A different kind of Africa rifle
- Thread starter Ardent
- Start date
Cold air is denser than warm air. Waves propagate slower in a denser medium, maybe giving the appearance of higher velocity with doppler radar. I seriously doubt this would be measurable in a 30 or 50 degree temperature range at the distances we are talking.
More likely to me is that the bore and chamber are tightening in the cold, any farmer can tell you that barbed wire fences get tighter in cold weather. I'd think this would raise velocities.
More likely to me is that the bore and chamber are tightening in the cold, any farmer can tell you that barbed wire fences get tighter in cold weather. I'd think this would raise velocities.
Ardent
CGN Ultra frequent flyer
I fired the -33 cold soaked round in a room temp barrel from indoors, a few mins after the room temp shot string. Was an equal barrel for all compared, except the round was so cold it burned your fingers. I shoot from a heated shop out a door when I only need a hundred yards.
I've shot in -19 two days in a row. Both days the ammo was left outside overnight. Very cold ammo. One day the rifles were cold. The next day the rifles were kept in the truck until loaded and shot, heater was blowing 25c. Almost no change in speeds from cold to warm gun, with cold ammo.
I talked with Infinition, the guys in Quebec who build the Labradar. They said the speeds will be within .1% in any temp. Battery life suffers in the cold, that's it.
I'm no longer too worried about temperate stability in powders. Realistically most of my target shooting is done in temps from +5 to +15, and hunting shots are at moderate distance on generous vital sized targets. The biggest changes I experienced was at temps close to +30c. In temps like that, I got better things to do than be at the range!
I talked with Infinition, the guys in Quebec who build the Labradar. They said the speeds will be within .1% in any temp. Battery life suffers in the cold, that's it.
I'm no longer too worried about temperate stability in powders. Realistically most of my target shooting is done in temps from +5 to +15, and hunting shots are at moderate distance on generous vital sized targets. The biggest changes I experienced was at temps close to +30c. In temps like that, I got better things to do than be at the range!
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Ardent
CGN Ultra frequent flyer
Been working on two iterations of the alternative Africa rifle, the 7.62x39 and the same setup with a 6.5 Grendel barreled action. If the 6.5 gains my favour, and I’ve been shooting and load developing for it more than the x39 so I suppose it’s gaining, I’ll trim the 25.6” barrel down to 18.5 or 20” and assemble the same setup. The 6.5 is superior in every aspect except the ammo availability, so I’d travel it with the x39 barrel headspaced as a spare and a strap wrench.
Loads to date as I always like finding this stuff online for background, only safe and tested in my rifle naturally, everything’s H4895 as I only have one powder in camp despite a bench full back home, will try others next time,
7.62x39
25.5grs H4895 Fed SR Match primed, Hornady brass, 174gr Sierra Match King 2.300” OAL 1740fps, 1701fps from CZ527 no pressure
28.0grs H4895 Fed SR Match primer, Hornady brass, 174gr Sierra Match King, 2.300” OAL 2053fps, CZ527 no pressure signs, compressed
29.0grs H4895 Fed SR Match primer, Hornady brass, 174gr Sierra Match King, 2.300” OAL 2046fps, CZ527 no pressure signs, compressed - Accurate 0.940” group
30.0grs H4895 Fed SR Match primer, Hornady brass, 174gr Sierra Match King, 2.310” OAL 2148fps, CZ527 no pressure signs, VERY compressed.
6.5 Grendel
29.0grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2557fps moderate pressure
29.2grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2545fps, 2562fps, 2547fps moderate pressure - Accurate! Bughole group, 0.34” group. The node.
29.3grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2650fps, 2617fps, 2629fps moderate pressure - Accurate! Bughole group.
29.4grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.293” OAL, 2620fps, 2620fps, 2606fps 1.75” group
29.5grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2636fps, 2629fps, 2643fps moderate pressure
29.6grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2653fps, 2622fps, 2603fps
29.7grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.304” OAL, 2613fps, 2573fps, 2565fps 1.21” group vertically strung
30.0grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2678fps, 2639fps, 2640fps, 2665fps, 2685fps safe pressure - Frozen -30 2668fps
Loads to date as I always like finding this stuff online for background, only safe and tested in my rifle naturally, everything’s H4895 as I only have one powder in camp despite a bench full back home, will try others next time,
7.62x39
25.5grs H4895 Fed SR Match primed, Hornady brass, 174gr Sierra Match King 2.300” OAL 1740fps, 1701fps from CZ527 no pressure
28.0grs H4895 Fed SR Match primer, Hornady brass, 174gr Sierra Match King, 2.300” OAL 2053fps, CZ527 no pressure signs, compressed
29.0grs H4895 Fed SR Match primer, Hornady brass, 174gr Sierra Match King, 2.300” OAL 2046fps, CZ527 no pressure signs, compressed - Accurate 0.940” group
30.0grs H4895 Fed SR Match primer, Hornady brass, 174gr Sierra Match King, 2.310” OAL 2148fps, CZ527 no pressure signs, VERY compressed.
6.5 Grendel
29.0grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2557fps moderate pressure
29.2grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2545fps, 2562fps, 2547fps moderate pressure - Accurate! Bughole group, 0.34” group. The node.
29.3grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2650fps, 2617fps, 2629fps moderate pressure - Accurate! Bughole group.
29.4grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.293” OAL, 2620fps, 2620fps, 2606fps 1.75” group
29.5grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2636fps, 2629fps, 2643fps moderate pressure
29.6grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2653fps, 2622fps, 2603fps
29.7grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.304” OAL, 2613fps, 2573fps, 2565fps 1.21” group vertically strung
30.0grs H4895 Fed SR Match primer, Starline brass, 130gr Berger Hybrid OTM, 2.300” OAL, 2678fps, 2639fps, 2640fps, 2665fps, 2685fps safe pressure - Frozen -30 2668fps
Ardent
CGN Ultra frequent flyer
A big thanks to Folklorestatus for the help with the rear sight, put it to work. Cut the 16mm dovetail into the sight, and then hid the sight blade inside a recess cut in the base of the Warne ring. Kept the rear sight as a backup this way and added the second point of attachment for the scope. It was holding zero perfectly with only one ring actually mounted, so this should prove plenty solid, and maintain a backup sight.
She’s done, just need to play with the lighter bullets now.
That is a pretty spiffy rig....so your 16mm dovetail is cut in lto the dovetail sight insert correct? Is the dovetail sight insert sintered or soldered in place or just held with Allen compression screws?
Re; 7.62X39 or 6.5 Grendel... my vote is forget the Grendel, even if it is ballistically superior... your whole concept is "light, compact, handy and with available ammo anywhere." Switching to the Grendel and carrying a second barrel in 7.62 defeats most of those objectives and just makes it awkward and inconvenient... I would just stick with this one in 7.62X39 and do the Grendel in a different rifle... but I agree, that the Grendel is a cool little round.
Ardent
CGN Ultra frequent flyer
Yea I agree, plus this thing hits way beyond any range it has business shooting at as a 7.62x39. The fact the reticle lines up is just too neat too. Plus with the Mark 4 you can just zero preferred loads, and also surplus junk, and record where they hit then dial in the zero for whichever load any time on the turrets.
Spoke a little soon did a lot of 174gr MK shooting today and it’s a hoot, I think that 500 yard junk ammo group will look pretty bad soon, these shoot. Interestingly with the barrel mount groups grew by about 25%, now 1.25 MOA but think I might have to fiddle with charges slightly to find the new sweet spot the harmonics are different.
The rear sight is just drifted very snuggly into its dovetail, the scope uses it to prevent vertical oscillations when firing, the rear mount assures the lateral stability in this case.
Really liking the little adventure rig, quick mag changes and feeds slick, weighs in the high 6s all up, nil recoil, handles like a sweetheart.
The flush mags are 3+1 but only fit the models designed for them, I’m not a fan and would actually opt for a 10 round if available and may have to make one out of two 5s.
Spoke a little soon did a lot of 174gr MK shooting today and it’s a hoot, I think that 500 yard junk ammo group will look pretty bad soon, these shoot. Interestingly with the barrel mount groups grew by about 25%, now 1.25 MOA but think I might have to fiddle with charges slightly to find the new sweet spot the harmonics are different.
The rear sight is just drifted very snuggly into its dovetail, the scope uses it to prevent vertical oscillations when firing, the rear mount assures the lateral stability in this case.
Really liking the little adventure rig, quick mag changes and feeds slick, weighs in the high 6s all up, nil recoil, handles like a sweetheart.
The flush mags are 3+1 but only fit the models designed for them, I’m not a fan and would actually opt for a 10 round if available and may have to make one out of two 5s.
Ardent
CGN Ultra frequent flyer
With the scope at 1.5x I’m finding it as good or better than good irons, I say or better as I like the illumination for quick shooting. Wouldn’t plan to take it off unless it broke, and I’d opt for a standard receiver bridge mounting setup if going on and off with it.
Johnn Peterson
CGN Ultra frequent flyer
- Location
- Chemainus B.C.
Don't know if my eye sight issue in past is the same as what you're experiencing. Mine was cataracts. My sight issue really came to the forefront in 2014 heading for an Antelope hunt on draw in Alberta. Didn't want to pass on the hunt as it would be highly unlikely I'd ever get another draw. After a successful hunt, following my return home the surgeon determined it was time for the corrective surgery. I was informed, the procedure and standard lenses were covered by the medical plan. I was questioned concerning 'activities'. Stating I still had an interest in handgun shooting so I'd like a clear sharp front sight picture at about 3' away. Also, with hunting, I'd still like to see the horns on a Blacktail at 150 yds. He immediate response was symphony lenses. An $1,500.oo/eye. NO complaints!!
Don't know if my eye sight issue in past is the same as what you're experiencing. Mine was cataracts. My sight issue really came to the forefront in 2014 heading for an Antelope hunt on draw in Alberta. Didn't want to pass on the hunt as it would be highly unlikely I'd ever get another draw. After a successful hunt, following my return home the surgeon determined it was time for the corrective surgery. I was informed, the procedure and standard lenses were covered by the medical plan. I was questioned concerning 'activities'. Stating I still had an interest in handgun shooting so I'd like a clear sharp front sight picture at about 3' away. Also, with hunting, I'd still like to see the horns on a Blacktail at 150 yds. He immediate response was symphony lenses. An $1,500.oo/eye. NO complaints!!
Well that is pretty awesome! Unfortunately, my vision is purely the result of aging... one of my buddies is a top eye surgeon and he tells me there is not much they can do for it... I am not debilitated or anything, but having had perfect vision for most of my life it is a pain getting used to reading glasses... and the ocular lenses on all of my scopes are cranked out to the max.
Johnn Peterson
CGN Ultra frequent flyer
- Location
- Chemainus B.C.
In my case, following the surgery and when they took the eye patch off, after a day or two, I couldn't believe the difference!!!!!! The clarity and brilliance of colours and the clarity and fine definition of detail was like
Donald Trump, 'fake news'. I couldn't get in fast enough to get the right eye done.
Ardent
CGN Ultra frequent flyer
Only loading .311s, I had the 527 7.62x39 Carbine a dozen years ago and tried 155gr .308 bullets and could never best 1.5” groups from a solid benchrest. These .311s have come under an inch shot off a truck tailgate and think there’s potential yet to tighten them.
