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Posted: 2/10/2008 3:30:18 PM EDT
| I'm thinking of doing a spare lower up as a 20 inch 6.8.Any suggestions where to get a quality upper from?Kotonics seems to be good from what I can find. |
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I'd suggest the 18 inch Kotonics. Unless you plan to shoot iron sights, there is a very negligible velocity gain from 18 to 20 inches with the only advantage to the 20 inch being sight radius. In fact, 16 inchers shoot fine and wring about 98% of the velocity out of the cartridge. But something draws me to the 18 inch. I just think it will be a little quiter for hunting and maybe a little less muzzle flash. FYI according the 6.8 information page that is stickied at the top of this forum, you only lose 36 fps between 20" and 16" barrels. Probably make most of that up from 16 to 18" since 6.8 was designed for short barrels. -David Edgewood, NM |
If you plan to use one for hunting or comp and want to do a lot of proactice that is a great idea. You need to use the same stock trigger and scope on each. This way you will have the same trigger break, cheek weld, and sight picture. You could note your zeros and switch the scope back and forth if you use a LR mount. Then you could use the cheaper 5.56 to practice. Obviously to save money you would just need separate uppers. Thought this would be obvious but figured I'd better say it. It would also make you have to read the wind better as the 5.56 is a lighter bullet. Then use the 6.8 for Comp and hunting for more serious practice. The duplicate setup is really a great idea for the more CQB defensive setup carbines. As the round counts get very high when taking classes and with that type of practice. So you have a5.56 trainer and a 6.8 goto. I to agree with the 18" middy lenght instead of the 20". It gives about the most you can get from the SPC round becasue of case capacity. You can't use powders slow enough to take andavtange of the extra length. If the 18" is good enough for Navy and Army Spec Ops in their SPRs then it should work for us. Also the 20" uses the rifle gas system which was never meant for the 6.8 and is less versitle. It doesn't like low pressure rounds because of the pressure curve of the 6.8 and can short stroke. Cold weather also can excasberate this. With what I have in mind going forward, I would get a 18" 6.8 if I could do it over. I would have a 18" SPR type in 6.8 SPC then a 12" SBR in 6.8 build with a duplicatge of it in 5.56 for training. Both 12" would have the PWS Piston System on them. I will probably still do this. I think the 6.8 is the ideal CQB, SPR, DMR round based on their discribed missions. Tim |
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