300 WSM low velocity issue?

[KINDA-NEW-GUY]

Stiller LA
Brux 1-10 27" #3 contour
Norma brass
Ptg reamer with throat for 215s

I have tried many different combinations of bullets and powders. I seem to fall way short of expected velocity with every bullet. I am currently shooting 168 classic hunters with 64.2gr H4350 at 2865fps. They are super accurate but an increase in powder reaches pressure signs before any reasonable 300 WSM velocities. I can get this speed or very close to it with a 308. I bore scoped the barrel after cleaning and can't see an issue. What could be the issue? I have heard of other people having the same velocity issues with Brux barrels but I want to make sure that I have eliminated all other possibilities of me being the problem.

 

[Medium rare]

Have you tried to contact brux? I heard they have awesome customer service and they will probably make it right if it's a quality issue.

 

[dragman]

Contact brux. Those numbers are way off. Something is up

 

[Steve Blair]

Stiller LA
Brux 1-10 27" #3 contour
Norma brass
Ptg reamer with throat for 215s

I have tried many different combinations of bullets and powders. I seem to fall way short of expected velocity with every bullet. I am currently shooting 168 classic hunters with 64.2gr H4350 at 2865fps. They are super accurate but an increase in powder reaches pressure signs before any reasonable 300 WSM velocities. I can get this speed or very close to it with a 308. I bore scoped the barrel after cleaning and can't see an issue. What could be the issue? I have heard of other people having the same velocity issues with Brux barrels but I want to make sure that I have eliminated all other possibilities of me being the problem.

What are the pressure signs? My Brux .300 WSM barrels, albeit 34", easily achieve 2865 fps with H4831 SC and 230 Hybrids. I had one that tuned about 60 fps slower but it was tuning and not pressure related. Mine have .280" freebore, 9.75" twist and I also use Norma brass.

 

[Ledd Slinger]

Ive never been able to achieve really high speeds with any Hodgdon powders, H4831 being the worst, but that's really low for that bullet weight and barrel length in a 300 WSM with any powder.

Try some RL17 if speed is what you're looking for. The new RL23 would also work well. If it won't go fast with RL17, then there's definitely something else going on.

Just to be sure, verify your chronograph is working correctly by using someone else's chrono. Your chrono may have fallen out of calibration or perhaps was being effected by improper lighting angles from the sun.

 

[Ledd Slinger]

One more thing...

Im sure you are an experienced shooter, but I was wondering if this is your first rifle chambered in a 'magnum' round? If not, I apologize.

One thing to always consider is the muzzle blast when chronographing magnum cartridge loads. The muzzle blast is considerably larger than the 308 Win you mentioned. If muzzle blast is flying across the chronograph, it can throw your readings off. My personal rule of thumb is to keep a bare minumum distance of 10 feet from the muzzle of the barrel to the front of the chronograph. With even larger magnum rifles like my 338-375 Ruger, I space the chrono out at least 12 feet, sometimes even 15 feet.

 

[dkhunt14]

Wow if you have a throat for 215's you should get a lot more then that. I have seen a few reamers messed up lately, freebore not what it should be. Brux has a .298 and a .300 bore in 30 caliber. I use the .300 so I don't pressure up as quick. What are your signs of pressure? Also as mentioned you maybe need to check your chronograph. Matt

 

[KINDA-NEW-GUY]

What are the pressure signs? My Brux .300 WSM barrels, albeit 34", easily achieve 2865 fps with H4831 SC and 230 Hybrids. I had one that tuned about 60 fps slower but it was tuning and not pressure related. Mine have .280" freebore, 9.75" twist and I also use Norma brass.

Ejector mark and stiff bolt lift.

 

[KINDA-NEW-GUY]

One more thing...

Im sure you are an experienced shooter, but I was wondering if this is your first rifle chambered in a 'magnum' round? If not, I apologize.

One thing to always consider is the muzzle blast when chronographing magnum cartridge loads. The muzzle blast is considerably larger than the 308 Win you mentioned. If muzzle blast is flying across the chronograph, it can throw your readings off. My personal rule of thumb is to keep a bare minumum distance of 10 feet from the muzzle of the barrel to the front of the chronograph. With even larger magnum rifles like my 338-375 Ruger, I space the chrono out at least 12 feet, sometimes even 15 feet.

I've had two 300 wsm's before and two 7 saum's one 7remington mag. I tested it with a shooting crony, and two magneto speeds. The drop to 1000yds matches measured velocity.

 

[dragman]

There is a problem, Bad barrel, possible bullet issue, REALLY SLOW lot of powder???
No reason it shouldn't be 3100 or more with that bullets. Your speeds are more like 210 bullet speeds.

 

[KINDA-NEW-GUY]

@dragman thats exactly my feelings. I'm just trying to go down the list and make sure I check everything before I jump to conclusions. And the powder is spot on with my 6.5x47's. And in my .308's. And the bullets measure out to spec.

 

[dragman]

Call brux, new barrel time
It sucks but it happens sometimes. My one brux 300wsm is hammer couldn't be happier with it. I'm sure they will do right by it.

 

[Ggmac]

I'd slug the barrel and check bore dimensions , confirm freebore length ,
But I'd say a call is in order . Better to give them as much info as possible .

 

[TimS]

Don't know what velocities you are looking for, but I'm getting 3150 from my Winchester High Wall. 168 Barnes BTTTSX with 70.1 gr RL 19.

Might seem like a mild load but very accurate and comfortable to shoot.

 

[JamesnTN]

Man I must be way off the pace I'm shooting around 2925 from my 30" WSM with 190 VLD

 

[Ledd Slinger]

Sounds like you've got your bases covered. Done about all the verification a guy can do before calling the barrel manufacturer.

My last 6.5 Rem Mag barrel was a 26" McGowan 1 in 8.5" twist. It would push the 140gr Berger VLDs at 3150 fps with 51gr of RL17. Any more powder and my primers would start to flatten and the pockets would wear out after 3 firings.

My new 6.5 Rem Mag barrel is a plain Shilen CM also at 26", but has a slightly tighter 1 in 8" twist. So almost identical. But the Shilen barrel allows me to load 52gr of RL17 and gives me 3209 fps with the 140gr Berger VLDs with no pressure signs whatsoever. Stopped there because accuracy was so good.

Two different barrel manufacturers, same chamber, same length, nearly the same twist, but notably different speed and pressure characteristics. If anything, I would have expected the McGowan with the slower twist to be more forgiving with pressure. But that wasn't the case.

 

[JohnKielly]

Ejector marks can be a consequence of cases sized too small for the chamber resulting in the case backing up & peining on the bolt face. Stiff extraction is a common complaint of many of my friends who use short magnum cases to shoot F class. They blame it on the heavy case walls that tend not to spring back enough after firing to release from the chamber.

 

[Larryh128]

It sounds to me like it's a .298 bore not a .300.

 

[dkhunt14]

Ejector mark and stiff bolt lift.

Is the bolt lift stiff from the start or hard right at top like bolt Click? Matt

 

[KINDA-NEW-GUY]

It's hard all the way through the bolt lift.
I like to hot rod a lot of my cartridges, I'm 100% certain this load isn't even remotely warm for this bullet/case combo. No carbon ring, everything is surgically clean, and I even took a look with my bore scope to confirm.