Double Duty rifle, 5.56 chamber, shooting 223 accuracy comprimise

I understand the difference in SHTF and match ammo.  My question is how much accuracy will I sacrifice by shooting 223 match in a 5.56 chamber.  I understand that 5.56 has slightly more generous chamber dimensions than 223.

I will be building  a new upper in an 18" SPR type config.  I would like for it to be as accurate as possible but also be able to use it for a SHTF rifle. I want to stock up on cheaper 5.56 ammo for general use and match type of ammo for hunting and longer range shooting.

Or can I buy match grade 5.56 ammo which will complement my SHTF ammo stash?

Use .223 Wylde which will retain the 5.56 body.

shouldn;t be an issue.  I can get 1 inch groups out of my chromed lined 5.56 bushmaster at 100 yards.

by using .223 in a 5.56 bore is less a compromise in accuracy and more of a failing to utilize the full potential of the weapon. I would think you are giving up more fps than accuracy.

Based on my admittedly elementary knowlege, I would assume this would more likely to effect fragmentation rates etc.

HTHb

Quoted: shouldn;t be an issue.  I can get 1 inch groups out of my chromed lined 5.56 bushmaster at 100 yards.

what he said

WHy would you get a SPR barrel with 5.56 chamber?  You guys are missing the point.  There is NO REASON to do that when you can use Wylde and have the same reliability.