6.5 SAUM, 6.5 Creedmoor, 7mm-08

[Greyfox]

26cal offers a great deal.
Best overall -for specific use, could be different than you think.
Personally, I believe accuracy trumps all else. And accuracy means shooting enough to have & hold it.
I also believe that it all begins with a bullet. Pick a bullet and build around it.

With this, I know of no 26cal bullets where capacity greater than 260AI is appropriate. That is, there is no gain (only loss) in 26cal, beyond that provided by 260AI capacity. And I'm not talking muzzle velocity only, but also barrel life, fastest powder filling the case, highest viable peak pressure, lowest muzzle pressures per barrel length, best brass, shooting system weight & recoil, etc.
I can & do match or better anything a 6.5x284 does with 260AI capacity(using a 6.5wssm Imp) with 140gr bullets.

For medium ranges(~600yds) with 123-130gr bullets(good up to white tail deer), and all attributes mentioned, I don't think you can better the 6.5x47L. It's perfect for just that.

The 6.5CM is merely a lost puppy in between.

While I own and like the 260/AI, I much prefer the case design of the 6.5x284 for the sweet spot of 3000FPS/140 gr load for LR hunting. Barrel life has been beaten to death with this round, but I have not found it to be much different then its counterparts when subjected to comparable shooting conditions and used with slow burning powders. With Lapua or Norma cases it's exceptionally accurate, and the cases last for 12+ loadings. I have been forever plagued by short case life/premature loosening of primer pockets with the design of the 308 case and its derivatives...keeping pressures within spec....regardless of the brass manufacturer. For competition/PRS/mid range hunting I really like the 6.5x47 Lapua with a 130gr at 2900FPS.

 

[5RWill]

While I own and like the 260/AI, I much prefer the case design of the 6.5x284 for the sweet spot of 3000FPS/140 gr load for LR hunting. Barrel life has been beaten to death with this round, but I have not found it to be much different then its counterparts when subjected to comparable shooting conditions and used with slow burning powders. With Lapua or Norma cases it's exceptionally accurate, and the cases last for 12+ loadings. I have been forever plagued by short case life/premature loosening of primer pockets with the design of the 308 case and its derivatives...keeping pressures within spec....regardless of the brass manufacturer. For competition/PRS/mid range hunting I really like the 6.5x47 Lapua with a 130gr at 2900FPS.

It's hard to beat the 6.5x47 for efficiency and case life. It's really absurd. I asked a friend the other day how that case can be pushed well beyond it's limit and still get 12+ firings with ease. Hell i hear of people getting 30+ annealing.

I have 2 friends running 38.1gr of varget one with 130gr hybrids and one with 140gr Hybrids. Which to my knowledge is well above max, and i'm guessing well around or above 65k PSI. With 4166 i went all the way to 37.6/37.8 before pressure signs. Which i had no intention of running just wanting to see what it gave. I had been running 37.0 and decided to revisit my load using Scott Satterlee's OCW method. Running a 23" barrel i get right at 2850 with 130gr Hybrids with 37.0 and got 2920 with 37.8.

 

[57K]

I think it makes sense because it's the first commercialized 6.5 short action magnum cartridge supported by a major player in the industry. The marketing as a PRS cartridge doesn't fit to me. I see it's uses, especially in ELR matches but outside of those i don't see it surpassing the 6.5CM or 6mms in use.

Not sure i see the point in 7 PRC when you already have 7 WSM and 7 SAUM.

Anywho Dad's SAUM is finally done, going to give to him on his birthday. Had it throated for 140gr Elite hunters, aiming for 3100fps with h1000. We shall see, the weight came out nearly perfect at 9lbs without the can and bipod.

With Hornady behind the 6.5 PRC, I get your point. However, the 6.5 CM is firmly established and served very well with rifles and ammo along with fairly light recoil as far as the average shooter.

From what I see, and has been pointed out here is that we now have 3 - 6.5mms that essentially do the same thing while only one is a standardized cartridge that never got off the ground with the 6.5 Rem Mag. I suppose we'll be able to call the 6.5 PRC "standardized" soon enough with factory ammo from Hornady. But still, the major riflemakers will have to get on board as well, and it does have the advantage of the 6.5 CM in being able to seat bullets longer in a short action.

That's my point about a possible 7mm PRC. It could do what the .284 Win couldn't with its length restrictions. I don't believe a 7mm CM would match 7mm-08 ballistics as close as the 6.5 CM matches the .260 Rem. And standard pressure .280 Rem @ 50,000 CUP or 60,000 PSI doesn't improve over the 7mm-08 and requires a standard action. One of the most popular AIs is the .280 Rem AI. Seems to me like a 7mm PRC could do for the 7mm what the CM (Hornady) did for 6.5mm.

I have liked the 7mm-08 since Rem first offered it in factory rifles and ammo. It does everything it was advertise to do in a pretty easy to shoot platform. As far as factory rifles it is typically among the most accurate calibers you can buy. The 7mm-08 Rem AI doesn't seem to improve it in the way that .260 AI improves the .260 Rem, and since a 7mm PRC would not technically be a magnum like the 7mm SAUM or WSM, and with lower recoil with the ability to load "down" to the 7mm-08 level, I can see a lot of potential for such a cartridge.

 

[Mikecr]

I could put together a system that would get infinite case life from a 6.5x47.

My accurate mid-node from 6.5wssm Imp(260AI capacity), 28" barrel, is 3025fps/140gr with only 47.4gr IMR 4350. My accurate barrel life(two barrels so far) is consistently 1850 rounds. That's 650 more than a 6.5x284. I don't FL size, or neck size, or anneal, or trim, no problems, and my cases will last forever.
By QL this is right at SAAMI max, 65Kpsi, and it's very accurate at mid node(most common competitive) & 16.5lb form.
Testing for 'MyMax', the point of needing body sizing, took me over 3200fps.
But this doesn't just happen. It takes a plan.
I'm confident a 260AI would perform just the same -with a plan.
The excessive 6.5x284, with greater area, and more and slower powder does nothing better.

These are just opinions of mine. No way to prove best. But it doesn't hurt to slow down and consider this stuff. Pick your bullet, pick your capacity.

 

[5RWill]

I have liked the 7mm-08 since Rem first offered it in factory rifles and ammo. It does everything it was advertise to do in a pretty easy to shoot platform. As far as factory rifles it is typically among the most accurate calibers you can buy. The 7mm-08 Rem AI doesn't seem to improve it in the way that .260 AI improves the .260 Rem, and since a 7mm PRC would not technically be a magnum like the 7mm SAUM or WSM, and with lower recoil with the ability to load "down" to the 7mm-08 level, I can see a lot of potential for such a cartridge.

I see what you're getting at with the 7 PRC now. The hindrance of the 7mm-08 is that while the .284/7mm projectiles sport some of the highest BCs in their normalized weight class it simply can't manage the oomph to really justify them over a 6.5mm round over a similar charge weight. Also find it strange that the AI for a 7mm-08 doesn't really offer near the gain that the 260AI does over the 260. Having said all that i'm not sure how you couldn't term it a magnum, as it will undoubtedly require a magnum bolt face, require modified AICS mags or magnum mags that hold 2-3rds less compared to the 7mm-08, and having almost 1/2 the powder capacity more than the 7mm-08 itself. For all intensive purposes the 6.5 PRC is a modified 6.5 RCM, i'm not sure how that denotation would change just by going up to 7mm. I do see the benefit and point, though oddly enough couldn't you acquire similar feats with the 7 SAUM or 7 WSM?

 

[57K]

5RWill, I'm thinking the ability to load bullets further out of the neck would have the same advantage it does with the 6.5 CM and hopefully the 6.5 PRC. And maybe performance equal to the .280 AI. The twist rate would likely be the same or close to 1 in 9.5".

Since these rounds are shorter versions of an already "short magnum" and sill longer than the SSMs, I'm not much concerned about labeling. But your point is well taken. It would require a "magnum" bolt-face. Really the only necessary mod other than the appropriate chamber. That might make it more attractive to rifle-makers.

Dealing with pressure is part of my vocation, so the points about pressure nodes are well taken. I would like to see if a 7mm PRC would be the equal of the .280 AI at 52,000 CUP/62,000 PSI where many of the short magnums are rated 65,000 PSI and previously 54,000 CUP.

I'm sure there are guys here who know more than I do. A 1 in 8" twist rate for the 6.5 CM and .260 Rem might be the ticket. Then twists for older 6.5 x 55mm Swedish Mausers are even faster. I really don't know how much thought cartridge designers have put into this. My SPEER #11 load manual states that 45,000 PSI is max for 94 Swedes and that start charges should be considered max for the 94s. The twist rate there was 1 in 7.5". So, if the Swede can handle warmer loads with modern bolt rifles, it seems that the twist rate should be appropriate for velocity gains. That is exactly what CZ does with their 550 models chambered in 6.5 x 55mm @ 1 in 8.75" or thereabouts. I'm not so concerned about stabilization as I am the consideration of pressure.

We know that time is a function of pressure measurement, so obviously time in bore, or dwell time will be longer in a faster twist barrel. And I realize we're talking micro-seconds here. But still, I wonder if 1 in 8" is the right twist for 6.5s faster and warmer in pressure than the 6.5 CM and .260 Rem. And with the longer dwell time/higher pressure comes higher burn temps of the propellant charge. Just my hypothesis, but I believe some of these short-lived barrel issues could be helped somewhat with slower twists where calculators like Berger's would show plenty of stabilization with slightly slower twists. I can't say if CZ was aware of this when they gave the 550 a 1 in 8.75" twist, but I suspect it was, and done so for those who load to modern pressure levels that the cartridge case is capable of.

With fairly minimal cost differences, 7mm-08s could be manufactured for 7mm PRC and hopefully with 24" barrels for sporters, Customs at 26". This for mass produced rifles. That is essentially what's done for 7mm WSM and it's been some time since I've seen a 7mm SAUM in anyone's catalog except for maybe Remington's. That would also remove any proprietary cartridge envy, for lack of a better term.

The differences in powder charge weight for 7mm-08 and 7mm WSM are not so great if say you look at a 150 gr. bullet. And true, start charges for the 7mm WSM are close to 7mm-08 performance. Hopefully, the 7mm PRC would be about midway in-between. I think it could be a great combination cartridge.

Sorry for being long-winded, but getting back to the OPs question in case it hasn't been resolved, I'm like the poster who mentioned his 7mm-08 150 gr. Handload at 2900 FPS vs around 2750 FPS with a 140 in the 6.5 CM or .260 Rem. That's why I'd go with a 7mm-08 over either and probably more from a hunting perspective. But, the 7mm-08 was also born from rifle competition (Silhouette).