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BobLor
Reply with quote  #1 
How is the 6CM cartridge doing have not heard too much lately?
joesr
Reply with quote  #2 
Bob,

I am the creator of the 6mmCompetitionMatch cartridge. We have about a dozen chamberings out there right now, and all of the feedback I'm getting is just as I expected.

The accuracy is under 1/2 MOA from almost every load tested and once a load is picked by the shooter it is better. Some shooters claim better than 1/4 MOA from their best loads. I am not keeping a log as to the distances my customers are testing loads, however all are 200 yards or more.

The most interesting thing I'm hearing is on the topic of velocity. Some of my shooters are pushing this cartridge. Shooting the 115 DTAC and H1000 the reported velocity is 3,150 fps and with N560 3,300!

I'm sure the N560 load is going to affect barrel life. However, this report is very impressive. I expected the velocity result from H1000 as the 6CM has larger case capacity than the 243 Win. and we were able to get 3,050 fps with H1000 from the 243 Win.

However, I'd like to have some of my customers report on this so that you can hear it from them.

Good Shooting,

Joe Hendricks
Hendricks Shooting Improvements
hendricks4@comcast.net

45acp
Reply with quote  #3 
I have close to 1500 rounds through the 6cm. A good portion of the round count was from load testing. I've used VV560, VV165, H1000, H4350, H4831, RE22.

I wanted to fully explore the possibilities of the new cartridge in terms of velocity, accuracy and barrel life. Here is what I learned:

1. All above listed powders will shoot sub 1/2 minute groups.
2. The most powder I shot with, that would fit in the case and still be reasonable in pressure was 51gns of H1000 - so, case capacity is significant.

3. Fastest I could push 115 DTAC - 3340fps. This was when it was 31 degrees outside, and the barrel was new. I was using close to 49 grains of VV560. I tried the same load when it was 70 degrees, and the barrel aged 600 rounds, and the results were NOT similar. The pressure was much higher (blown primer) and the velocity was much lower (3280 fps). Therefore, I have settled on VV 165 pushing a 115DTAC at 3230 as my 600 - 1000 yard load. It only gives .4 to .5 moa, but my targets are big enough for that not to be an issue (High-Power Rifle Comp.)

4. If you are looking for fast lock-time for off-hand - go to Sierra 70 MK. The 6cm will throw it out there at around 3500 fps. with no pressure signs. I use H1000 for that one.

5. In an effort to increase barrel life, I searched for an accurate reduced load for 200 yard rapid strings. If you use Hornady 105Amax or Sierra 107 moly MK, Load 43.5 of H1000 for a velocity of 2790 fps. This has almost no recoil and is the most accurate of all I have tried. I have several 1/2" 200 yard groups from both bullets. This being said, the 6cm is capable of pushing the 105 and 107, seated deep for rapid fire which increased pressures, at around 3200 fps safely. For slow fire with bullet seated out more, you can easily get mid 3300's...but that is not necessary at short ranges (1-300 yds)

6. Throat erosion at 500 rounds - .010
Throat erosion at 1000 rounds - .015
Throat erosion at 1500 rounds - .019

I think I caused the majority of the early erosion by testing velocity limits during the first 500 rounds. Since I have stopped that stupidity, you can see my erosion has slowed.

7. At the rate the erosion is going, and watching all deterioration closely with my borescope, I am predicting a barrel life of 3000+. I will keep you updated if you want - just send a PM - I'll respond as the barrel progresses.

Conclusion: I shot the 6xc last year and went through 3 barrels. My wife chased me around the yard with a baseball bat when she found out how much I spent on barrels. I switched to the 6cm because I believed in the concept of using very slow powders to reduce throat damage. This was not possible in the 6xc due to case capacity limiting velocity. With the 6xc, using a relatively fast powder like H4350 would only push the 155 at 3030 fps max. That was with a fast powder filled to the mouth! With the 6cm, I am now able to reduce my loads with the 43.5 H1000 load, and still get the same accuracy as the 6xc but with less throat erosion due to the slower powder. I have confirmed this with my borescope - it is no longer a hypothesis.
Since most of my shooting is at short ranges (75%) I can use that reduced load 75% of the time. However, when the occasion arises for the need for speed - the 6cm is ready for that challenge with its 51-52 grain case capacity. It's hard to beat a 115 DTAC moving at 3300 fps - check your wind charts - it is almost a scoring ring difference at 600 in a 10mph crosswind vs the 3000 fps 6xc.

That's all I know...hope that helps
BobLor
Reply with quote  #4 
Great report, makes me more anxious to receive my 6CM barrel
Bob Lorenz
rhino
Reply with quote  #5 
what is the 6cm made from?

RHINOUT!
45acp
Reply with quote  #6 
It is fire-formed with un-touched .243 brass. In other words, no sizing down necessary before fire-forming. If you think about it, that should tell you what the chamber dimension are. Fire-forming a 243 case moves the shoulder up and forward to 30 or so degrees. There are a few other differences in dimensions, but none so severe as to cause stress on the case being fire-formed. Those whom have fire_formed a 6xc from 22-250 brass know all about that concept....

rcw3
Reply with quote  #7 
45acp

You have made informative and detailed postings here, but I always find it hard to evaluate forum postings and place the information posted in perspective when the poster won't put his or her name to it (kind of like trying to evaluate an anonymous tip).

It see you just registered on the forum and these are your first postings. Perhaps you will let us know who you are?

Robert Whitley
rhino
Reply with quote  #8 
So basically its an Wildcat .243.

What advantage does it have over a 243 WSSM which I am planning as my 6mm project? Other than the obvious use of Lapua brass?

RHINOUT!
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