300 WSM - Your Velocities?

[Logan1080]

I have just went through load development for my 300 wsm and this is where I am at:

175 LRX (.508 G1 BC)
63.9 grains H4350
Magnum Primers
.050" Jump.
24" barrel
2000' elevation.

These are steady around 3030 FPS on my chrono. However my bullet drop at 275 yards and 375 yards are -12" and -24" respectively. These figures are more drop than my BC calculators are saying. Then 500 yards is between 42" and 44" which is pretty accurate - ballistic chart says -41".

When I true my velocity it says I should be at 2824 FPS, when I true the BC it says it should be .325. Barnes says there BC's are dead accurate and that my chrono must be wrong but this is the 5th rifle I have loaded for and it always seems to follow loading guide. I will say 3030fps with 63.9 grains of H4350 seems on the fast side so I would like to verify with others.

 

[Justin Crossley]

I would check, double-check, and triple-check all your inputs into your solver before adjusting anything.

I would also double-check the zero with a minimum of 10 rounds. Make sure you are actually centered.

Also make sure you are using a scope that is proven to hold zero and adjust correctly.

If any of the three things I mentioned above are not correct, you will be chasing your tail.

 

[Logan1080]

Zero was set and then I shot a tall target and never adjusted elevation in the scope. Just a good old tape measure to measure drop. From there I tried dialing in the drop and realized my turrets are definitely out when it comes to dialing it in.

 

[limpet]

My 300 wsm was shooting 175 lrx with 63 grains of h4350 Norma brass and standard primers at 2965 out a 24” barrel so the velocity doesn’t seem that unreasonable. It could be your scope to bore height is off or just a wonky scope. I’ve had pretty good results inside 500 with their BC. Also I’d guess funky scope if you said it’s not dialing properly. Also what did the calculator say the drops at 275 and 375 were supposed to be so we have comparison.

 

[Logan1080]

My 300 wsm was shooting 175 lrx with 63 grains of h4350 Norma brass and standard primers at 2965 out a 24” barrel so the velocity doesn’t seem that unreasonable. It could be your scope to bore height is off or just a wonky scope. I’ve had pretty good results inside 500 with their BC. Also I’d guess funky scope if you said it’s not dialing properly. Also what did the calculator say the drops at 275 and 375 were supposed to be so we have comparison.

275 was 7.75” at 275 and it was actually 12”. 375 yards was 18.86” and it’s actually 24” (averages for 3 shot groups).

 

[limpet]

I plugged in the data you gave me into strelok pro. With a scope height of 1.62” and this is what it gave me. What calculator are you using? Can you give us some screenshots of your data entry to see if we can catch an error?

Looks like I switched the estimated vs actual drops when I read your response.

 

[Logan1080]

I plugged in the data you gave me into strelok pro. With a scope height of 1.62” and this is what it gave me. What calculator are you using? Can you give us some screenshots of your data entry to see if we can catch an error?
View attachment 784462
Looks like I switched the estimated vs actual drops when I read your response.

Sight height is 1.875” and I’m using the Burris calculator as well as the Hornady app.

 

[BCsteve]

I'm also running 175gr LRX in my .300WSM. I'm loading 64.5gr of H4350 at 2970fps in a 24" Winchester M70.

 

[Logan1080]

I should add that a 6.5 creedmoor I just developed a load for using the 127 gr LRX and same chrono to measure velocity punches out bang on in my two different ballistic apps for 275 and 375 yards. So that shows me that my chrono is reading accurately.

 

[Jfjfrye]

Not 175s. But WSM information none the less.

 

[Logan1080]

yeah I’m thinking my velocities are accurate

 

[35WhelenAI]

Agree with others to double check the inputs to the calculator. Velocity is where it should be for that bullet weight in general.

With that said, to be off only 2 inches with the human factor at 500 yds and have what must be larger discrepancies you have mentioned at shorter range has me scratching my head a bit. What are the calculated drops at 275/375 yds compared to the -12" and -24" you got respectively?

You said when you true things the BC comes out at .325. That BC would not have you at your actual drop at 500 yards if it trues things out at the shorter range. If I'm reading it right, after truing the 500 drop would be way off from your actual

Barnes uses time of flight in a 300 yd underground range to find BC, and I have found them to be accurate in the grand scheme.

On a tangent, I see Barnes shows 67.1 gr H4350 for 2996 mv as max load with 175/180 gr LRX in a 24" bbl. Your charge weight is a good bit lower than that and getting a bit more velocity. Probably nothing in it, as velocity is a good gauge of pressure and you are not much over from published velocity. Just interesting the velocity is what it is with 3.2 gr less powder, even taking powder lot to lot variations into account from my experience.