McGowen Precision AR-15 6-ARC build
#19
GF, so you think they have a slow barrel? Or maybe a cheap made in China Chronograph?

If you look at Hodgdon data for 107s in both 6 CM and 6.5 CM,  without making a spreadsheet, it looks like about 3000 or so should be expected with 107s in 6 CM and  3100 with 6.5 CM. Makes sense since the narrower caliber will have a bit more bearing surface.  70s in .223 vs 6x45 are a little closer in the Hodgdon data, but it does look like they run a little faster in the 6x45.  In my experience I am running 70s just shy of 3k with a very mild load in a 24" 6x45 while I ran 69s just over 2900 out of an old 24" 5.56. A large portion of the difference could be due to The 6x45s BHW-ness, though.

I've got 3 of the powders Hornady lists for 105s in the ARC. I might load up some 105 RDFs that are useless for me in a 1:8 twist at the midpoints and see how the velocity matches up in my 243 LBC. A given charge should run a little slower with the slightly larger case, right?  (Offset by BHW-ness).

I'll add, it seems that Hornady pretty much flubbed this rollout. Not criticizing the caliber, but how they've rolled it out.
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Messages In This Thread
RE: McGowen Precision AR-15 6-ARC build - by danm - 07-01-2020, 06:23 PM
RE: McGowen Precision AR-15 6-ARC build - by danm - 07-29-2020, 05:26 PM
RE: McGowen Precision AR-15 6-ARC build - by StoneHendge - 08-31-2020, 05:50 PM

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