H4350 or H4831SC for 140 A-Max in 260 Rem?

[Jason]

I'm down to my last pound of H4350 and am having trouble finding more (like most other reloading components) right now. I do have a couple pounds of H4831SC on hand, though, and the data on Hodgdon's website suggests that the H4831SC will actually push the heavier bullets just a bit faster than H4350 in the 260 Rem. It all looks close enough that I doubt I would go to the trouble of working up a new load with H4831SC if I could find more of the H4350. What do you guys think? Have your 260s done better with H4350 or H4831SC with the heavier (~140 gr) bullets like 139 Lapua Scenar, 142 Sierra MK, or 140 A-Max on rams?

[DanDeMan]

Jason,

Both powders have worked equally well in my 260's launching heavy bullets.

[Joaquin B]

41.5 grs. of H4350 or 44.0 grs. of H4831 develop velocities of approximately 2670 fps in my rifles with excellent precision, using 140 Hornady. AMAX, 142 Sierra or 140 Berger bullets in my .260 rifles.

[Bigfoot]

Jason don't forget that you could alway re-chamber for a more efficient cartridge (hm, say like the bobcat) and you would stop wasting all of that unnecessary powder. 32 gr of 2520 is moving the 140amax at 2650 as measured by a functioning oehler 35p chrono (not that crazy crony piece of crap).

Food for thought. You won't want to shoot the chicken loads at rams like I keep doing. The 95 gr vmax only takes half the rams.

[Jason]

Thanks, but I'll pass on the 260 Pipsqueak. I want a bit more than 2650 out of my ram loads.

[Pete]

WHY?

[Ferret Master]

If you run the ram loads much past 2500 fps your bullet dwell time on the ram goes to pot and you loose actual knock down power and burn your barrel up faster. Years ago I did experiments with a ram mounted on Thompson linear motion bearings with spring backings. When the ram was struck the ram moved against the spring and the movement was recorded on paper with a pencil mounted on the shafts. With all calibers it was shown that with Siearra MKs, Lapua's and Hornadys there was a point of diminishing returns in velocity. If the bullet hits the target to fast it flies apart expending the energy to the wind with very little dwell time. There is a point where the bullet stays together just long enough to transfer it's energy to the target, dwell time, and produces knock down power. Extra foot pounds of energy produced by the higher velocity only has relevance on living tissue, AR 500 steel just doesn't care. The bullet still flies apart but after transferring it's energy to the target. The 140"s started out at 2500 fps produced almost 4" of movement and the ones started out at 2700 fps produced less than 2" of movement. .30, 7MM, and 6MM all produced similar results.
A crude version of this test can be done by observing the size of the circle of paint disturbance on the target. A large splatter usually means bullet moving to fast. My son was shooting a .260 with 140 MK and knocking down every ram hit. The match director was shooting .260 same bullet at almost 2700 fps only knocked down 3 of the seven he hit. Match director strikes produced >3".5" circles, my sons strikes produced < 2".
Ferret Master

[Bigfoot]

Ferret master that was an excellent scientific answer. Why do I have the feeling you must have written for Presicion Shooting at some point? Thanks.

[RBriscoe]

The short answer to "why?" is that loads that slow simply don't work everywhere.

That said, there are some people who have had remarkable success wit such loads. Go figure.

I tried H4831 some time back and did not see enough difference to warrant changing from H4350. I'll just say that I would shoot either one I could get.

The current situation reminds me of a prior primer shortage. Everyone proudly shot anything they could lay their hands on.

Rick

[DanDeMan]

Evening,

I posted about optimum MV's for 6.5mm ram loads a while back on this thread, but erased the post due to not wanting to be confrontational. What the heck, why change?

Some of the MV suggestions on this thread are way, way out in la, la, land. The bottom-line is; a considerable amount of well controlled experimentation and much match ram-shooting decisively showed that between 2,750 and 2,825 fps delivered max ram knockdown-performance with 139 Scenars and 141 Cauterucios. With a hot load driving the 139 Scenars to 2,925 fps ram knockdown-performance fell. I did not run any tests with the Sierra heavy 6.5mm bullets.

If one does not tolerate recoil well, by all means, shoot what is comfortable and fun.

[RBriscoe]

I will just say this in addition to what Dan said. My experience with 139 gr Scenars and Bob's 141 gr bullets mirrors the result of his testing.

The velocity cut off for 142 gr Sierras appears to be about 2,750 fps. Above that I experienced a fair number of ram failures with a big paintball like splotch rather than a nice small bullet mark. This is not a criticism of the MK. It is a fine bullet, but it simply will not tolerate the impact velocities which the other two will. The MKs seem very well suited to velocities around 2,700 to 2,725 fps. I used to shoot them as turkey loads at that velocity when it was windy.

There are any number of other people who have independently reached the same conclusions as Dan. If you do not shoot at a range that requires the additional remaining energy of loads that deliver the velocities Dan describes, then just shoot whatever combination works for you. If go to other ranges, ask around about the rams so you won't be surprised.

Cheers,
Rick

[Bob259]

Just ask KItty what happens to a 6.5 when you try to squeeze a little more FPS out of them.... If I recall correctly it was a nice gray cloud and the animal wiggles.. or was that laughing Faster is not better.

[Jason]

As other have mentioned, I have no desire for argument and have put off replying. I do know that when I was pushing the 139gr Lapua Scenars and 140gr A-Max bullets at 2650fps, I rang approximately 15% of rams that I hit at Pe Ell. Since I changed loads and am now pushing them at 2740fps, I have not rang any of those that I have hit in the last few matches. I have not seen any big splatters on them or the swingers from this faster load.

[RBriscoe]

Just ask KItty what happens to a 6.5 when you try to squeeze a little more FPS out of them.... If I recall correctly it was a nice gray cloud and the animal wiggles.. or was that laughing Faster is not better.

Bob,

With all due respect, it simply depends upon the bullet.

You are unquestionably correct that, if the result is a large splotch, the impact velocity is more than the bullet will tolerate and the only way to improve performance at that point is to reduce the velocity.

One thing not discussed here is the choice of barrel. "Once upon a time in a galaxy far, far away"...6mm cartridges were the thing to try. People experienced bullets "blowing up", i.e. coming apart in flight before reaching the target. It was generally believed that the type of rifling was a factor in this occurrence (along with the rifling twist, velocity and even whether the bullet was coated (moly was popular back then)). The theory was that cut rifled barrels engraved the bullet jacket deeper than button rifled or 5R rifled barrels and so the jacket was damaged/weakened more. Someone over at Benchrest Central with a technical background even made some calculations to estimate the point of jacket failure based on RPMs at a given velocity and twist rate and estimates of the depth of the engraving on a bullet jacket. As I recall it, his calculations very closely approximated the experiences of quite a few people. Dan could probably give you a more detailed engineering explanation of this, but I think the basic concept is pretty straight forward. The thinner the jacket at the engraved areas the weaker it is. Under the best of circumstances, the bullet holds together only very briefly upon impact with the ram. If it is weakened, it only stands to reason that it will hold together for a shorter period of time.

As with many things, YMMV.

Regards,

Rick

[Edit] P.S. Obviously, it also matter where you hit the ram. A "heart shot" or other hit near the center of gravity of the ram will result in you trying to push the whole animal off the rail. A high rump hit will either topple the ram or push the rear leg off the rail and requires less energy. The rails matter as well, but that is another subject entirely, as is the steel used for the ram and whether the animal is bowed for constant impacts on one side. The thickness of the ram is also critical. For example, if a ram happens to be 1/2 inch thick instead of 3/8 inch thick, the energy requirements are very substantially increased.

[Ferret Master]

I went back to my notes to check and did not see any advantage between 140 gr range bullets in reference to ram movement. We were using AR 400 steel standard NRA Spec weight. If I get time I might try a AR500 ram they do ring differently. I agree if folks are using non standard rams all bets are off. One thing I noticed on our old range was that our stands were not solid and when a ram was hit part of the energy of the strike was used to rock the whole assembly and not solely to separate the ram from the stand. For testing purposes we placed all test shots in a 3" circle in the center of the ram.
One other thing to consider is direction of the wind. I our tests the wind was almost completely calm. A wind coming from directly behind the ram is murder while blowing against the ram is your friend.
On the subject of where to hit the rams I might suggest that the nose is most advantageous. A number of years back my son and I had the opportunity to have dinner with the gentleman that went on the win the match rifle national championship that year using a 7mm BR using the Hornady 162 bullet. He told us that he was shooting them at about 2250fps. Since he had shot ten in a row that day I found it hard to believe that he was moving his bullets that slow with that much success. I had rung 3 that day with 168's moving at 2550. He offered to go back to the range with us after dinner to demonstrate how well his loads worked. My son and I went down and set a bank of 5 for him after which he shot all five in the nose. What can I say, If I could shoot I could use the 130's for rams.
At the 2775 level the flame temperature and pressure level really take a toll on the barrel throat, charcoal is awesome when cooking steaks but it sucks in the barrel throat.
Not trying to start a fight, everybody has there own observations and opinions. That's what makes this sport so much fun!