6mm,6.5mm

[steve]

6mm Super LR cartridge ,6.5 mm Super LR cartridge thoughts on these two

[FW Conch]

Welcome to the Brotherhood :-). I am a 6.5 fan all the way. The 6.5mm Super LR looks like a worthy improvement to the 260Rem, if you feel you need it, and want to go to the extra expense. JMHO

[stomp442]

Great cartridges but my thoughts are if you are going to go through the hassle of improving the cartridge just as well go all the way and Ackley improve it. Get all you can out of it.

[darkker]

http://www.6mmar.com/site/mobile?url=http%3A%2F%2Fwww.6mmar.com%2F65_SuperLR .php#3018

From that link alone, I hate them both.
Strikes me as a 260AI, just AI'd to be like the cool kids in fashion, but not address the detractions.
Neck and shoulder fluff aside, it is the same case length as the 260. That means that you are going to have to seat long bullets deeply into the case on many short actions, same problem the 260 has compared to the Creed/Lapua currently.
My next issue is the general full court press of BS, again this could just be the website I linked, but, Rant-on:

We are told that it is very easy to make brass with no neck trimming, when using 308 family cases... The EXACT same can be said, when using the same cases to make Creed, so what. We are told that "Winchester brand 243 cases hold the Pressure well". That is a buzzword statement that should make your BS meter ring and fall off the wall. " holds Pressure well" is the same as saying "no Pressure signs". At the absolute very best, that is only better than nothing; but no more and don't let anyone ever tell you different. Also FYI Winchester sold their cartridge case business over a decade ago, it is all least-cost bidding work that has had several suppliers in that time, with varying QC standards. Last I looked they have NOT listed what alloy specs and heat treat specs go into their cases, since the 1950's. It has LONG been well known and documented in the industry and Gun rags, that VERY carefully calibrated copper crushers, used by HIGHLY trained techs, can't accurately report pressures above roughly 45,000 psi. There are variances on the orders of 20,000 psi!! So now I'm to believe that an average reloader/novice to reloading can somehow magically stare at the cases/primers of an unknown alloy & heat treat, and magically tell me what pressures the cartridge is running??!!
We get told that using his super hero vision for Pressure, he can chrono 2900+ fps. There is a lot of that going-on in the Creedmoor as well. While I don't think it's advisable, many many run their Creedmoor that hard, getting hard to find people who don't unfortunately.

"Classic Pressure signs" in today's currently manufactured rifles, TEND to show-up, when you are above 70,000 psi. Here is a great example. These loads sounded/felt great, nothing out of place, and the chrono was fine. Brass and primer looked as good as anything you've seen; the Pressure Trace said we were about to blow the end of the barrel off from secondary ignitions (ask Charlie Sisk about doing this).
http://i78.photobucket.com/albums/j84/Darkker13/Mobile%20Uploads/Screenshot_2015-01-31-15-00-18_zpsmopqcu83.png

We were told this spring that the new Whiz-bang FlatLine bullets can be pushed 1-2 weight classes faster with no pressure signs, when using 4895. We tested that too, yep, B.S.!! In fact this notion of super low drag was tested against a Pro Hunter. Same cases/primer/charge yielded...? Yep, same Pressure. We also busted the caution of using slow powders, but I don't have that Trace handy.
http://i78.photobucket.com/albums/j84/Darkker13/Mobile%20Uploads/Screenshot_2015-09-08-18-59-03_zpst4w0ukh1.png
http://i78.photobucket.com/albums/j84/Darkker13/Mobile%20Uploads/Screenshot_2015-09-08-19-00-14_zps3pazhbys.png

Do you have interest in one of them? Then please build and let us know what you think!!! If it is just the whiz-bang appeal, prepare to be disappointed. Choose because of interest, not magic.

[LongRange]

i looked into both these awhile ago and didnt see any advantage to either over a 243 a 6mm CM or a 260 or a 6.5 CM and an improved version of the 243 or 260 will out preform either SLR.

[steve]

LongRange (http://www.savageshooters.com/member.php?33356-LongRange)
what improved version of the 243 or 260 would you suggest

[steve]

darkker (http://www.savageshooters.com/member.php?175-darkker)
same problem the 260 has compared to the Creed/Lapua currently. what problems are you talking about?

[steve]

FW Conch
thanks for the welcome
what makes look like a worthy improvement to the 260Rem

[darkker]

it is the same case length as the 260. That means that you are going to have to seat long bullets deeply into the case on many short actions, same problem the 260 has compared to the Creed/Lapua currently.


darkker (http://www.savageshooters.com/member.php?175-darkker)
same problem the 260 has compared to the Creed/Lapua currently. what problems are you talking about?

As I said, the case length makes it such that if chasing powder capacity is your game, you will have to seat the heavy match bullets rather deep. The Creed/Lapua don't suffer that same fate.

[FW Conch]

"busted the caution of using slow powders". I guess this is the one where we have been told that low loads of slow powders can cause detonation? If this has been debunked as an old wives tale, I didn't get the memo? I always thought the damage that was experienced was caused by low case volume of the slow powder? If not true, then something else must have been going on?

Seeing the pressure trace results is invaluable, but it just makes me want to see more. I'm sure my action can handle 110,000psi, but I know the case will fail way short of that. I'm not up on the details of secondary ignition, but I know that it is a bad thing, that can cause big damage. Some years back, Hand Loader Magazine did an article on how many times most of the lead brands of rifle cases could be reloaded before failure. It would be great to see this sort of testing applied to pressure, using the trace results, taking cases up to the point of failure.

But, back to the OP! :-). If these conditions can exist in the clamberings in question, I would think the same is true in almost all Wildcats and Improved chamberings? :-)

[LongRange]

what improved version of the 243 or 260 would you suggest

there is a 30deg version which is basically what the SLR is and supposedly feeds well from a mag..and there is the 40deg version which can get you much faster than a standard 260 or 243 but most likely at the cost of a shorter barrel life.
i just started playing with the 40*IMP 260 and like it so far...i also shoot a standard 260 that i also really like...this is just my opinion so take it for what its worth...if your looking for a very accurate long lasting 6mm the 243 or the creed...if your looking for the same in a 6.5mm the 260 would be my first choice and the creed 2nd

if you want reliable feed 30deg if you want speed 40deg...but like i said the hot rodding comes with a price.

[darkker]

FW Conch,
No, the caution about slow powders was again from the fluff of the FL bullets, and the speed claims. Using something like 4895 was supposed to give warp speed with no pressure, while use of something slow like CFE would not produce high velocities. The results were exactly what would be expected from a 150-155gr bullet.

Secondary ignitions can likely be from a few things, but Charlie(Sisk Rifles) and we, ran into it as a matter of the bullet out-running the gas, then "stalling" momentarily. The pressure wave slams into the bullet, causing a No Bueno situation.

The above traces were fired in a Ruger Predator. The Pressure Trace system is calibrated to, IIRC, 85,000 psi. So above that is uncertain, but in some high pressure/failure tests there was a load that registered around 108,000 psi. Was that ACTUALLY the pressure? Can't say due to calibration, but it wasn't good. If you go back to the hay-day mentioned for Olin and the 30-06 cases, they used Alloy C260 with a heat treat spec of 85,000 psi. Well when you could measure the brass starting to reach tensile strength and stretch..... Guess where your pressures were?

For the OP and general good of knowledge, using VERY progressive propellants are much more intriguing to me. So as an example in the Creedmoor, H4350 is the generally excepted "go to powder". It's burn curve is classic and the same as seen above. The general curve doesn't change with pressure, so the velocity is rather linear with pressure(assuming you are running in it's happy zone). Using something very progressive like Superformance, due to the area under the curve you can get very high velocities at much lower pressures. This progressive curve DOES change with pressure, so running full-tilt, won't magically gain you much speed.

140gr match bullets, the Creedmoor is realistically a 2700-ish fps cartridge @ 60,000.
Now look at it with Super down around the 50,000psi mark. Pretty cool, huh?

http://i78.photobucket.com/albums/j84/Darkker13/Mobile%20Uploads/Screenshot_2015-01-11-14-00-36_zpsrz6rkepr.png

[steve]

.308/7.62x51 - Reamed and Polished - Cleaned, Polished, Deprimed, Primer Pocket Crimp Reamed - Needs to be Sized and Trimmed before Loading - 1000 Units
what do you think about the brass and sized to .243 and 260 ?

[LongRange]

i dont know about sizing to 6mm i think thats going to turn into more work than its worth...sizing to 260 might be ok...id size a piece or two and then seat a bullet and measure the loaded neck size...most mil brass is pretty thick and when sizing down all the brass has to go some where and most times its the neck shoulder junction.

[steve]

longrange which would be you first choice in the 6mm the 243 or the creed ?
Thanks

[GaCop]

Great cartridges but my thoughts are if you are going to go through the hassle of improving the cartridge just as well go all the way and Ackley improve it. Get all you can out of it.

+1! :thumb:

[LongRange]

longrange which would be you first choice in the 6mm the 243 or the creed ?
Thanks

id have to go with the 243 but only because of brass...ive seen the 6mm creed in action and they are ridiculously accurate...just keep in mind both are about 1500 round barrels + or - a few rounds.

[LoneWolf]

I'm on my second 243 barrel used for competition. If you feel you have to shoot Berger Hybrids then I'd go Creedmoor or the Lapua variant in a 6. Otherwise 243 has been highly competitive for me with quite a few top placings and a few wins overall.

I've been shooting the 105 AMAX.