6mm ARC Velocities

[ckt3]

95s in the mid 2700 fps range may also align better with quick drop (?)

 

[DeepMauka]

we got 2800 ish, cant remember exactly but know it was over 2800, with the 95s. they were not as accurate. I admit i went back an forth between 95s at 2800 vs 107s at 2630 but more accurate. my gun shot a legit 3/8th group with the 107s and shot 108 eldm factories at 2580 pretty much thru the same hole so i went with the 107s. right or wrong i dunno

That’s where I was at too. Slower, but way more accurate. I’ve got 50ish still loaded up of the 95s and lever, but after that’s gone I’m trying the 108s and varget or xbr. The 95s and lever was around 1.2” and 108s were under, but 250-300fps slower making it a 550yd and in at sea level. I have a 20” Howa Mini

 

[HairyScandinavian]

For those of y'all who've shot the 108 M's and 107 TMK's with similar loads are y'all seeing either one has an edge on a wee bit more speed? Not that it matters I'm curious because the weather sucked again yesterday and today so wasn't able to go shoot. Now I got 4 rifles I'm sitting on waiting to test loads so I'm sitting here thinking of what to do with the 5th I'll be adding when I work through some of the others.

 

[Tanner]

For those of y'all who've shot the 108 M's and 107 TMK's with similar loads are y'all seeing either one has an edge on a wee bit more speed? Not that it matters I'm curious because the weather sucked again yesterday and today so wasn't able to go shoot. Now I got 4 rifles I'm sitting on waiting to test loads so I'm sitting here thinking of what to do with the 5th I'll be adding when I work through some of the others.

107s should take a higher charge to hit similar velocities as the bearing surface is greatly decreased compared to a a 108, but you should be able to achieve the same speeds…

 

[KY_coop]

With the bearing surface being less, wouldn't that mean less drag and able to achieve same velocity with less powder?

 

[HairyScandinavian]

Went back today with some ten shot loads, we're not gonna talk about groups they were terrible which is confusing because the previous 5 shots were promising, this was more than a sample size issue something else is just wrong. Anyway I figured I'd put up some velocity comparisons. 18" gasser suppressed.

Avg: 2729 - 29.4gr Lever 95 TMK at 89 degrees.
Avg: 2689 - 29.4gr Lever 95 TMK at 68 degrees.

Avg: 2650 - 29gr SBM 95 TMK at 89 degrees.
Avg: 2649 - 29gr SBM 95 TMK at 68 degrees.

So the Lever moved 40 fps for 21 degrees air temp and the Staball Match moved 1 degree which is obviously within margin of error.

 

[Tanner]

With the bearing surface being less, wouldn't that mean less drag and able to achieve same velocity with less powder?

Not in my experience; less bearing surface means less pressure which would equate to less velocity… however, all rifles and handloading situations are as unique as women…

 

[Treelineasassin]

Not in my experience; less bearing surface means less pressure which would equate to less velocity… however, all rifles and handloading situations are as unique as women…

I agree with this. However lower psi allows you to add more powder. A 107tmk VS say a 108 eldm, the tmk has WAY less bearing. I bet it'd prob make another 60-80fps over the eldm. That's what I found with the 85.5 hybrid VS an 88eldm, the Berger could run near 100fps faster at same visual pressure signs on brass.

 

[Tanner]

I agree with this. However lower psi allows you to add more powder. A 107tmk VS say a 108 eldm, the tmk has WAY less bearing. I bet it'd prob make another 60-80fps over the eldm. That's what I found with the 85.5 hybrid VS an 88eldm, the Berger could run near 100fps faster at same visual pressure signs on brass.

Makes sense for sure. I was shooting 108s at 2900+ but started seeing pressure (6 CM) At higher ambient temps. The 107s at 1/2gr less powder with the first load I tried shot 2870 with zero pressure signs… so your logic is tracking there.

 

[HairyScandinavian]

I agree with this. However lower psi allows you to add more powder. A 107tmk VS say a 108 eldm, the tmk has WAY less bearing. I bet it'd prob make another 60-80fps over the eldm. That's what I found with the 85.5 hybrid VS an 88eldm, the Berger could run near 100fps faster at same visual pressure signs on brass.

If that's the case I need to quit screwing with these 95's and load some 107's to test. I bought them for the wife's bolt gun but maybe I should steal them.
I just settled on a final load for my 6.5 with 147 M's, now it's making me want to start all over and try the 153's. Does this reloading tinkering ever stop?

 

[Plague]

21” barrel. This load is on the hot side in warmer temps. Had some heavy ish bolt lift when it was upper 60’s.

 

[Treelineasassin]

If that's the case I need to quit screwing with these 95's and load some 107's to test. I bought them for the wife's bolt gun but maybe I should steal them.
I just settled on a final load for my 6.5 with 147 M's, now it's making me want to start all over and try the 153's. Does this reloading tinkering ever stop?

153tmk does NOT have a short bearing. It's 0.060 longer than a 156 berger. BC isn't an upgrade from the 147. Stick with what you got if it's working

 

[HairyScandinavian]

153tmk does NOT have a short bearing. It's 0.060 longer than a 156 berger. BC isn't an upgrade from the 147. Stick with what you got if it's working

Thanks for the clarification, I hadn't even looked at the 153's yet as I figured they'd be even slower.

 

[SanAntonioShooter]

Didn’t see a threads specifically for 6 ARC, so figured I’d get this going for people to share velocities and barrel lengths on their 6 ARC. This should help folks get a baseline of what to expect when they are considering building one.

16” Proof stainless AR barrel, suppressor, factory ammo. Accuracy was about equal between the factory 108 eldm and factory 103 eldx. These are the first shots down the barrel so I am expecting them to speed up and settle in a little.


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Nice Group!