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Which 7mm?

summitsitter

Sergeant
Full Member
Minuteman
Sep 29, 2008
320
1
42
Crowville, Louisiana
Okay guys if ya had to build one and only one LR .284 caliber rifle what would it be. Like to go 1200/1300 yds with it. Already have a 280AI but recently aquired another 7mm barrel and wanting to build a dedicated LR rifle with it. I like the WSM but seems brass is pretty hard to come by. Straight ol' .284 Win. maybe? I don't know, guess that's why I'm looking for yalls opinion. I'm even up for some wildcats.
 
I've read some pretty impressive stuff about the 300win/7mm improved...non improved version has the name of 7 Practical I think. Brass should be easier to locate and some people are claiming awesome performance with this. Look into it if you haven't already and see what you think.

I shoot a STW and really like it. I'm not seeing the barrel life problems with it that have been brought up and beat to death. My only gripe about it is the brass availability....and current 180 Berger availability. I don't see the merit of the 7 LRM that Gunwerks pushes. I think the only headstamped brass available is from Hornady and isn't of great quality. The 7 RUM has its drawbacks as well...mainly in-efficiency and over bore. Regular old 7 mag is hard to beat but wouldn't be a great 1200-1300 yard gun. Kirby Allen makes a line of "Allen Magnums" and his 7mm variant is (I believe) an Ackley improved 338 lapua necked down. Unreal ballistics can be achieved but he makes no bones about barrel life. He openly admits he chases the maximum performance that is safely attainable.

Good luck with your build!
 
Guess I'm on the other end of the spectrum when it comes to case capacity in the 7mm bore. The largest case I'd personally consider would be the good old 7mm Rem Mag, but I'd be much more likely to go with a straight 284. I've got three of these, along with another LR rig in 280AI, and have had good results with 180 Hybrids & VLDs out to 1400yds with the 284s.

I built the 280AI as a test to see if the extra 6grs of case capacity over the 284 would give measurably higher velocities. Used a Krieger 5R in hvy Palma contour, finished at 30", on a new LA M700 that I'd trued, and bedded the bbl'd action into a McM A5 with cheekpiece mod done by stockdoc and PTG Stealth DBM. After a fair amount of testing with H4831, 4831SC, & IMR7828SSC, I've yet to find loads that would give substantially higher velocities than what I get out of 28" & 30" 284s. Although the 280AI's accuracy is good, all three of the 284s have a slight advantage in that respect, as well as being more consistently accurate than the 280AI. Got enough time & money invested in the 280AI to keep me interested in shooting it, but will likely shorten the bbl to 26" to make it a bit less awkward to handle.

Descriptions of the rifles in the attached photo: Top is a LR prone target rifle built around a BAT 3LL w/30" Krieger hvy Palma in a Robertson H&H stock in their 'Vermont granite' color scheme. Next is the 280AI as described above. 3rd is the 1st 284 I built, with another LA M700, 28" PacNor 3-groove in a custom HV contour, McM A5 w/BO M5 DBM. 4th is the DTA SRS with 28" Bartlein DTA blank that I chambered for 284.

ETA: The only 'clean' score (200-8x) I've yet shot in a 20rd match at 1000yds was with the M700 284 in the McM A5 stock; I had the other bbl for it on the rifle at the time, which is a 30" Bartlein hvy Palma. Was shooting Berger 180 VLDs with H4831 in a load that was running right at 2800fps. That was out at the CRC's range near Byers, Co. back in July of '07 when they were still running LR weekends with a 3x600 any/any on Sat, followed by a 3x1000 any/any on Sun.
 

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280, 280AI and 284 are perfect "one and only" 7mm cartridges. Anything less leaves a bit too much performance on the table and anything more is overbore and too hard on barrels.

...my opinion only, of course...

If you've already got a 280AI, why get something else?
 
Okay guys if ya had to build one and only one LR .284 caliber rifle what would it be. Like to go 1200/1300 yds with it. Already have a 280AI but recently aquired another 7mm barrel and wanting to build a dedicated LR rifle with it. I like the WSM but seems brass is pretty hard to come by. Straight ol' .284 Win. maybe? I don't know, guess that's why I'm looking for yalls opinion. I'm even up for some wildcats.

If you like the WSM, then look at going to 7-300 WSM so you can use 300 or 270 WSM brass. Which is available from Norma and others, much easier than the actual 7WSM brass. That's exactly what I did on one that's currently still in build process for that exact reason.

If I didn't already have the action it's being done on, I'd also do it on a Long action to maximize what it can do by not cramming the bullet so far in the case.
 
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280, 280AI and 284 are perfect "one and only" 7mm cartridges. Anything less leaves a bit too much performance on the table and anything more is overbore and too hard on barrels.

...my opinion only, of course...

If you've already got a 280AI, why get something else?

I'm in this camp.
 
Personally my top 3 7mm cartridges are (in ascending order of performance) 7 SAUM, 7 LRM, and 7/300 Norma Improved. It all depends on how much money you want to put into it, your preference of short or long action, and what components you can get your hands on. Good luck and keep us posted.
 
HodgdonExtreme' opinion pretty well nails it as far as my own thoughts on 7mm rifles. I've got another Krieger 7mm 1-9tw sendero blank, and had seriously intended to use it for a 7mm-08 Imp 30*. But the more I thought about it, the less sense that build made. A 28" 284 is about the minimum for my needs, which is mostly target shooting at 600-1000yds, yet will reach out to 1400yds with no problem.

A 7mm-08 or Improved build on a repeater using AICS 308 mags would require even 162s to be seated pretty deep, and I just don't believe it'd do anything that my 260 Imp 30* with 140 VLDs or Hybrids won't do better. If you were going to use a 7mm-08 only for hunting - say with 140s - I'd agree that it's a good choice. But for 1000+yds, where you'd want to shoot at least a 168VLD, the 280, 280AI, or 284 would leave it in the dust, especially with mag length ammo.
 
What are some of the further distances you have been successful?

This was my first "deer" rifle and I started shooting it when I was 14. In addition, the rifle had a straight 4X Nikon, so I didn't shoot game after 400yds. I am confident the cartridge would have performed, but didn't want to out shoot my scope. Last year, I purchased a Cooper 6.5-284 Norma, so I will be shooting the 6.5 and a 6XC (once its finished) going forward.
 
Straight 7mm-08 seems to work well here. I borrowed a 'SAMMI' Clymer reamer and with a 28" bbl and a full case of Superformance I can get 162 Hornady nearly up to 2900fps before pressure peaks. Seems plenty zippy to me and fits in an Accurate/Alpha Ind. .308 magazine at 2.930" OAL a touch off the lands.

Duperformance is a temperature-stable ball powder that's made here in the US and so it's somewhat available relative to the other imported 'Extreme' powders. Flows very nicely through a measure too...
 
This was my first "deer" rifle and I started shooting it when I was 14. In addition, the rifle had a straight 4X Nikon, so I didn't shoot game after 400yds. I am confident the cartridge would have performed, but didn't want to out shoot my scope. Last year, I purchased a Cooper 6.5-284 Norma, so I will be shooting the 6.5 and a 6XC (once its finished) going forward.

Glad it has worked for you. Caliber debates within 300 yards for hunting is almost silly to me as just about all center fired cartridges work. 300 - 600 yards you see some seperation, past 600 the magnums shooting the heavies really start to pull away. Smaller calibers might match or even slightly beat the trajectory but they can't match the energy. My choice was 7SAUM on a long action. I got to shoot a mule deer last year at midrange and it preformed well. 2 days later my buddy took his with my rig at about the same range. If I can get a doe tag this year I am going to try to stretch things a bit.
 
Strait .284 Winchester would be my suggestion. I own one and its a tack driver. Is a good round for competition or hunting. But you don't mention your intended use for the rifle.

One comment you made was about brass availability. There is no high quality brass available for the .284 Winchester and it is hard to come by. Winchester is the only company that makes strait .284 brass, but for accuracy work, I am not a big fan of Winchester brass. My rifle is used in F-class competition and I neck up Lapua 6.5-284 and had my chamber reamed to use this brass. I little extra work, but there is a night and day difference in the consistency and life of the Lapua brass.

My other choice for hunting would be the .280 AI. A bit harder on barrels, but a great game killer. If you are using the gun for hunting, this is the way I would go. Quality brass is available from Norma.
 
Like stated in other posts....."What are you using the gun for?"

The .280AI is very good and very accurate but if the choice between that or a .284win. I feel the .284win. will be more consistent over the .280AI.

.284win. vs. the different version of 7mm mags? The 7mm mags. on F-Class guns they are only getting 600-800 rounds out of the barrels. Got guys with .284win's. getting up to 2k. So barrel life advantage goes to the .284win. over the mags.

My F-Class gun is a .284win. and you cannot do anything wrong. My finish barrel length is 32". I'm running 180gr. Berger's 2900fps out of the gun. Shot it in a mid range match earlier this summer. Won the match and shot a 200-11x with the gun at the 500 yard target.

Later, Frank
Bartlein Barrels
 
Only one? Hard to beat the good ole 7 mm Rem Mag. Available everywhere, factory ammo is as common as any round ever made, better performance than any of the short mags is possible. All reasons I went with the straight 7rm when I asked myself the same question for a build. Barrel life is proportional to performance, if you want better life you can down load it to 284 level and get closer to that, but you can't go the other way and get 180s over 3000 with a 284 without a tremendously long barrel. The 7rm is not the best at anything, but it is very versatile with awesome potential.
 
7LRM.

Loving it.


I have one as well.

It's a powerhouse for sure, ought to REALLY pay off if Berger ever releases the 190s.


Kind of getting frustrated with the quality of the brass though.
 
Im a 7rem mag fan as well. Im getting 3200-3400fps with the 162 super performance. And with 168 SMK my zero and dope are the exact same, so the speed with the 168 should be the same. I get my ammo from HSM. Im working with a buddy to begin reloading for it.
 
284 Shehane maybe?

This what I went with after months of thinking it over. In the end plentiful Lapua brass was the deciding factor. Given my success with my 6.5 SLR Improved I wish I had just designed my own wildcat from scratch. All in all I'm very happy with it though.

I'm running it on a 1086r action with a manners mini chassis bdm and aics mags. I mention this because a smith I had mentioned this to before it was built said it would not work, but it does and I have yet to experience any feeding issues with any of my magazines to date.
 
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