compression

[hepburn]

I wonder how many of those having bulging caused by the wads are resizing their brass each time they load. Sizing brass can reduce diameter of neck considerably depending on die and size of chamber. It could be more likely to expand case regardless of wad material. I use poly and can use 3/8" with no bulge but I use only fired cases & finger seat bullets. I have never experienced what some are calling trapped air under wad.

[hepburnman]

I dont resize after firing but I do have a special neck design (40-65) where the case-neck side walls are parallel for up 1/2" to give extra support/alignment to the bullet. Therefore if the polywad starts into the case with interference it will stay a tight fit. It does not seat in more than the 1/2". I thumb press in my bullets too. If you have a standard case-neck that tapers then at some point your polywad should not be an interference fit and the air can then escape.

[Lumpy Grits]

Sorry - I meant to say that I compress my powder >0.300" and not 0.035".

It's not trapped air-The wad is squeezing outward and bulging the case wall. BTDT-went back to fiber.....
Gary

[beltfed]

It would be interesting to try that 0.380" compression
using no wad, just a piece of newsprint and see if maybe
its the powder that is compressing and expanding outward near
the top of the column to bulge the case.
beltfed/arnie

[Lumpy Grits]

Arnie-I run .380 or so compression and it was the .060 'poly' type wad that caused the case wall bulge. No issue with .060 fiber
I do wonder if the annealed case neck could also be a factor here.
For folks that use around .250 or so compression-The poly would be a good choice.
BTW: When I compress, I hold the case in the die for a 5 count, to be sure the air has bled out.
Gary

[beltfed]

Indeed, the soft annealed case neck will be more susceptible to bulging.

[MSalyards]

I never compress with a wad and I never have powder stick to my compression die. Not saying what's right or wrong, just sayin!

[Lumpy Grits]

Indeed, the soft annealed case neck will be more susceptible to bulging.

No issue with .060 fiber in the same batch of cases.
G.

[Kurt]

Hepburn I get the bulge using .060" poly wads and I don't compress the powder with them. I use a OJ carton wad over the powder and compress with it. I use the poly wad on the lube wad. A poly wad is sort of like lead you cant compress it with out heat. In my case my chamber wall is very tight and those cases are at the fired diameter, no sizing that makes the wad a tight fit in the case and it pushes out where it rests. These cases are new just fired once and I annealed them so they are still soft. With that bulge I cannot chamber the case even with out the bullet so I run them through a sizing die to knock that bulge down and even doing this it will push out again but not as far as it was first seated so it still makes it a tight thumb fit but I use this round in a 44-1/2 Stevens action that will cam the case in with out a problem and the bullet does not get pushed back like it would if it was oversized.
Normally I use a .030" poly wad in a tight chamber or a 1/16" fiber wad that will compress enough so it does not bulge the case neck. A '030" poly will crown keeping the pressure off the case wall. If I want .060" wads I double the .030"
The poly wad seals the bore better then a fiber of the same diameter.

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[Lumpy Grits]

Kurt-Have you had any case stretching issues with poly?
I did in both my .45-70 and .45-90.
G.

[Kurt]

Gary I just started using .060" poly wads so I cant say. I use wads cut from Ice cream buckets and they are a little thicker then .030", around .037" but I just got a bunch of 1/16" LDPE and it's their first use in a tight case neck case.

[Lumpy Grits]

OK-TNX
Do keep an eye on case OAL after firing.
Good luck,
G.