Flame Cutting with PPCBoos?

[303Guy]

Having had my shooting day cancelled, I had to play with something so .... (I have had a good day by the way) I tested a full-house load with a hard cast PPCBoo in my 'test tube'.

210gr on top of 42gr AR2209/H4350 in a PMP case. (The case may not mean much to most but it has a thick wall and holds a whole 3gr less powder). The case was neck sized.

Penetration was ±250mm (less than one foot).
Weight retention was 125gr (60%).
Pressure would be around what I would aim for with J-words i.e. 'normal'.

Here is the result alongside a rejected boolit - due to patch cut through at the base.

http://i388.photobucket.com/albums/oo327/303Guy/MVC-375F.jpg

Beautiful rifling impressions on one side.

http://i388.photobucket.com/albums/oo327/303Guy/MVC-376F.jpg

Disaster on the other side!

http://i388.photobucket.com/albums/oo327/303Guy/MVC-380F-1.jpg
http://i388.photobucket.com/albums/oo327/303Guy/MVC-377F.jpg

I can only guess that the patch cut through on the second boolit at the base. There was no sign of it as with the first boolit. The case neck doesn't seem to have expanded on firing!

[Pepe Ray]

Perhaps you can positively ID flame cutting , having the subject in hand and probably a magnifier,===
However, All I can see is damage that, IMO, occurred at the target.
Keep trying, I like it.
Pepe Ray

[303Guy]

Usually, the pic shows more than the eye can see but this time I am having difficulty showing in the pic what my eyes see - being able to hold it in the light and turn it in my fingers and using strong reading glasses.

http://i388.photobucket.com/albums/oo327/303Guy/untitled-2.jpg What looks like impact damage is actually flame cutting.

The lower circle shows rounded erosion on either side of a groove impression. There is actually no impact damage to the last bit of boolit near the base. One of the flame cut channels can be followed into the impact damage area (above the L/H circle).

The L/H circle shows a deep channel eroded into the base of the boolit and down a land impression.

[StarMetal]

Notice where the good rifling marks are, undamaged, protected by the big pieces of expanded alloy. Where you claim gas cutting notice there are no pieces of expanded alloy protection that base from target damage. Not a conclusive picture of gas cutting.

Joe

[303Guy]

Not a conclusive picture of gas cutting.No indeed. The picture is not very convincing at all. Unfortunately my ancient camera just doesn't have the resolution to magnify the image - I tried and it just gets grainy! Y'all gonna just have to trust me on this one. :drinks:

[Lead pot]

#10 bullet shows signs of alloy too hard for the bore diameter.
Gas cuts sort of look like a mouse nibbling on the bullet base. The cuts might be just a short distance or the full length of the bullet shank.

http://i22.photobucket.com/albums/b302/940Leadpot/IMG_0001-1.jpg

[montana_charlie]

Three-Oh-Three,
So...if that reject had the patch cut through at the base, it kinda indicates your bullet seating process is on the verge of 'no good'. Do you suppose the gas cutting stems from the same kind of patch damage?

Less neck tension, or more mouth flare, seems to be in order there, for maintaining patch integrity.

Annealing cases also comes to mind...
CM

[longbow]

I've not seen gas cutting with PP boolits but that looks just like the gas cutting I get with smooth cast boolits if undersize.

Normally the gas cutting occurs at the grooves and trailing edge of the lands (that is grooves and lands in the barrel) at least in my experience.

Lead pot: was there a noticible decrease in accuracy with the gas cut boolit(s)?

Longbow

[Lead pot]

I got a notice my pictures are a little to large so I'm playing with smaller files that still show details.
Here are some bullets that show a little undersized.
Bullet 1&3 are the same sized (length and diameter) but #1 was cased with 1/18 lead and tin. and patched .0005 over bore diameter and the paper used was .0023 thick. It was the proper diameter for this load but the patch was not quite far enough past the shank, bare lead got in contact with the lands. Bullet #2 is a .40 calibre patched to .002 under bore using a thicker paper with 1/30 alloy this bullet stripped as well as #3 that bullet was cast with 1/20 alloy @ .0025 under bore diameter.
Look at bullet #1 and #3.
#3 shows a bullet with not enough sidewall support and the ogive was pushed back during upset to fill the bore/groove. It's surprising that most of the displacement is in the nose of the bullet than the sides.
I don't have many bullets that were shot with smokeless powder and with a PP but I wish I still had records of the few I had and pictures of these bullets that where patched under bore diameter and over to show what they look like and I won't comment about them with out having the proper records in front of me, but you would be surprised with the results compared with some of the statements made on some of these forums.


http://i22.photobucket.com/albums/b302/940Leadpot/IMG_0841.jpg

[Lead pot]

Long bow.

I cant say those bullet were shot at close range into snow just for the purpose to see what alloy/patched diameters do.
I never recovered a reliable bullet with records of bullets that had identification marks on the bullet bases and written down information about the load used.

[303Guy]

Do you suppose the gas cutting stems from the same kind of patch damage?Yes. Well, not exactly the same, as the reject cut through on initial case mouth entry so I gave the case more flare. I suspect the hard alloy and too hard a neck wore through the edge of the patch.


Less neck tension, or more mouth flare, seems to be in order there, for maintaining patch integrity.

Annealing cases also comes to mind...Exactly what I was thinking! (On all three counts). Thanks for the confirmation, CM.

However, something stopped me from annealing that case and trying again (before the beer :mrgreen: ) and that was the fact that the neck had expanded so little that it would not accept another PPCBoo with some difficulty. In short, I might just want to size the rest of those cases to 8.0mm ID (.315"). The patched base shank is 8.1mm (.319"). After managing to 'twist' a few more PCBoo's into that neck, the patch came out shiney and measured 8.02mm (.316"). (The 'twisted in PCBoos seated up on the 'dough-nut'). A repeated firing of that same case will reveal whether the ID will remain stable. Could be useful, no? (It has a thicker case wall and neck than usual).

I managed to get a few 'more convincing' pics of the flame cutting. This time the damage is well into the 'mushroom' shield zone. (Hey .... these are quite clear! [smilie=w:)


http://i388.photobucket.com/albums/oo327/303Guy/MVC-392F.jpgThat line that runs from about 5 o'clock on the base rim and well into the 'mushroomed' area, is a flame cut on the trailing edge of the land. There is a little dark spot to the right of it which is quite a deep eroded hole - possibly where a flaw existed?

http://i388.photobucket.com/albums/oo327/303Guy/MVC-393F.jpg

The same set of flame cuts but from a different angle to change the shadow/lighting.

[303Guy]

Mmmm .... curiously, I just picked up another unpatched but sized and swaged boolit and right there on half the circumference at the rimm of the base is a distinct 'flaw line' at which it appears that the piece of lead expanded! I measures it and it is proud by some .03 to .04 mm (.001" to .0016") - hard to measure as the fault line covers nearly 180° of the circumference.

I shall attempt to take a pic of this flaw tomorrow. (Bed time for me now - I've got another 11 hr day ahead of me!:-|)

Lead pot, that boolit #10 shows interesting little finger like flame cuts! Thanks for your input.

[303Guy]

Here are pics of the shank base defect. Hopefully, you folks will be able to see what I am talking about. It's not quite so clear in the pics.

http://i388.photobucket.com/albums/oo327/303Guy/MVC-394F.jpghttp://i388.photobucket.com/albums/oo327/303Guy/MVC-395F.jpghttp://i388.photobucket.com/albums/oo327/303Guy/MVC-396F.jpg

[montana_charlie]

Seems like our weather is gonna be downright nasty for the next six days, or so.
There should be some snow drifts to throw bullets into...but those drifts will make it tough to get feed out to the cows.
Might even mean no trips to town for a week.

Been waitin' all summer for this.

Yippie (I think)...

CM