Pressure question on 300 WSM

[tim_w]

Winchester brass almost always has a higher vol and is lighter in weight. Maybe someone can post a current case vol for the 300wsm brass. I could be wrong but but IIRC winchester 300 wsm vs adg is about 3gr h2o. Win being the higher vol. I think the cases themselves weighed in around 229gr. You can weigh yours for comparison.

Given that, you can subtract about that amount from the powder load data from those using win brass.

You picked the best brass going with ADG IMO. Both are good but ADG has shown to be stronger. Until the day we have lapua wsm brass if ever ADG has proven very good.


Once you get a load developed I prefer to load the cases you plan to use all with the same loads from the begining (virgin brass) so they have the same history. By that I mean do the same mild fireform load. Then load them with your developed load for the same number of loadings. Keep them sorted & together. Keep track of the load history on them.

If you choose a node at least 1 gr below where you see any ejector marks or case head growth 50 cases can last that barrels life. Anyways point being keep your cases sorted by load and history.

If you want best case life grab one of the flame annealers that go for around $300 and use it after every firing on a SAAMI chamber. If you want the best get an AMP for $1500.

If you do the above you should get 25-30+ reloading from cases.
Remember very small changes in bullet seating depth can have significant effects on group size and pattern. 0.003" adj steps is a good amount. You can refine from there, if needed, once your zero in on the tune.

 

[tim_w]

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!

This is good advise.

 

[Chesterrose79]

I found that eld x and ELDM bullets pressure out quicker than others. I think it's due to them having more bearing surface. I bet if you try a Berger projectile in the same weight category it won't show pressure as quick.

 

[Rick Richard]

I found that eld x and ELDM bullets pressure out quicker than others. I think it's due to them having more bearing surface. I bet if you try a Berger projectile in the same weight category it won't show pressure as quick.

Same opinion

 

[tim_w]

Try the Berger 215 hybrid has a 0.463" bearing surface & g7 0.354

 

[Window]

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.

X2

 

[Boisedoc]

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!

I like it. I am looking for 2650-2700 fps ultimately as this will do everything I need it to and then some. The Hornady book has an H4350 recipe I may try that for now. Seems a little fast from what I've read. The learning curve is fun and I am glad I was able to spot the extractor marks before any primer changes or a truly heavy bolt. I think I stopped well before hitting danger. I had the brass just about perfect as the shoulder is about .0025" longer on the fired brass. The new ADG brass was actually long at the shoulder for the chamber

 

[Muddyboots]

I am leaning more toward you really do not have a solid measurement for maximum CBTO by jamming into lands with a dummy round. Which can result in false CBTO and too close to lands. Thus maybe hitting pressure too soon. I would wait until you have the modified case and find your CBTO with a more exact CBTO.

 

[Boisedoc]

Thank you everyone!

 

[Boisedoc]

How close to danger is this? Danger meaning catastrophic failure. On the left 62 and then 62.5 grains H4831sc

 

[Chesterrose79]

How close to danger is this? Danger meaning catastrophic failure. On the left 62 and then 62.5 grains H4831sc

Showing the beginning of pressure. Primer isn't flattened on the edges yet and no firing pin cratering. I wouldn't continue with any more powder.
I found with my 300wsm that in order to get the velocity that I wanted pushing the heavies I had to try about 4 powders to get good accuracy and fit within my short magazine as well. I also tried shorter projectiles so I could have more room to adjust seating depth.
Finally settled on 200gr hotcor with N555 powder.

 

[LongBomber]

Was that the first loading of that brass? You are fairly low in charge weight compared to all the wsm's I have played with. Out of about a dozen they have all gotten over 65gr with 4831 and various 200gr class bullet. I shot a pile of 208amax and 208eld's from a couple of them, up in that same powder range.
The last rifle runs 66.3gr behind a berger 200.20x in adg brass, at 2905fps from a 26" barrel. I would think you would be close to 2650-2700 with that combo.
ADG brass is about the best you will find for the wsm, maybe one day lapua will make a wsm case.

 

[bonie]

With that much neck tension you can be pushing well into the lands, at a setback of .020 you may still be too long. a modified case with very little throat resistance will serve you better.

 

[sedancowboy]

If you will send me a fired case I will make you a modified case for free just pay shipping.
You can PM me if you want to pursue that.