OK...Here is the story. I was looking for a bolt gun for long range shooting and local competitions when the AR witch hunt occurred. I bought a brand new Rock River Arms LAR8 Varmint A4 with the 26" Wilson cryo-teated Barrel. It is easily a .5 moa rifle with good ammo but I will give the range report in another post sometime. I began to modify the rifle for long range tactical matches and local fun competitions to 1000 yds. The bolt gun is coming.
The Falcon Industries Tactical ERGO grip with palmshelf went on first. It took 5 minutes with the right Allen wrench and some loctite. Its a nice piece of kit. Make sure you order the one with for the "large frame" rifle or you will have a gap at the rear of the grip where it follows the receiver.
Adding the Magpul PRS, which many here have done to various rifles, onto the RRA LAR8 became an adventure which I will detail as there has been a lot of confusion and misinformation:
The Challenge: RRA and Magpul advise that the PRS is not compatible with the LAR8 but do not say why. Here you go. Because of the design of the RRA LAR8 (ambi bolt release position), the charging handle pulls rearward further than the charging handle of most AR10 type rifles. This is nearly unnoticeable until you try to add the Magpul PRS AR10 stock onto the LAR8. The charging handle will run into the adjustable cheek weld of the PRS if the cheek weld is raised preventing you from cycling the bolt carrier. This gives you 3 options which you have to weigh individually before we move on:
The Solution(s): 1) Install the Magpul PRS onto the LAR8 buffer tube with the supplied hardware from Magpul and lower the cheek weld to use the charging handle OR leave the cheek weld down all the time (fine if this fits you).
2) Install the PRS onto the LAR8 with the supplied hardware and cut off a small portion of the adjustable cheek piece with a fine bandsaw and buff until appearance is acceptable (which varies wildly among us all). As Magpul now includes a vented machine screw to hold the PRS onto the rife, the function of the rifle will remain unchanged.
3) Add the DPMS 1" AR15 Buttstock Extender from Midway or Brownells to the LAR8 in addition to the Magpul PRS to preserve the full function of the PRS AND the rifle charging handle. BUT....BUT......There is a catch. In this set-up, because you are using the DPMS extender, you must now use the DPMS hardware as the Magpul screw is now too short. The head type of the DPMS machine screw is slightly different (angled VS pan head) than the one Magpul supplies for the PRS but it DOES work. This is because it was designed for the standard A2 stock. The larger problem (depending on who you talk to) is that the DPMS machine screw is NOT vented as was the original screw from RRA and the PRS screw from Magpul. According to the RRA folks, using a non-vented screw to fasten the PRS to the buffer tube COULD result in OCCASIONAL short-stroking as excess oil or condensed water in the buffer tube causes a hydraulic lock in the buffer tube. The vent in the screw allows the oil or water to be ejected out the back of the tube as the rifle cycles (into your shoulder i guess).
To find a quick solution for the vented machine screw. I contacted Magpul, DPMS and RRA and, unfortunately, no one wants to produce a vented a screw of the correct length for the Rock River LAR8 + Magpul PRS combo. We are, after all, combining products from 3 manufacturers which, evidently, is one too many. RRA and DPMS have their screws sent to them. Magpul did not want to tell me who makes their short ones even if all I wanted was ONE longer one. I am sourcing my own currently. The screw that comes from DPMS for use with their 1" extension is a slotted, angled head machine screw with a thread length of 1 1/4" and the threads are 1/4 x 28 fine. You can find them in a good hardware section of a local store or order them from Fastenall. I am having a machine shop attempt to vent them for me today. The vent hole measures .080 (eighty thousands). I believe this is the correct solution (although not the quickest) to the Magpul PRS + RRA LAR8 problem as it does not change the function of either the fine rifle that RRA produces or the fine buttstock that Magpul manufactures. More to come. Thanks for sticking with me on a long post.
The Falcon Industries Tactical ERGO grip with palmshelf went on first. It took 5 minutes with the right Allen wrench and some loctite. Its a nice piece of kit. Make sure you order the one with for the "large frame" rifle or you will have a gap at the rear of the grip where it follows the receiver.
Adding the Magpul PRS, which many here have done to various rifles, onto the RRA LAR8 became an adventure which I will detail as there has been a lot of confusion and misinformation:
The Challenge: RRA and Magpul advise that the PRS is not compatible with the LAR8 but do not say why. Here you go. Because of the design of the RRA LAR8 (ambi bolt release position), the charging handle pulls rearward further than the charging handle of most AR10 type rifles. This is nearly unnoticeable until you try to add the Magpul PRS AR10 stock onto the LAR8. The charging handle will run into the adjustable cheek weld of the PRS if the cheek weld is raised preventing you from cycling the bolt carrier. This gives you 3 options which you have to weigh individually before we move on:
The Solution(s): 1) Install the Magpul PRS onto the LAR8 buffer tube with the supplied hardware from Magpul and lower the cheek weld to use the charging handle OR leave the cheek weld down all the time (fine if this fits you).
2) Install the PRS onto the LAR8 with the supplied hardware and cut off a small portion of the adjustable cheek piece with a fine bandsaw and buff until appearance is acceptable (which varies wildly among us all). As Magpul now includes a vented machine screw to hold the PRS onto the rife, the function of the rifle will remain unchanged.
3) Add the DPMS 1" AR15 Buttstock Extender from Midway or Brownells to the LAR8 in addition to the Magpul PRS to preserve the full function of the PRS AND the rifle charging handle. BUT....BUT......There is a catch. In this set-up, because you are using the DPMS extender, you must now use the DPMS hardware as the Magpul screw is now too short. The head type of the DPMS machine screw is slightly different (angled VS pan head) than the one Magpul supplies for the PRS but it DOES work. This is because it was designed for the standard A2 stock. The larger problem (depending on who you talk to) is that the DPMS machine screw is NOT vented as was the original screw from RRA and the PRS screw from Magpul. According to the RRA folks, using a non-vented screw to fasten the PRS to the buffer tube COULD result in OCCASIONAL short-stroking as excess oil or condensed water in the buffer tube causes a hydraulic lock in the buffer tube. The vent in the screw allows the oil or water to be ejected out the back of the tube as the rifle cycles (into your shoulder i guess).
To find a quick solution for the vented machine screw. I contacted Magpul, DPMS and RRA and, unfortunately, no one wants to produce a vented a screw of the correct length for the Rock River LAR8 + Magpul PRS combo. We are, after all, combining products from 3 manufacturers which, evidently, is one too many. RRA and DPMS have their screws sent to them. Magpul did not want to tell me who makes their short ones even if all I wanted was ONE longer one. I am sourcing my own currently. The screw that comes from DPMS for use with their 1" extension is a slotted, angled head machine screw with a thread length of 1 1/4" and the threads are 1/4 x 28 fine. You can find them in a good hardware section of a local store or order them from Fastenall. I am having a machine shop attempt to vent them for me today. The vent hole measures .080 (eighty thousands). I believe this is the correct solution (although not the quickest) to the Magpul PRS + RRA LAR8 problem as it does not change the function of either the fine rifle that RRA produces or the fine buttstock that Magpul manufactures. More to come. Thanks for sticking with me on a long post.
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