adam_mac84
04-13-2018, 07:12 PM
oooh, the 9mm cast loading... the finicky beast that it is.
Got my 9mm loads dialed last year for the G34. Perfection.... sold that gun :shock:
Struggling with the new M&P 2.0
Leading is following the grooves, which according to Chapter 7 of the 'bible'
Streaks, following the rifling. If the leading is seen to "follow the rifling" (i.e. streaks that twist down the barrel in close association with the rifling grooves), then this is a tell-tale sign that the bullet is cast too hard and failing to obturate. Obturation is usually thought of as a plastic deformation that swells the bullet's diameter, but it also leads to a back-filling of engraving defects along the trailing edge of the land. If the bullet is cast too hard to obturate, these defects will not be back-filled and gas-cutting will take place through these voids, following the trailing edge of that particular land. This effect can be mitigated somewhat through judicious choice of lube, but lube by itself can only do so much. The real solution here is to go with a softer bullet and a better lube.
I think at times, it has been a bit more toward the chamber than the muzzle, but can't say that is consistent... We will say 60/40 chamber to muzzle leading.
It cleans up with a bit of scrubbing after a 200 rd range trip without too much problem. I would not consider it HEAVY leading.
My considerations thus far:
38 expander
Slug 0.3555
Boolit .357 (largest that will chamber in the throat). 124gr TC, and 130gr 2rRN (lee, cast heavy)
Maintains diameter after pulling boolit
Smokes DTPC - 400 x 10 min after liquefaction of coat. Dropped in water for quicker handling. Pass smash test
Powders. TiteGroup. W231. WSF
Velocities tested :
WSF. 1041 (fair accuracy), 1110 (poor accuracy)
TG. 1087 (3.8gr best accuracy), 1113
231. 1083 (3.9 gr best accuracy), 981 (poor accuracy)
WSF tested with 5050 at 1110fps and RS (WCRS) at 1041
TG was all WCRS
231 tested 1083 with AC 50/50 1083, and same load with WCRS (also accurate). ACRS accuracy was garbage (50 rds, leaded)
Basically, all had similar leading interestingly. Poorest accuracy were with ACRS, no significant change in leading.
Previous tests with WCWW had leading as well, no velocity recordings. were at same loads as above, but stopped pursuing as WCRS had previously worked for me
Alloys:
Range scrap - (tested 2B pencil test (suggests just over 10BHN)
Range scrap - water dropped (tested H pencil, skeptical... that'd be ~22)
50/50 RS/WW - did not pencil test, assume hard
ACWW - Tested B. Just harder than RS. Seems legit, question the actual hardness numbers I received
WCWW - Have not tested with pencil,
My gut was to go harder, and investigate more with WCWW, but I think that is the wrong way to go. If I have to get it throated, I guess I can... or keep scrubbing with chore boy
Did I miss a step in here? I felt like I did my homework pretty well.
My good loads will shoot a 100 on a B8 at 15 yards off hand, which is about as good as I shoot on a good day, and good enough for gaming (for my skill).
Got my 9mm loads dialed last year for the G34. Perfection.... sold that gun :shock:
Struggling with the new M&P 2.0
Leading is following the grooves, which according to Chapter 7 of the 'bible'
Streaks, following the rifling. If the leading is seen to "follow the rifling" (i.e. streaks that twist down the barrel in close association with the rifling grooves), then this is a tell-tale sign that the bullet is cast too hard and failing to obturate. Obturation is usually thought of as a plastic deformation that swells the bullet's diameter, but it also leads to a back-filling of engraving defects along the trailing edge of the land. If the bullet is cast too hard to obturate, these defects will not be back-filled and gas-cutting will take place through these voids, following the trailing edge of that particular land. This effect can be mitigated somewhat through judicious choice of lube, but lube by itself can only do so much. The real solution here is to go with a softer bullet and a better lube.
I think at times, it has been a bit more toward the chamber than the muzzle, but can't say that is consistent... We will say 60/40 chamber to muzzle leading.
It cleans up with a bit of scrubbing after a 200 rd range trip without too much problem. I would not consider it HEAVY leading.
My considerations thus far:
38 expander
Slug 0.3555
Boolit .357 (largest that will chamber in the throat). 124gr TC, and 130gr 2rRN (lee, cast heavy)
Maintains diameter after pulling boolit
Smokes DTPC - 400 x 10 min after liquefaction of coat. Dropped in water for quicker handling. Pass smash test
Powders. TiteGroup. W231. WSF
Velocities tested :
WSF. 1041 (fair accuracy), 1110 (poor accuracy)
TG. 1087 (3.8gr best accuracy), 1113
231. 1083 (3.9 gr best accuracy), 981 (poor accuracy)
WSF tested with 5050 at 1110fps and RS (WCRS) at 1041
TG was all WCRS
231 tested 1083 with AC 50/50 1083, and same load with WCRS (also accurate). ACRS accuracy was garbage (50 rds, leaded)
Basically, all had similar leading interestingly. Poorest accuracy were with ACRS, no significant change in leading.
Previous tests with WCWW had leading as well, no velocity recordings. were at same loads as above, but stopped pursuing as WCRS had previously worked for me
Alloys:
Range scrap - (tested 2B pencil test (suggests just over 10BHN)
Range scrap - water dropped (tested H pencil, skeptical... that'd be ~22)
50/50 RS/WW - did not pencil test, assume hard
ACWW - Tested B. Just harder than RS. Seems legit, question the actual hardness numbers I received
WCWW - Have not tested with pencil,
My gut was to go harder, and investigate more with WCWW, but I think that is the wrong way to go. If I have to get it throated, I guess I can... or keep scrubbing with chore boy
Did I miss a step in here? I felt like I did my homework pretty well.
My good loads will shoot a 100 on a B8 at 15 yards off hand, which is about as good as I shoot on a good day, and good enough for gaming (for my skill).