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300 wsm chamber issue

32" is too long for a WSM barrel. 28" will give you more velocity , less pressure and no soot.
I ran into the same problem with the WSSM's. 26" barrels always produced more pressure, less speed and soot on the case. I trimmed the barrel back 1 inch at a time, and when I got to 23", I got the best speed, no excessive pressure and no more soot.
I don't understand this. I've read Mike Rescigno's articles on the 308 and 300 winmag. That's why my 300 winmag had 24" barrel. That being said, this post is about me having a problem. Lol
 

32" is too long for a WSM barrel. 28" will give you more velocity , less pressure and no soot.
I ran into the same problem with the WSSM's. 26" barrels always produced more pressure, less speed and soot on the case. I trimmed the barrel back 1 inch at a time, and when I got to 23", I got the best speed, no excessive pressure and no more soot.
Interestihg.
Brass spring back after firing, with pressure still in the barrel, bullet had NOT exited the muzzle.


The measurement with calipers above the web measure .560 on some brass after firing
Would still seen like secondary pressure spike? Bullet moving to soon or extra long throat?
 
32" is too long for a WSM barrel. 28" will give you more velocity , less pressure and no soot.
I ran into the same problem with the WSSM's. 26" barrels always produced more pressure, less speed and soot on the case. I trimmed the barrel back 1 inch at a time, and when I got to 23", I got the best speed, no excessive pressure and no more soot.
How many rounds did you have on the WSSM barrel before you started cutting? How many rounds did you shoot after each cut?

To the OP my 30" 300wsm shoots 2950 with a 208gr and h4350 no issue with the brass sealing. Your loads seem slow to me. Are you getting pressure signs?
 
How many rounds did you have on the WSSM barrel before you started cutting? How many rounds did you shoot after each cut?

To the OP my 30" 300wsm shoots 2950 with a 208gr and h4350 no issue with the brass sealing. Your loads seem slow to me. Are you getting pressure signs?
I don't see any pressure signs. The load work up was going fine and then the soot started. Now it soots almost every time. I guess H4350 and some 230 hybrids. That seems to be a process of elimination that is easy to do.
 
H4350. Neck is .340 (barrel is marked). Loaded round is .338
I like the idea of changing powder to faster.

What is the MEASURED fired brass outside neck diameter?

Will a bullet fit into the fired brass neck?
If bullet will not go in, its a sign of low pressure, (in factory chambers) Tight necks may be different?

Suppressor or silencer on the muzzle?
 
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I like the idea of changing powder to faster.

What is the MEASURED fired brass outside neck diameter?

Will a bullet fit into the fired brass neck?
If bullet will not go in, its a sign of low pressure, (in factory chambers) Tight necks may be different?

Suppressor or silencer on the muzzle?
Sunday when I get home. I'll measure.
 
Interesting. I came across something exactly like this with a throated barrel. Check your overall length. Make sure that you are touching the lands. Or even can tuch them with a seated bullet. How much is left in the neck of the bearing surface, not the bolt tail. Just the bearing surface, how much is left touching in there?
What I found on the one I was dealing with, is the bullet would jump, and by the time it sealed itself in the rifling, and the primers ignition was doing this. it was already completely out of the neck. so the brass, would Allow the gasses to escape around the outsid before expanding and forming correctly.
Try a long bearing surface projectile like a 220 smk or longer Lapua bullet. Something that moves the ojive ferther forward. Than let me know if this works to stop the problem.
 

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