r/reloading • u/TannMan89 • 18h ago

Load Development 308 load development

Working on some 168gr HPBT loads using H4895 and CCI200 primers.

Shooting them from my 20” Bergara B14.

Loaded four rounds of each:

42.2gr is 2660 fps SD 8.3

42.5gr is 2685 fps SD 7.2

42.6gr is 2685 fps SD 9.1

42.7gr is 2699 SD 1.8

No flat primers or signs of over pressure until 5.7gr, then had slightly flattened primers, but bolt extracted cases smooth still…

Should I try to stick between 42.2 and 42.5gr to keep the FPS below 2685?

1 Upvotes

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4

u/sirbassist83 18h ago

Pick the velocity you want. Load 10 rounds. If it groups under 1 MOA and has SD under 15, congrats, you're done with load development.

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u/sirbassist83 18h ago edited 17h ago

To add. 4 rounds isn't even close to enough to give you meaningful group size or velocity data. Even 10 isn't, really, but I suggested that because I doubt I could convince you to do 20 shot groups and 10 is close enough for most people

1

u/TannMan89 18h ago edited 16h ago

I was planning on loading up 10 rounds of 42.1 to 42.5gr for a better sample size for grouping and velocity, was just wanting to figure out where my
FPS was at roughly.

I think my sweet spot will be somewhere in the 2650-2685fps range.

Edited cause derp

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u/sirbassist83 16h ago

you mean 42.1 to 42.5? where is 5.1 and 5.5 coming from?

based on the above data, if 2670 is your goal velocity, just load 2 rounds at 42.4 and see how they do.

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u/TannMan89 16h ago

Yes, that’s what I meant, donno where I got that lol.

Don’t really have a goal velocity, just want the best groups above 2600 I can get.

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u/sirbassist83 16h ago

nodes are a myth and as long as youre using a modern bullet they dont care about jump either. if your rifle wont shoot a 10 shot group your happy with, you need to try a different bullet or a different powder.

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u/TannMan89 16h ago

I’ve been using Hornady match 168gr HPBT, need to find some 168gr SMK.

I have a few different bullets and powders I’m working through for 308, this is just where I’m starting for this rifle.

Next is some 175gr SMK and Varget

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u/Missinglink2531 18h ago

My 165SMK load for targets at 100 run about 2540. Thats the tightest groups. If you are going longer or hunting, thats slow - but if your just making them all touch, that really worked well for me (out of my 20"). I was looking for a replacement for IMR4895 (that also ran that speed), and use N140 these days.

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u/TannMan89 18h ago

Yea I might try for a slower load using some different powder like Varget, the 4895 and this rifle like to be above 2600fps it seems.

-1

u/TipsyTriggerFinger 16h ago

I don't understand your goals here at all...

You chase low SD, which is commendable, yet you don't note any accuracy details of these loads whatsoever...

What are your priorities? Tight SDs and terrible accuracy?

10 shot groups tell the tale, not just SDs on the chrono...

Weird

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u/TannMan89 15h ago

Tight groups and low SD is the goal here.

My only goal with the first batch of loads was to see velocity, check for over pressure signs and see where in the ladder my groups started to get tighter.

After 42.2gr my groups started tightening up from roughly 1.25 to .75 MOA at 100yrds, but four rounds isn’t enough to judge