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Trying to decide... 284, 280AI or 7RSAUM for F open.

dragman said:
7SAUM - I am currently shooting (two in)this caliber - found it very easy to tune and I really like it. .....and it shoots lights out!
Low recoil(in a properly stocked, weighty rifle), very accurate, and awesome ballistics.
 
Dragman, This Isnt the first time I have heard people saying the 280AI is finicky compared to the 284 Shehane and 7 RSAUM. Why would you say that is? Is the velocity spread wider than the short fat cases due to the long skinny nature of the 280AI brass? What sort of ES/SD are people really getting with their 280AI's?
 
I think it's case design, I have gotten the AI's to shoot well but it seems that the load window for error is very small. some calibers always shoot well and shoot lights out with a certian load. I have found the 300WSM to be this way, the 284 and the 7SAUM are like that too just not as dramatic. while most of my 280's either shot lights out or bad. kind of like running a performance car.
 
I would say get a .284 with a .317" no turn neck. Neck up Lapua brass. Shoot 180gr. Berger's with H4831sc. Earn your Ma or HM card. By then, you will not have to ask anyone what you want to build.
Just a thought. Craig
 

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Magnum performance and long barrel life? Aint that what we are all after(besides accuracy).

Anyway, I think you should seriously look into the 6.5 4S. GA Precision`s iteration of the 6.5 SAUM. This thing is a beast. 3150fps with 140s is a mild load, no big deal; and if you run it like that consistently Mr George Gardner is claiming 3000+ round barrel life. Maybe he just got a good barrel, but personally, I trust his word to say the least. IMO that man is not the type to lie and blow smoke. If you want a serious long-range Elk busting hammer, you can push 160gr Matrix VLDs at 3000-3100 fps or more according to Mr Rich(elkaholic on LRH) with his 6.5 Sherman Shortmag(6.5 SAUM). Thats a .680 G1 BC bullet(conservative estimate) at 3000 fps(conservative load)! Thats on the heels of a .300 Win Mag running 215gr Bergers at 3000 fps!! And the sectional density and penetration of a load like that combined with its size/recoil simply cant be beat. Youll basically have something with penetration akin to, well, as I said a .300WM with 215gr Bergers or 230gr Bergers. By all accounts, the 160gr Matrix bullets are serious business and perform admirably on large game. I really dont see why the 6.5 SAUM/160gr Matrix combo is not being embraced more heavily outside the LR hunting community. Most of the guys at LRH.com get it, but Im telling yall, that SAUM/160 Matrix combo is a force to be reckoned with and IMO will catch on like wildfire soon if brass availability goes up. For a SHORT action cartridge, its gonna be hard to beat. I emphasize that, because, atleast in Mr Rich`s case, with his 6.5 Sherman Shortmag version of the SAUM, he shortens the case slightly to around 6.5 Creedmoor length, so you get a true short action cartridge. IE; the 6.5 SS can be loaded on out there with 140s or 160s at mag length.

Speaking of elkaholic though, if youre considering a .280AI you also must consider the .280 Sherman. Its basically a .280 Gibbs with a longer neck. Has all the same case body dimensions as a Gibbs case but its formed from a .270 Win case or 6.5x65mm case so you end with a longer neck. Must say a glorious cartridge. This will do anything/everything the 7mm SAUM will do with widely available brass. Im really surprised noone thought of it sooner. I cant remember the exact numbers, but he basically took a .270 cartridge case, pushed the shoulder forward/shorter neck(IIRC .290" length neck but I could be wrong), blew out the case taper to like .012, 40-degree shoulder, and obviously necked up to .284. Im going off a real foggy memory here so correct me if Im wrong on any of those numbers(very rough estimates). But anyway, in talking to elkaholic, according to him the H2O capacity of the .280 Sherman came out to around 72-74gr H2O. So youre easily talking about SAUM, if not WSM territory in regards to velocity. 180gr Bergers at 3000 fps wouldnt be too much trouble. I wouldnt be surprised to see that case push them to 3100 fps. Its really a brilliant idea. Hes also got a 6.5 Sherman and .300 Sherman as well. And then the 6.5 Sherman Shortmag. Id really like to get a hold of a Pre-64 M70 or maybe a beat-to-hell M1917 Enfield or 1903 and chamber/rebarrel it in his .300 Sherman. Apparently hes getting 3100 fps with 190gr bullets of his own design. LOL 3100 fps with 190s in a `06 sized case, thats insane obviously .300 Win Mag territory. To be sure though, I dont know the specs on his 190gr "SXR"(as he named it) bullet design but Ive seen them and they look to be VLD profiles with aluminum tips. It could have a very short bearing surface, but either way 3100 fps with 190s in what amounts to a .30-270 Win-Improved is downright impressive.


If I was building a F-Class Open rifle, I would seriously consider the 6.5 SAUM and .280 Sherman. With the Sherman, you will not find a faster cartridge from a `06 size case/.473 bolt face, its basically a .280 with 7mm SAUM performance. With the 6.5SAUM, well, you basically get .260 barrel life with performance akin to brass-busting 6.5-284 loads if the 3000+ round barrel life is truly the norm with mild loads.
 
I have experience with neither the 284 nor the 7 Saum, though I have heard they both offer advantages. In the area of 7mm cartridges, I shoot 7mmRem Mag, 7x57, and 280AI. I have found that I can duplicate the characteristics of the other two by selectively loading the 280AI. It is a great cartridge even in the 03A3 rifle in which it is chambered. I highly recommend it as a consideration for an addition to your rifle battery.
 
Straight 284
RL-17 will get you up in the 2900 fps plus with accuracy. I was not happy with 4350 and have shot this load from temperature range 20's to 90's



 
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Straight 284
RL-17 will get you up in the 2900 fps plus with accuracy. I was not happy with 4350 and have shot this load from temperature range 20's to 90's

I've seen people get superb results with the 284 with this powder, and at impressive MVs as here. However, I've also seen some people have no end of issues with the combination. In one case, the rifle was a 1,000 yard F-Class winner for a series of matches then abruptly stopped performing. Not a barrel life issue, not an ambient temperature issue. Not only was the round count low, but the user was one of the UK's top Benchrest and F-Class riflesmiths and that barrel was borescoped up hill and down dale without any faults being found. After some false restarts, a new load with a different powder was worked up and performance was restored but at the more usual mid 2,800s fps level. Nothing at all had been changed when the 'collapse' occurred - even the same manufacturing lots of brass, primer, Berger Hybrids, and Re17 - and not a change in jump either due to throat erosion. Although the most dramatic example I've seen, it mirrors what other people have found too. (But others shoot a barrel or two out with Re17 loads without any such problems. Go figure! :confused: )
 

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