Unburned powder kernels - how significant?

[303Guy]

I test fired a load of W748 and found unburned kernels in the bore. The load was 20gr under a 167gr boolit with Dacron filler. The penetration and the 'recoil' if one can call it that would indicate reasonable velocity. Recoil was a push and the muzzle blast was greater than the same load in H4227.

I could increase the charge until I get complete combustion but I'm wanting a gentle launch, rightly or wrongly.

[fishhawk]

My thinking would be more consistent velocity if you burned all the powder instead of some of it and who knows how much from shot to shot.

[Whiterabbit]

my most accurate factory 20ga slug ammo for my handi USH 20 ga ultralight leaves unburned kernels all OVER the bore.

Still shoots more accurate than every other sabot slug I tried. So it stays.

For shooting real metallic cartridges? dunno. all mine after load dev burn fully. Some lead, some don't seal the case against the chamber all the way, but none leave kernels in the barrel.

I tell you what though, if I ever find an accuracy load one day and then I discover that unburned kernels are left in the barrel? I'll still shoot it.

[pworley1]

Unless there is a significant amount left in the bore I would not be concerned as long as you are getting good velocity and accuracy.

[bangerjim]

Three things that get me to the "powder in the barrel" syndrome:

1. very VERY light load
2. too light a crimp
3. too slow a powder for what I am doing

I do not worry about it as long as it goes boom and the boolit goes where I want it.

[Bent Ramrod]

I believe Ken Waters remarked on the unturned powder in the bore when he developed low pressure loads for the straight walled rifle cases with slow powders like 4831. He said the accuracy of such loads was good nonetheless.

i've had it happen with slow powders like 4831 with cast boolits and with powders like 5744 and 4759 with light loadings. Sometimes I blow the burnt powder out of the bore before firing the next shot because an occasional grain sometimes winds up in the chamber, but from all indications, the part of the powder that burns does so very consistently.

[303Guy]

Thank you guys. Very encouraging. I can imagine a healthy boom from this load with a fairly high muzzle pressure. It should be fun! The load is a bit unconventional. The boolit is seated in an unsized neck by creating a paper towel 'cup' that takes up the clearance then dipping the loaded boolit and neck into molten lube which 'glues' the boolit into the 'cup'. It does leave the bore pretty well lubed which may upset things for the next shot. I guess range tests will tell. That could take a while as everything goes in slow motion for me these days.