KMM696
NES Member
Nice!!! That's a deal even if the barrel were halfway done. Let us know what you think of that action when you get it all put together, will you? I've been drooling on Bighorn's stuff for a while.
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Changing calibers on a Savage model 10 for a PRS training rifle. Tools required? Process? Parts? Bolt head??
- Thread starter dcmdon
- Start date
6 CM would be a closer match to 243 Winchester.
- 6 CM has a 2k psi higher SAAMI max pressure
- 6 CM is a shorter cartridge to let you load longer/heavier bullets at mag length
- 6 CM usually tops out at 112gr bullets, 243 win usually tops out at 100gr bullets
- 243 win usually has a twist rate of 1:9 or 1:10
-6 CM usually has a twist rate of 1:7 or 1:8
- Using the same bullets, 6CM is usually faster than 243 win thanks to the increased pressure
- 243 win has a shallower shoulder, so theoretically it will be more likely to feed if there is something off with the mag/follower
Now, if you had a custom 243 barrel made with a tighter twist and had the room in your mags or didn’t care about mag-length cartridges, you could definitely run 243 win that was functionally nearly identical to 6 CM.
But as far as 6.5 CM, I think it easily fills any of the past roles for 243 win.
dcmdon
NES Member
My goal from the beginning of this thread has been to build a .223 training rifle. Something accurate that is cheap to shoot.
But with that said, the .243 is a 6mm rifle.
So let's compare .243 vs 6.0 Creedmoor.
Generally speaking the newer cartridge has been designed to throw a heavier, longer bullet longer distances. Its MV is going to be lower, but the bullet's aerodynamics will be better.
Factory ammo for a 6mm Creedmoor ranges from about 85 gr to 115 gr.
In contrast, factory ammo for .243 runs in the 75gr to 100 gr range.
The other issues with the .243 are that the case has a very short neck which introduces variability when loading heavy bullets.
Finally, the last issue, and this is relevant to factory rifles only is that rifles chambered in .243 tend to have a slower twist, which is optimized for lighter bullets.
I hope this helps.
This is a great article written by one of the truly really really freaking smart guys doing YouTube videos in the gun world.
243 Win -vs- 6mm Creed (Which is better?) – Ultimate Reloader
ultimatereloader.com
groundscrapers
NES Member
thread it and put a brake on it. It should settle fast enough to watch for trace. Spotting trace with a .223 is a little harder however.My goal from the beginning of this thread has been to build a .223 training rifle. Something accurate that is cheap to shoot.
But with that said, the .243 is a 6mm rifle.
So let's compare .243 vs 6.0 Creedmoor.
Generally speaking the newer cartridge has been designed to throw a heavier, longer bullet longer distances. Its MV is going to be lower, but the bullet's aerodynamics will be better.
Factory ammo for a 6mm Creedmoor ranges from about 85 gr to 115 gr.
In contrast, factory ammo for .243 runs in the 75gr to 100 gr range.
The other issues with the .243 are that the case has a very short neck which introduces variability when loading heavy bullets.
Finally, the last issue, and this is relevant to factory rifles only is that rifles chambered in .243 tend to have a slower twist, which is optimized for lighter bullets.
I hope this helps.
This is a great article written by one of the truly really really freaking smart guys doing YouTube videos in the gun world.
243 Win -vs- 6mm Creed (Which is better?) – Ultimate Reloader
article misses on one major factor of why 6 creed raised and kinda lost its original popularity. a 3k+ fps bullet means you will wear out your barrel in around 1k shots.
so 6mm dasher or BR caliber that uses same 105/107gr bullet but uses 30gr powder instead of 40+, and speeds at 2700-2800 fps quite dramatically increases longevity of the barrel.
I mean, you can run slightly slower loads in 6 CM easily. It’s not a huge case where you’ll have variability due to too little powder. Then, if you have an occasion to need a faster bullet, you can use it.
Yeah, factory 6 CM is going to be on the hotter side, but Dasher and BR don’t even have factory offerings, so that’s moot.
Lastly, a comparison to 243 Win means hunting implications to me. On snipershide, 6CM users seem to be getting closer to 1,500 and that’s with competition use, 1,500 rounds for hunting is a lot of life for most hunters, and I’m sure the barrel life would be extended if you’re not shooting 10 round quick strings for the life of the barrel.
dcmdon
NES Member
I agree with you. But the comparison was between 243 and 6 CR and barrel life between those two should be pretty similar.
Similar MVs for a given weight, similar powder capacity, etc.
If I build a PRS style 6mm gun, it would probably be a 6 GT based on what I know now. I'm not going to pretend to be an expert. It seems reasonable. But there may be better choices. From what I've read, the primary benefit of slightly longer 6 GT COAL is better feeding from AICS mags.
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