Please educate me. Why 7MM Remington Magnum for the US squad on the upcoming F-Class World Championship.
Why 7MM Remington Magnum
- Thread starter Desert Fox
- Start date
7MM Magnum can be construed as either Remington, Winchester Short, Weatherby or Ultra Mag by the uninformed visitors on the US F-Class site. Are they afraid to reveal what cartridge they're going to use. 
7MM RSUM is a good choice although a 7WSM will be just as good. Must be the slightly long neck of the RSAUM.
7MM RSUM is a good choice although a 7WSM will be just as good. Must be the slightly long neck of the RSAUM.
BigDMT
Desert Fox said:
Plus for less recoil and barrel heating I'm sure.
Not sure about less recoil. I shoot the 180 Berger on my 7WSM with 30" Broughton and it sure hell I felt the recoil. My rifle weigh around 18 lbs. My barrel gets hot quick also, especially shooting in Southern California weather during spring and summer.
BigDMT
Desert Fox said:
I'm talking about the other reasons to use the SAUM instead of the WSM. The "SAUM" has less recoil and barrel heating. I wasn't talking about the WSM
Those 2 cartridge are almost identical.
BigDMT
Desert Fox said:
Ok.... :
Desert Fox said:
284's and shehane have to be run past 11 to get up to 2900fps. In Raton heat, that is a train wreck you don't want.
The larger RSAUM, 280R and improved can reach these speeds at sane pressures.
There were quite a few shooters using RSAUMs, 280's and WSMs at your US Nationals last Sept.
The 7-300WSM and 7 WSM just add a couple more grains of case capacity so you can lower pressures for the same speed or try for the next higher node.
I developed the 7 Mystic many years back which was a variant on the 280 improved. WOW, did it shoot and was so easy to develop with moderately toasty loads. Case volume was almost exactly as the RSAUM today.
If Berger ever gets a over 190gr bullet developed, I bet we see 7RM's on the mounds.
If you are wondering on bore life, yes, they suck but if you want to play with huge ballistics, it is going to hurt in many ways.....
Jerry
The first time I used my 7 WSM at 1000 yards competition, it was a total disaster. It was summer and the temperature hovered around 85 degrees. With 65 grain of Reloader 25, I was pushing the Berger 180 VLD at around 3000fps. We have 30 minute to shoot 25 rounds into the target. After 12 rounds the impact started to rise incrementally in the tune of quarter MOA every shot. The barrel was really hot. After that some shot never got to the target... the bullet just disintegrate in mid air. I never finished my string. At first, I blamed it on the bullet, so I called Berger and told them what happened. Berger sent UPS to pick up the remainder of the bullet, about 400 rounds, at the same time dropped me a replacement. As it turned out, it was my barrel after all. I scoped the barrel and noticed erosion and cratering on the throat area. The barrel has less than 300 rounds through it. I didn't suspect it at first since the rifle will still shoot 1/4 minute.
So going back to the choice of 7RSAUM for the US squad, I still think, a 284 Winchester shooting the 180 grain bullet at 2850 fps will be a better choice. But then again what the hell I know.
So going back to the choice of 7RSAUM for the US squad, I still think, a 284 Winchester shooting the 180 grain bullet at 2850 fps will be a better choice. But then again what the hell I know.
Huge difference in bore wear with a large case run at 90%
The WSM run at 2900fps would double your bore life at least. Still sucks but....less
Running a 284 to try and hit 2850/2900fps would give the same tuning issues as you saw. Way too much pressure
Some have had to back down to 2700+ to keep things from melting. That 200fps does matter at 1000yds in a gale.
F Open with big 7's and 300's are likely the direction to come. Cost and bore life isn't going to get any better so shooters will have to start thinking in terms of multiple barrels per season and/or setting back every 3 to 500 rds.
Expensive, you bet but there is no ballistic free lunch.
Can you be competitive with a smaller option? Of course and given the right conditions and skill, you can win too. Wind reading will always determine this game.
But at a place like Raton where condition changes can be so abrupt, that ballistic edge will save points eventually as long as you can drive it.
Who says the US team members dont have a bucket of barrels to draw from too?
Jerry
The WSM run at 2900fps would double your bore life at least. Still sucks but....less
Running a 284 to try and hit 2850/2900fps would give the same tuning issues as you saw. Way too much pressure
Some have had to back down to 2700+ to keep things from melting. That 200fps does matter at 1000yds in a gale.
F Open with big 7's and 300's are likely the direction to come. Cost and bore life isn't going to get any better so shooters will have to start thinking in terms of multiple barrels per season and/or setting back every 3 to 500 rds.
Expensive, you bet but there is no ballistic free lunch.
Can you be competitive with a smaller option? Of course and given the right conditions and skill, you can win too. Wind reading will always determine this game.
But at a place like Raton where condition changes can be so abrupt, that ballistic edge will save points eventually as long as you can drive it.
Who says the US team members dont have a bucket of barrels to draw from too?
Jerry
Mystic, I started a thread a few weeks ago about reduced loads in the short mags. Is a short mag backed off to 2800 a lot harder on a barrel than a straight 284 at 2800? If so, why? I need practice more than anything, so I am looking for a round with decent ballistics that will last 2000+ while I learn the ropes out to 600 y. Lately I'm thinking about a 7mm-08 or straight .284 with 168 and 175 sierras.
A lot of good info here:
http://forum.accurateshooter.com/index.php?topic=3806718.0
A lot of good info here:
http://forum.accurateshooter.com/index.php?topic=3806718.0
XTR
F-TR obssessed shooting junkie
ScottMc said:
If you want to learn at 600 get a .223 and shoot in F-TR. Seriously, you give up nothing to a 308, at mid range, barrel life is great, bullets cost 1/2 what all the others do and you burn 1/2 to 1/3 the powder. (all you need to do is find Primers). If you set it up on a Savage F class rifle (not a TR) you could switch back to a full on open rig with a bolt and a barrel change.
I think that if you want to shoot mid range open a 7-08 with 162 Amax's would be fun to play with but I've never looked at the ballistics to see how it would stack up.
scott, running a straight 284 with 180s at 2800 will take less powder than running a reduced charge in a larger case to get the same velocity. Case volume is the reason - it still takes more powder to reach the same velocity (2800) in the larger case. For a more extreme example, look at a 6 Dasher compared to a 243 Win. The smaller case is just more efficient - ie - the Dasher takes less powder to get the same velocity with a given bullet weight than the much larger 243 case.
Actually, a straight 284 with sane loads, using a powder with low flame temp like N165, will give pretty reasonable barrel life. I shoot my 284s with H4831 more often than not, and though I've yet to shoot one of them long enough to need replacement, using a Hawkeye borescope I'd guess they're all going to last 1200rds at the very least, more likely 1500-1700rds. If you're loading for MR matches or practice, you could always go with one of the lighter bullets like the 162 AMax at 2700fps and extend bbl life even further.
Actually, a straight 284 with sane loads, using a powder with low flame temp like N165, will give pretty reasonable barrel life. I shoot my 284s with H4831 more often than not, and though I've yet to shoot one of them long enough to need replacement, using a Hawkeye borescope I'd guess they're all going to last 1200rds at the very least, more likely 1500-1700rds. If you're loading for MR matches or practice, you could always go with one of the lighter bullets like the 162 AMax at 2700fps and extend bbl life even further.
BigDMT
flatlander said:
Yessir. Same reason I can get same velocities as a 6.5-300 wsm or 264 win mag with my smaller 6.5 rem mag case using a lot less powder. Its just more efficient.
Even if it was the 7mm Rem Mag it would still do the job w/ proper dies and loads in a good rifle. It is a very accurate long range caliber with bearable recoil. It is a good killer too out to about 1200 yards. There is plenty of good components and would be just as accurate as the other 7mm's. Efficiency doesn't necessarily mean accuracy as long as powders are available with the proper burning rate even if it is a little overbore.
BigDMT
DanConzo said:
Correct, but effieciency does mean less recoil and barrel heating which usually equates to more rounds down range with consistent accuracy.
I'm still can't grasp at the concept of a cartridge burning 18 percent more powder will erode the bore less. I understand the correlation between pressure and temperature but we are talking probably a difference of no more than 5,000 psi maybe.
There's a correlation between powder burnt and pressure which equates into throat erosion on a barrel. The larger capacity cases may be burning more powder but, they aren't creating the excessive pressure spikes which really heats and eats the throat out of a barrel. If one can utilize the slower burning powders, which you usually use more of, that create more velocity with less pressure it can be achieved that way also! Is it making sense now?
Mike
Mike
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