Developing a new load, a few questions

[Killerbren]

Hi guys, I've been lurking on this site for years but thought I would finally join to get your opinion about something.

I'm developing a new load for my 300 Win Mag, I have a decent 180 gn TTSX but since it is only travelling at 2900 fps I wanted to speed it up a little bit. I've decided to go with the Barnes 175 gn LRX for the high BC, running H4831SC powder.

I loaded up 8 rounds, basically trying to find a safe max. Starting at 69.0 gr and working up in 0.5gn increments. I went and shot them today and have 2 questions.

1) this is the first time Ive had a chrony for load development and was allittle suprised. Some of the loads were actually slower than the previous although they had more powder. Is this common? reloader error? Chrony error maybe? here is my results:

69.0 - 2677
69.5 - 2766
70.0 - 2824
70.5 - 2812
71.0 - 2801
71.5 - 2923
72.0 - 2949
72.5 - 2867

2) this question is about pressure signs. With 72.5 gr i'm noticing a small amount of primer flattening. No stiff bolt, no cratered primers, no extraction marks. Would it be safe to keep increasing until I see some of these other signs. The reason I ask is because my last load wasn't the fastest yet my primers were quite flat. I was using 69 gr of IMR4831 which is well under the max for that load. I've attached pics of my primers.

Unshot, round primer

Some flattening, 72.5 gr H4831SC (0.5 gr past published safe max)

My previous recipe, 69 gr of imr4831, well below published max

I'm using federal 215 primers, which from what ive heard are softer than others. Should I keep increasing powder charges until I start seeing other pressure signs or should I keep it where it is? Im trying to get it well into the 3000's, closer to 3100fps if possible.

 

[Greyfox]

It's not unusual to see variations with chronograph results. It can be lighting effects, velocity spread, or both. Generally, I like to shoot at least 3 shots, more often 5 or more to get an average velocity and ES. Flattened primers can occur with sub maxiimum pressures. I have gone as high as 76gr with 175gr. Bullets with H4831sc. I would increase your current max in ,5gr increments. If you see cratering, ejector marks, or experience a stiff bolt, I would back off a half grain,

 

[HuntFarther]

I am sure we use 77-80 grains of h1000 with the 185 bergers in a couple guns. You should work up but I think you would be really happy in this ball park.

 

[Killerbren]

Update: Ive continued my loads increasing in 0.5 grain increments and i'm quite high. Last load I shot was 78 grains of H4831SC. Published max in the barnes book for a 180g ttsx is 72, but if I remember correctly for a 168g ttsx the max is 74.5 grains. Since im shooting a 175 LRX I would say the published max for my bullet would be in the 73.5 grain mark.

My primers are still round, no stiff bolt, no cratering. I shoot a sako 85 finlight, so a well made gun. Am I flirting with disaster with this? Im sure I would of seen pressure signs by now, but there are a few recipes on the web that are posting 80 grains.

here are my speeds.

73.0g - 2923fps
73.5g - N/A
74.0g - 2917fps
74.5g - 2956fps
75.0g - 2976fps
75.5g - 2996fps
76.0g - 2956fps
76.5g - 3030fps
77.0g - 3044fps
77.5g - 3044fps
78.0g - 3058fps

Im in a good range, I wanted 3100fps but realize that is probably not obtainable.

 

[Lefty7mmstw]

Like a previous poster said go to a slower powder and you'll see some speed increase.
Mil surp lots of h4831 were often capable of 3150 fps with 180 grain pills in a 300win even in a 24" tube. I shot some surp. 4831 my uncle gave me in a 24" bbl rem 300 win and 75 grains was 3150 fps with a 180 at normal pressures. The new stuff doesn't seem to produce the velocity as well as old war surp. stuff.

Switch to h100 or rl22 and you'll hit your 3100 fps rather easily.

 

[1SevenZero]

I would do as the others say and start looking at different powders. Because I'm a chicken, when I start to see pressure signs I stop and back off.

I'm sure you have, but I have to ask... Have you looked at some reloading manuals to find a basic recipe that will get you the speeds you want and remain in safe pressure levels?

I have a Nosler manual and it's pretty good.

Also here is a sight that I feel is very informative.

Talking about over pressure.
The Rifleman's Journal: Cartridges: Long Range Reloading Safety - .308 and Others

The Rifleman's Journal
The Rifleman's Journal: Articles Index

 

[Grumulkin]

I don't use a chronograph to work up a load and I don't try to get to some magic velocity. What I go for is best accuracy.

As for pressure signs in a strong bolt action rifle:

1. If bolt lift is hard, you've gone too far.

2. If you get a pierced or blown primer you've gone way too far.

3. When you work up a load, accuracy generally gets better to a point as the load is in creased and then starts to deteriorate. The accuracy deterioration is a sign that you're past the optimal load and moving into excessive load territory. Many time there will also be a marked difference in where the load prints on paper when this point is reached.

4. If there is still a little roundness to the edge of the primer and none of the above apply, the load is probably OK.

5. If there is cratering of the primer the load is probably excessive or the hole for the firing pin is a bit bigger than necessary.

 

[X-man]

You can get a flat primer and a funny looking bolt face from over doing it on the size die.
When you fire an over-sized case if slams into the bolt face flattening the primer and making odd marks on the cartridge head.
If I were a betting man I would look there for your "pressure problems."
You should also check for potential case head separation.


RL-22 and H-1000 give me 2970 and 2900fps respectively with the 200gr Accubond.
Both powders are a bit better choices for accuracy at top velocity.

 

[1SevenZero]

You stated you exceeded the published max safe by half a grain already. Just know those limits were established by people with far more experience and access to equipment we can only dream about.

My vote don't push it further.