Load data on a clean barrel

[Dirtdevil]

Here's my question. When you guys start working up loads for a rifle ,do you start on a clean barrel or do you fire fouler rounds before you start gathering data. How many rounds ?

 

[Huntnful]

I normally go out with a clean barrel and shoot 3 foulers, before shooting for load data. Once I have a load, I don't clean it that much as long as it's shooting good. But during development I start with a clean barrel almost every outing so I have a consistent baseline during testing.

 

[RegionRat]

Here's my question. When you guys start working up loads for a rifle ,do you start on a clean barrel or do you fire fouler rounds before you start gathering data. How many rounds ?

Are we talking about a virgin barrel or one that has been stabilized with some history?
Are we talking a discount store off the shelf hammer forged factory rig, or a high quality custom rig?

It would be the load developer's responsibility to know the history of that barrel and if it resets quickly after cleaning or takes several rounds to settle back into it's groove.

Not to mention, there is more than one level of cleaning. To keep it simple, let's just call the lighter side a solvent cleaning, and the heavier side a scrub.

You don't need to waste many rounds to season a higher quality barrel after a solvent cleaning, and even after a serious scrub it should only take a few rounds to "reset" a rig to where shots are going into the group.

I would figure that out before I started load development by burning up some middle of the road ammo using the bullet and recipe you plan to test with the more serious load development effort.

Let's assume we don't know anything about the barrel and it is virgin.
Let's assume a typical carry weight hunting rifle or varmint rifle with a high quality custom barrel, not a low quality mass produced barrel.

I would start with a cleaning and borescope the barrel and making sure the chamber is clean and dry.
Assume we will have to boresight optics.
I would pick the bullet and recipe I hope to use, and load around 50 rounds of the middle of the road pressure at roughly 0.020" jump.

It usually takes only a handful of rounds to zero the scope, so this is the first light cleaning stop, but we have already watched the velocity from the very first shot. Now we study how quickly the barrel cleans up and we scope it.

The next critical observation is how long it takes for the shots right after this cleaning to go back to their group.

By observing several cycles of shots and cooling, you will get a chance to observe the velocity and group behavior.

Let's assume that it took 10 shots to boresight, then you cleaned, and took at least 4 more groups for a rough total round count of 20 - 30 shots.

I would then do another light cleaning and observe the bore, then follow up with another set of at least two more groups to see how long before the shots stabilize in group and velocity.

At this point, you are at about 50 rounds.
You have cleaned the barrel at least 3 times, and observed how many rounds it took to settle.
You also can tell if the barrel is stable, still speeding up, or if it hates that first bullet or powder.
You can also see how the rig acts after it is fouled, cooled off, and how the cold bore shot behaves.

All of this answers if you are ready for any serious fine tune load development and if you will need just one shot or more shots to get steady data. In for your range report.
YMMV

 

[Varmint Hunter]

Starting with a squeaky-clean barrel, the first few rounds rarely end up in the group of subsequent rounds. They rarely group together either, as the barrel gets a bit fouled. It is also good to realize that the first round out of a clean barrel usually has the lowest velocity, and that the velocity will stabilize after a few rounds.

These are generalities but are commonly seen. I'd suggest shooting 3 rounds out of a clean barrel before shooting to determine the potential of any particular load.