If you can't find an aem5. Just an option
- Thread starter Nostradumbass
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If you can't find an aem5. Just an option
I finally finished my mk12 mod1 this afternoon. I can't find the correct a.r.m.s. rings so it's running mark 4s for now. I want to replace the trigger and I have my eye on the correct front sight, but money is getting thin! All things considered, it's up and running at least.
Have you used one of these? I went to the site and I’ma little unclear about building the baffle system
If you can't find an aem5. Just an option
The rifle is so much easier to carry and quieter than what was around at the time (2008). Got to play with one overseas. The 77gr ammo and suppressor made a pleasant diversion from standard fare. Not to mention breaking contact was safer with a full auto; suppressor off and lots of fire & noise! The other options were less "cool" M110 (bit of a long pig), M14 EBR, and of course the M107 (pack mules were hard to come by
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) No I haven't. Unfortunately I live in a state that I can't own one. Do some research on form 1 suppressor. Tons of info and a friend of mine just moved to Montana and filed for his form 1 and was good to go in 30 days
I’ve done form 1’s before. I’m just curious about the baffling for this system.
From my understanding there is a spacer built into the back of the tube to create a chamber behind the muzzle. Looks like cups only go so far down the tube and hit a stop. I may be wrong on that though. Never used this.
The looks of it with the carbon handguard, the AEM brake/collar and suppressor. The military history is also cool but less important to me.
As far as being clone correct and costing a fuckton, I think thats dumb to do.
Is there a more capable 556 rifle you could build? Sure, on paper at 100y.
In a practical application though, I'm not sure how much more capable you can make a little 77gr bullet at range, regardless if it groups 1/4" better than the old outdated MK12.
As far as being clone correct and costing a fuckton, I think thats dumb to do.
Is there a more capable 556 rifle you could build? Sure, on paper at 100y.
In a practical application though, I'm not sure how much more capable you can make a little 77gr bullet at range, regardless if it groups 1/4" better than the old outdated MK12.
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So here’s where I am so far, still need an optic. No where near clone correct but it makes me happy. One major problem though, it’s not cycling correctly. Ejects spent case at 3 O’clock, bcg doesn’t lock back on empty mag or load a second round. Air moves freely through the gas system with a plugged chamber and air introduced at the muzzle. I only fired 5 rds of Win M855 through it. BCG was torn down and oiled properly prior to testing. 
Every part is new, do I send a hundred rounds through it one at a time to allow parts to mate up? Doesn’t seem right. What do I do?
Specs:
Aero upper and lower
Aero NiB BCG
BA premium 18” SPR contour barrel
Rifle length gas
CMMG gas block triple checked for placement and carefully dimpled for set screw using a dimpling jig
Mil-spec internals/recoil spring/rifle buffer
Allen Engineering brake and collar
Specs:
Aero upper and lower
Aero NiB BCG
BA premium 18” SPR contour barrel
Rifle length gas
CMMG gas block triple checked for placement and carefully dimpled for set screw using a dimpling jig
Mil-spec internals/recoil spring/rifle buffer
Allen Engineering brake and collar
What's the gas port size?
.0935 is what ballistic advantage tells me. I don't have pin gauges to verify
And what about buffer weight? Dunno what the heat comparison would be between M855 and Mk262 but keep in mind the design is focused around that being the 262 which is definitely a warm load. Maybe try different ammo too.
Should be plenty. You can get a rough idea of port size if you have a decent selection of drill bits. I have a BA SPR barrel that had the same issues. Port was .07ish, had to drill it to .09ish to get function.
I'd love to get my hands on some 262, but it doesn't seem to be very available at the moment. The 855 is the highest pressure ammo I have in the stash. It's a mil-spec rifle buffer, I may play around with the weights just to experiment, but I think that is just a bandaid and not the right fix for the problem. I sort of expected it to work well with factory 855. Is it common to change rifle buffer weight to account for less dwell time in this configuration?
Depending on the ammo you run I would say yes in just about any case. But that’s starting to get out of my pay grade. Doesn’t necessarily have to be 262 that you try either. Really just anything other than the M855 just as a data point.
SG Ammo has their Mk262 in stock from IMI, got in some yesterday.
That’s a better port size than the .1-.105 called for in Mk12 specs as most here aren’t in need of Arctic capabilities.
An adjustable gas block really sweetened up how my .103 gas port barrel shoots.
I just saw the IMI in stock at SG. Ordering now and will give that a try prior to messing with weights. Thanks for the help gents.
I only have a handful of tungsten weights in order to dial in a 300BLK pistol and that's only going to make the buffer heavier anyway. I've been wanting to go with a JP setup since I first saw them and it looks pretty customizable so that's the route I'll most likely take if it comes down to it. Thanks for the tip. I had considered getting some aluminum bar stock and cutting lengths to swap out steel buffer weights to see what would happen, but I also don't want to cause premature wear on internals. First I'll verify again that air is moving through the system, but I'm confident that it is, then try the 77gr ammo, then mess with weights.
Absolutely. Let us know what you come up with.
Dump all the weights out and try it empty just for diagnostic purposes.
I found some supposedly mil surplus mk262 on gun broker recently it wasn't cheap and I didn't buy it but check there
So BA is known to jack up port sizes at times...just might want to check...
My "milspec" A2 kit had a weak recoil spring...went with Sprinco Green and cured my ejection pattern...
I guess I should get some gauges that allow me to verify the port size while I'm at it.
Hey guys, just an update real quick. I was able to hit the range today to do some testing. Still don’t have any 77gr. yet, but I wanted to shoot so I went out. I messed around with buffer weights. I acquired some .500” aluminum round and .500” delrin round. I don’t have a digital scale but I do have a cheap powder scale that only tells me grains. For scientific purposes, I measured out .600” lengths and cut the rods. Aluminum weighed in at just about 81 grains. Delrin was just about 42.5 grains. Fun project but swapping weights in the buffers did nothing for me to be honest. After fooling around for about 80 rounds the rifle started acting right, meaning it was stripping the next round off the mag and locking back on empty. I had the same issue with the M16A1 clone in the photo. Using Okay Surefeed 20rd and magpul M3 mags, the A1 clone is reliable in my mind, the Mk12 is still a little shaky but seems to be running much better. Nothing I own runs with tulammo, shocker, but seemed to be ok with PMC X-tac, did real well with M855. I’m hopeful with 77gr and now maybe parts are mated, things work well. I was running the bolt fairly wet with Lucas oil and it seemed to get gummy once dirty, not to mention it was only upper 30’s today, even though Lucas says -38*F. I don’t know. I cleaned everything and put light coats of Lucas CLP on everything. I’m waiting on an optic and the 77gr for the next outing and see how it runs. Today was a glorious escape. 
It's top 10 or even top 5 on my aesthetics list. The MOD 0 speaks to me. I haven't shot it but heard it's pleasing to shoot even if there are better options out there. I'll eventually get around to building something with maybe a folding stock and the handguard at least.
What optic did you decide on getting?
I decided on the Primary Arms GLx 2.5-10x44 with the FFP ACSS Raptor reticle, with their corresponding mount. It seemed like there were a lot of pretty good reviews on it across the net and I didn't really want to spend more than what it costs, especially since I have another rifle that needs some kind of optic as well. I'm sure it will fit my needs just fine. I'm currently shopping around for something 1-6 or 1-8 for a carbine. Sitting on a couple hundred rounds of 77gr to try out once the optic arrives Monday.
Boron Nitride / nickel-boron is nowhere in any .mil or USSOCOM drawings or specs.
I have not been impressed with ANY examples I've ever seen this stuff on, from the beginning when Fail Zero started pushing it at the Infantry Conference at Fort Benning.
Yes, it's hard. No, I saw no lubricity advantage over using a standard military bolt and carrier group liberally lubed with LSA, CLP, or a few others. Your experience is typically what I saw -- as the lube burned off it got gummy as fouling built up. It would be a lot worse with a suppressor.
Damn nice collection you got there.
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Thanks Sinister. Is there a different lube I should try? I got into the habit of cleaning and applying the Lucas Extreme Duty oil pretty liberally upon initial assembly prior to first shots.
With the SPR, I cleaned it real well Friday night after the range and used the Lucas CLP and followed this diagram:
With the SPR, I cleaned it real well Friday night after the range and used the Lucas CLP and followed this diagram:
I don't have experience with Lucas, although I know they make lots of automotive, bicycle, and gun stuff.
I've used LSA since I was a teenager back in the 20th century, otherwise Mobil 1 synthetic 30-weight motor oil in a plastic squeeze bottle. A GI quart can of LSA will last you several years.
What your graphic training aid (above) says is fair guidance. I usually put a drop or two in the cam pin track (one in front of the bolt cam pin hole, one behind) and on the bolt tail.
If it's shiny it gets a drop, smeared with your finger (shiney surfaces on the carrier, cam pin, and bolt). The firing pin gets lubed just being in the carrier.
Per the GI manual there's supposed to be a drop in the gas key, but I really think that just gets vaporized and blown out. Lube on the firing pin seems to help clean up quicker, though.
I've used LSA since I was a teenager back in the 20th century, otherwise Mobil 1 synthetic 30-weight motor oil in a plastic squeeze bottle. A GI quart can of LSA will last you several years.
What your graphic training aid (above) says is fair guidance. I usually put a drop or two in the cam pin track (one in front of the bolt cam pin hole, one behind) and on the bolt tail.
If it's shiny it gets a drop, smeared with your finger (shiney surfaces on the carrier, cam pin, and bolt). The firing pin gets lubed just being in the carrier.
Per the GI manual there's supposed to be a drop in the gas key, but I really think that just gets vaporized and blown out. Lube on the firing pin seems to help clean up quicker, though.
That's a darn shame.
My brother shot both PAC and LANT Fleet and the All-Navy as a Coastie. I started in 1999 as an (Army) invited guest and went Distinguished. I learned a shit-ton from the Navy teams (both East and West Coast) and shot with a LOT of active and retired sailors.
My first experience with 77s came from the Fleet Matches. All shooters (regardless military or civilian) drew Crane-issued commercial HSM 77s or M118 7.62. If you didn't have data you'd better at least be centered-up and zeroed.
I think part of the Mark 12/SPR's mystique came from the fact that on 9-11 it was really the only hot-rodded M4/M16 hybrid generally available to "Vanilla" (non-JSOC) SF/SEALs that was free-floated and had a reach advantage with different variable scopes that were not ACOGs or rare 1-4 Schmidt-Benders.
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We used to have a lot of Coasties in Hampton Roads that shot with us. We still have a couple. Maybe we all shot together one year.
I've got an ARMS #40 rear sight I'm replacing with a #40 L. If anyone is interested, send a PM.
I dont own one, but i did like i think it was chris kyles take on it. In the book i read he said he would swap in his m4 full auto lower, not because he ever used it but because he liked having options. Pretty damn cool
Hey Boone, can you give me some specs on this little guy? curious on barrel length, gas length, and handguard length. Thanks!
It’s just a Daniel Defense MK18 with a elcan 1-4. Not clone correct, as I’m not a purist.
Block II “clone” in the works currently.
I shot Atlantic Fleets 88-94. Shot All-Navy 88-94 with exception of 89 when I was recalled to the boat. Shot Interservice Rifle in 91 and Nationals in 93. In 91, the All Navy's were at Camp Pendelton, CA. In 1990 they were at Dam Neck and the PacFlt team shot on the East Coast. I think 94 was the last All Navy in a single location at Dam Neck. The guy who took the top Active Duty Grand Aggregate was CDR RJ Thomas, a Vietnam Navy Cross awardee (as a PO2 SEAL) who fought off VC with just his M1911A1 after a helo crash until help arrived.
We used to get a good contingent of USCG from Cape May. I remember Fred Tierney for sure. Shot with him on a pistol league in CT 96-99. There was a USCG GM (Dale Rader) that went to Crane to work under Dobber as a rifle armorer. Put together some nice M14s for the CG. We also got a bunch of Marines from MCSFBn who trained there and Army who knew folks at the matches and got in on the EIC matches. Lot of good times there, Quantico and Perry.
Back when I was shooting Navy, the only 5.56 issued was M193. There wasn't MK262 in general use yet. Even the NSWDG guys who shot with us at the matches had to shoot M852 (and in 89 or 90 we got M118 Special Ball ... some LOW scores that time). They had some newfangled Winchester plain-white box ammo loaded with 175s in 93 or 94. Very good stuff they used for the Any rifle/any sight match. I had a CLE AR back in 91 or 92 and tried to convince the Match Directors to let me shoot it with 69gr ammo at the matches, but they said I would have to bring at least 2500rds in case someone else wanted to shoot a NM AR. So I shot M14.
Never saw an issued MK12, even at Dam Neck. Just too early for it, I guess. First time I saw an SR25 was on that range, though. They hadn't called it a MK11 yet.
Sorry, all I feel is, "Meh, just another fucking AR!".
That's because you're probably a youngster and maybe not in-service.
Before and just after 9-11, the generic military person's options were M16A2 or M4, and not many options to add accessories.
You are lost...
True story. I first saw Mk12 Mod 0 in Iraq in 2005. Some ODA cats were next to us on the FOB in Hiit, and I was like "OooHHhhHhhh what's that cool thing?" Those guys were doing some serious work in town almost every night.
So, for those of you that haven't reloaded for the PRI Mod 0 upper with the Douglass barrel:
The chamber is probably a minimum spec. Even the 1x fired brass could be easily pushed into my Lyman chamber check gauge. Just needed minimal work in my Mighty Armory die.
The chamber is probably a minimum spec. Even the 1x fired brass could be easily pushed into my Lyman chamber check gauge. Just needed minimal work in my Mighty Armory die.
So, for those of you that haven't reloaded for the PRI Mod 0 upper with the Douglass barrel:
The chamber is probably a minimum spec. Even the 1x fired brass could be easily pushed into my Lyman chamber check gauge. Just needed minimal work in my Mighty Armory die.
Where's the pics of this thing?
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