6CM testing Results
- Thread starter joesr
- Start date
Did some shooting with my 6cm sunday. Shot steel at 500,800,1000.. Had first rounds hits on all except 1000. Lowered. fps 15 in shooter program. And then continued to have a great time. 1000 yard plate was 10x10. No problim. Couldnt see it with nacked eye. But loved watching it bang when berger hit it.
I started this year doing some experimenting with moly coated bullets and H4350.
On target results were GREAT. Very high X counts and very good groups off the bench.
Chronograph results were even better. 105 Hybrids at 3308 with ES of less than 10. 46 Grains of H4350 and BR2 primers.
After about 1500 rounds I checked the seating depth of the chamber. The chamber had moved .040â€. That is more than it moves after 4000 rounds with H1000!
The barrel still shoots extremely well. Two weeks ago shot a 200-14X at 1000 yards. (115 Berger VLD with 48.0 H1000). However, I can tell there are some signs of the barrel going. My zero’s are changing every day for the short line loads (mag length ammo), and that is an issue.
It is important to note that during my moly experiment I shot H1000 for more than ½ of my rounds and H4350 for only my long range loads (600 and 1000 yards). Even 40% (estimated) of the rounds during the first 1500 with H4350 it was tearing up the barrel.
Bottom line is that I confirmed, to myself that for the game I play, this cartridge is best suited shooting only H1000 or a similar very slow burning, single based powder. As soon as you try to push the cartridge by utilizing a slightly faster burning powder barrel life suffers.
I thought I would share this so that no one else has to go through the experiment.
Joe H
On target results were GREAT. Very high X counts and very good groups off the bench.
Chronograph results were even better. 105 Hybrids at 3308 with ES of less than 10. 46 Grains of H4350 and BR2 primers.
After about 1500 rounds I checked the seating depth of the chamber. The chamber had moved .040â€. That is more than it moves after 4000 rounds with H1000!
The barrel still shoots extremely well. Two weeks ago shot a 200-14X at 1000 yards. (115 Berger VLD with 48.0 H1000). However, I can tell there are some signs of the barrel going. My zero’s are changing every day for the short line loads (mag length ammo), and that is an issue.
It is important to note that during my moly experiment I shot H1000 for more than ½ of my rounds and H4350 for only my long range loads (600 and 1000 yards). Even 40% (estimated) of the rounds during the first 1500 with H4350 it was tearing up the barrel.
Bottom line is that I confirmed, to myself that for the game I play, this cartridge is best suited shooting only H1000 or a similar very slow burning, single based powder. As soon as you try to push the cartridge by utilizing a slightly faster burning powder barrel life suffers.
I thought I would share this so that no one else has to go through the experiment.
Joe H
Joe, [br]
I would characterize H4350 as more than "slightly" faster than H1000. The obvious next step faster than H1000 would be H4831. H4350, while producing excellent results in a variety of cartridges, is known as hard on barrels. If you have enough case capacity, VV N165 might be a good prospect. It has a lot of the same characteristics as H1000, the caveat is cost.
I would characterize H4350 as more than "slightly" faster than H1000. The obvious next step faster than H1000 would be H4831. H4350, while producing excellent results in a variety of cartridges, is known as hard on barrels. If you have enough case capacity, VV N165 might be a good prospect. It has a lot of the same characteristics as H1000, the caveat is cost.
Dang Joe, "Two weeks ago shot a 200-14X at 1000 yards." Thats kick a$$. That 6CM never stops amazing me. Altho it takes a great trigger driver to shoot that score also.
Joe, having what i think is one of the mid length reamed barrels what is your thoughts on throating it out so the bullets could be seated out longer and get closer to that neck/shoulder junction?
Thanks,
jim
Joe, having what i think is one of the mid length reamed barrels what is your thoughts on throating it out so the bullets could be seated out longer and get closer to that neck/shoulder junction?
Thanks,
jim
Jim,
You can do that. However, I have tried it and it actually has had no effect on accuracy or velocity. The accuracy with the original reamer is under ½ MOA at all ranges and probably closer to ¼ MOA from most barrels.
Velocity does not improve, but requires ½ to 1 grain more powder to achieve the same velocity due to the slight gain in case capacity.
My new reamer is slightly longer, but still has the 115’s seated so that the boattail is below the neck/shoulder junction.
I don’t know who came up with the idea that for boattail bullets you have to keep the body of the bullet inside the neck and not below. I understand that for single shot actions where you want to maximize case capacity. However, the myth that seating the bullet deeper affects accuracy, in my experience is just a myth.
Do what you think is best for your shooting. I don’t think you will improve accuracy or hurt the accuracy. Also, I think the velocity we get with H1000, with the shorter reamer is about the same you will get with a longer throat. You will just need slightly more powder.
Also, I have had some people try longer barrels than 28â€. Conventional wisdom would be that the H1000 isn’t all burned up on a bullet exiting the 28†barrel and possibly a 30 or 32 inch barrel could increase velocity. The feedback I have, from several shooters is that a longer barrel makes no difference. Velocities are all but identical from a 28†barrel and a 32†barrel.
One would reason that the velocity would either go up or go down when changing the barrel length by 4â€. However, real world results show it is all but the same.
Joe H
You can do that. However, I have tried it and it actually has had no effect on accuracy or velocity. The accuracy with the original reamer is under ½ MOA at all ranges and probably closer to ¼ MOA from most barrels.
Velocity does not improve, but requires ½ to 1 grain more powder to achieve the same velocity due to the slight gain in case capacity.
My new reamer is slightly longer, but still has the 115’s seated so that the boattail is below the neck/shoulder junction.
I don’t know who came up with the idea that for boattail bullets you have to keep the body of the bullet inside the neck and not below. I understand that for single shot actions where you want to maximize case capacity. However, the myth that seating the bullet deeper affects accuracy, in my experience is just a myth.
Do what you think is best for your shooting. I don’t think you will improve accuracy or hurt the accuracy. Also, I think the velocity we get with H1000, with the shorter reamer is about the same you will get with a longer throat. You will just need slightly more powder.
Also, I have had some people try longer barrels than 28â€. Conventional wisdom would be that the H1000 isn’t all burned up on a bullet exiting the 28†barrel and possibly a 30 or 32 inch barrel could increase velocity. The feedback I have, from several shooters is that a longer barrel makes no difference. Velocities are all but identical from a 28†barrel and a 32†barrel.
One would reason that the velocity would either go up or go down when changing the barrel length by 4â€. However, real world results show it is all but the same.
Joe H
Both of mine are Krieger's, both 7.5 twist, 1 is 30" and 1 is 27". I have a Lawton that is 7.65 twist that Dave Bruno chambered orginally, and the previous owner had his BIL rechamber from a Lawton action to a Savage action and short chambered it. I melonited the Lawton barrel before finding this out :
, so had an extra die and had a buddy cut it down. Now I really have a custom cartridge, I call it the 6CM Short. It will get 105's out of it hopped up fast.
My 27" barrel is at round count of 3900+.Still shoots realgood. My 30" is at 1300. My next barrel will be a 1-8 twist using 105 class bullet.. I have used nothing but H-1000 in the 7.5 barrels.
, so had an extra die and had a buddy cut it down. Now I really have a custom cartridge, I call it the 6CM Short. It will get 105's out of it hopped up fast.My 27" barrel is at round count of 3900+.Still shoots realgood. My 30" is at 1300. My next barrel will be a 1-8 twist using 105 class bullet.. I have used nothing but H-1000 in the 7.5 barrels.
The only barrel that I mentioned here that is melonited is the Lawton. I did not check the chamber with my 6CM go-gauge prior to sending it and 5 other barrels 4 which belonged to friends and the 6th was my 7RSAUM. The Lawton barrel is stored away, waiting for the 27" to go south. I will run it in Tac and have Dave chamber me another 6CM. As far as meloniting goes, in fact if that is the correct wording for it, I don't know other then what I've read. I've only put 75 rounds down the 7 and the Lawton barrel has not been fired since treatment. The only thing I can go on is accuracy is still there, and I do not believe Butch Lambert would steer you wrong, among someother well knowns. Real Happy with the 6CM (Competition Match) Thanks Joe.
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