Chrony speeds


October 10, 2011, 12:43 PM
Finally got my Chrony replaced so I will go out again Wed. and check some more reloads for velocity. I already did accuracy testing. My ? is...Does a clean/dirty barrel have any impact on bullet velocities. Watching football yesterday and got to thinking about this. Or maybe it doesn't matter??:banghead:

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October 10, 2011, 02:28 PM
I'd have to say no.
Well maybe.
I'd think a shot from a just cleaned barrel with a thin layer of left over solvent lube would be faster then from a dry fouled barrel.

But it's hard to fire more then one shot from a clean barrel.
Then it's dirty.
And you have to fire more then one shot to get an average velocity

Cleaning it between shots would not represent "real world" shooting conditions either.


October 10, 2011, 03:18 PM
With weak loads and a rough bore it might. I shot some .32acp through an enfield with a filthy bore using a chamber adapter and got very low velocities (200-300fps IIRC) and one squib.

After I shot some .303 ammo through it and cleaned up the barrel some, I tried the .32acp adapter again, and the velocities went up considerably (700+fps IIRC).

I've never had a noticeable variation in velocity with standard ammo in any guns whether the barrel was clean or filthy though.

October 10, 2011, 03:41 PM
I would think it could have a small impact on velocity, but not enough to make any real difference.

October 10, 2011, 03:55 PM
I know velocities go up a little each shot, as the barrel heats up....Well, at least in my barrels.:)

Hondo 60
October 10, 2011, 07:33 PM
Depends on "how dirty" it is.

If you've got 10 years worth of leading & carbon buildup, then yes, it will affect velocity (and accuracy).

If you're talking about the 5th shot from what was a clean gun, then no.

October 11, 2011, 12:52 PM
I've found that the first two shots through my freshly cleaned rifle barrel run higher than the remaining shots in the string. Not big variations, usually around 150-200 fps more.

I solve the problem by just blasting a couple rounds "into the berm" before I get serious about recording the speeds with my chronograph. Either that or just erase the first couple of shots from the string before looking at the SD, MAD, and Average Speed.

This accounts for why my "cold bore" shots are always 1" high and the rest in a nice tight group.

October 11, 2011, 08:58 PM
yes. some shoot a "fouling" shot or two before shooting for group score. cleans out the leftover oil, etc. first shot out of a cold, clean barrel is usually out of the group. i note the position of the first shot out of a ccb. very useful when going hunting.


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