6.8 SPC-1000yds

R

R.DesJardin

Guest
Yes, 1000yds.
When the 6.8 first came out I was intrigued and bought a 1st Production Run Rem. 700, 24" bbl. SS. So not having shot it much I dug it out and decided that the Sierra .277-135gr MK (BC-.482) should be a good choice for some LR shooting. Well a little load data from Sierra and bam, this thing shoots good for a factory rifle. Definitely under a MOA. I still need to crank up the load a little to get max. fps. Surprisingly the trajectory was very close to my 20" Rem. VTR, .308 Win shooting 175gr BTHP's. And little recoil.:)
 
6.8spc at 1000yds.

Don't mean to be a spoil sport and Im sure somebody will put me in my place, but at a 1000yds I would have thought that I could catch them in my hat. A very unsure of himself Murphy.
 
Doubts

No problem Murphy.:)
Dust of the ballistic calculator:
6.8 SPC 277-135MK-24" bbl-1000yd MOA 42.82
BC~.482
FPS 2525
1.75 scope ht.
100yd zero
1000yd fps 1148

Now the 308 Win-175gr 20" bbl-1000yd MOA 39.26
BC~.494
FPS 2600
1.75 scope ht.
100yd zero.
1000yd fps 1201

I found this incredible but true.
Will be doing max load/fps/accuracy testing in the AM and confirm 6.8 fps numbers using Oehler equipment.
 
My Pacnor bbl'ed Savage sporter will digest the original SSA 115 gr Extreme bullet loaded ammo with only slightly flattened primers. I bet CCI BR primers would solve the flattened primer issue. The velocity was in the high 2700 - low 2800 range.

The later batches of SSA ammo were slowed down to the 2500/2600 range.
 
I don't argue that the 6.8 SPC cartridge can be laoded to give supersonic velocity at 1000 yards, but only with the cartridge loaded over the OAL and/or pressure limits of a magazine fed AR-15.

Not that there's anything wrong with using the 6.8 SPC cartridge outside of it's SAAMI design specs in a bolt action. just dont expect that performance from a 24" barrel AR-15. There are several cartridges which will fit an AR-15 magazine and comfortably reach 1000 yards supersonic. The 6AR, and 6.5 Grendel are examples.

While I don't consider the 6.8 SPC to be a great 1000 yard cartridge, particularly because of wind deflection, I'd suggest that Murphy uses a hat made of several layers of kevlar. The 135 SMK from a 6.8 SPC Rem 700 will be carrying over 400 ft-lbs energy at 1000 yards. More than a 32 ACP at short range.
 
Yes, if you shoot the early SSA loads in my AR15 the primers won't just be flat, they will be OUT [ as in laying on the ground ]. I have it on good authority that if I lengthen the throat the problem will be solved. I need to compare the jam length between the Pacnor chamber and the ER Shaw chamber [ AR15 ].

Actually I need to just sell all my 6.8 stuff :D
 
Its like driving a Moped when you ahve a nice Harley sitting in the garage.
 
Bolt Gun

I was aware of the COL short comings in the AR type platform, that's why I posted my bolt action results.
Using longer COL-2.450" in a bolt gun gives this little cartridge a different outlook.
I did some load testing this morning and got much higher velocities.
I stopped when I could see the case getting shiny spots from bolt opening. The bolt lift was still easy and primers showed no flatting but I felt compelled to stop, because it just didn't seem possible to have the 135's going that fast. I'll try to get these loads pressure tested in the next week or so, I'll post where I'm at then.
 
A little bit surprised.

I must confess that the velocity figures for this cartridge when fired out of a bolt action are alot better than those quoted by the ammunition companies. Would be interested to know the sort of speed that is obtaniable with 90g Sierras, as they should make the 6.8 into a fine varmint caliber. Don't think I would worry too much about the 1000yd business as there are too many good slippery cartridges about like the 6.5 /284 for the 6.8 spc to be competitive. Just stick to shooting varmints and small deer and you will get the best out of your rifle. Murphy.:)
 
Choices

I won't recommend the 6.8 for 1000yd competition. I have a .284 Win for that, but that case also suffered from being designed for a short magazine system(Win. Mdl.88). I just thought I'd share some info that has passed us by with the assumption that the 6.8 is a semi-auto round.
It seems that no thought the 6BR case was a good 1000yd choice until it was formed into a Dasher. Food for thought?
 
Shooting

Sorry for the confusion, my reference was that with the right loading in the right rifle the SPC-135gr MK combo has a similiar exterior ballistic performance to the venerable M118LR load for the .308 Win(is this a 1000yd cartridge) no not for BR but still capable of LR accuracy.

Would be interested to know the sort of speed that is obtaniable with 90g Sierras, as they should make the 6.8 into a fine varmint caliber.
Click to expand...
What about fps data for a Speer 90gr TNT(seated long), that I should be able to come up with.:)
 
This is correct

R.DesJardin said:
Sorry for the confusion, my reference was that with the right loading in the right rifle the SPC-135gr MK combo has a similiar exterior ballistic performance to the venerable M118LR load for the .308 Win(is this a 1000yd cartridge) no not for BR but still capable of LR accuracy.,,,,,,,,,,,,,


Peter
Click to expand...
 
For competition it is a waste of time---too many other good choices out there..
 
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