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Re: The new AR.....
Posted: 05 Jul 2015 15:44
by Ranch Dog
RBHarter wrote:Well the cast is going to work out .
It's a little slower than I had hoped but there is still plenty of room to work on up.
The 27-130 FP for today weighed 136.5 at 5 rounds each load.
H4198
CCI 41
FEDERAL brass
20.0 1889-1923 with core speeds bringing it to 1915 average .
20.5 1934- 1978 and an average 1950.
Groups were good at 35 yd high and left. This AR is very cant sensitive (probably something to do with sights being 2" above the bore)
. The groups seem to be closing . Speer lists 22.3 as a maximum load with their 130 SP so without to much worry I will proceed on up. I need to hit 2150 for legal reasons according to the Strelok calculator. It will give me the 100yd 1000 ftlb level needed here . I'm inspired.
Sounds good. You want me to run it through QuickLoad? If so, I would need the bullet diameter (.277?), length and weight (137). Also, the cartridge OAL.
Re: The new AR.....
Posted: 06 Jul 2015 10:45
by RBHarter
That would be great . I'll get numbers tonight .
Re: The new AR.....
Posted: 08 Jul 2015 07:52
by RBHarter
So I'm a little slow
I have
COAL 2.115
bullet length .945
shoulder is .399
head is .415
This is federal srp brass in a SPCII chamber a very subtle but none the less Ackley like "fix".
CCI 41 primer 137 gr 27 130 fp
I started with 20.0 H4198 the case looks like it will take 24 compressed. Speer shows 22.3 for their SP 130 that has more case intrusion and the SAAMI chamber. I have everything decapped or primed or I would have gotten a water weight.
Re: The new AR.....
Posted: 09 Jul 2015 06:31
by Ranch Dog
He is something to start with. I should have verified the specific 6.8 cartridge as it was not mentioned in the barrel post so I used 6.8mm Rem SPC. Same with barrel length, went with 20". Also, we didn't talk about your alloy or pressure you wanted to use that alloy at so I ran the calculations at 42.0 KPSI as a maximum which most water quenched WW or Lyman #2 alloys will survive if gas checked. As far as powder compression goes; I limited it to 105% of the usable case capacity, a slight compression.
The PDF is attached.
277-130_420KPSI.pdf
Re: The new AR.....
Posted: 09 Jul 2015 06:54
by RBHarter
Thanks RD !
At this point I'm actually using 75/25 WW -1-20 and water dropping for 16-bhn and checking with Hornady checks it is only 16" bbl looks like those last 4" are pretty costly.
Re: The new AR.....
Posted: 09 Jul 2015 08:12
by Ranch Dog
RBHarter wrote:Thanks RD !
At this point I'm actually using 75/25 WW -1-20 and water dropping for 16-bhn and checking with Hornady checks it is only 16" bbl looks like those last 4" are pretty costly.
At lunch time I will run it at 35.0 & 38.5 KPSI and rerun the 42.0 KPSI all with with the 16" barrel. That should give you benchmarks in case you see your alloy fail (leading).
Re: The new AR.....
Posted: 09 Jul 2015 11:11
by RBHarter
Does it handicap for altitude? I'm about 4000 ft . The first 20 have gone w/o a problem.
Re: The new AR.....
Posted: 09 Jul 2015 13:27
by Ranch Dog
RBHarter wrote:Does it handicap for altitude? I'm about 4000 ft . The first 20 have gone w/o a problem.
No pressure altitude compensation is needed.
Re: The new AR.....
Posted: 09 Jul 2015 20:04
by Ranch Dog
It might be a couple of days until I can run the numbers. Got busy packing today, have another grandson on the way and he is coming sooner than expected.
Re: The new AR.....
Posted: 11 Jul 2015 12:59
by 62chevy
Ranch Dog wrote:It might be a couple of days until I can run the numbers. Got busy packing today, have another grandson on the way and he is coming sooner than expected.
Good news RD. How old is he?