BP bullets need more lube ?

[fourdollarbill]

Why do BP bullets need more lube than reg CB's ?
I don't have one I just want to know.:coffee:

[Springfield]

Because the powder burns dirtier and the barrel will carbon up and destroy accuracy unless the lube is sufficient to keep the fouling soft.

[AZ-Stew]

The TYPE of lube is important with Black. Petroleum-based lubes will gum up when shooting Black. I understand SPG is the "standard" for BPCR shooters, but since I don't shoot them, I can't give first hand knowledge.

Regards,

Stew

[JeffinNZ]

I don't buy into the whole idea of lube keeping BP fouling soft and here is why.

Approx. 50% of the BP charge is supposed to be left in the bore as residue/fouling. If you are shooting a .45-70 then you are likely to have 30-35gr of fouling from each shot. How much lube would it take to keep this moist? WAY more than your bullet can carry.

Now also consider the surface area of the bore of our .45-70 barrel. .45 time Pi times the length of the barrel. For a 30 inch barrel that's about 40 square inches of surface area. That's a lot of steel to cover wth lube to keep fouling soft.

My belief is that lubes for BPCR must be such that they create a microscopic layer on the barrel steel that works towards inhibiting tenacious fouling build up. In simple terms, the lube stops the BP fouling sticking to the edges of the rifling. IMHO.

[Dan Cash]

I don't buy into the whole idea of lube keeping BP fouling soft and here is why.

Approx. 50% of the BP charge is supposed to be left in the bore as residue/fouling. If you are shooting a .45-70 then you are likely to have 30-35gr of fouling from each shot. How much lube would it take to keep this moist? WAY more than your bullet can carry.

Now also consider the surface area of the bore of our .45-70 barrel. .45 time Pi times the length of the barrel. For a 30 inch barrel that's about 40 square inches of surface area. That's a lot of steel to cover wth lube to keep fouling soft.

My belief is that lubes for BPCR must be such that they create a microscopic layer on the barrel steel that works towards inhibiting tenacious fouling build up. In simple terms, the lube stops the BP fouling sticking to the edges of the rifling. IMHO.

Jeff,
I shoot lots of black powder in .45-70 and .45 Colt. In my novice period, I used some inferior bullet lube and actually fired some commercial cast pistol bullets with a commercial blue wax lube over black powder charges. I hope to tell you the fouling, after three or four shots, was as hard and dry as a Home-Ecconomics class pork chop. There may be something to your theory about lube keeping the fouling from sticking to the rifling/bore but I assure you, proper lube does keep the fouling soft.

Regards,
Dan

[44man]

Yes it does keep it soft if it is a good lube. Even with a 36" 45-70 barrel there will be a grease ring form on the muzzle and a dry patch can be pushed through.
A poor lube needs a soaking wet patch even with the same boolit and lube amount.
I would not use SPG as the standard, it dries out and the last 10" of barrel will be hard and dry. Shooters have to drink a lot of water and use a blow tube to blow moisture down the bore between shots.
Most of us use a slightly damp patch on the end of a bristle brush between shots but with a good lube, many shots can be taken without wiping.
I took my balance of SPG to a shoot with over 200 guys there. I put it on a table at half price. Later I changed the sign to FREE, yet had to bring it home to mix with a bunch of other stuff.

[Wayne Smith]

I don't buy into the whole idea of lube keeping BP fouling soft and here is why.

Approx. 50% of the BP charge is supposed to be left in the bore as residue/fouling. If you are shooting a .45-70 then you are likely to have 30-35gr of fouling from each shot. How much lube would it take to keep this moist? WAY more than your bullet can carry.

Now also consider the surface area of the bore of our .45-70 barrel. .45 time Pi times the length of the barrel. For a 30 inch barrel that's about 40 square inches of surface area. That's a lot of steel to cover wth lube to keep fouling soft.

My belief is that lubes for BPCR must be such that they create a microscopic layer on the barrel steel that works towards inhibiting tenacious fouling build up. In simple terms, the lube stops the BP fouling sticking to the edges of the rifling. IMHO.

Jeff, you are partially right. Actually, BP is about 47% effective, 53% left behind, but this includes all the smoke and particles pushed out of the barrel at each shot. I stated "about 47%" because it is different with each powder. Over half of what is left behind gets pushed out of the barrel, thus all the smoke and small holes in the snow. Actually the fouling sticks and the next boolit pushes the rest out. When you clean after firing a chain of shots you basically are cleaning the fouling from the last shot.

[WARD O]

Once you've developed a good load you will probably find that the residue in the barrel more resembles a sooty coating. The rifling will still be visible and distinct and not covered over and invisible. A good load usually means a compressed powder charge matched with your bullet, lube and primer. From a hunting standpoint I usually shoot 5 or more shots when testing loads without cleaning or blowing between shots. Then I clean between test load groups and start again.

I use baby wipes as they come premoistened for patches - I cut them to about 2.5" squares and they work quite well. 2 or 3 of these patches followed by a dry cotton patch and I'm ready to test the next load.

Ward

[montana_charlie]

Approx. 50% of the BP charge is supposed to be left in the bore as residue/fouling.
Perhaps 50% of the charge becomes 'residue', but where is it actually located after the shot?
Some is bound to spew out of the muzzle...right behind the bullet.

Would the remaining 'fouling' be 40% of the charge...or maybe only 10%?

There would also be some amount of the lube that must be included in the total load of fouling.

Shoot a 45/70 loaded with a standard charge, with a known weight of lube on the bullet. Then, clean the barrel with damp cotton patches...but weigh each patch before you run it through the barrel, and again when it comes out.

When the bore is essentially clean, check your weights to see how much total fouling they picked up, and try to estimate how much of that is the lube.

It ain't a perfectly designed experiment, but it might be useful...

CM

[JeffinNZ]

I understand that the bullet pushes out the fouling from the last shot (more or less) but I still maintain the lube probably doesn't keep the fouling soft as much as it prevents a situation occuring where the fouling can really take hold in the barrel steel and especially the leading edges of the rifling.

[John Boy]

Would the remaining 'fouling' be 40% of the charge...or maybe only 10%?

Charlie is correct about the variable percentages.
The foul is potassium carbonate and sulfide in the bore and is really dependent on 4 factors:
* The relative humidity (RH) on the day of shooting - Below 37-40% RH, gunpowder is less hygroscopic v when RH is above 40%. Cold days - more foul, hot days - less foul ... even a light hard gray foul. These are blow tubing days to put more water into the bore IMHO to wet the foul existing in the bore
* The bullets design, ogive and GG's can push more foul out of the bore v other designed bullets
* Use of a hard wad such as LDPE are helpers to scrape foul from a bore
* Leaving 1 GG unlubed, a 'bore scraper' can remove more than normal the amount of foul from the bore

As for the lube, yes petroleum products are a No No. Leaves a hard crust in the grooves. It can be debated but IMHO a lube comprised of mutton tallow or soy wax produce the best softest 'wet' fouls