6.5 barrel installed, semi annual removal of 1 pound of carbon, gunk, and fowling.
6.5 barrel installed, semi annual removal of 1 pound of carbon, gunk, and fowling.
"What would a $2,000 Geissele Super Duty do that a $500 PSA door buster on Black Friday couldn't do?" - Stopsign32v
Getting close.
Work up ammo loaded?
So I just started down the path of load workup for my 6.5. I also read the stuff JP had about loading for the 6.5 in a gas gun. Mine is 24" McGowen custom barrel, 24", 8.5 twist, and. Fulton high pressure bolt.
First range trip was yesterday.
123 gr Nosler Custom Comp's
Hornady brass, new
CCI-200's
38.5 gr Varget
Loaded to 2.750 OAL (couldn't go much longer as virtually no bullet in the case due to the boat tail)
Very mild load. No case swipes, brass looked perfect, and primers were nice and rounded with no cratering. Despite zero load development, produced several 200 yard 5 shot groups in the 1.25-1.5" range. 10 shot groups right around 1.5-1.75".
I am bumping the charge up to 39.0-39.5 next trip.
I do think that the 120-130 gr class bullets just work really well in a gas gun. They can be pushed fast enough to crutch their lower BC and they are definitely easier on brass. Recoil is minimal and probably the Pinnacle of the ballistics/accuracy than can be easily achieved from a semi auto!
We took out the barrel today and it went pretty well. The Am. Gunner 140 grain ammo shot faster than I expected, 2638fps with an SD of 5. Pretty impressive for bulk ammo. Mark loaded up a ladder starting at 39.4 of H4350 and finished with 40.4 grains. We did 3 rounds of each and feel we found the low node at 36.6. The first three loads all had the SD5 and 2536-2540 fps. So we could bulk load the 143's and be very consistent loading for 39.6 and if we were a little high or low, we would still be dead on. ( thanks Don). But we feel that we need to go higher to find the high end and we want to be on the high node.
With the limited 3 shot groups nothing shot over moa and mostly closer to .5 to .75 groups of three. Several were two shots in one hole and one other right beside it. Only one load was a full MOA , 40.2, so whatever. The last group was 40.4 and we saw 2593 fps. We expect next trip to find the sweet spot at over 2,600 fps. If we can find a high node there, then thats our load for a bit.
I sent Mark a chart if we can get it uploaded.
PB
"Air Force / Policeman / Fireman / Man of God / Friend of mine / R.I.P. Steve Lamy"
Using your 39.6 accuracy node, I would have expected the scatter center to be ~40.6, which you saw starting at 40.2 and probably 40.4 as well.
So your next node above that is like 41.8-42g. THATS going to be a stout load since its just at and over max per Hodgdon at 41.8... BUT its worth exploring above book max to see what goes on in your gun. I would creep up on it obviously. In mine, with Varget and 123's, book max is 39.8... Im at 39.9 and running right at their velocity numbers should be(their 39.8 data says 2888, im at 2900 with .1g more). I think I was all the way up just over 41g before I hit pressure, in my gun. There was no way I was going to my next accuracy node(theoretically 42.3g).
Last edited by rjacobs; 08-19-18 at 16:48.
Rjacobs, that's what I noticed as well. Although I was using 147's. At 38.6 grouping was right on and has been. When I hit book max, there was pressure signs. Velocities at 38.6 have been right along book value. Couple that with nothing getting beat and distances from ballistics being what they are I didn't bother going higher. When I get my bolt gun built there may be some room to play.
illegitimis non carborundum
I’m hoping when I get a bolt down the road , that I can use same ammo, but the bolts do tolerate pressure so much better it’s hard not to push the load up.
And when you max out distance, it’s even more tempting to tweak your load.
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