Colt Doe Flattop Modernized Edition
Here is my ultimate h&r 635 form 1 sbr VA preban, I have had good luck with, thanks in part to this reddit forum and blowback9s youtube videos and research threads from this reddit forum. Performance is consistent with a 2:30 ejection with 124 grain maxxtech.
This project took weeks of ,off and on hand fitting and tolerance checking. After reviewing expenses this is roughly the most expensive forged and modern rollmarked ar9 I think you can build in blowback configuration that is duty grade.
Unloaded no magazine weight 6lbs 10 oz unloaded with mag 7lbs 4 oz
Build list:
Lower : H&R 635 Stripped black anodized doe lower with new spiral stainless roll pins, fresh colt smg ejector hand fitted, nfa form 1 engraving with the following included parts
Dark hour defense 7075 enhanced carbine buffer tube with anti tilt and 3 drain holes ( v seven 2055 lithium duty grade rebrand)
V seven titanium endplate dlc stacked twice
V seven anodized ul aluminum castle nut
V seven buffer retainer
Heavy buffers.com 12.5 oz carbine buffer w springco yellow(fitted bumper, was to long from factory)
Norgon ambi catch
Rail scales gi angled mag button
Kac trigger guard
Forward controls 601 take down pins
Magpul miad 1.1 with titanium grip screw and locking washer
Kns cnc nitride stainless selector and take down detents
Egw cnc nitride bolt catch plunger
Rock river milspec colt 9mm smg bolt catch (replaced included one was found tk be out of spec)
Kns .1550 gen 2 nitrided ss anti rotation pins for added strength
Rarebreed l315 frt trigger pack (november 2025)
Magpul ctr black with limbsaver stock pad
H&R 32 rd ss mags, have asc orange follower mags identical to the h&rs in next rotation that appear to be phosphate over the ss not glossy black.
Upper:
Colt cage code rollmarked smg flat top stripped cerro upper
RCA ar9 bcg (only bolt i could find with cnc ar15 extractor and integrated carrier key with no weight or finish inconsistency)
Iron City rifle works titanium 9mm TIN firingpin(reduce light strike chance and improve suppressed use)
V seven enlarged port door rod
V seven ultralight 9mm dust cover (oem was an a4 that was rounded and did not seal)
Giesslee urgi black charging handle
Arms 71 rear sight zero'd 25 yards
Holosun Aro Evo Spr red
Liemohn mfg DOE 1/2x28 chromelined 4140 threaded barrel assembly w heatshield and pinned front sight system
Cornstock armory 9mm 1/2x28 plan b nitride stainless compact flash hider w gen 2 accu washer rocksett'd
Was checked with carbonfiber 9mm dowell rod for concentricy with it being dead center
Suppressor
Brand: Resilent Suppressors RS9
Equipped with a forward controls branded revival defense nitride stainless plan b adapter torqued and rocksett'd
Port pop is not noticeable just alot of gas everywhere, not directly at the shooter indoors i did not get tears in eyes but i smelled enough carbon to think it was secondhand smoke from nearby chain smokers.
How reliable is the DOE Ultima and how did it function in frt?
Rof is roughly 790 unsuppressed, and 830 suppressed
After 10 32 rd mags of 124gr suppressed fire I had some hesitation inbetween springs of fire with no malfunction just a slight rubbing lurch between mags 7 and 9. That went away after switching to unsuppressed on the 10th i suspect its just break in and carbon build up, along with 2 failure to feed malfunctions when subjected to the same suppressed mag on 11 and 12, but went away when. When a different mag was used.
How accurate in frt ?
This has a surprisingly large amount of climb in FRT at 25 yards requiring I fire 3-4rd bursts to keep my groups within a fist sized hole suppressed or unsuppressed, with multiple points of contact from a barricade helping keep longer strings of 5-'6 rds within a dinner plate at 25 yards.
This is a tac driver with rds touching in semi auto at 30 yards, even with irons, with this arms 71 buis being very forgiving, the front sight post was aligned and pinned perfectly from liemohn mfg.
This is a very robust ar9 with recoil similar to my carbine 55.6 11.5 commandos with an h3.
In conclusion, with my final notes
I suspect if I get more hesitation I will switch to a springco white
I have a blueforce gear non padded black and grey pull tab sling not shown that i have for it if i wish to take it to matchs in the future going forward.