Got a good deal on a bunch of speer 125gr TNT rounds and so I've been working on some loads. Went to the range yesterday and had something very weird happen once I got into the hotter loads.
H110 powder, WSR primers, and once fired frontier brass for all rounds w/o crimp. Shot out of an 8.5" noveske match barrel 1:7 twist. Velocity recorded with my LabRadar chronograph
10x 17.5gr 2.060" coal -- 1864 avg fps sd 26 1.5" spread
10x 18gr 2.075" coal -- 1924 avg fps sd 29 1.2" spread
10x 18.2gr 2.075" coal -- 1931avg fps sd 18 0.8" spread
10x 18.5gr 2.075" coal -- 1944avg fps sd 22 0.75" spread
10x 18.8gr 2.075" coal -- 1978avg fps sd 14 1.2" spread
10x 18.8gr 2.100" coal -- 2054avg fps sd 25 0.6" spread
10x 19gr 2.100" coal -- 2098avg fps sd 19 0.4" spread
Zero pressure signs in any cases, obviously published load data hasn't properly tested this projectile.
Anyways, i have two questions. First, does anybody have any explanation as to why I had such a large increase in velocity with the slightly longer 18.8gr rounds?
Second, doesn't 2100fps seem pretty damn high out of an 8.5" barrel? Avg was 2098 but I had two rounds at 2112fps. Maybe someone with quick load can crunch some numbers for me but that just seems like a helluva lot of pressure. I'd like to see if I could work up to 20gr of powder but these might be close to or over max pressure. Again, no pressure signs on the case but the chrony tells a different story.
Someone please help me understand these numbers!
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Re: Someone please help me understand these numbers!
What happened that was wired?McAda441 wrote: ↑Sun Jan 19, 2020 9:57 am Got a good deal on a bunch of speer 125gr TNT rounds and so I've been working on some loads. Went to the range yesterday and had something very weird happen once I got into the hotter loads.
H110 powder, WSR primers, and once fired frontier brass for all rounds w/o crimp. Shot out of an 8.5" noveske match barrel 1:7 twist. Velocity recorded with my LabRadar chronograph
10x 17.5gr 2.060" coal -- 1864 avg fps sd 26 1.5" spread
10x 18gr 2.075" coal -- 1924 avg fps sd 29 1.2" spread
10x 18.2gr 2.075" coal -- 1931avg fps sd 18 0.8" spread
10x 18.5gr 2.075" coal -- 1944avg fps sd 22 0.75" spread
10x 18.8gr 2.075" coal -- 1978avg fps sd 14 1.2" spread
10x 18.8gr 2.100" coal -- 2054avg fps sd 25 0.6" spread
10x 19gr 2.100" coal -- 2098avg fps sd 19 0.4" spread
Zero pressure signs in any cases, obviously published load data hasn't properly tested this projectile.
Anyways, i have two questions. First, does anybody have any explanation as to why I had such a large increase in velocity with the slightly longer 18.8gr rounds?
Second, doesn't 2100fps seem pretty damn high out of an 8.5" barrel? Avg was 2098 but I had two rounds at 2112fps. Maybe someone with quick load can crunch some numbers for me but that just seems like a helluva lot of pressure. I'd like to see if I could work up to 20gr of powder but these might be close to or over max pressure. Again, no pressure signs on the case but the chrony tells a different story.
What story did the chronograph tell that was different?
300 Blackout, not just for sub-sonics.
Re: Someone please help me understand these numbers!
I found that charges from about 18.6 to 19.5 begin to demonstrate the 'case fill/seating depth/velocity/pressure' effect that Dellet frequently mentions. I am also certain that he knows more about this particular powder and bullet combos than many credible sources. I'm sure he can help with your question.
Re: Someone please help me understand these numbers!
I see how that could be confusing. It was a very long winded post. Basically I'm curious as to why there was such a velocity difference in the 18.8gr rounds with length being the only variable. Next can I keep pushing this round past 19gr or should I stop there? 2100fps seems pretty damn fast to me out of an 8.5"!
- bangbangping
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Re: Someone please help me understand these numbers!
I’ve never used that bullet, does it jam that short?
300 Blackout, not just for sub-sonics.
Re: Someone please help me understand these numbers!
No not at all. It cycled beautifully and was very accurate.
- bangbangping
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Re: Someone please help me understand these numbers!
No idea. But I sounded confident, didn't I. Plus it's a Noveske.dellet wrote: ↑Sun Jan 19, 2020 2:31 pmI’ve never used that bullet, does it jam that short?
Re: Someone please help me understand these numbers!
Jackass, you had me measuring bullets.bangbangping wrote: ↑Sun Jan 19, 2020 2:57 pmNo idea. But I sounded confident, didn't I. Plus it's a Noveske.
It’s short for weight, a bit shorter than a 110 VMax or Varmageddon.
Pretty sure the chamber issues with Noveske stopped when they went from 8.2” to 8.5”, but it’s a good reminder to always check.
Oddly Speer does not have data for that bullet, thought maybe I just learned why.
300 Blackout, not just for sub-sonics.
Re: Someone please help me understand these numbers!
Back to the actual question.
Drop 19 grains in a fired case, rest a bullet on the powder and measure.
What’s the length?
Drop 19 grains in a fired case, rest a bullet on the powder and measure.
What’s the length?
300 Blackout, not just for sub-sonics.
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