I thought this would interest
@frenchman. I vaguely recall a debate over the accuracy of the SL8 though I can't find the thread/posts. Anyway, this is directly related to the thread title as this doesn't get more Euro 5.56 than the HK G36.:
Mounted my Trijicon VCOG 1-8x on the SL8/G36 conversion and zeroed at 100 yards this weekend. Unfortunately, I didn't have time to go through all the different bullet weights to figure out which was most accurate for the 1 in 7 twist bull barrel that comes on the SL8 (vs. the pencil barrel on the G36). What I know is that the heavier 5.56 match rounds are more accurate and consistent than the lighter ones. I ended up zeroing with M855 (I have a ton of it), and then shot some 69 and 74 grain match ammo. 69 was decent, 74 was more so.
Rifle is sub MOA with the right ammo. Didn't take a lot of work to get there either.
For specs: HK SL8 w/ 20" capped bull barrel converted by Black Ops Defense to an HK G36 with an 18" barrel w/ Surefire muzzle brake. Magazine is the HK mag conversion to STANAG mags, so it takes/shoots double stack mags vs. the proprietary HK single stack. Went with the ACR stock, because I prefer it to the standard G36 options and the AR stocks look silly on it. I opted for the Hera Arms Gen 2 lower vs. the G36 lower and mag block conversion. The Hera is aluminum, sturdy and well made and has various adapters for stocks. The pistol grip is more like an AR grip with texture and storage vs. the plain G36 grip. Internals are all HK, including the trigger. This allows an easy conversion back to an SL8, albeit one that could take single or double stack mags depending on the bolt/mag well used.
With optic, weighs in at 12lbs unloaded. Optic weighs almost 2lbs. Bull barrel accounts for a bit of this as well. For comparison, a G36 weighs in at 8lbs bare and an SL8 at 9lbs. I see the difference in weight vs. the G36 as the heavier barrel, aluminum carry handle (G36 is polymer), Hera aluminum lower receiver (HK receiver is polymer), VFG, sling, BUIS. ACR stock is slightly heavier than a standard G36 stock.
Only issues I've had with it are aluminum 10 round mags don't release properly. 30 round prebans work fine as do various polymer mags. However, I can't put 30 rounds in the mags, have to go with 29 as the mags won't sit properly and lock in otherwise. I vaguely remember a drill sergeant telling me back in basic to not fit 30 rounds in and always go 29 with various M16's back in the day, so maybe this is a more common issue than I recall. I'm old and can't remember well that far back.
Ergonomics are good. Manual of arms and dealing with jams (had one light primer strike and FTE) were simple to deal with and field stripping is quick, albeit not as quick as an AR and requires a tool to remove the rear screws holding the stock/receiver. Only issue I really have is the optic is mounted high and requires keeping your chin welded to the stock instead of your cheek. It's a little awkward and takes getting used to if you’re accustomed to an AR flattop. I may address it by getting a lower carry handle.
This is what the HK started life as: