6.8 chambers- SAAMI, SPCII, DMR, 6.8x43, Noveske Mod 1

[constructor]

Noveske lists the freebore as .100

But how would i check that anyway? seating a bullet long and pushing it into the lands? then take some measurements? of course mark the bullet with sharpie. And use a properly sized piece of brass.

Any other things that i would need to do? or a better method?

You need a square nosed bullet, bullets usually don't touch the rifling where it is .277 dia they touch in the curve of the ogive somewhere so if you turned a flat based bullet around it would be easier to find where the lands start.

[Dude-Sweet]

SPH should do the trick... I got a bunch of those. Thanks for the tip. Will check it out tomorrow.

[Dude-Sweet]

Ok So I tried to use a SPH seated backwards...But it would not go to the lands at all. Just kept shoving the bullet deeper into the case. Makes me wonder if there is a stepped angle in the chamber preventing the flat base from reaching the lands. Or maybe I just need to crimp the snot out of it with the FCD?

I also tried seating the SPH long 2.39" . No marks on the ogive.

I have some 110 accubonds I will give a try with, but not sure if those will work either. I might need to scrounge up some 130-150gr to get the ogive to touch lands.

Will update later today.

ETA; I seated the 110gr accubond to 2.543" dropped the bolt on it, and re-measured. 2.448" I then dropped the bolt on the shortened dummy round again. it remained 2.448"

Best I can tell that gives me the .100 freebore

Constructor- does this seem accurate to you? Anything else I should do?

[constructor]

Ok So I tried to use a SPH seated backwards...But it would not go to the lands at all. Just kept shoving the bullet deeper into the case. Makes me wonder if there is a stepped angle in the chamber preventing the flat base from reaching the lands. Or maybe I just need to crimp the snot out of it with the FCD?

I also tried seating the SPH long 2.39" . No marks on the ogive.

I have some 110 accubonds I will give a try with, but not sure if those will work either. I might need to scrounge up some 130-150gr to get the ogive to touch lands.

Will update later today.

ETA; I seated the 110gr accubond to 2.543" dropped the bolt on it, and re-measured. 2.448" I then dropped the bolt on the shortened dummy round again. it remained 2.448"

Best I can tell that gives me the .100 freebore

Constructor- does this seem accurate to you? Anything else I should do?

There is no doubt in my mind that if J. Noveske says it has a .100 leade, it has a .100 leade.
Most bullets when loaded to 2.29 have at least .100 jump to the lands, in your case with that bullet if you loaded to 2.3 it would still have .148 jump to the lands, that is a long jump.

[Dude-Sweet]

There is no doubt in my mind that if J. Noveske says it has a .100 leade, it has a .100 leade.
Most bullets when loaded to 2.29 have at least .100 jump to the lands, in your case with that bullet if you loaded to 2.3 it would still have .148 jump to the lands, that is a long jump.

Indeed it is. I haven't tested the 110gr accubonds for accuracy yet.

I have tested the 100gr accubonds quite a bit though. My rifle loves those things seated at 2.295. groups the very nicely. Did a little bit of testing with the 110 SPH and they did ok...but I am not happy with them yet and need to do more tweaking.

Until spring-time I won't be able to do much more testing with various bullets. So for now the 100gr accubond is my go-to load. Will be curious to see how some of the other bullets work for me.

Thanks for the input, and for posting all the info about various chambers.

[tbready]

Only the chrome lined Xtremes and MK68 Recon(Lothar poly) had the DMR-C, that summer is when SSAs brass had thicker necks and I enlarged the necks of the chamber to help solve those issues.

So my nitro carb'd recon barrel is 6.8 X 43 then?

[mtnwinds]

H, in your original post you say, "We added a very small amount of taper in the neck and body to aid extraction, the freebore was increased to .2775 from what the DMR chamber had,....."

That's a typo, right?

[joshuades]

The diameter of the freebore, not the length.

[constructor]

Correct, diameter of freebore.

[Nick M]

There have been lots of threads about this lately for some reason so I'll try to explain it.
Formal names first, slang after.

Thanks for all the info. And your comitment to the 6.8, it makes my needs easier to come by.