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Posted: 1/13/2010 1:49:59 PM EDT
Ugh I have an issue Im hoping you guys can help me out with or help me to better understand. Im currently building a MK12 Mod0 clone/SPRish type rifle. For my setup Im using a Vltor MUR1A upper, Noveske 18.5" SPR barrel, and a PRI Gen III free floated tube with the ARMS rail mounted along the top to make the upper receiver and PRI tube one continuous rigid shooting platform. Heres my question/problem: the Noveske barrel has an intermediate gas system with a pinned gas block in which the PRI tube will completely cover the gas tube and block; which is what I want, but upon further research I noticed the upper ARMS rail terminates before the end of the upper reciever allowing you to mount your rear BUIS on the reciever thus completing the ARMS rail. The rear BUIS would in turn line up with a barrel mounted flip up front BUIS/gas block, which is not what I had intended on using. I was planning on using Noveske gas block and keeping the gas system covered by the rifle length PRI tube. So if I use Noveske's gas block and mount my BUIS on the rail A. will they be in the way of the optics when folded down and B. there will be an empty space at the end of the receiver where it looks like your rear BUIS SHOULD go and Im afraid itll look kinda retarded. I dont even know if you guys will understand what Im trying to say lol but if you do; any help, suggestions etc etc??? I could really use it right now!!! 
JD |
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Took off My ARMS 40 and scope. Just put some sites I had laying around. The front site is a far forward as the rail has a cross slot to put it. You best bet is to not use the top rail and just use the front small rail and the receiver itself or not use the PRI http://i151.photobucket.com/albums/s143/crowdlg/IMG_00942.jpg Thanks so much for taking pics for me! I agree it totally does look stupid. I do however want to use the ARMS rail with the rear BUIS mounted where it should go. What about this, what if I use a different length PRI tube, ditch the Noveske gas block and use a barrel mounted flip up front BUIS,like the PRI flip up fornt BUIS. Would that work? I wonder exactly how long an intermediate gas system is?? I want the PRI to cover the gas tube completely, maybe they make one that will cover it, but allow me to use the correct front BUIS? If they do will the ARMS rails be to long at that point because of the shorter PRI? |
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You can still use the PRI flip front site in front of the Noveske gas block and not have a gas tube run through it.
If you do not want this at all I have not good advice. If you are using it as a SPR and will scope it just leave off all the irons. Maybe just get a 40L or 40 to cover the space in the rear if you must and not have a front. |
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Found this PRI tube
PRI The overall length of this forearm is 9" I beleive the intermediate gasy system is about 1 to 1 1/2" shorter than a 12" rifle length gas system, so will the tube cover it and allow for mounting of the flip up BUIS/gas block and also will the ARMS rail now be too long?? |
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You can still use the PRI flip front site in front of the Noveske gas block and not have a gas tube run through it. If you do not want this at all I have not good advice. If you are using it as a SPR and will scope it just leave off all the irons. Maybe just get a 40L or 40 to cover the space in the rear if you must and not have a front. How long is your PRI tube on yoru rifle and how long is your gas system? |
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The PRI rail will not work with that shorter PRI tube. Front of the reciver/back of baller nut to end of PRI tube is 12 and 1/2 inches. If your Intermediate gas block is going to be under the tube then use the PRI flip site and it will all be hidden. So you think just use the PRI flip up BUIS/gas block, but dont actually use it as a gas block; only as BUIS and everything will work out asthetically? Will it be ok to have like 2 gas blocks even though only one is actually used as a gas block? |
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So you think just use the PRI flip up BUIS/gas block, but dont actually use it as a gas block; only as BUIS and everything will work out asthetically? Will it be ok to have like 2 gas blocks even though only one is actually used as a gas block? That's what I would do and Yes I think it would be fine. |
I cant beleive there's not a better soloution to this problem lol. I really appreciate your guys helping me out, I just dont want this to turn out to be hoaky. I prob will do just what you guys have suggested Im just surprised no one else has come up with a better soloution. Thanks again guys! 
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You could also mount a standard front sight base the same way the Mark 12 Mod 1 uses them without the gas tube. This would be cheaper and would probably look just fine.
BTW I built a Mark 12 Mod 0 style using PRI's 9" barrel and their rail connector upper. It's mid gassed and runs and looks just fine. Nobody says you have to be 100% correct, only you, if that's your goal. Perfectly good rifles can have a bastardized heritage taking what you like the most from any system you choose. |
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The best solution would be to use a barrel with a Rifle gas system and built it like a Mod 0 is supposed to be or Build that Noveske barrel with some other standard style quad rail and make it look like a Mod 1. Thought about that too bud but I really like the look of the MOD0.
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You could also mount a standard front sight base the same way the Mark 12 Mod 1 uses them without the gas tube. This would be cheaper and would probably look just fine. Are you saying use the PRI flip up as just a sight and use the Noveske gas block as the gas block? Thats what the other 2 gentleman had suggested. I might be confused and misunderstanding you my friend. |
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Waiiiiit a minute here!!!! Is that what your doing there, the 2 gas block trick? Can you pleeease post more pics as well as give me your specifics such as barrel mfg and gas system length,PRI tube length, flip up sight make,etc etc basically all ur specs!! Thanks JD!!!!!!!!
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WHY NOT JUST DITCH THE ARMS SPR RAIL ALTOGETHER??? MOUNT THE FRONT SIGHT ON THE PRI FOREND. MOUNT THE REAR SIGHT ON THE RECEIVER. THEN GO WITH A LARUE SPR SCOPE MOUNT. Hey Wes thanks for taking a look! I really like the idea of the ARMS SPR rail and one of the guys posted a pic of what looks like the 2 gas block setup. Im so up in the air now,lol. How much for the Noveske DB coated switchblock barrel WITHOUT the fitted bolt? |
Mine is in 6.8 SPC so it’s a mid-length gas system. PRI Low Profile Gas Block Which is under a Rifle Length PRI Forearm With an ARMS SPR-PEQ Rail ARMS #40 L rear BUIS And a PRI Front Sight (not being used as a gas block) |
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http://i85.photobucket.com/albums/k65/AR15_Fanatic/SPR%20Mk12%20Mod%200/SPR-WoodsPB.jpg Mine is in 6.8 SPC so it’s a mid-length gas system. PRI Low Profile Gas Block Which is under a Rifle Length PRI Forearm With an ARMS SPR-PEQ Rail ARMS #40 L rear BUIS And a PRI Front Sight (not being used as a gas block) Man your rifle looks awesome AR15_Fanatic!! Thanks for all the info, seems like Im getting closer to a soloution. OK next question is since yours is a mid length gas system and mine would be an intermediate one, would there even be enough room to sneak the PRI flip up on there with the Noveske gas block already inside the tube?? |
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Mark 12 Mod 0 SPR Upper in 5.56mm
Code: 07-55618-SPR-B Price: $1,978.00 link to PRI Quantity in Basket: None Quantity: Mark 12 Mod 0 SPR upper assembly is an accurate copy of the original SPR uppers currently in use by the SOF in Iraq and Afghanistan. The 18" barrel is 416 stainless steel and is capable of MOA accuracy. The flattop upper receiver has a PRi Gas Buster Charging handle with big latch, ARMS #38 PEQ2 sleeve, ARMS #40 flip up rear sight, PRi free float carbon fiber forearm, PRi Flip Up Front sight and intermediate gas system. Head spaced bolt and standard carrier are also included. Available in 6.8mm and 5.56mm. Upper assemblies require 3 days for inspection and testing prior to shipping. Uppers can be shipped next day or second day air after the 3 day period. This is directly off PRI's web page and it says INTERMEDIATE GAS SYSTEM!! Now Im even more confused? I thought they were rifle length gas systems and thats what everything worked as far as 1 gas block etc etc.... 
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http://www.rainierarms.com/?page=shop/detail&product_id=956
"Noveske SPR contour incorporates an intermediate-length gas system, and a .749 inch seat for a barrel mounted front sight in front of a rifle length handguard for MK12 mod0 configuration." |
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http://i85.photobucket.com/albums/k65/AR15_Fanatic/SPR%20Mk12%20Mod%200/SPR-WoodsPB.jpg Mine is in 6.8 SPC so it’s a mid-length gas system. PRI Low Profile Gas Block Which is under a Rifle Length PRI Forearm With an ARMS SPR-PEQ Rail ARMS #40 L rear BUIS And a PRI Front Sight (not being used as a gas block) Nice looking weapon! I'm just starting a build like that. Mine's also 6.8, but with an intermediate gas system. I'm glad this thread came up, I was having the same questions! |
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http://www.rainierarms.com/?page=shop/detail&product_id=956 "Noveske SPR contour incorporates an intermediate-length gas system, and a .749 inch seat for a barrel mounted front sight in front of a rifle length handguard for MK12 mod0 configuration."  
I was told by person's who shall remain unamed that this would not work with a barrel mounted flip up BUIS and a rifle length handguard. This person works for a well known vedor, maybe I just confused him or didnt ask my initial question to him properly? EIther way Im happy now and AR15_Fanatic I owe you a case of beer and if you ever in CT i will most definately deliver. Thanks soo much!
Also thanks to all that chimed in to help!
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Lol I swear Im not usally this anal!!!! [/div]
I understand. You are spending a lot of money and don't want a bunch of parts in front of you that do not work together. It will be fine. Just build it with both the gas block and the site and don't worry about it. It has been proven it can and is done this way. |
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http://www.rainierarms.com/?page=shop/detail&product_id=956 "Noveske SPR contour incorporates an intermediate-length gas system, and a .749 inch seat for a barrel mounted front sight in front of a rifle length handguard for MK12 mod0 configuration."
I was told by person's who shall remain unamed that this would not work with a barrel mounted flip up BUIS and a rifle length handguard. This person works for a well known vedor, maybe I just confused him or didnt ask my initial question to him properly? EIther way Im happy now and AR15_Fanatic I owe you a case of beer and if you ever in CT i will most definately deliver. Thanks soo much!
Also thanks to all that chimed in to help! Well the best way to ensure it will work is to call Noveske and ask if the gas block on their intermediate gas system barrel extends beyond a rifle length forearm. If not you are GTG. Noveske 541-479-6117 |
| I saw an SPR back years ago that used the PRI FF tube and the PRI top rail. The rifle length top rail had a few inches cut off of the end of it so that a flip sight could be mounted on the rail of the FF tube to allow the BUIS to be on the same plane. I am thinking it was Jason with JTAC Supply. Maybe you can try emailing him to see if he knows what I am talking about. I was going to go this route on an SPR build but never carried out the plans. |
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http://www.rainierarms.com/?page=shop/detail&product_id=956 "Noveske SPR contour incorporates an intermediate-length gas system, and a .749 inch seat for a barrel mounted front sight in front of a rifle length handguard for MK12 mod0 configuration."
I was told by person's who shall remain unamed that this would not work with a barrel mounted flip up BUIS and a rifle length handguard. This person works for a well known vedor, maybe I just confused him or didnt ask my initial question to him properly? EIther way Im happy now and AR15_Fanatic I owe you a case of beer and if you ever in CT i will most definately deliver. Thanks soo much!
Also thanks to all that chimed in to help! Well the best way to ensure it will work is to call Noveske and ask if the gas block on their intermediate gas system barrel extends beyond a rifle length forearm. If not you are GTG. Noveske 541-479-6117 The front of the gas block sits about 1/2" back (inside) the end of a DD lite 12", which measures similar to a rifle length hand guard from another. The barrel measures .735" in front of that. The sight would need to tighten down a little more than on a .750" barrel. Just my .02 cents, YMMV. |
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what about the PRI top rail? |
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what about the PRI top rail? http://www.pri-mounts.com/mm5/graphics/00000001/05-073-06_LGR.JPG
it has slots much further out to the front Hey bud I saw the PRI rail but I just dont like it quite as much as the ARMS. Im sure its a quality piece of kit but just not for me.
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| Well the official word is in...I just got off the phone with the guys from Noveske, they said by using a 12" forearm the gas block will be completely covered thus not allowing you to use the PRI flip up front sight gas block as a gas block. Thanks soo much for everyones advice and suggestions. At this point Im going to go with a Douglas barrel from Compass Lake Engineering. Anyone care to tell me there expieriences with the Douglas? Are they as a good a shooter as the Noveske? Thanks again. JD |
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At this point Im going to go with a Douglas barrel from Compass Lake Engineering. Anyone care to tell me there expieriences with the Douglas? Are they as a good a shooter as the Noveske? Thanks again. JD Good choice. No point in using a mid length gas system for a rifle designed to use a rifle length gas system. Here is my CLE Douglas 18". It's a terrific shooter, very accurate, cleans up easily, no POI shift when warming up, one of my most important criteria. On PRS equipped lower. 
On ACS equipped lower. 
My Mod0 has a Krieger 18" SPR barrel, but the CLE Douglas would look the same. 
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At this point Im going to go with a Douglas barrel from Compass Lake Engineering. Anyone care to tell me there expieriences with the Douglas? Are they as a good a shooter as the Noveske? Thanks again. JD Good choice. No point in using a mid length gas system for a rifle designed to use a rifle length gas system. Here is my CLE Douglas 18". It's a terrific shooter, very accurate, cleans up easily, no POI shift when warming up, one of my most important criteria. On PRS equipped lower. http://bellsouthpwp.net/e/d/edwin907/_C206720.jpg http://bellsouthpwp.net/e/d/edwin907/PRS3.jpg On ACS equipped lower. http://bellsouthpwp.net/e/d/edwin907/_B216624.jpg My Mod0 has a Krieger 18" SPR barrel, but the CLE Douglas would look the same. http://bellsouthpwp.net/e/d/edwin907/SPRb.jpg My god man you have some AWESOME rifles there!! I actually have already saved the pic of your MOD0 prior to this lol. Heres a question, which do you like better, the Krieger or the Douglas? Which do you think is more accuate etc etc.JD |
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Quoted: Heres a question, which do you like better, the Krieger or the Douglas? Which do you think is more accuate etc etc.JD
Thanks for the compliments. The Krieger is a better barrel, but it's a lot more $$$ (but it did come with a matched bolt) and it seems to have a slight accuracy advantage in that I have shot better groups with it, plus it's service life is supposed to be the best. All that said, I can see no reason to get anything other than the CLE Douglas. I got mine from PDC with a WOA upper receiver which was checked for M4 feed ramp cuts matching those in the barrel. It works great with the OPS 12th suppressor. I left it natural SS as when the suppressor is mounted, none of the barrel is visible, the OPS collar and LaRue gas block cover the rest of the barrel. One word, it you use the LaRue Tactical low profile gas block and the OPS collar, you will have to remove about a tenth of an inch from the front of the LaRue gas block to gain clearance so the OPS collar ill sit on the barrel shoulder properly. Most people would use a gas block without the forward extension, or in the case of your Mod0, the PRI flip up front sight (which I love). |
| Just spoke with Frank White at Compass Lake. What a nice guy he is, took time to answer all my crazy questions as well as give me some opinions. He recommeded the Douglas over the Krieger as Im not a competition shooter and dont need the extended service life of a Kreiger. The Douglas' are air gauged and concentric w/in .0002 from end to end. You can have them bead blasted and M4 feed ramps put on them. Theyre also obviously rifle length gas systems which alleviates all my issues, and you cant beat the price $330 give or take your options. Im impressed with CLE. |
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If the gas system is completely covered by a rifle length rail/tube then you would simply utilize that option while employing the PRI solely as a front sight (unless RatzAzz is correct about barrel diameter).
Edwin’s garage has certainly seen some sexy firearms (don’t let him post any photos with NV scopes; you might be tempted to sell your first-born to get one). He also brings up an excellent point, you should be sure to get an "upper receiver which was checked for M4 feed ramp cuts matching those in the barrel." When I purchased my barrel and upper the feed ramps were so off that I had to send them back and have the upper replaced with something that matched. Oh and don’t forget to post pics when you finish your build. |
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My Mod-0 is built using a Douglas barrel and I have been very happy with it. about .75moa My Mod-1 is using a WOA barrel and shoots almost was well. about 1-1.25 moa Oh thats awesome to hear. Ill post pics as I start to receive parts, and of course the finished rifle. Im still waiting for my lower from Wes, but I know KAC has been dragging their feet. Cant wait to start building!! 
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Oh thats awesome to hear. Ill post pics as I start to receive parts, and of course the finished rifle. Im still waiting for my lower from Wes, but I know KAC has been dragging their feet. Cant wait to start building!! KAC lower? That will be awesome, I love mine. The ambi controls are nicely executed, as is the QD slling mounts. For the LMT Defender 2000 lower I use on the Mod0 I also have a 2-stage KAC trigger, KAC receiver ambi QD sling mount, ambi mag & ambi safety, Add all this and you migt have well bought the KAC lower! Here is a NV pic (fanatic warned you, LOL), but it may change as soon as I get the new NV scope, this D-760 may go to the Mod1. 
Damn I'd like to build an identical rifle in 6.5! |
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Well some of the parts are rolling in! I just received my Knights complete lower with ambi controls, match trigger and SOPMOD stock, i already have the Vltor MUR1A upper, MOE grip, Youngs NM BCG. FYI KNS pins will not work on KAC lowers with ambi controls. Promise to post pics of the parts I already have and the finished project soon.
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