6CM testing Results

[joesr]

I had a brief testing session today as the wind kicked up and it rained.

However, what I did get down range is interesting.

Cartridge: 6CM
Rifle: Tubb2000
Sights: Iron
Distance: 200 yards
Temp: 70
Brass: Nosler 243, fireformed to 6CM
Primer: CCI BR2


115 Berger VLD, 49.0 H1000, Jump 0.040", 3163 avg vel, SD 14, ES 35, Group: under 3/4"
115 Berger VLD, 49.5 H1000, Sticky bolt, didn't finish

105 Berger Hyb, 50.0 H1000, Jump 0.040", 3267 avg vel, SD none recorded, ES 18, Group: under 3/4"
105 Berger Hyb, 51.0 H1000, Jump 0.040", 3308 avg vel, SD none recorded, ES none recorede, Group 1.25"

The point is that I'm amazed at the velocity from the 105's. I need to repeat this and probably play with the seating depth as the 105's seated deeper had a group that opened up signifficantly.

It is important to note that 115 load with 49.0 and the 105 load with 50.0 and 51.0 had no pressure signs.

It is also important to note that the weather got bad towards the end so the opening up of the 105's group is probably more wind and rain related than the load.

Simply, I was impressed with the velocity and group size from the 105's today.

On another note, I am impressed with Nosler brass. In the Tubb2000, Lapua, regardless of the load sticks on opening because of the short web. Nosler does not have this issue and can, as proven, be loaded hotter without issue. Lapua works well in my Winchester with the same loads and same chambering. I can go into detail as to why I believe the Lapua doesn’t work well in the Tubb2000. But that is another topic.

Joe H

 

[Dgd6mm]

Joe, that's good info and good shooting with Irons, but that's the norm for you. What barrel and lenght is that? I'll be needing a new 1 coming up. I've got over 3300 rounds down the first 1 I had David chamber. Yesterday I had a 5 shot .3 inch at 100 yards with my bipod and 5-20x50 HD SS scope. I shot some 105 Hornaday AMP's when there was 3000 rounds down the tube. The results were 3-5 shot groups at 100 yards with the same setup as above under .25. I told Jim today that I'm about ready for another barrel. Keep doing what your doing Joe.

Don Dunlap

 

[joesr]

Same thing....28" Bartlein, 1:7.5 twist, straight 4 grove. I don't seem to have success with the 5R or 5C or what ever they call it. Possibly they work with the little 6mm's, but I belive the 6CM requires the fatter more aggressive rifling offered by the 4 grove barrels.

Joe H

 

[Steve Blair]

Same thing....28" Bartlein, 1:7.5 twist, straight 4 grove. I don't seem to have success with the 5R or 5C or what ever they call it. Possibly they work with the little 6mm's, but I belive the 6CM requires the fatter more aggressive rifling offered by the 4 grove barrels.

[br]
I have a "little" 6mm Remington with a Bartlein 5R, 8" twist and it does just fine. Berger 105 Hybrids at ~3130 from 26". On the flip side, my 32" Krieger-barreled 4-groove also shoots the Hybrids very well from conventional rifling. YMMV

 

[Dgd6mm]

I've heard there had been problems with the Bartlein 5R 7.5 twist chambered in 6CM. I like my Krieger's and my Lawton. I may try a Bartlein 4 groove 7.5 twist for my next 1. I need to start looking now for whatever I get.

 

[rcw3]

On the issue of Lapua brass not working well in the 6CM - there's no mystique there - Egolf did not design the 6CM chamber with adequate clearance at the base for Lapua brass that has a good bit larger web diameter than Winchester, Remington and other makes of brass. Doesn't make the 6CM a bad cartridge, it just means that Lapua brass is not optimum for use with it. I cannot use Lapua brass in my 6CM because the back of the 6CM chamber too small for Lapua brass, but since the domestic brass runs .003" or more smaller at the web and base of the case, that all works fine. If you happen to have a barrel where the back of the 6CM chamber is a little looser and a batch of Lapua brass that has a web a little smaller then you might be able to use it but I would not plan on it.

Robert

 

[Brad from ND]

I wish this thread would have been around before I ordered parts and built a rifle. Chad Dixon hung a Bartlein 7.5 twist 5R barrel on a Surgeon action for me. I am also using Lapua brass. I just fireformed 200 cases with cream of wheat last weekend and didn't have any chambering issues but I guess it will be something to watch.

 

[Brad from ND]

Robert, I bought that barrel from you. Maybe I should have told you what I was going to build with it. Oops, I guess I'll find out.

 

[teele1]

I've had no issues with Lapua brass chambering in my 6CM and I'm at least on the 6th or 7th firings on this brass. Thanks Joe as always for 6CM updates.
jim

 

[Hoser]

No issues with Lapua brass here either.

 

[rcw3]

As I said: "If you happen to have a barrel where the back of the 6CM chamber is a little looser and a batch of Lapua brass that has a web a little smaller then you might be able to use it . . .".

Just because people use Lapua brass in their rifles and it works fine doesn't mean it works for all, and just because it does not work in my rifle doesn't mean it won't work for all. From a chamber design perspective, when you get the diameter of the chamber at .200" forward of the bolt face virtually the same as or less than the web diameter of the brass, that can be a recipe for a constant sticky bolt (a "click" at the top of the bolt lift - - always happens with Lapua brass in my rifle but not with domestic brass that is about .003" smaller at the web than Lapua brass).

Robert

 

[teele1]

thanks for that info Robert

 

[Brad from ND]

Robert, I didn't mean any disrespect with my comments. I was actually make a joke about it but unfortunately sarcasm doesn't come through in text.

Take care

 

[Gundog64]

I wish this thread would have been around before I ordered parts and built a rifle. Chad Dixon hung a Bartlein 7.5 twist 5R barrel on a Surgeon action for me. I am also using Lapua brass. I just fireformed 200 cases with cream of wheat last weekend and didn't have any chambering issues but I guess it will be something to watch.

Brad,
I run a Bartlein 7.5 5R on my 6CM long range gun. No problems here and I have not heard anything really biased on the 5R rifling other than what Joe just posted. Shoot it and see but I dont think you have any real worries with the barrel choice. My first group at 100 was .272, cannot ask much more than that. By the way Chad built my rifle also.

 

[Dgd6mm]

I called David Bruno the other day about chambering another 6CM for me. My Krieger's shoot outstanding, but may try a Bartlein. I do shoot some Lapua in my BR rifle, but mostly Winchester brass. In my Tac rifle I shoot nothing but Winchester brass. Gundog64, how many firings do you have on your brass now? No issue's with the 5R? Joe and Robert both give good info. Sticky bolts are a bad issue in a run n gun.
Anyone else thats running a 6CM Bartlein 5R with Lapua brass that feels like chiming in on how their rifle is doing, please do so. I need to make a barrel choice soon.

 

[rcw3]

I am not aware of any issue with 5R rifling having adverse issues with the 6CM (or any other cartridges) vs conventional 4 groove, etc. I have heard some of the 6PPC bench shooters feel that the conventional rifled barrels are best with the small 6mm bullets in short range bench shooting, but I do not believe that's applicable to something shooting 105-108's or 115's, etc.

Robert

 

[Steve Blair]

I have shot a lot of 199's and 198's(solid 50 to 60% x counts) with this barrel and I have another just like it waiting for me when needed.

John,
Is this sling or F-Class and at what range? I shoot 6BR and 6mm Remington in F-Open Mid-Range and the 6CM interests me for that application.

 

[teele1]

Steve,
I shoot my 6CM in F/Open and tho I'm may not be as good a shot as John or others I'm a Master because of the 6CM.
jim

 

[Dgd6mm]

John,
I shot some 105 Hornaday AMP's at 850 yards with a load of 49 grains of H-1000 that I threw together. First off at 100 yards I printed 3-5 shot groups .25, 1 other group a tad bigger. POA, POI did this on purpose. At 850 my target was a 4" claybird, 7 out of 7. This is out of my Tac rifle, Savage action, Bipod in prone. There was over 3000 rounds down this barrel at that time. I run the 115 DTAC at 3153 fps most of the time. This thing still hammers and I'm confident that it will stay like this to at least 4000 rounds. Joe's have and I don't see why this barrel should be any different. I'm gonna keep shooting this 1 till 1 MOA.

 

[tbeasley]

Hey guys
So after the cruel and unusual punishment of fire forming (mostly due to my fault) I took Dave Kiff's advice and load the bullets backwards. Believe it or not Hornady 95gr SST backwards with 46.5 H1000 gave me a 1.0" group at 100yds for 8 shots.


My rifle sits now:
Stolle Panda F-Class action
Kreiger 1-8, 1.25 straight finished at 28.25"
Robertson F-Class stock.
Chamber is a .270nk with a .100fb

Using a .265 bushing
49.0gr H1000 & 107 SMK = 3050fps (used a CED chronograph)

Does my velocity seem a bit slow? Or is it pretty spot on for the given amount of powder? Its very accurate!! But i want to speed it up a bit and see where the groups start to open at.