Clean barrel effects

[truck driver]

I was at the range the other day testing some loads for the 35AI and checking repeat ability on my loads with CFE223.
I had cleaned the barrel and for the first time since getting it back from J.E.S. I could see the bare metal in the bore. The first shoots out of the cold barrel surprised me as it was 50fps and 2" lower than the second two shots with the same load, 68grs of CFE223 200grAB Velocity avg for three shots was 2943fps. In the picture you can see the first shot at the top of the target center. and the next two shots above it. The first shot was 2884fps out of the clean barrel the second shot was 2994fps and the third was 2947fps. I'm going to shoot this one again to see if it is more consistent in a fouled barrel. the next three shots were with 67grs of CFE223 with the 200gr AB and the barrel was allowed to cool while I walked the 200yds round trip back to the bench. The velocities were #1-2921,#2-2919 and #3-2947fps for an avg of 2929fps with a ES of 23fps.
I included the targets and since I'm new at chronographing is this normal or can it be expected from a clean and then fouled barrel? Chrono readings were taken 10ft from the muzzle of the rifle. I was set up with the rifle and ammo in the shade with the chrony in full sun temps were around 72*f

 

[longrangehunter]

Depends on the gun, the first round over the chronograph on a cleaned gun is usually( almost aways) from what I've seen faster. Reason being the barrel is dry, the powder and copper act as a lube vs. what you might think to a point, over 100+ rounds like at a Match. Unless the oil in the barrel caused the velocity to be lower, too much can cause huge spikes in velocity, worse when it gets cold.

I always toss out the first 2-3 rounds from the readings, wait for the barrel to cool, and then take my readings. A warm barrel will also show slower readings as long as you're not leaving the round in a warm chamber and then firing the gun.

 

[rodell]

I've seen it both ways. It depends on the friction in the barrel and the bullet type. Finely lapped barrels will show less variation than coarse ones.

 

[truck driver]

It's a fresh cut barrel with around 75 rounds down the tube. and still holding copper.

 

[JD338]

My 338 RUM hits the same POI clean or dirty.
You can see the oil ring from the first shot out of a clean barrel.

I never clocked the first shot so I can't speak to the speed difference.
JD338

 

[truck driver]

Jim that Rum does group well. Oh and is that your 49 cents worth? :roll: :lol: :lol: :mrgreen:
Oh I couldn't resist that one sorry Jim I'm full of it this mourning.

 

[SJB358]

I've got some that will put fresh rounds into the same group but mostly, the cut rifled tubes need some rounds through them to straighten up..

 

[truck driver]

I've got 3 more 68gr CFE223 200gr AB loaded and waiting to see if it repeats with a clean barrel.

 

[Charlie-NY]

I've shot thousands and thousands of rounds over the chronograph and clean my rifles at regular intervals. I have never seen a clean barrel produce anything other than velocities that were lower than normal. Friction is lower, pressure is lower & velocity is consistently lower. However, average velocity is usually returned by the 3rd round.

Just my observation.

 

[ElmerThud]

I found that running a meths soaked patch through the barrel to remove all traces of oil cleared up the 'fouling shot' issue.
But the rifle still shoots tighter groups with some copper in the barrel, so after the first three shots and shooting from 'cold' between each shot, the 2nd group was always maybe 1/8" closed up.

Man it's a chore waiting for the barrel to go completely cold between shots, but worthwhile to get that first killing round into the quarry in just the right place.

Never thought of testing the same way over a chrono. Great idea & one to try.
Best wishes, ET

 

[Dwh7271]

Man it's a chore waiting for the barrel to go completely cold between shots,

ET,
Best argument I've heard for more rifles. "I need this so I have something to shoot while the barrel cools on the first one" :lol: :lol: Logical progression then is, well then I need another to shoot while the first two are cooling.

 

[SJB358]

Man it's a chore waiting for the barrel to go completely cold between shots,

ET,
Best argument I've heard for more rifles. "I need this so I have something to shoot while the barrel cools on the first one" :lol: :lol: Logical progression then is, well then I need another to shoot while the first two are cooling.

Oh man.... Seems like you've became the target now ET!

Charlie, I agree with everything you said about speeds and such with clean bores.

 

[ElmerThud]

Man it's a chore waiting for the barrel to go completely cold between shots,

ET,
Best argument I've heard for more rifles. "I need this so I have something to shoot while the barrel cools on the first one" :lol: :lol: Logical progression then is, well then I need another to shoot while the first two are cooling.

Looks like I did become the target Scotty :lol: but there's good sense in that comment from Dwh7271...my firearm certificate comes up for renewal in 3 months for the next five years, so how many rifles should I put on there 'to acquire', but also having to consider how I explain the the cash spent on them to my wife :? Should I use her reply when I ask 'is that new'..'no sweetie, I've had it years' :lol: :mrgreen:

 

[Darkhorse]

My old M700 in 7mm Mag. has always shot to POI with either a cold barrel, a fouled barrel, or both cold and fouled. I have not checked velocity but any loss can't be much from looking at the grouping. No matter, after final shooting I clean the barrel then fire 3 to 5 shots before I'll take it hunting.
Can't say the same about my Browning A bolt II .300 Win. Mag. It needs at least 3 shots fired to have adequate fouling to produce good groups at original POI. Cold barrel it will shoot to POI as long as there has been at least 3 rounds down the tube.

 

[HomerOz]

G'Day Fella's,

Truck Driver, in my experience, the first bullet out of a clean barrel, almost always goes low!
I've since learn't this isn't always the case (see Dark Horse above), and a below example.

The most left hand bullet hole in this 5 shot group, is the first shot out of a spotlessly clean barrel?
As they say, go figure!

Hope that helps

Doh!
Homer

 

[truck driver]

Thanks fellows for all the input. Like some of you I have noticed different effects from clean barrels vs fouled barrels and I think it has a lot to do with the smoothness of the barrel. My 257 Roberts will shoot to the same poi fouled or clean and it has a Douglas XX air gauged barrel on it and has not been out of the wood since the gun smith installed and the barrel and bedded the factory stock to the action, The Ruger M77 30-06 I had fully bedded and barrel floated is the same way. The M700 35 Whelen I own I haven't shot enough to know what it really is capable of and was just getting into it when the 35 AI came on the scene and has captured my full attention.
I have been tempted to fire lap the barrel but with out any prior experience with this I'm hesitant to do it since it shows a lot of promise the way it is and hoping it will only get better as I shoot it and the cut rifling smooths out with out harsh measures to smooth it out.