COL for 6.8 SPC

[jdberger]

What's the standard COL for 6.8 SPC?

I was setting up my machine this evening and looked at IMR's specs and they say 2.260 with a 115gr bullet.

Then, for giggles, I measured a Remington round. That came out at 2.240 with a 115gr FMJ bullet.

Concerned, I measured a Silver State Armory round and it comes in at 2.210 with a 115gr OTM.

So what's correct?

I'd think that Remington probably has a good idea because they developed the round, but SSA is actually manufacturing it and is seen as pretty much the standard.

Help.

[ocabj]

Different bullets have different ogives. Hence, different seating depths required.

Use the COL defined in your data manuals. If you don't have any for that specific bullet, you'll want to call the bullet manufacturer for the data for 6.8SPC.

Or you could just set dummy rounds to mag length and manually chamber to see if the bullet is hitting the rifling upon being chambered.

[Technical Ted]

I reload 115 gr SMK, 115 gr Hornady BTHP and 110 gr Hornady V Max to 2.29" +/- 0.002".

Based on measurements taken with a bullet seating OAL gauge I could use a longer OAL, but my PRI mags will only allow for a max COAL of 2.3".

[arfan66]

Interesting...I measured an SSA LE/MIL 115gr OTM round and it came out to 2.242" and their Sierra Match King 115gr OTM round (essentially the same thing without a cannelure) came out to 2.257".

Jeff

[ar15barrels]

Start by loading the first round to 2.29" and check it in your magazine and barrel.
If it fits without touching the lands, then start load development at that length.
If you are working with cannelured bullets, just seat to crimp into the cannelure.

[Technical Ted]

If you are working with cannelured bullets, just seat to crimp into the cannelure.

If I were to seat bulk Remington 115 gr FMJ to the middle of the cannelure, I'd wind up with a COAL of roughly 2.23". Seated to the bottom of the cannelure, but not in the cannelure I'm getting COAL of 2.245" +/- 0.004" (They aren't the most consistent and they shoot like crud, but they were cheap).

Just measured a couple of Hornady 110 gr BTHP w/ cannelure facture rounds and the COAL is 2.23".

[jdberger]

Well, I said screw it, loaded the Hornady 115gr OTMs to the cannelure. COAL was somewhere in the middle, there. The bullet didn't touch the rifling and the round chambered and ejected fine (dummy round).

We'll see how it shoots on Saturday.

I'll have to get a bullet seating OAL gauge one day.