Pressure question on 300 WSM

[Boisedoc]

I have my new 300 WSM build with a SAAMI chamber. I went out to just do some pressure testing today. Ran 212 ELDX over 4831sc and a federal 215 primer. I loaded a dummy round with .002" neck tension and jammed it into the lands. Then backed off .020 from there and ran a ladder from 60-66 grains at 0.5 grain jumps. Saw a slight ejector mark at 61.5. Shot 62 and saw it a little better. Shot 62.5 and the bolt was a little heavy and I stopped. I have all the room in the world on my long action. Hornady has the round loaded at COAL of 2.92". Hogdon is running their data for 4831 sc at 2.860. I am running 2.986 COAL although I loaded it to CBTO while loading. Hogdon says max load is 66 at a little over 2700fps. At 62.5 I'm at 2560. Should I back the bullet in to 2.92 or 2.86 and try again to work up? Maybe .020 is causing pressure too early? Or try h4350 as Hornady has in their manual or H1000?

Thanks

 

[sedancowboy]

New gun, new brass, new everything. Let the gun tell you what it will shoot. I would go back to 61.0 and try a seating depth test. You can try another powder but let your gun tell you what it will take. The manuals didn't use your barrel or brass so don't worry about more speed at this time.
This is why we start low and work up. Everyone says it and the manuals do too. Are you sure of your base to the lands measurement?

 

[Boisedoc]

I'm not 100 percent sure as I am new to reloading. I did the Eric Cortina method and put a little wax on a bullet that was too long and let the gun seat it. I have a Sinclair over all length guage. Maybe I'll try that first and see if the length is off.

 

[sedancowboy]

Ok good to know. We can help you. If you have a SAMMI chamber then it is not going to be longer than standard. I would imagine you are close to the lands at 2.986 COAL. I would load Three at 2.950, Three at 2.925 and three at 2.900 and see what happens they should get better or worse at you progress. After you get some fire formed brass and get your barrel broken in then you can start to find pressure. I have found that the ELD-Xs like some jump. Also remember that new brass will take a little more powder than fireformed brass so if you are on the ragged edge of pressure with new brass you will be over pressure when you go to load it again and you will be scratching your head. The new brass absorbs energy as it is expanding to fit your chamber is why will tolerate more powder. I am only talking about a grain or grain and a half.

 

[tim_w]

Edited: Questions already asked

 

[tim_w]

My suggestion since you are new is just try the coal in the hrdy data and see what you get.

What brand cases are you using?

For the fireform load choose something on the lower end.

Set the cases aside you saw ejector marks on for now.

 

[Boisedoc]

Thank you. I'll measure the chamber again as well. I have ADG and Norma brass.

 

[lancetkenyon]

First, use only ONE headstamp/brand of brass. Do NOT use both unless youbplan to work up two separate loads.

What brand brass does the book use that you got the info from? Different brass will have different case capacities. What is max in one might be overpressure in another, or below max is yet another.

What primers was the book using. Some are hotter than others.

What barrel length? Does book length differ from yours? Expect 25-30fps per 1" of barrel length change. Also, if yours is new, expect 60-120fps slower than the book velocities until it speeds up.

A lot of variables with bullet lots and powder lots too. I have seen same brand powders change 50-75fps between lots. Not usually, but it can happen. Bullets can change shapes between lots. Longer bearing surface = more friction = lower fps.

A loading data book recipe is a guide, not a Bible.

 

[Boisedoc]

Thank you. I used ADG brass. The load data I was following was Hogdon. They used Winchester brass and a Winchester LRM primer.

 

[Boisedoc]

Looks like they used a 24" barrel. I'm using a 21". They write 2770 at maxed load

 

[jsmitt6]

ADG brass is great stuff. I would back off max load the book says by 10% and use the coal the reloading book says. Once you find some velocity nodes (think 2-3 different powder weights shooting similar speeds) then try messing with seating depth if you aren't happy with accuracy results.

 

[Boisedoc]

Hornady load data has Winchester brass and the win LRM primer out of a 24" barrel with a 1:10 twist. They have a COAL 2.920 and write 2800 velocity max out of 62.5 grains of H4350. I have that powder as well. I will also go back and remeasure my chamber with a Hornady over all length gauge as soon as I can get a modified case. I do have a 1:9 twist barrel but I wouldn't think that would increase pressure?

 

[Boisedoc]

ADG brass is great stuff. I would back off max load the book says by 10% and use the coal the reloading book says. Once you find some velocity nodes (think 2-3 different powder weights shooting similar speeds) then try messing with seating depth if you aren't happy with accuracy results.

Thank you.

 

[jsmitt6]

Thank you.

you are welcome. You will find that almost everyone works up loads differently. This is what I have done for 7+ years and has worked well for me. Start by using what the book says for COAL, powder, primer type, etc and then start tweaking things as you go. You should expect anywhere from 75-100 fps slower than book due to your barrel length. Not, an issue but something to note.

My recommendation is find a load that shoots to your liking and then take it and go kill something with it. Too often we, myself included, worry too much about speed this, lighter that, what if this. Remember it should be fun!