Is pressure too high? .30-06, IMR 4350, 165 grain Accubonds

[flintlock.50]

Today I shot my best group ever with my Rem 700 .30-06. The load was 165 gr Accubonds & 60 gr IMR 4350. The bullet is seated 10 mils off the lands. 5 shots at 100 yds measured 0.608 inch. It would have been much less but for the first shot (upper left).

I'm thrilled with these results, but I'm a bit concerned about the pressure of these loads. I only partially resize my cases, so they are always a bit tight going in and coming out. Unfortunately my chronograph battery died so I didn't get any velocities. (Chronographing these loads was why I went to the range in the first place!).

The Hodgdon site lists 60 gr as maximum load for the Sierra SPBT. HOWEVER, various manuals list 58-59 grains as maximum for the 165 gr bullet. I routinely get much less than published velocities. For me, 59.0 grain loads chronograph 2770-2800 fps, considerably less than what my manuals report AND what I see on various forums.

Today's shells show just the beginnings of a shiny spot where the ejector pin hits the shell. Other than that, I see no signs of high pressure. The primers aren't flattened, and there appears to be minimal cratering around the firing pin.

My manuals talk of a shiny spot from the extractor pin as the first sign of high pressure. However, this shiny spot doesn't jump out at you, though the closeup pictures make it very obvious.

Does this look like high pressure? Has anyone else have experience with 60 grains of IMR 4350 pushing 165 grain Accubonds in an ought-six? What do you think?

Thanks!

 

[hodaka]

I'm not an expert at reading primers but 60 gr. seems a bit stout to me and this looks like cratering to me. I've no experience with Accubonds but I typically load Hornady and Sierra 165's in the 57-58 range to get the accuracy I want out of my Ruger #1. Damn nice group though but I bet you can back off a bit and get similar results.

 

[mehavey]

This is a classic example as to why primers are not a pressure indicator. The primers
are not only normal, but have very rounded edges.

The brass, or the other hand, tells the story. Ejector cut-out extrusion in near every one.
Since Nosler is a very good case, you are hitting 70,000psi+. (QL says 69,000 w/ an OAL of 3.34")
Drop it at least two grains.

 

[iraiam]

I looked at my manuals going back several years, you are 2-3 grains above max charge for that bullet weight. (3 grains above max in Nosler books)

Nearly every manual I looked in showed 57 grains of IMR 4350 as a max charge, I have to drop back to 150 grain bullet to find a max charge of 60 grains of IMR4350, just for the record I own 14 reloading manuals most of which I just looked through.

 

[243winxb]

If you can feel the ejector mark with a finger nail, your too hot. Some factory loads will look just like your fired brass. But the ejector mark will not be raised. Brass life may be short at high pressures, about 3 firings till primer pockets get loose. I load IMR 4350 @ 57gr with a 150 Sierra.

 

[flintlock.50]

I didn't get to 60 grains on my own. The Hodgdon web site shows 60 grains IMR 4350 for the 165 gr Sierra SPBT. Barnes shows 59.5 grains for their 165 grain XLC BT.

What I don't understand is how these manuals are reporting so much higher velocities (than I get) with lower charges. Example:

Barnes 165 gr XLC 59.5 gr 3064 fps
Barnes 165 gr XBT 57.0 gr 2895 fps
Sierra 165 gr SBT 56.0 gr 2900 fps
Nosler 165 gr 57.0 gr 2832 fps
Hornady 165 gr 57.0 gr 2900 fps
Sierra 165 gr SPBT 60.0 gr 2934 fps (from Hodgdon online)

59.0 grains gives me 2830 fps. (The velocity I reported in my original post was a bit low.)

 

[mehavey]

From Hodgdon website"

165gr SIE SPBT
3.33"
H4350 / 59.0 / 2938 49,400 CUP

Are you perchance equating H4350 with IMR4350?
QuickLoad notes that if the actual reported load above (w/ Winchester cases (vol 70.6gr)) is used w/ a 24" barrel, it gives ~2,900fps/59,000psi

 

[flintlock.50]

I'm not confusing H4350 with IMR 4350. Check out the following.

From: http://data.hodgdon.com/cartridge_load.asp (for .30-06)

165 GR. SIE SPBT IMR 4350 .308" 3.300" 60.0C 2934 57,600 PSI

This is two lines below the H4350 data.

 

[iraiam]

Test barrels are different lengths, a 24" barrel will net a higher velocity than a 22" barrel. It is defintely on the risky side to change out components in recipes, using an XXX brand bullet with a YYY brand recipe is ill advised. This is why I have so many manuals on hand.

I looked at the recipe you are using on their website and I would say that the difference is bullet, the same website lists other brand of bullets of the same weight, yet they list nearly 60K psi with much less IMR4350.

I am of the opinion you should either discontinue that recipe or use the stated bullet that the recipe calls for, and re-work up.

 

[SL1]

The data is for a Sierra bullet, while you are using a Nosler bullet.

My experience with Nosler bullets is that they give somewhat higher pressures (and thus velocities) than Sierras with the same powder charge, etc. I think that is mainly due to the substantially thicker jacket on the Noslers.

Why your pressure is high but your velocities are low is a bit of a mystery.

Could those ejector marks have been present BEFORE you fired these loads?

SL1

 

[mehavey]

Nosler 6th edition lists
2,832fps
IMR4350/57.0 MAX
165gr Accubond
24" Lilja barrel

No matter the velocity, once you start getting those ejector marks (especially in Nosler-type brass), you need to back off...

 

[flintlock.50]

I can find ejector marks on other brass fired with lower charges, but I have to use a strong magnifying glass. The pattern on today's marks is different and shinier, though I can just barely feel it with my finger nail. The shiny look is what caught my attention.

I did have to play with the lighting to get the marks to show up well in the pictures, especially pics 3 & 4.

My Rem 700 has a 22 inch barrel. Speer used a 700 with 22 inch barrel. My Nosler manual says they used a 24 inch barrel. Sierra's data is from a 26 inch barrel. Barnes and Swift used 24 inch barrels.

Maybe the extra barrel length explains the velocity difference, but that seems like a lot for just 2 inches.

I'll definitely reduce the load. 59.0 gr doesn't show the shiny spot. It has OK accuracy, but nothing like the group above.

 

[ripnbst]

You could just leave the load where it's at. Yes it higher than published but you wouldn't be the first guy who had a load worked up that was past published max.

How was the gun's operation? Bolt tough to lift? Tough to retract case from chamber?

If no to both then you could just keep the load where it is. I would just be very careful when loading not to go any further. How accurately is the powder feeding in your press?

The difference in barrel length will definitely have an effect on your velocities vs published.

 

[Jim Watson]

Cratered and tool marked primers (even though not flat to the edge.)
"Tight coming out."
Ejector marks on the solid casehead.

That is not one pressure sign, it is three. You are on the safety margin of your rifle and brass.

 

[Kimber84]

Shoot I'm only running 56 grains behind a 150g Interbond, getting around 2830 fps and sub MOA to MOA performance

I would definetly back off like you said and retest...

 

[flintlock.50]

I always throw my loads a bit light, then add powder using a scale to get the final charge.

I had not noticed the tool marks on the primers. Thanks for pointing that out, though I'm not sure this is abnormal. I'll have to check the primers on some lighter loads I've shot. I've seen pistol primers flattened like a pancake! (Definitely very high pressure!) Compared to those, these don't show any high pressure signs.

Same thing for the cratering. The cratering I see on these doesn't look like the cratering I've seen on pistol loads that were too high pressure. And I recall seeing just a bit of this type cratering on almost all my loads.

The first picture (in my original post) is closest to what you see with the naked eye. Much of the detail in the other pictures is readily visible only because I played with the lighting to get the best effect and the pictures are highly magnified.

ALL my shells are tight because I don't full length re-size them. I DID notice that the bolt was harder to open on one shell, but the shell extracted without any effort at all.

 

[Kimber84]

Everything you've shown so far screams pressure. I would back down on the charge.

I'm certainly no reloading guru like some here, but the facts you've presented are plenty clear.

 

[old roper]

There is always two manual powder/bullets and Hodgdon manual list max load with 165gr Sierra bullet @ 60gr/IMR-4350, 2934fps.

What started me on having 30-06 build was that load as I work up a new factory Rem 30-06 with 24" barrel and I got 2936fps with 165 gr bullet. In my Bartlein barrel 30-06 60gr/IMR-4350 with 165gr AB @ 3066fps same load in my Shilen barrel 30-06 @ 3076fps and both those barrels are longer than 24".

My start load from Hodgdon manual 56gr/IMR-4350 with the Bartlein barrel rifle was 2874fps and that's about 140fps faster than published data which is on par with some of my builds like my 280AI. Only advantage I have is I don't need max powder to get published velocity depending on which manual I'm using.

 

[PawPaw]

I was surprised to find that Nosler now puts their data online, like the powder companies do.

The .30-06 page is here, and shows the Accubond at a max load of 57.0 grains of IMR 4350.

Nosler's Load Data page is here.

 

[AllenJ]

Ejector marks are always a pretty good sign of excessive pressure, much more so than flattened primers in my experience. I have to agree with those that say your pressure is excessive.