25WSM
Well-Known Member
Mram I have a solution to your problem. Pretend it's a 308win and now just like that it's fast.
Shep
Shep
Lapped with JB test
- Thread starter Mram10us
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The thing about being able to push a given bullet to a certain velocity is that: it is only beneficial if you can get to the next node up and if that node proves to be more accurate, wider & more consistent than a lower velocity node.
Lapping might be the wrong term. The goal was to polish the barrel to help remove some friction to add speed. Again, just a test. It still shoots very well, so I'll do more testing on another rifle. Thanks for the info guys.
ntsqd
Well-Known Member
I wonder what the results have been from Superfinishing barrel bores? I can't imagine that someone hasn't tried it by now, but I've not seen it talked about. I know that Superfinishing the gears in a transmission can have a dramatic effect on reducing the operating temperature. I would expect that Superfinishing a bore would decrease the copper fouling tendency. I would not expect it to have much effect on velocity, but I've been wrong before.
Sometimes too smooth isn't good. This might be the case with bores and copper fouling. Doesn't carbon act as a lubricant? If the surface was so smooth that there was no place for any carbon to embed, I would think fouling could be worse.
bigngreen
Well-Known Member
Polishing is the opposite of what you want for velocity, when the Cheytac was being prototyped my father in law was lapping the barrels with 80 grit to get the velocity. Most barrels are in the 220 is range average.
I wouldn't expect a 210 to be that much faster, the 215 guys will get more velocity with a shorter bearing surface!
Eagleye242
Well-Known Member
You are probably getting about correct speeds for what you are working with.
I do not have a 300 WSM anymore, but I have had 2 over the past 5 years or so.
They were in the mid to high 2800's with the 210 LRAB using RL26 or Norma MRP
I am running a 26" #1 Ruger, rechambered to 308 Norma Magnum, and with that
unit, using 75 grains of retumbo, I get mid to high 2900's with the same bullet.
I shot a Bull Moose with it last fall, the bull was not impressed, but I was, lol
The extra barrel length and slightly more powder capacity account for the 100 fps,
IMHO. Regards, Dave.
I do not have a 300 WSM anymore, but I have had 2 over the past 5 years or so.
They were in the mid to high 2800's with the 210 LRAB using RL26 or Norma MRP
I am running a 26" #1 Ruger, rechambered to 308 Norma Magnum, and with that
unit, using 75 grains of retumbo, I get mid to high 2900's with the same bullet.
I shot a Bull Moose with it last fall, the bull was not impressed, but I was, lol
The extra barrel length and slightly more powder capacity account for the 100 fps,
IMHO. Regards, Dave.
This always threw me off. Guys will say a polished chamber is bad cause the case has nothing to grab, but then argue the polished surface of a bore increases drag....always got me thinking. Airplanes want a Polished finish for less drag. I'm probably missing something.
I know a perfectly clean bore gives me 20+FPS slower for the first shot and equalizes after the third with this barrel. Played with that the other day
Bruce Treloar
Well-Known Member
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I like jewelers rouge ( JB ) having used it on most of my stainless benchrest barrels for years. I can't see any decrease in barrel life if used sparingly. I'd rather have a tack holer for 2,000 rounds than average accuracy for 3,000. Factory black barrels ( Chrome moly ) are usually rough and even after lapping with a cast metal lap they shoot better with JB. In years gone by we tried just about everything like tooth paste, brass cleaners like Silvo and Brasso all which seened to imbed and case a lot more copper fouling. Even after cast lapping with 210 to 230 aluminium oxide fouling is a problem for quite a few rounds. Once again good old JB helps to overcome this problem faster.
ntsqd
Well-Known Member
Below the waterline on boats there is some evidence that a less than smooth finish results in air being captured by that surface roughness, which creates a boundary layer that is easier to shear than water. Less drag on the hull = faster boat.
The comparison isn't direct though, that is why I've wondered. Thru logic I can make an initial argument in either direction. Sure would be nice to know what experience has shown to be the case in a carefully controlled experiment.
Carbon can act as a lubricant (graphite) and it can be an abrasive (diamond), really depends on its chemical form. Does not have to be a diamond to still be abrasive.
Racing slicks have more traction on dry pavement than treaded tires.
Bullets have more friction or grip on a smooth barrel than a less smooth barrel.
In a chamber the brass is expanding into the crosshatch of the surface of the chamber and prevents slippage.
Bullets have more friction or grip on a smooth barrel than a less smooth barrel.
In a chamber the brass is expanding into the crosshatch of the surface of the chamber and prevents slippage.
dwightb
Well-Known Member
The more dimples you put on a golf ball the better it flys! That's why the PGA says how many dimples there can be. Dimple a car's finish and it gets better gas milage! Hard to dimple a bullet with out a sabot. Every thing can be an abrasive with time and effort. I would be more worried about the rod and patches than the JB. Too smooth is not good except on ball bearing and races!
I was going to take a picture of my JB containers to show the difference of the two but you beat me to it
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