I have a '44 Long Branch, 2-groove, which is in excellent condition. It wears a PH5 and FS22A. It has proven to be very consistant, and with practice, I have been improving my group sizes.

Over the past couple of hundred rounds or so, it has developed a problem in that the POI drops as the barrel warms. Today I conducted a test at 100 yds, bench firing 4 strings of 5 rounds with negligible time between each, allowing the barrel to warm progressively.

The results of the 4 strings are:
- string 1 - 1", dead centre (well chuffed!)
- string 2 - 1.75", 2" low (and slightly to the left, but that was probably me)
- string 3 - 2.25", 4" low
- string 4 - 2", 6" low

Whilst details will have been affected by my use of iron sights, and my less than stellar technique, I think the trend is clear. I am very pleased with the group sizes, but that drifting downwards... It used to be very consistant vertically.

The Screw, Guard, Trigger, Front has not worked loose, and is still snug.
The Screw, Guard, Trigger, Rear is likewise.
The Butt has not loosened.
The Barrel will pass a .303 gauge, but a .304 gauge won't even start, so the barrel is not shagged out.
The muzzle has about the requisite 4 lbs of pressure, or at least it does not seem any different from when the rifle was consistant.
The Parker Hales are rock-solid.
I tried to make everything as consistant as possible from string to string.

To sum up, I can't find anything that has changed, or is loose.

I am at a loss as to what to investigate or twiddle next.

I'd really appreciate any suggestions/help/ideas/informed opinion.

Cheers.
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