increase my hit percentage, I will, because most often, misses don’t tell us nearly as much about our shot under the conditions we fired as a hit would. An unseen miss is a complete loss of that investment. A near miss, which hits the target at 1500yrds gives me feedback to learn. A tiny bullet which doesn’t give much splash, which goes unseen, is as bad as a miss. A light impact which doesn’t elicit much target response in mirage is as bad as a miss. So in a game where accomplishments at every 50-100yrd increment take a sizable improvement in gear or skill, making your gear more forgiving is a real advantage.

Sure, it might be like tuning a stockcar to run 2MPH faster than the field, or engineering a triathlon bike to weigh a half pound lighter, but that’s the game. Man and gear have to be at the top of their game.

Does the average Joe with his ONE rifle, who has never fired a shot past 200yrds benefit from a 7 Practical over a 7 Rem mag? Nope. Does a guy like David Tubbs benefit from running a 33XC instead of a 338LM? Yup.

I don’t do any competitive shooting other than some local action pistol, but I look at it just like racing. If your in it for a hobby, sure do whatever you want. But if your in it to win it, no half measures, go big or go home. If you want to win you have to have as good or better equipment than the other guy. Sure sometimes you can upset everyone because the other guys didn’t have there program together, but eventually your going to be competing with guys that are as good as you and have the best equipment they can get. So if you can spend $10,000 for something you can win with even against someone as good as you, or $5,000 to for something that’s guaranteed to put you mid pack no matter how good you are, it wasn’t really a bargain was it?