IMR 4831 and new bullets

[JohnyRingo]

I am currently shooting a Browning XBolt 300 H&H Mag with 180 grain Accubonds with 67 grains of IMR 4831. I am getting decent accuracy, around 1 MOA, but I have 3 other rifles that shoot 1/2 MOA. I am considering changing bullets to see if my rifle likes those bullets better. The issue I have is that my rifle has a detachable box magazine that only gives me about 3.644" of COAL.

The 3 bullets I would like to try are all longer than the Accubonds (1.380" and .507 B.C.) I am currently using. I am looking at the Barnes 175 grain LRX (1.472" and .508 B.C.), Barnes 180 grain TTSX (1.488"and .484 B.C.) and the 174 grain Hammer Hunter (1.4" and .484 B.C.). With the Accubonds, I already feel like bullet is slightly compressing the powder. If I go with a longer bullet, it will only get worse. Plus, I am having a little bit of a feeding problem at 3.644" and was going to try 3.62".

I'm kinda leaning towards the LRX because of it's equivalent B.C. to the Accubonds over the Hammers because of it's lower B.C. Hammer bullets advertise their B.C. at .247 G7. If you convert it to G1, it comes out at .484, which is lower than the Accubonds.

Anyway, I am just wondering if compressing the IMR 4831 a little more to accommodate the longer bullets is going to be a big problem. The only other powder I have is the IMR 4895 and that is too fast for larger bullets.

 

[44hunter45]

The usual safe practice reduce your loads by 10% and work back up when you change a component.

67 grains of IMR 4831 is already overmax based on the Nosler book and QuickLoad. (The Hodgdon web data for IMR 4831 in 300 H&H and 180 grain bullets is dangerously wrong)

So - yes. "Compressing the IMR 4831 a little more..." is going to be a problem. IMHO

 

[JohnyRingo]

I have cross referenced the 67 grains of IMR 4831 with 5 or 6 different reloading manuals. I don't see any signs of overloading. I think I am going to check into a 6" drop tube to see what this does for consistency in my loads and see if this improves the accuracy of the Accubonds before I start messing with new bullets. I will probably back off to 65 grains and start over from there.

 

[Tom_Nguyen]

Anyone use IMR 4831 to load 300 WM?
Thank you for any data sources

 

[Dan O]

Johny I load my 300H&H with Fed 215, 65.0gr. IMR 4350, 180 Accubond. Nosler has this as their max load for this powder. It shoots MOA and when run through the chronograph showed 3009 FPS. This is out of a 24 inch barrel in a Rem 700. I have not tried IMR or Hogden 4831.

 

[AlaskaHunter]

Every rifle is different...I get the most accurate load in terms of lowest SD/ES and smallest groups with 64.0 gr IMR for 180 gr.

Nozler does list their most accurate at 62 grs and MAX 66.0 gr IMR4831.
https://load-data.nosler.com/load-data/300-holland-holland-magnum/

 

[JohnyRingo]

I did some reading yesterday and maybe I am diving down the wrong rabbit hole. My last 5-shot group with the Accubonds was right at 1 MOA with an ES or 26 fps. What I read is if the ES spread is that good, then I should be looking at barrel harmonics.

 

[DRS]

For what it’s worth I’ve gotten good results with h4350 and 180 Accubonds in my 300 H&H x bolt.

 

[mtmuley]

You shooting far enough for the BC of a bullet to even matter? mtmuley

 

[JohnyRingo]

You shooting far enough for the BC of a bullet to even matter? mtmuley

Probably not, while hunting anyway. Most of my shots are under 300 yards. I do like to stretch my shots out in the summer though, shooting rocks. Plus, I'm a math teacher and all the numbers can become pretty obsessive.

 

[mtmuley]

Hammers are killing bullets. mtmuley

 

[JohnyRingo]

Hammers are killing bullets. mtmuley

I'd like to check them out. I emailed both owners about their long bullets and my short detachable box magazine. I haven't heard back from them. I'd like to try their 181 Hammer Hunters. They have a shorter 174 grain bullet too, but their B.C.'s are measured in G7 and I'm not familiar with that measurement.

 

[AlaskaHunter]

I did some reading yesterday and maybe I am diving down the wrong rabbit hole. My last 5-shot group with the Accubonds was right at 1 MOA with an ES or 26 fps. What I read is if the ES spread is that good, then I should be looking at barrel harmonics.

With my 300 H *& H, I record velocity standard deviations in each 5-shot group along with group size while
varying IMR4831 in increments of 0.5 gr, starting near the min published load.

Typically there is a powder charge where the standard deviation is substantially smaller than other powder charges.
For example from last October, with a magnetospeed chronograph:
stdev: 16.9, 10.6, 19.8, 17.2, 17.8, 4.6, 14.9, 12.6, 15.9
Then confirm velocity variations with 5-shot groups the next day by shooting the load with original 4.6 std dev and loads below and above.

After confirmation of the powder/primer with low velocity variation,
work on 5-shot groups incremental bullet seating depths at that specific powder charge.
With monoliths like Barnes TTSX or LRX, I start at 0.050" off jam and increment in 0.020" out to 0.150" off jam.
Confirm the next day by shooting 5-shot groups at the increment above, at, and below the best bullet seating groups.

 

[JohnyRingo]

With my 300 H *& H, I record velocity standard deviations in each 5-shot group along with group size while
varying IMR4831 in increments of 0.5 gr, starting near the min published load.

Typically there is a powder charge where the standard deviation is substantially smaller than other powder charges.
For example from last October, with a magnetospeed chronograph:
stdev: 16.9, 10.6, 19.8, 17.2, 17.8, 4.6, 14.9, 12.6, 15.9
Then confirm velocity variations with 5-shot groups the next day by shooting the load with original 4.6 std dev and loads below and above.

After confirmation of the powder/primer with low velocity variation,
work on 5-shot groups incremental bullet seating depths at that specific powder charge.
With monoliths like Barnes TTSX or LRX, I start at 0.050" off jam and increment in 0.020" out to 0.150" off jam.
Confirm the next day by shooting 5-shot groups at the increment above, at, and below the best bullet seating groups.

What powder charge and bullet combination are you currently using?

What method of measuring jam do you use?

 

[mtmuley]

I'd like to check them out. I emailed both owners about their long bullets and my short detachable box magazine. I haven't heard back from them. I'd like to try their 181 Hammer Hunters. They have a shorter 174 grain bullet too, but their B.C.'s are measured in G7 and I'm not familiar with that measurement.

Dividing the G7 value by .514 will give you a relatively close G1 number. I'd call Steve. Quicker than E-mail. I can find out for you if he's in the shop today. mtmuley

 

[AlaskaHunter]

What powder charge and bullet combination are you currently using?

What method of measuring jam do you use?

That was for 180 gr TTSX with IMR4831, Norma Brass, shoulder bump 0.002, skim turn neck.
With virgin brass I uniform primer pocket/deburr flash hole.
I also use an expander mandrel instead of the conventional sizing die expander/decapping stem.
I seat the bullet with a LE Wilson seater and an arbor press.
I use Erik Cortina's method of measuring jam:

 

[JohnyRingo]

Here are some measurements I just gathered:

COAL distance to lands = 3.653"
My current COAL with Accubonds = 3.64"
Current jump = 0.013"

Because of feeding issues, I want to adjust COAL to 3.63", which means a 0.023" jump.

Height of 67.5 grains of powder in case = 2.107"
COAL with Accubonds resting on powder = 3.487" (no compaction).
COAL with LRX 175's resting on powder = 3.579" (no compaction).
COAL with TTSX 180's resting on powder = 3.595" (no compaction).
COAL with Hammer Hunter 181's resting on powder = 3.644" (slight compaction).

It doesn't look like I will have any issues with trying out the LRX's and Hammer Hunters. I do plan on using a drop tube and dropping the powder charge to work up a new load.

 

[EastTNHunter]

Have you tried the NAB at the reduced OAL? It’s a fine bullet. If I were to change from NABs to a mono it would be to the Hammers. I’m not good enough to be able to take a shot on game beyond 300 or 350yd, and even then everything would have to be just right to attempt it.

I’m not concerned about a compressed load as long as I’m not getting pressure signs. In fact, some of my most accurate loads are compressed