Exactly how precise do you want to get? I only ask because the 18" FN barrel (if it’s the 18" CHF that I think it is) isn’t the most accurate barrel out there. Is it accurate enough to make combat effective hits out to 300 - 400 meters? Yes it is, but will it produce sub MOA groups at those distances? I’m not entirely sure it will, as precision shooting wasn’t what it was made for.
Yeah I’m not really trying to build a precision AR, and I don’t think the suburban and wooded environment around here really calls for it, I mostly just wanted something with a bit more range and accuracy potential than I’ve got now. The big question was whether it was better to modify what I already have or start over with a new upper.
Since I’ve already got the FN barrel it makes the most sense to use that, and with the distances the gun is most likely to be used at, it will probably be sufficient.
I’ve used the 16" CHF FN barrel on multiple builds, and had great success with them. If you chose your parts wisely you can build a functioning upper for a very small additional investment, probably $300 or less.
So I’m looking at low profile gas blocks and I notice that most of them, even BCM’s, seem to be the set screw type. I had thought that set screw gas blocks were kinda iffy, but are they pretty much the standard for low profile ones?
Get a large ballpeen hammer, large diameter punch(or a punch divoted for the taper pins), and a block of wood on a solid surface (concrete floor) and see if they will come out before making your decision on a rail. Should pop out unless the front sight was phosphated on the barrel.
Pretty much. Most folks dimple the barrel and they are fine. The Giessele blocks are set up for both. These are the ones I prefer: https://algdefense.com/carbon-steel-gas-block.html ($39.99) the stainless steel is twenty bucks more: https://geissele.com/super-gas-block.html
The instruction on the links should walk you through dimpling any gas block (drill sizes may vary).
Or you could hacksaw/dremmel and file/sand the existing gas block in place, and spray a little high-temp paint on it… then you have a pinned gasblock.
A properly shaved and dressed FSB is the most sturdy low-profile gas block you can have. It’s already on there and is already pinned.
If you want a LPGB on your existing barrel, this is the correct course of action.
Have you tried other ammo with it? Other match offerings may get you better results.
I was wondering about set screw gas blocks for the other barrel mostly. I’m leaning toward leaving the midlength barrel alone now, but if I change my mind about the midlength I’d definitely still opt to just cut the FSB down instead of replace it.
I’ve tried a few different loads in it. Oddly, despite the 1/7 twist the gun has shown what seems to be a slight preference for lighter loadings. Prvi M193 consistently shot better through it than Prvi “Match” 69gr, and it seemed to like 55gr Hornady VMax as well. Winchester Ranger 55gr SP shot pretty well too.
I decided to give the IMI 77gr a try because I wanted something that would hypothetically buck the wind a bit more. I’ve since seen that Magtech 77gr Match seems to be a bit cheaper on average than the IMI and I may give that a try too, but currently the gun is zeroed for the IMI and It’s what I keep on hand for the gun.
Not that you don’t already have enough opinions in this thread, but there are a number of free float rails that bolt up to a standard GI barrel nut… The easiest way to get the result you’re looking for is to take off your handguard, cut down the FSP in place, and install the free float handguard over the top of it.
FYI, for most handguards of this nature, you’ll have to remove the handguard retaining ring (AKA ‘slip’ ring, or ‘Delta’ ring) and spring, as well as the handguard retainer behind the front sight post. They are not reusable when you are finished, but they are inexpensive parts.
True, but you won’t find a more solid gas block than a shaved A2
Just as a point of interest, I took the gun in question out today and figured I’d shoot what I assumed was some mediocre NATO-reject Bosnian M855.
It actually grouped quite a bit better than I was expecting with the exception of the lower right hand group, which I’m going to go ahead and blame on shooter error.
Actually, operator-error flyers ruined a couple of otherwise pretty damn impressive groups. I was shooting off a bag but was still a bit wobbly today for some reason.
I suggest trying some federal or BH match offerings, 69 and 77gr, maybe some ithers as well, to see what it can really do. Different lots of 183 and 855 are all over the place. You look like that combo is shooting about 3” (are thise 3” circles on 3 of your targets?). A lot of what i thought was shooter error went away when i fed it match ammo.
Fed fusion is also good. I get 1.3” consistently with 62 gr, and ive seen similar numbers from other members.
I see a few 1” groups posted with the 75gr fusion.
…and try 10shot groups. The difference is significant IMO. Notice if you combine 2 of your groups above, any2, its almost the same as if you overlayed them all.
I am pretty sure I threw at least a couple of those shots but I measured each group with some digital calipers and wrote the size on each target. One group is 3.25", the one I botched pretty badly. The rest are all under 2", with the one in the large bullseye coming in at just under 1.5".
These are group sizes that aren’t that far off of what I get with with IMI 77gr “Match”. So I definitely think trying some other match loads is worthwhile.
My enthusiasm for dicking with this gun is starting to fade, even non-free floated, it really does seem to shoot fairly well.
Unless you are loading up a sling or bipod I don’t see a compelling reason to change to a FF.
I vote either A. Don’t dick with it because dicking with stuff is overrated (coming from a serial dick wither) or B. Centurion C4 Midlength Cutout Rail.
Sent from my iPhone using Tapatalk
I once was in your shoes, with a midlength FSP plastic hanguard AR. Mine had a Noveske N4 barrel that I felt had to have much more accuracy to offer. I went with the centurion C4 mid cutout requiring minor dremel surgery to remove the delta ring assembly and the handguard cap. Its a beautiful well made rail but my groups didnt really change.
With Irons, an aimpoint H1 and an acog the groups were very comparable to groups I shot with those optics prior to the barrel floating. The carbine was of course now much heavier and bulkier which I put up with till I switched it all back last summer and a much happier man for it.
Another midlength I assembled, a basic BCM with FSP also shot comparably in the week or two that I shot it with plastic hanguards as it did with the Geissele rail installed over a cutdown FSP. It was the same story with my first AR, a 16" bushy carbine, that I shot for a few years before upgrading to a troy vtac alpha rail. Loved the rail for what it was and for being my first AR project, but accuracy was not noticably improved then either. The bushy is long gone except the lower and the BCM keeps its rail, the basic BCM barrel so far being the favorite so far of the few AR barrels Ive had.
My take away from all of this (for me anyway) was that a rail probably will not dramatically or even noticeably improve accuracy. Id only consider it for a rifle built up with longer range shooting being the main purpose. Otherwise I dont attach enough stuff to justify it and plastic hanguards of today are 100x better than the old legacy plastic.
…and I havent touched any of my dressed up ARs in weeks since I picked up an LE trade in 6520 for myself. Id almost forgot what carbine really was!
Sent from my SM-T350 using Tapatalk
I’ve been shooting iron sights a lot lately as well. Mostly my Retro builds. I’ve got an LE trade-in 6520 as well though.
Yeah, despite my initial burst of interest in free floating the midlength I think I’m going to leave it alone. I’ll either build another rifle with the FN barrel at some point or save it for the next iteration of the current rifle when I eventually shoot the barrel out on it (probably years from now). At that point I’ll probably use a free float handguard but for now I guess I’ll stick with the ol’ A2 front sight base.
I’d consider trying the Centurion C4 but I rather dislike quad rails.
The only change I’m making to the gun at this point is to experiment with going back to a VFG in place of the handstop. Way back when this gun had an Aimpoint PRO on it I had MOE handguards and a Magpul VFG but when I started shooting it with magnified optics I found the VFG an impediment to shooting off a rest, so after I got the BCM PKMR handguards I stuck a handstop on there instead as a compromise.
In shooting it at closer ranges with the Steiner on 1X I found myself wanting an actual VFG again like I have on my HD carbine so I stuck my extra BCM short VFG on there last night, but put it farther forward than I had the Magpul, with the idea being if I were shooting off a bag or something the VFG in its current position might be far enough forward to not interfere. I’ll probably test that next Tuesday.
I’ve done a fair bit of 100yd shooting with the Steiner (I wish I had access to a longer range so I could test out the BDC but I don’t currently) but comparitively little closer range 1x stuff. I dunno if it’s my eyes or what (They do kinda suck) but I find the Steiner on 1x to be clumsy compared to an Aimpoint, or even irons. But, where I have my iron-sighted and red dot bases covered with other ARs, I thus consider the Steiner to mostly be pulling duty as a magnified optic first, with the ability to go 1x in a pinch. Still, I intend to work on that some more.