? wet chamber = case separarion ?

[Range Gypsy]

I'm hoping someone can enlighten me.

I was reading the new "Handloader" and Mike referred to a wet chamber caused by a too short blow tube resulted in case separation.

I am new to BPC and so far have swabbed between shots. I have a blow tube made from one of my cartridges so I should be OK. [smilie=1:

Here's the but...
I have seen other competors using "stubby " blow tubes or borrowing "something that will sorta fit" I was not aware of a danger here. Am I right in thinking a blow tube must reach the front of the chamber? What occurs that moisture in the chamber can cause a case separation?

~ Range Gypsy

[Mike Venturino]

Wet or oily chambers keep the cartridge case from "gripping" the chamber walls during firing, hence the brass flows forwards. At the least cases will stretch and at the worst they will completely separate. I've had them stretch so much without coming completely apart that you could see the beginning of the rifling imprinted in the case mouth.

Its best to use a blow tube the full length of the chamber. Many guys who wet patch between shots also dry the chamber with a shorter brush.
MLV

[longranger]

Yes I have the same experience as Mr Venturino,I dry my chamber after wiping, my brass no longer stretches nearly as much.
And thank you Mr. Venturino for enlightening me on the 40-70SS.My favorite to tinker with.
Fan # 21-22?, glad to see you feeling better.:brokenima

[martinibelgian]

Mmmmm, maybe I should try wetting my chamber in order to stretch my brass a bit??

[Multigunner]

Liquids in a chamber also restrict expansion of the case neck, increasing pull strength and pressures.

[SlamFire1]

I know this is almost two years old, but I only found this recently. I was totally surprised to hear from a BPCR shooter his experience of case stretching. With moisture in the chamber he had seen cases with rifling engraving, the case must have stretched into the throat.

I have never seen this with bottle necked smokeless cartridges. I have been lubricating 223, 308, 30-06 cases for years. Maybe it is decades now. These cases are used in gas guns and would have had case neck separations if it were not for the fact that I leave RCBS case lube on the cases, or I apply paste wax to loaded cases. (paste wax dries hard and does not attract dirt) It is true that lubrication breaks the friction between case and chamber, and for automatic rifle mechanisms, that is good. I took one set of 308 LC cases 22 reloads in my M1a. I still have some of them, I sectioned cases that had case neck splits, body splits, absolutely no case head separation. I push the shoulders back .003” and case life is outstanding and accuracy is outstanding. :happy dance:

These cases earned me my Distinguished Rifleman Badge years before the CMP cheapened the award by giving leg points to those shooting reduced course matches with "as issued" M16's and Garands. :groner:

Not only have I left RCBS water soluble lube on bottleneck cases but I have left it on straight walled 9mm, 45 LC. Never saw anything unusual.

I recently tumbled a couple of thousand of 45 ACP, 45 LC, 44 Mag and added Meguairs car wax to the walnut. I had read of others doing this and as they said, it really did increase the polish on the cases. It also left wax on the cases. I could feel it. That wax had been reduced somewhat after sizing but the cases still felt waxy. I have been firing those cases and nothing horrible is happening length wise, stretch wise, any wise.

Rimfire cases are often covered in wax or bullet lube. Been shooting small bore for years, never seen anyone with a pulled apart case.

There must be something in the pressure curve and the crimp that causes slick BPCR cases to stretch but not smokeless cases.

Maybe the pressure curve of Black powder cartridges is so low, the cases so long, that they have to have clean sidewalls and chambers or the cases will be pulled up the throat. I assume the culprit is neck tension between the case and bullet, I don’t know what else could be doing this when the sidewalls are not clinging to the chamber.

[semtav]

http://i957.photobucket.com/albums/ae53/S2D/003-1.jpg

[Gunlaker]

Slamfire1, an interesting twist with respect to case separationin black powder rifles is that you don't even need any neck tension at all to have a separation. I've heard it's not at all uncommon to experience case separation in Schuetzen loads where the bullet is loaded into the chamber ahead of the case. Interestingly, compressing the powder often solves the problem I understand. I might experience this soon myself as this is the next type of shooting I'm going to explore.

I have personally experienced case separation in a BPCR. It was the first rifle I loaded with BP. A C. Sharps .50-140 that I'd been wiping between shots. In my excitement, I neglected to dry the chamber. The case separated and the upper half was lodged tighly into the rifling.

Chris.

[bigted]

semtav,,,what exactly are we looking at in your photos...and more to the point what is the cause??

looking for some enlightenment as ive been blowing into my barrel with nothing but a plastic hose stuffed up to the mouth of the breech...not wiping the chamber and im sure it is moist as the clear plastic tubing has condensed moisture in it as well. so far nothing has happened weird but i have yet to get moa accuracy too so maybe???

[SlamFire1]

Slamfire1, an interesting twist with respect to case separationin black powder rifles is that you don't even need any neck tension at all to have a separation. I've heard it's not at all uncommon to experience case separation in Schuetzen loads where the bullet is loaded into the chamber ahead of the case. Interestingly, compressing the powder often solves the problem I understand. I might experience this soon myself as this is the next type of shooting I'm going to explore.

Wow!. I would never have thought that.

I am trying to remember if I lubed my 45-70 cases and fired them that way with smokeless. I have at least 100 loaded with a 405 and AA5744. I am going to lube them and see if anything funny happens.

May take a while, I have a SIG P220 to sight in and a bunch of XTC and Small Bore matches to get good zero's before I truck off to Camp Perry.

[Joe C]

I've had a couple case separations over the last 2 years , and each time i think it was because i failed to dry the chamber after pushing a damp patch thru it .

In both instances i was lucky enough to be able to push a tight patch down the bore and push the piece of case (both times about the first inch of the case) out of the barrel......

Both times i was shooting PP bullets that are a loose fit in the case, they are finger seated.

You have to remember that black powder "bumps up " a soft lead bullet when it is ignited, (not so with smokeless) so the bullet , even though loose when loaded , becomes a tigher fit in the case.

If the case cannot "stick" to the chamber walls because of lube , or moisture on it , it is possibe for the bullet to pull the front of the case out with it ....

Joe

[semtav]

semtav,,,what exactly are we looking at in your photos...and more to the point what is the cause??



I was shooting the 40-82 at a gong shoot in a real wet blizzard. I was also blow tubing too much. probably one blow would have been enough.
I needed to mop my chamber form the looks of it.

[45bpcr]

I had these case seperations a couple of weeks ago.

My first foray with paper patching. I use the correct size blow tube in my Sharps.

I saved the rest of the rounds and will take them apart one of these days.

I'm wondering if it was because the rounds were loaded for 8 months.

45Bpcr

[Joe C]

45bpcr

You might want to try and give the bullets a twist in the case to see if they are still loose ,and haven't adhered to the case walls somehow.

Also make sure that the inside of your case necks are clean, and there is no fouling for the bullet/paper to "grab onto".
I mentioned in a previous post that when the cartridge is fired the bullet bumps up while it is still in the case and if it has something to grab onto it can pull the front of the case with it .

This is not much of a problem when using grease groove bullets because the case walls are lubricated when you insert the bullet.

Joe

[45bpcr]

Here's many pictures.
I seat bullets with neck tension. Freshly loaded, you can't turn the bullets.
I don't use a crimp however and leave a very slight flare on the case mouth.
I just reduce it enough to chamber easily.
The load used very little compression. When doing load developement I always start with little to no compression and work my way up.
Like I said, I'll take the remaining ones apart one of these days and see what they look like.

45bpcr

[45bpcr]

PS
Do you shoot at Ridgeway Joe? I'd love to get there mid / late summer this year

[montana_charlie]

Here's many pictures.
The cases that are charged, compressed, and have the wad installed look like you use LDPE (poly) wads.
Your separated cases looked like they tore right at the base of the bullet.

You might see if vegetable fiber wads act differently ...

CM

[texasmac]

Some of you guys might be interested in reading a short article I authored some time ago titled, CASE STRETCHING & SEPARATING IN BLACK POWDER CARTRIDGE RIFLES. If so go to
http://www.texas-mac.com/Case_Stretching_and_Separating_in_BPC_Rifles.html

Wayne

[Joe C]

45bpcr

Sent you a PM .

Joe

[EDG]

Years ago, there was a photo of a BPCR muzzle at discharge on the cover of a magazine. Basically it looked like a burning dirt clod was being blown out of the muzzle. I think the hard sharp grains of black powder grab the inside of the case when the round is fired. Without friction from the rifle chamber the black powder clod just pulls the front end of the case off. This does not happen with smokeless and wet or oily chambers. I have lightly lubricated many smokeless rounds to enable a bottle neck case to fire form better. I have never seen anything like a case separation other than in Lee-Enfields.

[texasmac]

Hi Ed,

I tend to agree with you about the frictional affect of black powder, but will add that case splitting or separation is definitely possible in modern high-power smokeless ammo in a SAAMI spec'd chamber. I ran into it in a Rem. 700 in .30-06 and, after verifying the chamber specs, conducted an experiment to identify the cause. It turned out that, although the headspace was quite small (only 0.002"), after full-length resizing and firing the case 12 to 13 times, the accumulated affect resulted in the case splitting in front of the thick section ahead of the rim. In this situation, slightly lubricating the chamber would have reduced the possibility of splitting since it would have allowed most or all of the case to move back slightly, not only the rim. Of course it would also increase pressure on the bolt.

Wayne

[EDG]

Hi Wayne,
I agree that you can separate a bottle neck smokeless case in the that manner or with gross headspace with fewer shots. I do not think the powder grabbing the case mouth plays a big role as it does with BP.

EDG

[SlamFire1]

Of course it would also increase pressure on the bolt.
Yes you will increase the load on the bolt, but as long as your loads are within SAAMI specs, which is the pressure/load level the action was designed to support, nothing will happen.

If you put 500 lbs in the back of a ¼ ton truck nothing evil is going to happen, outside of increased gas consumption and a longer braking distance, because the truck was designed to carry 500 lbs. You put 1000 lbs in the back of your ¼ ton truck, you will acclerate wear on the springs, struts, ball joints. At some bed load the tires will pop and the axles bend.

Trucks and actions are designed to carry loads. For an action, if you don’t exceed the design loads you will get a normal service life out of the thing.

Actions are designed assuming zero cartridge case friction. However it may be darn near impossible to ever reach design loads with SAAMI spec cartridges as there is always case friction.

You can see this in the analysis conducted by Varmit Al:

http://www.varmintal.com/a243z.htm

Only when you reach physically impossible low levels of friction is there any issue with a 243 Winchester. The computer shows case head issues with physically impossible levels of friction. But this is only science fiction as you cannot ever get the coefficient of friction that low.

What he does show is with smokeless cases and oiled cases the case head is not stretched. Peening will occurr if there is too much headspace, but peening will occur clean chamber or wet. Low friction cases will accelerate peening. Because peening is always bad this provides another reason to control your headspace.

I generally push back my case shoulders .003", probably some are pushed back more.

Smokeless propellants are operating at 50,000 psia. I have no idea the maximum pressure you can get out of blackpowder, is 20,000 psia the max?

I assume with the black powder cases the case head obdurates and no gas release occurs, but maybe the inside pressure is not enough to support the case against the inside friction of the bullet.