Home Forums Reloading Big Game Rifles Hogdons 6.5x55 160g H4831 load

Last week I decided to load up a bullet I haven't shot in many years; the 6.5mm 160 grain Sierra SMP. I saw that Hodgdon has H4831 listed a max charge of 48.0 grains with a Hornady 160g showing 2,524 fps. That's decent velocity for a 160g bullet using the older Swede pressure limits. But 48.0 grains seems a rather...generous...amount of powder. But this is from Hodgdon, not "some guy" off of the Internet.

I loaded up a mini-Audette ladder starting at 43.8g and going up to 48.0g in 0.6gr increments. I took them to the range on Saturday morning to get an idea of velocity and potential accuracy nodes using a LabRadar chronograph. Unfortunately, I missed the reading on the first shot (43.8gr) due to a chronograph alignment issue. Which is too bad as the reading would have given me a heads up and more confidence on my second reading...

Shot #2 (44.4 gr) clocked at 2,557 fps. That gave me a pause as the max load of 48.0g was supposed to show 2,524 fps. At this point I didn't have enough information to determine if it was a bad chrono reading or if I was over-pressure.

Shot #3 (45.0gr) clocked at 2,598 fps and nearly locked the bolt up!

Obviously, continuing to shoot would be foolhardy.

I would like your opinions as to why you think my results are so different from Hodgdon's. I tried to keep as much the same as possible.

Hodgdon:
Brass: Winchester
Bullet: 160g Hornady RN
Primer: Wincheser WLR
COAL: 3.000"
Sized: Full-length?
Brass Life: New?
Distance from lands: Unknown

Mine:
Brass: Winchester
Bullet: 160g Sierra SMP
Primer: Wincheser WLR
COAL: 2.990"
Sized: Neck Sized (Lee Collet Die)
Brass Life: 4th Loading (not annealed)
Distance from lands: 0.008"

The is the first time this brass has been neck-sized with the LCD. The brass chambered smoothly with no noticeable resistance. The 2.990" COAL is what I've always used with my Reloder-22 loads. This is a factory CZ 550 American 6.5x55 SE. I've never found it to be tight chambered. This same batch of brass is used with my other standard loads and shows no undue pressure issues.

Is it just due to the differences in bullets? I wouldn't think there would be enough difference in bullets for this large of a discrepancy. Because I'm close to the lands?

I checked the latest Hornady, Sierra, and Lyman manuals.
Sierra didn't list a H4831 load.
Hornady has a recommended maximum of 42.3gr of H4831 @ 2.970".
Lyman lists a maximum of 46.0g of H4831 @ 3.000".

Is Hodgdon's data just a bit hot? Ideas?

Thanks.

Azar - I load for a Tikka T3X and a M96 (I once had a CZ550 in the same caliber). I've found, like you, considerable variation in reloading data with most of the older manuals using the M96 or M38 and 46,000CUP as the MAX pressure. Initially, I assumed that using new brass and a newer, more modern, rifle in this caliber would yield significantly higher velocities than that published by all the powder and bullet companies. I found my M96 had a rather "generous" chamber and full length resizing demonstrated an excessive amount of stretching even on moderate loads. When I loaded the same rounds in the CZ, I could reload my cases more times, but could not drive the bullet significantly faster. While researching further, I found some of the brass I was using had the "head size" of the 30/06 at .470 where all the "datum" specified for the case indicated the correct size was .476 (Lyman #47) to .480; a case head size more like the 8X57 round. I then relegated my old cases to my M96 adjusting my die to "partial" resize. This procedure helped, but did not extend the life of my cases more than one or two extra firings in the M96.
For the CZ, I bought new Lapua cases and a couple dozen Norma cases I found at a gun show. Both cases met the "published" standard for the 6.5X55 and have shown the "hoped for" longevity of most of the calibers I work with (.223, .243, .270, 30-06, .35 Whelen, 9.3X62, etc.).
Now (finally), that brings me to your subject of reloading the 160gr Sierra semi-spitzer bullet in a "modern" 6.5X55 or S.E., which designates the Europeans higher pressure standards. My initial thought was I had "broken the code" on being able to exceed the velocity numbers, I would surely succeed using new properly "spec'd" cases in my Tikka. I did succeed, as did you; however, just not the way I expected. Practically all the reloading data I was using used a "test" firearm with a 29.5" barrel whereas my CZ550 had a 20.5" (carbine) and my new Tikka T3X has a 22.4" BBL Logically (if that actually figures in - ha!), if I can achieve the same velocity from the much shorter barreled rifles accomplished by the long barreled M96 with long case life, excellent accuracy, and "legendary" trajectory, I have accomplished quite an achievement! The various reloading manuals record the following with 160gr bullets (double check for accuracy!): 1) Sierra - 2500fps with a 29" BBL 2) Hornady - 2300fps with a 29" BBL 3) Lyman #50 - 2386fps with a 24" BBL 4) Norma - 2519 with a 24" BBL. While not all these sources sources use H4831, they give a "base line" for loading the 6.5X55 and what velocities we can expect.
You (and I) have reached 2500fps with a 160gr bullet in a much shorter barrel than that used in a much longer one! You also accomplished this feat while using much less of your "chosen" powder to reach this power level! Why? Maybe because your rifle has much tighter chamber tolerances, shorter "lead", or more defined rifling due to "tooling" that isn't 124 years old! Hopefully the 6.5X55 will continue to be more popular as we enter the "second faze" of the 6.5 Creedmore "craze".

I believe the Hornaday is a two diameter bullet and the Sierra is not. Don't have any Sierras on hand to measure but at least the old lots of Hornaday's were two diameter.

This has caused many to proclaim the 6.5s are erratic and yes they are if you mix two diameter and conventional bullets at max loads/max seating. This is another point that made the .264 Winchester less popular. The original chambering had almost no throat for two diameter bullets. I think Winchester may have changed this from the earliest runs but not sure. If they did the reputation was already out and hard to undo.