Slower velocity than expected, 300 H&H mag

[jebel]

This is not technically a reloading question, as it involves factory ammo, but this feels like the right spot. Apologies if you disagree.

A friend has a old 300 H&H mag that saw a lot of use by his father (maybe his grandfather, too). He doesn't shoot it much, but the other day we had it at the range, so he put some rounds through it. He shot Nosler TrophyGrade ammo with 180 grain Accubonds. I had my chronograph with me (LabRadar), so I clocked the velocities.

The average velocities he got were 330 fps slower than advertised by the manufacturer. I would expect something slower than stated, given the difference between the length of test barrel and the actual barrel (I don't know the exact difference), with a bit of marketing enthusiasm thrown in, but 330 fps seems like a lot. 2950 fps vs. 2620 fps.

My question is whether you think the size of the difference might indicate an issue with the rifle. Would one expect significant losses in velocity like this from a barrel that has been shot out? Or does this difference not surprise you - 330 fps slower than expected, or about 11% less than advertised?

Curious.

Other details - I used the LabRadar on a known cartridge and rifle immediately after testing the 300 H&H and it produced expected velocities. 100% of the 300 H&H rounds were picked up by the LabRadar (6 shots). The SD of those 6 shots was 32 fps (ES of 82). It was about 45 degrees Fahrenheit out.

 

[257Tony]

Just as likely that its just a slow batch of ammo. Gonna have to try a different load, that will tell you if its rifle or ammo.

 

[jjmp]

Your gonna get slower speeds in colder weather that for sure,if that 300 has been shot that much the throat is worn n so is the rifleing , lots of shooting takes its toll ,neglect n rust , cause pitting ruins barrels , lots of senerios,have someone borscope the barrel n throat , might just need a rebarrel . Back in the day cleaning practices were lacking unless you really loved n cared for your rifle ,Lol to many shooters even today talk about not even cleaning their rifles, for way to many rounds fired , I'm not buying that at all ! Bore guides , one piece cleaning rods ,copper solvents,bore mops, all cheaper then replacing Barrels , gd luck & then again the barrel mite be Prestin,or just need a good cleaning I'm hoping that's the Case ,& long live that Family Heirloom !!!

 

[HARPERC]

I suspect it's a little this, and a little of that adding up.
330 FPS is a lot though if it's shooting good, and an heirloom it's not unusable.
In a 26" barrel with 200 grain handloads 2900 FPS isn't an unreasonable expectation.

 

[LoneTraveler]

What Make Rifle is this 300 H&H?
As old as you describe the rifle may be part of the low velocity.
I would suggest that you check the Firing Pin Spring.
I inherited a 1952-3 Rem. 722 222 Rem. It shot bad, slow velocity and even popped the firing pen dimple and allowed gas into the action.
Changed the Firing Pin Spring and it brought the rifle back like it shot in 1962 when I left for the Army.

 

[Jerry M]

make sure that the fired brass look like .300 H&H and has not been reamed to an improved version.

Also, make sure that the cartridges are really 180 gr and not something heavier. While on an elk trip to Montana, guys at the range checking zeros, had cleaned off their workbench and had .338 and .330 WM in the same box!!! An old hunter I knew would consolidate all his cartridges into one box: 150 gr, 180 gr, 200 gr round nose. Drove me crazy! In the .300 H&H a 180 gr bullet at 2,600+- is way to slow IMHO.

Good luck

Jerry

 

[HARPERC]

...make sure that the fired brass look like .300 H&H and has not been reamed to an improved version. .....

Good point. I started to go there, and let it go. Many .300 Weatherbys got their start this way.