lower velocity than expected

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sirhuntsalot

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Interesting day at the range yesterday with a new rifle (300 WSM; 24 inch barrel). The Chrony registered velocities that were quite a bit lower than expected. The temp. was a cool 9 degrees. 180 grain Accubonds over 67g of Re22 were recorded at 2760 fps (most sources indicated just over 2900 should be expected). 165 TSX's over 69 gr of Re19 were running at 2950 (sources indicated about 3100 was expected). These are near-max. loads accoring to most sources. Recoil and muzzle blast was milder than expected, really no more than my .30-06. Absolutely no pressure signs evident (not surprising). I've either got a slow barrel on my hands or the Chrony is wrong ( I'm leading towards believing the Chrony). I wouldn't have been surprised or disappointed with 100 fps lower than expected, but at least 200...?!

Has anyone else experienced such low speeds in a .300 WSM? Anybody ever concern themselves with Chrony inaccuracy or the need to calibrate them? Any suggestions for safely increasing velocity? The loads were mildly compressed, because of the long bullets and being constrained by a 2.86" magazine box. Would using a ball powder (W760, H414, etc.) be an option for stuffing more fuel in the tight space?

And the larger question...is a quest for 150 more fps a waste of energy? (but, heck, a .300 WSM is supposed to be a solid notch up from .30-06!).

As always, a new rifle is a mystery needing to be solved.
 
As far as I am concerned (does not mean much) the family of WSM do not accomplish any more and sometimes less than there longer counterparts. The only advantage I have seen being on the range shooting and observing these cartridges is it provides a short action vs long? what does tha mean to me not much. I have nothing aginst them or for them just my 2Cents.
If I was to buy one it would be the 270WSM crank out velocities close to the 270 Wby.
As far as the short case accuracy ove the long, I have yet to observe it, and has been to close to call.?
I do believe your velocity's you observed I have seen it as well with the 300 WSM at the range pushing 100 fps less than advertized, however as you say I won't agrue 100Fps here nor there!
Just my thoughts
Regards.

BTW how do you like the cartridge all in all??
 
You need t0 use a quicker burning powder, try H4350. In my Browning with 168 gr TSX and 67 gr of H4350 I get just over 3100 fps. If you aren't feeling recoil, you aren't getting enough pressure. Mine is abrupt. Those powders are better for the fullsize 300 win mag. The factory loads are quite hot, pretty close to max, 180 gr failsafe's in mine made the bolt a little sticky. The big difference in the 300Win/300 WSM is how hot the factory loads are, to get similar velocity the WSM has to be right at max compared to relatively mild 300 Win.
Try a quicker powder, H4350, H414, W760 shortmags.org has lots of info.
 
I've either got a slow barrel on my hands or the Chrony is wrong
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Not necessarily.If you have a great deal of reloading experience,you will have noticed that the velocities posted in the manuals often vary from the velocities produced in your rifle.For one thing the temperature will effect most powders burning rates and therefore velocity.My experiences have shown a difference of about 3fps per degree celcius so if you were shooting at 20degrees the velocities would likely have been about 35fps higher.Secondly every barrel and chamber is different.If your chamber is larger than the chamber of the barrel used in the manual,you will be producing less pressure and therefore less velocity.If your rifle consistantly produces less velocity with alll loads tested,this is likely the case.If your rifle only produces low velocity with one powder,you may have a slower batch of powder than the one used in the manual.You can work up the powder charge while watching for pressure signs and you may very well obtain or exceed the velocities listed in the manual without developing excessive pressure.Remember the maximum load and the velocities produced only apply to the rifle used by the people producing the manual.You do not have their rifle,so you can't realistically expect to see the same results in your rifle.Data printed in manuals are meant as a reloading guide,nothing more.
 
wsm

Newer doesn't mean better, I get 2511 fps with a 220 grain bullet in a 30-06 and 2582 fps in an 8mm Yugo Mauser with 185 grain Core-Lokt's. All the hype over the wsm line of rifles was a marketing thing to sell velocity seekers more guns.The 06 will be going strong when the wsm's run outta steam and get left in the gunsafe.

.338 mag
7mm mag
30-06
270 Win.
there hasn't been much in the way of firearm advancement since these calibers were made. Just a lot of bling , marketing blab and sales pitches.
 
Personally, I just use the manual listed load data as a starting point, and load up until I get pressure signs or the desired accuracy and/or speed is reached. If it's over the manual but working fine, then so be it. Just be SURE you know what pressure signs to look for, and be sure to test on a hot day or indoors, so you won't get surprised on some sumer day using a load you developed in January...

In my .204, for example, I am a few grains over 'maximum,' but my speeds are below. You can use speed as a rough indicator of pressure, so I'm comfortable that these loads are indeed within pressure limits of my particular rifle. My 22-250 is the opposite - I'm encountering pressure signs well before I hit the maximum listed load, and my velocities are a good 200fps high.
 
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faith in measuring devices

Thanks for the input. I'll load some faster burning ball powders and see how that goes. Stubble, I know about the relationship between temp and pressure (the reason I gave that info). You need to be consistently burning some very uniform loads to be able to quantify the temperature-based effects of such small, potentially statistically insignificant, increments. A change of plus or minus 30 fps over 10 degrees may be less than the standard deviation of the loads.

Which leads me to something I find interesting in this discussion...I suggested that the Chrony might be off and nobody supported that. Does that mean we have confidence in these devices? Do we believe that there are no issues of calibration or discrepancy, or accuracy & precision differences related to changing conditions? Seems like a lot of faith placed in a fairly inexpensive device. I may contact the Chrony folks and challenge that faith. If I do, I'll let you know what they tell me. Funny how we can be so diligent and details-oriented in one aspect and, in another, be content to go on faith.

Cheers.
 
I think it's more likely the load just needs a quicker burning powder, WSM factory velocities are hard to reproduce, they are loaded pretty hot right from the factory.

If you don't trust your Chrony, shoot them over somebody else's the same day. I would bet it's not the chrony.
 
switch to a fsster powder, it's no great feat with 4350 to get the 180's right around 3000fps, and the 165's sligthly better than 3100fps.
 
Your load of 67.0 grains falls about in the center of the loading range for the your cartridge and bullet selection. I would have estimated that your velocity would have been around 2800 FPS with the 180's.

Again, your load with the 165's is about the middle of the road for that loading and I would estimate a velocity of around 3000 FPS.

If you insist on using the powders you specified, then:
for 180's:

RL-22 From 61.0 grains to 71.0 grains
Winchester WLR Primer

and for 165's:

RL-19 From 61.3 grains to 72.5 grains
Winchester WLR Primer

(although I would prefer,
W-760 From 57.5 grains to 69.1 grains
Winchester WLR Primer)
 
I suggested that the Chrony might be off and nobody supported that. Does that mean we have confidence in these devices? Do we believe that there are no issues of calibration or discrepancy, or accuracy & precision differences related to changing conditions?
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I own two chronographs to backup my velocities.Aside from some sensitivity to light conditions with the early models,the chronies have shown themselves to be very reliable.I would put much more faith in my chronographs than in velocities posted in loading manuals.
 
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