You're the first and only person I've heard of that has damaged that area of the lower and found it needing replacement.
5r, marketing gimmick? No two lands pressing on opposing areas of the bullet is a gimmick? Had me sold when it shot better than my old Colt, resting, prone, or standing on hind legs like a man. That's some mighty fine marketing ploys.
It is 4140. Works good in car engines, so good enough for me!
meanmrmustard, you've been all over this forum touting how great the Smith Sport is and seem to take personal offense when someone disagrees. Hey, I admitted that it's a nice rifle for the price. I also admitted that it shot well. The fact of the matter is that the Sport is their "cheap" rifle and they had to cut corners to be able to bring it to market at its selling price. I'm not saying that there isn't value there. All I'm saying is that corners were cut. Even Smith recognizes this. If I remember right, the Sport uses 4140 for the barrels, but their M&P-15 uses 4150.
My opinion is that the better than average accuracy of Smith is due to the lack of chrome lining, not due to the 5R rifling, but I'll get to that. In any case, to say that there is something to 5R, just because the Smith shoots more accurately than your old Colt only shows that your testing method is lacking, since you have a whole test lot of TWO. All you can really say is that your Smith shoots more accurately than your Colt and this could be for any number of reasons.
As far as the trigger guard goes, are you proposing that it never happens because you've never seen it? I don't just use my rifle to shoot off of a rest at a range. For the times that I take my AR with me, I choose that rifle because it is tough, runs well in adverse conditions and is modular; so if something does get bent or broken, I can just swap the part out.
Tex, I'm a little surprised to see that you had this to say...
You talk about how their is no proof that 5r helps.. let me see your proof it doesnt help..just saying
I've also noted that you have quite a few posts on this forum giving opinions and making recommendations as though you have some experience with the AR platform; yet you have a thread running because you are having a very simple problem with a bolt stop that you can't figure out. There's nothing wrong with having a problem and asking for help, but it does indicate to me that you perhaps, do not have the experience that you are leading others to believe that you have. I became more convinced of this when it became apparent that you were unfamiliar with using ejection patterns to help diagnose problems and you had no idea what M193 was.
In any case, I'll answer your question. Over the past few years, messing with ARs and bolt actions, we (me and by buddies) have experimented with probably a dozen or so barrels. Barrels from Krieger, Rock, Bartlein, Pac Nor, etc. Some were three groove, some four groove, some 5 groove and some six groove. There were standard lands and grooves, polygonal and ratchet. What I've found is that a good quality barrel will usually shoot really well. No particular rifling exhibited any accuracy advantage over any other. As I said, I saw nothing that would lead me to believe that 5r offers any advantage over any other rifling, all other things being equal. What I have found that makes a difference is chrome lining. Barrels that are chrome lined do give something up in the accuracy department. The exception to this seems to be the Pac Nor (Noveske) barrels, which seem to exhibit very good accuracy with good ammunition.
What further confirmed my findings was a conversation that I had with the guys at Krieger. When I called to order my last barrel, I asked about the 5r rifling. The guy told me that I could have it if I wanted, but it really made no difference. The only reason they carry them is because people ask for them. I ultimately just told them to send me whatever I could get the fastest, which turned out to be a four groove version.
I'm not trying to knock anyone's equipment. I already said it, the Smith, and a few others, are nice for the price, especially if you're just going to be taking it to the range and plinking or leaving it at home for whatever role.
Guns are like anything else. There's good and there's good enough. From what I understand the OP has $1K to spend on a rifle so I don't see why he should settle for good enough when he can get good.