6CM testing Results
- Thread starter joesr
- Start date
I might as well include my (so far limited) experience with my 6CM...
My Tube gun build has been a bit of a star-crossed experience so far (got sent a 6mm Competition reamer, a tight-necked 6-6.5x47 Lapua with a 40° shoulder instead of a 6mm Competition Match, the bolt handle I had installed wouldn't run in the tube gun slot) but the gun is shooting great, after all of that.
I ended up with a .237" bore (this seems to be very important--the .236s don't, for some reason, play as nicely) Krieger 1:7.5 twist, the short-ish throat reamer that Joe uses, and a 700 action in an Eliseo stock. The lot of Nosler brass I had was really heavy and really thick, and even with formed brass, I couldn't get more than 49.0gr of H1000 in it. (I think Whitley posted a picture here or elsewhere of formed brass and H1000 filling up into the neck--that was probably Nosler brass. It seems to be very short on capacity) In fact, the same 49.0 grains of H1000 in un-formed Win brass doesn't come up as high in the case as the same load does in formed Nosler brass.
Anyway, how'd it shoot? With the formed Nosler brass, I shot some 105 hybrids into the lands (on account of not having the capacity to seat them any deeper with any degree of consistency) at a 600 yard match, and after dropping three points in a bit of sorting out a slightly slanted firing point, the gun shot very well: 197-9, 200-14, 200-13 (97-3, 100-6; 100-9, 100-5; 100-7, 100-6) I didn't chrony the load, though.
With un-formed Win brass:
49.0 grains H1000 (thrown charges), BR2, 70gr Berger FB (I think they're discontinued, I got 1500 of them a while back for about $9/100) and using a false-shoulder so I could shoot them for rapid-sitting, the cases formed up nicely (same headspace measurement at .400" as the heavier bullet loads, but the corners were still a little rounded in the shoulders) They shot very well--but it's the 200 yard target, so nearly everything shoots well there.
With un-formed Win brass:
48.0 grains H1000 (thrown charges), BR2, 108 Berger, again with a false shoulder (necked up to 6.5, then run back through the sizer) They fed fine for 300, and while I ended up with a 200, I couldn't buy an X for a 200-8--I'm chalking that one up to being new to the bolt gun in the rapids. At 600, however, I had a 200-14, (9X on the front, 5X on the back--and if I hadn't been a chicken with the windage knob, I probably could have turned four *tight* 10s at 9 into Xs on the back 10) I also haven't run that one over the chrony, but whereas I'm curious, I don't really care what it says. That load shoots, and I wouldn't be worried about shooting it in a match anywhere.
So, with a false shoulder, fireforming loads work very well fed from the magazine.
My Tube gun build has been a bit of a star-crossed experience so far (got sent a 6mm Competition reamer, a tight-necked 6-6.5x47 Lapua with a 40° shoulder instead of a 6mm Competition Match, the bolt handle I had installed wouldn't run in the tube gun slot) but the gun is shooting great, after all of that.
I ended up with a .237" bore (this seems to be very important--the .236s don't, for some reason, play as nicely) Krieger 1:7.5 twist, the short-ish throat reamer that Joe uses, and a 700 action in an Eliseo stock. The lot of Nosler brass I had was really heavy and really thick, and even with formed brass, I couldn't get more than 49.0gr of H1000 in it. (I think Whitley posted a picture here or elsewhere of formed brass and H1000 filling up into the neck--that was probably Nosler brass. It seems to be very short on capacity) In fact, the same 49.0 grains of H1000 in un-formed Win brass doesn't come up as high in the case as the same load does in formed Nosler brass.
Anyway, how'd it shoot? With the formed Nosler brass, I shot some 105 hybrids into the lands (on account of not having the capacity to seat them any deeper with any degree of consistency) at a 600 yard match, and after dropping three points in a bit of sorting out a slightly slanted firing point, the gun shot very well: 197-9, 200-14, 200-13 (97-3, 100-6; 100-9, 100-5; 100-7, 100-6) I didn't chrony the load, though.
With un-formed Win brass:
49.0 grains H1000 (thrown charges), BR2, 70gr Berger FB (I think they're discontinued, I got 1500 of them a while back for about $9/100) and using a false-shoulder so I could shoot them for rapid-sitting, the cases formed up nicely (same headspace measurement at .400" as the heavier bullet loads, but the corners were still a little rounded in the shoulders) They shot very well--but it's the 200 yard target, so nearly everything shoots well there.
With un-formed Win brass:
48.0 grains H1000 (thrown charges), BR2, 108 Berger, again with a false shoulder (necked up to 6.5, then run back through the sizer) They fed fine for 300, and while I ended up with a 200, I couldn't buy an X for a 200-8--I'm chalking that one up to being new to the bolt gun in the rapids. At 600, however, I had a 200-14, (9X on the front, 5X on the back--and if I hadn't been a chicken with the windage knob, I probably could have turned four *tight* 10s at 9 into Xs on the back 10) I also haven't run that one over the chrony, but whereas I'm curious, I don't really care what it says. That load shoots, and I wouldn't be worried about shooting it in a match anywhere.
So, with a false shoulder, fireforming loads work very well fed from the magazine.
rcw3
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NateG
Do you have a 6CM or a 40Ëš shoulder version of something like it? Maybe I don't understand your post and whether you got the reamer confusion worked out in the end so you ultimately wound up with a true 6CM.
I am not sure I understand why you have to do the false shoulder method with brass. Can you clarify this as I do not see that as typically necessary with a 6CM.
Robert
Do you have a 6CM or a 40Ëš shoulder version of something like it? Maybe I don't understand your post and whether you got the reamer confusion worked out in the end so you ultimately wound up with a true 6CM.
I am not sure I understand why you have to do the false shoulder method with brass. Can you clarify this as I do not see that as typically necessary with a 6CM.
Robert
I have a proper, 31° shoulder 6CM. The mix-up was that, intitially, the reamer sent was a "6mm Competition", a cartridge based on the 6-6.5x47 Lapua. I had to have the barrel re-chambered with a 6CM reamer, specifically, the one with a relatively short throat, though I can't remember the freebore length. (It's the one Dave Bruno has--Joe's reamer)
I used the false shoulder because, as Joe discovered, new Win brass has run smaller and smaller and recent lots have required putting the bullet into the lands to headspace off of. However, since I was going to be shooting an across-the-course match, I didn't want to deal with the harder bolt closing associated with having the bullets into the lands when shooting the rapid fire stages--so that meant a false shoulder. (And I already had the 6mm to 6.5mm tapered expander) It worked *really* well. No split necks, and no problems feeding or hard bolt closing.
My understanding is that with Norma/Nosler/Lapua brass (and older Win lots), the brass is bigger in some dimension (neck junction, perhaps?) that, like traditional Ackley chamberings, nothing needs to be done for fireforming. (No bullets in the lands or false shoulders) But I needed to do something with the Win brass and didn't want to stick the bullets in the lands.
I used the false shoulder because, as Joe discovered, new Win brass has run smaller and smaller and recent lots have required putting the bullet into the lands to headspace off of. However, since I was going to be shooting an across-the-course match, I didn't want to deal with the harder bolt closing associated with having the bullets into the lands when shooting the rapid fire stages--so that meant a false shoulder. (And I already had the 6mm to 6.5mm tapered expander) It worked *really* well. No split necks, and no problems feeding or hard bolt closing.
My understanding is that with Norma/Nosler/Lapua brass (and older Win lots), the brass is bigger in some dimension (neck junction, perhaps?) that, like traditional Ackley chamberings, nothing needs to be done for fireforming. (No bullets in the lands or false shoulders) But I needed to do something with the Win brass and didn't want to stick the bullets in the lands.
Update…..
When I initially came up with the design for this cartridge one of my goals was to get away from coating bullets.
I have been playing with moly coated bullets for one reason. I shoot the same rifle for across the course competition as for 1000 yard competition. Many of my fellow competitors are shooting straight 243 Winchesters with more velocity, using moly coated bullets.
Obviously, or maybe not, the choice of powder has to change when using moly coated bullets.
Initially, my tests with moly proved that my current loads with H1000 (49.0 grains behind both the 108’s and 115’s) had velocities reduced by as much as 150 fps with the same load.
I’m not going to waste your time all of my testing, but I have landed on two loads with moly coated bullets that initially appear to shoot very well.
With the 108’s I’m shooting 51 grains of H1000. This is giving me a velocity of just over 3100 fps. I use a drop tube to charge the cases and powder fills up to inside of the shoulder, but not into the neck.
With 115’s (Berger VLD) I’m shooting 49.0 grains of N4350. This is with the bullet jumping .040†into the rifling. Velocity is a stunning 3261 fps with ES of 7 fps from the one test of 5 shots. This is an increase, in my current barrel of over 300 fps from my standard load of 49.0 grains of H1000 with uncoated bullets.
With both of these loads the bolt lift is easier than the loads with uncoated bullets and the primers and brass have no signs of pressure.
I assume there will be some decrease in barrel life because of the use of H4350 for my 600 and 1000 yard loads with the 115’s. However, history has proven that with H1000 I am getting, consistently, 4000 rounds out of every cut rifled barrel (.237 dia, straight 4 grove); and given that fact I’m hoping that the introduction of H4350 for my “long range loads†will not affect the meaningful barrel life. (Meaningful barrel life to me is one season in which I normally fire between 3000 and 3500 rounds) My long range loads will be fired through the barrels for a maximum of 33% of the rounds.
My feeling is that the increase of 300 fps out of the 115’s is more valuable than the expected decrease in barrel life of a few hundred rounds.
It is important to note that I don’t know how long any of my barrels could have or would keep shooting accuracy to be competitive at the highest levels. I have always changed my barrels at the end of a season for the simple reason that I don’t want to start a new season with a barrel that I know will not last the year.
Just some more wood on the fire.
Joe
When I initially came up with the design for this cartridge one of my goals was to get away from coating bullets.
I have been playing with moly coated bullets for one reason. I shoot the same rifle for across the course competition as for 1000 yard competition. Many of my fellow competitors are shooting straight 243 Winchesters with more velocity, using moly coated bullets.
Obviously, or maybe not, the choice of powder has to change when using moly coated bullets.
Initially, my tests with moly proved that my current loads with H1000 (49.0 grains behind both the 108’s and 115’s) had velocities reduced by as much as 150 fps with the same load.
I’m not going to waste your time all of my testing, but I have landed on two loads with moly coated bullets that initially appear to shoot very well.
With the 108’s I’m shooting 51 grains of H1000. This is giving me a velocity of just over 3100 fps. I use a drop tube to charge the cases and powder fills up to inside of the shoulder, but not into the neck.
With 115’s (Berger VLD) I’m shooting 49.0 grains of N4350. This is with the bullet jumping .040†into the rifling. Velocity is a stunning 3261 fps with ES of 7 fps from the one test of 5 shots. This is an increase, in my current barrel of over 300 fps from my standard load of 49.0 grains of H1000 with uncoated bullets.
With both of these loads the bolt lift is easier than the loads with uncoated bullets and the primers and brass have no signs of pressure.
I assume there will be some decrease in barrel life because of the use of H4350 for my 600 and 1000 yard loads with the 115’s. However, history has proven that with H1000 I am getting, consistently, 4000 rounds out of every cut rifled barrel (.237 dia, straight 4 grove); and given that fact I’m hoping that the introduction of H4350 for my “long range loads†will not affect the meaningful barrel life. (Meaningful barrel life to me is one season in which I normally fire between 3000 and 3500 rounds) My long range loads will be fired through the barrels for a maximum of 33% of the rounds.
My feeling is that the increase of 300 fps out of the 115’s is more valuable than the expected decrease in barrel life of a few hundred rounds.
It is important to note that I don’t know how long any of my barrels could have or would keep shooting accuracy to be competitive at the highest levels. I have always changed my barrels at the end of a season for the simple reason that I don’t want to start a new season with a barrel that I know will not last the year.
Just some more wood on the fire.
Joe
rcw3
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Joe
49 gr. of H4350 with a 115 gr. moly coated bullet in the 6CM? Just a knee jerk reaction but that just does not seem correct. Are you sure you mean H4350? H4350 seems too fast a powder to put 49 gr. in there with a 115 gr bullet. Maybe I am wrong but I would rather people are safe than sorry.
Robert
49 gr. of H4350 with a 115 gr. moly coated bullet in the 6CM? Just a knee jerk reaction but that just does not seem correct. Are you sure you mean H4350? H4350 seems too fast a powder to put 49 gr. in there with a 115 gr bullet. Maybe I am wrong but I would rather people are safe than sorry.
Robert
Robert,
In my testing I couldn't believe it either. I agree it seems like way too much H4350 behind the 115. Initially I started with 42 grains and that produced low velocities and no pressure. I skipped the 43 grain load and went to 44 grains....again no pressure...went to 46 grains and no issues. On the first day of testing that was the maximum load of H4350 I had loaded (46.0).
The next day I went out with 45.0, 47.0, 48.0 and 49.0 test loads of H1000 with the 115. I started with 45.0 just to confirm my findings from the previous day. All was good and worked up to the 49.0 load and I don't believe it, but there are no pressure issues.
I still didn't believe it, but I went to a Malvern OH with the 49.0 load of H4350. The 49.0 of H4350 shot a 200-13X at 600 (should have been more X’s as it held great elevation). And like I said before there appears to be less pressure with this load than the 49.0 H1000 with uncoated bullets.
I'm going to shoot it again this weekend and then at the state championship next.
Understand that I am shooting coated bullets (moly), also I'm jumping them.
Apparently coating the bullets makes this much of a difference.
Let me say this, before anyone else tries this load, work it up from book. Be smart and safe.
Joe
In my testing I couldn't believe it either. I agree it seems like way too much H4350 behind the 115. Initially I started with 42 grains and that produced low velocities and no pressure. I skipped the 43 grain load and went to 44 grains....again no pressure...went to 46 grains and no issues. On the first day of testing that was the maximum load of H4350 I had loaded (46.0).
The next day I went out with 45.0, 47.0, 48.0 and 49.0 test loads of H1000 with the 115. I started with 45.0 just to confirm my findings from the previous day. All was good and worked up to the 49.0 load and I don't believe it, but there are no pressure issues.
I still didn't believe it, but I went to a Malvern OH with the 49.0 load of H4350. The 49.0 of H4350 shot a 200-13X at 600 (should have been more X’s as it held great elevation). And like I said before there appears to be less pressure with this load than the 49.0 H1000 with uncoated bullets.
I'm going to shoot it again this weekend and then at the state championship next.
Understand that I am shooting coated bullets (moly), also I'm jumping them.
Apparently coating the bullets makes this much of a difference.
Let me say this, before anyone else tries this load, work it up from book. Be smart and safe.
Joe
I stopped at 49.2 grains of H4350 in my 6-284 using naked 105 hybrids seated .015" from touching. This was a .236 bore 5R Bartlein 28" and they were running 3350fps. I'm joking when I say this, but the 6CM really is the "magic" cartridge. I wish I had known more about this cartridge before going with the 6-284. Keep it humming Joe.
Jason
Jason
rcw3
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You look at Hodgdon's website and the max load for a .243 Win with naked 107 Sierras is 37.5 gr. of H4350. Now o.k. the 6CM has a couple grains more in water capacity, and the Hodgdon loads are conservative, and you are running moly, although the heavier 115's increase pressure over the 107's, but 11.5 gr. of more powder still seems like it should be off the charts pressure wise. Maybe the joke's on me but I just have a hard time wrapping my brain around a load that stiff out of a cartridge with that capacity.
Robert
Robert
It does seem a bit high. I hit strong pressure in a 6mm Remington at 46.0 H4350 and 105 Hybrids. Granted, they were not moly coated but my Remington cases have 57.6 grains water capacity. That load was over 3400 from a 32" barrel and was pretty hard on the case. [br]
Just my 2¢.
Just my 2¢.
Somebody needs to clarify these loads before someone blows a gun up. 
IMHO
Regards, Paul
IMHORegards, Paul
boltfluter said:Somebody needs to clarify these loads before someone blows a gun up.
Regards, Paul
What loads in this 14 or so page thread would you be referring to?
One would think common sense would dictate a person work up any new load for a particular rifle cartridge combination he may personally own.
No?
Personal testing data is just that,,,right?
Guys its been a while since I posted on my 6CM and where im at with it.......Well i can say it is doing just fine.
5-shot group at 380yd 50.0 H-1000 108 berger (bullet in shoot-n-see was from previous session)
6-shots 400yd 108 bergers
Shot this Tuesday 9-11-12
match this Saturday 250yd match again with 108's
5-shot group at 380yd 50.0 H-1000 108 berger (bullet in shoot-n-see was from previous session)
6-shots 400yd 108 bergers
Shot this Tuesday 9-11-12
match this Saturday 250yd match again with 108's
awww...come on at least tell us what distance ;D... Good conditions I can group the 108's at 400yds like that...no BS either. 
Still good groups and this is what Im seeing so far with this caliber.... However there are other good ones too that burn less powder but lack the extra 150 fps. But I like what im seeing from it so far and have no desire to switch.. Thanksyou to the ones that have contributed to the success and making there finding public for all of us to see and enjoy.
Im fixin to chamber 2 more, One for me and another for a buddy. We are having both rem. actions on hs precision stocks and both will have benchmark 1-7.78 twist for the 115's and whatever we decide to shove down the barrel.
Varmin and critters look at!!
pics of the comp. rifles
Still good groups and this is what Im seeing so far with this caliber.... However there are other good ones too that burn less powder but lack the extra 150 fps. But I like what im seeing from it so far and have no desire to switch.. Thanksyou to the ones that have contributed to the success and making there finding public for all of us to see and enjoy.Im fixin to chamber 2 more, One for me and another for a buddy. We are having both rem. actions on hs precision stocks and both will have benchmark 1-7.78 twist for the 115's and whatever we decide to shove down the barrel.
Varmin and critters look at!!
pics of the comp. rifles
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