Hey guys! Been lurking for a while and finally though that I could provide value to this fine forum!
From my time spent reading up on this and other rifle forums, it appears that the M400 has a ton of haters. That, coupled with the fact that I have only been shooting for about three months should provide all of the forum's seasoned members complete and utter free reign to continue with said behavior. Since I have no experience with Sig Sauer other than an SP2022 that has accurately gone bang every time I have fired it for the last 3K rounds, I figured would jump in head-first on my first long gun build. Prior to purchasing the M400, I owned a DPMS Oracle for about a week. This was long enough for me to watch a few hours of YouTube AR field strip/dis-assembly/reassembly videos, purchase a bunch of armorer's tools and and learn how to take an AR down to it's last roll pin. As soon as I had the DPMS apart I switched out the lower for a billet job, quickly lost interest with the whole thing and traded it in on a M400 SRP.
Since I am new to all of this I don't feel comfortable speaking to the finer details of the rifle's accuracy just yet. All I can do at this point is turn little holes into big holes at 25 yard indoor ranges where I have run roughly 1000 PMC/Winchester/Federal 55gr rounds down the pipe. First thing I did when getting the M400 home from the fun shop was to thoroughly heat it with my wife's hair drier, and meticulously remove all signs of grease/protectant/oil with Walmart-brand 91 percent isopropyl alcohol followed by three subsequent re-heatings with generous bastings of FrogLube in between. The rifle runs like a top!
My plan is to update this thread with range reports, round counts and modification updates. If the M400 is as bad as some seem think it will be, this thread will definitely reflect it's negative performance. Many changes have been made to the original configuration but the heart of the rifle is all there (barrel, bolt, bolt carrier, upper/lower receiver). I have no special affinity to the Sig Sauer brand and I only purchased this one due to me being a lefty. I don't plan on delving into any scientific analysis that ends up turning this thread into a 48 page 1-7 vs. 1-9 twist rate debate. I am just going to shoot the crap out of it, put it through a few carbine classes and report back. If it does end up performing well then this thread's value will be that some other guy may stumble across this review in 2-3 years and gain some knowledge on the M400.
Here is my current setup:
Sig Sauer M400 SRP (base to build on)
Sub-par (by Mil-Spec standards)
Different but adequate (in my own opinion)
Above and beyond
Bolt Carrier Group
-Chrome lined bolt carrier
-MPI bolt tested???
-158 Carpender steel???
-Shot peened bolt???
-Black extractor spring insert
-Enhanced AR15-type bolt carrier (larger than AR15 style, smaller than M16 style)
-Properly staked gas key
-Phosphate coated bolt and bolt carrier (http://www.americanrifleman.org/arti...-rifle-review/)
-41V50 Steel - NOT VERIFIED (http://forums.1911forum.com/showpost...9&postcount=50)
-Chrome moly steel barrel (http://www.shotbusiness.com/Article/...cfm?newsID=379)
-Chrome-lined chamber and bore (http://www.shotbusiness.com/Article/...cfm?newsID=379)
-Chrome-lined barrel - (SIGM400_SELL-print.pdf)
-Chambered in 5.56X45mm NATO (MiniManual_HR.pdf.)
-Rifling: 1 in 7" RH twist
-M4-style feed ramps
-"F" marked A2 front sight on Enhanced models - (SIGM400_SELL-print.pdf)
-Press-fit railed gas block with tapered pins (takes a Dremel to get it off the barrel)
-Phosphate coating under FSB (MIL-SPEC is "parkerize" under FSB)
-Gas Port - .063 NOT CONFIRMED (http://forums.1911forum.com/showpost...9&postcount=50)
-Phosphate coated barrel - (SIGM400_SELL-print.pdf)
-Barrel Countour: Mil-spec M4 Profile - (SIGM400_SELL-print.pdf)
-Barrel Length: 16 in
-Number of grooves 6
-Muzzle end - 1/2 X 28 TPI (MiniManual_HR.pdf.)
-Ovalized composite handguard (SRP model) with double aluminum heat shields
-Pin in barrel extension for relieving pressure on extractor when bolt is in battery
-Six position buffer extension tube (MIL-SPEC) - (SIGM400_SELL-print.pdf)
-Properly staked barrel nut
-Standard carbine buffer (MIL-SPEC is "H" but since the Sig's BC is a hybrid between the AR15 and M16 styles, the provided buffer is mated quite well)
-.154" Diameter Fire Control Group (FCG) Pins
-Lower receiver - 7075-T6 aircraft grade - (SIGM400_SELL-print.pdf)
-Tensioning device for upper to lower receiver (spring, detent and hex screw)
-Ambidextrous rear quick-disconnect sling mounts built in to the lower receiver
-Ambidextrous mag release
-Flared magazine well with beveling on inside for faster magazine location and seating
-Milled serrations on front of receiver for improved purchase
-Upper receiver - 7075-T6 aircraft grade - (SIGM400_SELL-print.pdf)
-"T" marked, flat-top MIL-STD 1913 upper receiver
-Square forge marking - Brass Aluminum Forging Enterprises
-Limited Lifetime Warranty (MiniManual_HR.pdf.)
-PWS SM556 Flash Suppressing Compensator (installed after these pics were taken)
-Rainier Arms/AXTS Raptor ambidextrous charging handle
-Daniel Defense clamp-on low-profile gas block
-Troy 11" Alpah rail (switched to 13" in FDE)
-Troy M4 F&R folding battle sights
-IWC flush-mount QD points (on front and rear of rail)
-Surefire Millennium 951 w/ M93 base in FDE
-Primary Arms 3X long eye-relief magnifier
-American Defense flip-away magnifier mount
-Troy Squid Grips (2 sets FDE, 1 set BLK))
-Larue Index Clips (3)
-Custom dust cover
-Giselle SSA 2 stage trigger
-B.A.D.-A.S.S. ambidextrous selector (short and long selector arms)
-Stainless steel pins, and detents
-Magpul UBR buttstock
-Magpul Enhanced Rubber Butt-Pad 0.70"
-Magpul MIAD grip
-Magpul MOE Trigger Guard
-Magpul P-Mags, 30 rd w/ windows (8)
-Magpul Ranger Plates (8)
-TNVC LED upgrade for Surefire 951
-5.11 36" soft case (not pictured - The case in the pics is a 36" Drago)
-Pelican 1700 hard case
-Larue Tactical Padded Sling (QD version)
Here are some pics:
Here is where I was playing with different colored Squid Grips:
..and here is my ghetto dust cover!
MODS: Please move this thread if it is posted in the wrong section. Not sure if this constitutes a "build".