I am interested to know if the sighting radius of a 20" barrel makes any noticable difference in accuracy over a 16" barrel at 100 or 200 yards. (with iron sights) What is your experience? Thanks.

for me, very little, but after 200 yd., groups start growing.....

there was another thread about 2 weeks ago, search back, there were a lot of posts on this subject...........

Thanks Jem. I did find the post with a search of the word "accuracy."

You are talking about a 4" (16" midlength) or 6" (16" Carbine) difference in you sight length.

 My personal results have been mixed - with dedicated IRONS A1 or A2 handle I notice up to about 50% greater accuracy with the rifle over the carbine.  With normal BIS flatops guns I must admit that I have very similar resutls from carbine, midlength, SPR and rifle length sights.

Keep in mind I shoot Optics much more than irons these days.

HI  I have two BM's ,both flatops,a 20" and a 16"
w\ak break (14+ ")
I haven't done a head to head with irons so I can't
answer your question but----
I have done a test off the bench with the same lower with a nice trigger (jewell) and a decent scope(VXIII 3.5-10)
Various factory loads and a couple of handloads
Most loads shot tighter in the 20" by about 15%,could judge by eye the tighter groop.I tried
Win 55GR value pack (wall mart)
win 45gr Varmit      (wall mart)
BH 68 molly
BH55fmj
BH60sp
BH52 match
SA 55
The bh55fmj very nice 9/10 about 1" both guns
The win wall mart "Varmit 45gr" was about 1 1/4 in the short and a honest 1" in the 20". In my wall mart it sells for under $12 for a box of 40 I don't hunt game but the 45gr varmit was doing a job on pumpkins-only thing that would compare was some hot reloads in a 22-250 .  NHSPORT