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Old 08-27-2021, 11:37 PM
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Nemo288 Nemo288 is offline
Join Date: Jan 2011
Location: Badgerland
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From an old IMR data pamphlet (5/03):

REM. CASE; REM. 2 1/2 PR
.430" DIA.; 6.5" REVOLVER BBL.; 1.470" C.O.L.

powder      max  fps     CUP
700-X         4.9  740  13900
PB              5.7  750  14000
SR 7625     6.2  770  13800
800-X         6.9  695  13900
SR 4756     7.5  760  13600
IMR 4227  14.3  790  13700

One of my super-low loads was 4.5gr PB under a 240 SWC.
BUT it also had 13.5gr Grex filler which boosts pressure although the velocity was still only in the mid 600's.
I would say that ladder 5, 5.5, maybe 6gr would also work for PB with those light weight bullets of yours.
PB burns pretty fast and quite clean.
I believe PB stands for "porous base" and was designed to be a clean shotgun powder.
That makes it perfect for low pressure revolver loads.
Finally was discontinued a few years ago.
Wasn't selling well and the manufacturing technique was obsolete.

From another forum (2011):
"PB is the sole survivor of what was intended to be an entire line of propellants. The concept was to have a generic powder kernel that was porous, and to add the various inhibitors and additives to tailor burn rate, flash and other characteristics to the "sponge-like" kernels as needed.
It can be thought of as a second-generation powder: It's newer than such greybeards as Bullseye and Unique, but not nearly as sophisticated as almost any other powder we have today."

Powder Burning Rate Chart
lists PB as being right next to Universal in burn rate.
(and Universal as faster than Unique).
The 2 attached rate charts have PB faster and next to N320.
The charts below also show Universal as slightly slower than Unique.
My experience with 44's and QuickLOAD tend to show Universal as slightly faster than Unique.
We all know how accurate these charts are.
Attached Files
File Type: pdf Burn Rates - 2014-2015.pdf (78.0 KB, 4 views)
File Type: pdf 2012LoadDataBurnRateChart.pdf (42.8 KB, 2 views)
"Everything 44"

Last edited by Nemo288; 08-28-2021 at 06:15 AM.
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