BH209 Bullet move

[derfhunter]

A 209m primer will shove a loose fitting bullet-wool wad and most of the powder out of the bore, smokeless load.
I have not had a tight fitting bullet-sabot (60+3 of loading pressure) exit the barrel but it will move.
I believe when you have a good seal at the primer and breach plug with a closed breach system it will shove them out (loose fitting bullets).
On a gun with open breach system or a leaky system where the pressure can come back thru the plug or nipple, this is less likely
to push it clear out

 

[bestill]

I stated in other thread ive had bullet expelled from barrel with primer with no powder ignition this only happened to me with extremely loose bullet. Does some of powder charge burn id say yes but cant verify because bore clears with bullet.. powder was dry and no lube...

Smokeless powder takes heat and bullet resistance to get full complete ignition and optimal velocity.

A spark will ignite blackpowder because it is a explosives.

Smokeless powder burns and in a cartridge the bullet is pressed into casing creating a perfect seal as soon as powder ignition begins burning powder there's resistance and heat spikes and get complete ignition.
So blackhorn powder being used in a Muzzleloader recommends magnum primer and tight fitting seated bullet to get a environment similar to a cartridge to burn smokeless powder consistently and complete.

I can tell you from many pounds of blackhorn being fired a leaky restricted breech system and loose bullet or bullet not swelling properly greatly effects velocity at muzzle and efficiency of powder burn.

 

[Squeeze]

In regards to BH ignition,
I think its not so much a loose fitting to bore bullet, but a bullet not seated properly. A looser sabot/bullet will not cause ignition problems when seated well. (not so loose as easily slide and move in the bore. The issue there is more accuracy, not so much ignition)
(outside of the obvious loading...mishap) I am beginning to think the core of this problem lies more in the breechplug, and I would like to see an examination of it in this case. Was the vent liner installed? How worn is it? are there signs of previous gas cutting and/or erosion? and, how clogged or clear were the flame channel, and vent..

Edit: also, what was used on the BP threads? teflon tape or grease. (IE, could excess grease have migrated?)

 

[bestill]

Squeeze,
I can say for certain that my poof shots have came only with very loose bullet. I use custom breech plug that was designed specifically to shoot smokeless powder and never use grease on my plug only Teflon tape. And i definitely seat bullet firmly.
Im sure grease or oil contamination could have similar results.

Smokeless powder needs heat and resistance to get complete burn.

Say for example you pour a line of blackhorn across the floor and lite one end it will burn down the line no explosion . Do the same with blackpowder lite one end of line and it is immediately gone..
But put smokeless in a sealed chamber with bullet resistance and burn rate is almost immediate.

 

[Squeeze]

I have done the burn test with a bunch of powders, black, subs, rifle and shotgun. There must be an explanation in physics, or chemistry somehow, but for now, its just one of those conundrums that defy physics.
I have a .32 thats 209 primed I shoot patched roundball with BH powder, never a hitch. Same with Maxi balls. Shoots very well even. I shoot a few lbs at least a year of BH. in various guns.
I guess with the law of averages, when millions of shots are fired annually (at least, Im guessing) some wierd stuff is bound to show somewhere

 

[bestill]

I understand that we put 17lbs of blackhorn downrange in 3 guns in 2015
Without a issue only goofy experiences came with testing extremely loose sabotless loads

 

[52Bore]

I think it's pretty easy to understand with a cartridge, like you said the bullet is in the case + they are groove diameter an not bore diameter like a ML.
One things for sure, we can only see the results from each end of the barrel, we don't know what really happens in there.. If it's leaking enough at the breech end to not allow the powder to ignite - I think you have more issues than ignition.
I took a .452 bullet and put it in a Harvester crush rib and it measure 0.506" at the base of the bullet while inside the sabot (not end of sabot) and tapered to 0.502" at the nose end of the sabot. That's 0.006" circumference interference fit for a 0.500" bore, even if the bore was oversized to 0.502" it still seem like a lot of interference. Those of you who had issue, I wonder what you have?

 

[52Bore]

That 0.006" interference fit would be 0.003" interference all the way around the the sabot while loading.

 

[rangerod]

From what I have read total interference fit ideally would be a total of .003. If your bore measured .502 best fit would be .505. That really doesn't sound like much. For a long time I couldn't figure out what the right fit should feel like. Does that sound about right,or should it actually be .003 any given point on the sabot for a total of .006?

 

[bestill]

Imo .003-.004 interference is perfect
So if land to land was .502 i would want o.d of bullet sabot combination to measure.505-.506