OCW Safety Check (.308)

[thepatchcable]

I wanted to post some details about a load I'm working up and get additional eyes for safety. Based on the load data the max charge is 49.7g (155HPBT). Following the OCW method, I took 10% off the top to begin my load:

42.5 (min charge)
45.0
45.3
45.6
45.9
46.2
46.5
46.8
47.2
47.5
47.8

Should I continue load development to near max or stop? I have a chronograph so I will be able to gauge MV. Thanks all for your help and guidance!

 

[Skeptic1]

You haven't given us enough information yet to answer your question.
If the book says the max charge is 49.7 you have lots of room to grow. Why did you start all the way down at 42? 10% off of 49.7 should be just shy of 45 off the top of my head. What powder, primer?
I have to many questions to comfortably help you

 

[alamo5000]

I don't know about the specific method but in general one of the biggest skills you should learn is how to read brass.

I've had loads show pressure way before some of the published data, but given I was using different brass and primers.

Just shoot a few and keep going until you see something, then back off from there and do more fine tuning.

 

[thepatchcable]

You haven't given us enough information yet to answer your question.
If the book say the max charge is 49.7 you have lots of room to grow. Why did you start all the way down at 42. What powder, primer?
I have to many questions to comfortably help you

I didn't start down at 42 I just put it for reference. I'm using N550 powder with 9 1/2 Remington primers. My CBTO is 2.2395 for all cartridges.

 

[nn8734]

Nope. read rules or you will be.

I wanted to post some details about a load I'm working up and get additional eyes for safety. Based on the load data the max charge is 49.7g (155HPBT). Following the OCW method, I took 10% off the top to begin my load:

42.5 (min charge)
45.0
45.3
45.6
45.9
46.2
46.5
46.8
47.2
47.5
47.8

Should I continue load development to near max or stop? I have a chronograph so I will be able to gauge MV. Thanks all for your help and guidance!

What powder, primer, brass? Brass virgin or once fired? How many rounds on the barrel? Jump?

 

[thepatchcable]

What powder, primer, brass? Brass virgin or once fired? How many rounds on the barrel? Jump?

Once fired brass. OAL is around 2.85 with at least 2000 rounds fired. Also, this is a mag fed semi-auto

 

[nn8734]

Once fired brass. OAL is around 2.88 with at least 2000 rounds fired.

Jump? Dont care about OAL as long as it feeds reliably

Who’s brass? You do know that different manufacturers’ brass has different capacity that will impact your pressure threshold, right?

 

[OREGUN]

Start at 44 and load in half grain steps until you achieve the velocity you want or find signs of pressure. Then, back a grain away from the pressure or use the load that gave you the desired speed (and was a grain lighter than pressure signs started) and use that charge weight. Load development done. Your small charge steps are a waste of time this early in the process.

 

[Skeptic1]

OAL is around 2.85 with at least 2000 rounds fired.

At the risk of showing my ignorance. What the heck does this statement mean?

Sincerely

 

[thepatchcable]

At the risk of showing my ignorance. What the heck does this statement mean?

Sincerely

Sorry, my chamber length with this particular bullet is around 2.88 (measured with a gauge). I've loaded the rounds to 2.84~ COAL.

 

[thepatchcable]

Jump? Dont care about OAL as long as it feeds reliably

Who’s brass? You do know that different manufacturers’ brass has different capacity that will impact your pressure threshold, right?

Jump is about .020~ probably more. Brass is PPU 7.62x51

 

[nn8734]

Jump is about .020~ probably more. Brass is PPU 7.62x51

No experience with that stuff however i use 9-1/2 lrps and they’re great.

Id bring a mobile reloading station with you in case you run into something unexpected (like you started at way too high a charge weight).

Size, prep and prime like and additional 50-75 pieces of brass at home. Then (in addition to your previously loaded rounds) bring the primed brass, a small press which is mounted to some type of platform, bullet seating die along with a bottle of your powder (and a scooper), box of bullets (100 or so) and small digital scale plus your measuring tools for verifying seating depth adjustments and chrono/lab radar fo capture MV.

This way you can get all your D/T/E in one session.

 

[Near miss]

Start at 44 and load in half grain steps until you achieve the velocity you want or find signs of pressure. Then, back a grain away from the pressure or use the load that gave you the desired speed (and was a grain lighter than pressure signs started) and use that charge weight. Load development done. Your small charge steps are a waste of time this early in the process.

I recommend this too.
Just try the lowest hanging fruit, take the load .5gr under pressure signs and load 10 of that.
To make sure all is good, load 10 rounds .3gr up and down.

You are most likely good to go with that.