BIGTRUCKNUT Posted May 17, 2017 Report Share Posted May 17, 2017 Hey y'all, new to the forum and already picking your brains. Poked around, did a few searches, and read up here and on other sites but never got a definitive answer to an issue I had with the gas system/buffer assembly on my first time at the range with the new LR243. I had 3 goals last weekend on the range: 1. break in the barrel (shoot and clean, shoot and clean, etc etc), 2. get it to print on paper at 100, and 3. tune the gas system. I accomplished 1 and 2, failed on 3. Rifle is built with the following: - Aero Precision M5E1 upper and lower receiver and BCG - 24" X-Caliber barrel (8:1 twist) and compensator in .243 Win - SLR .875 adjustable gas block and rifle-length gas tube - Magpul Gen 2 PRS 308 stock - Aero Precision 308 rifle length buffer and spring This is my second LR build, the first being a pretty conventional LR308 from Aero Precision M5E parts. It shoots and operates fine. Tried to get sexy with this .243 though. As I said, wasn't able to tune the gas system completely. Since I was shooting cleaning, shooting cleaning and also trying to tune the gas block at the same time, I only loaded the magazine with 1 round each time to fire in order to tune it to get enough gas through to lock the slide to the rear - it never made it that far. The bolt came back far enough to eject the casing but not lock. Was shooting cheap American Eagle 75 grain varmint ammo and put 24 rounds through it in about a 2 hour period. When I got home I pulled the gas block off and confirmed that it was positioned over the gas port correctly. It felt like the 308 buffer spring was too strong. That said, after looking all over the internet I determined that the AR308 rifle-length spring has about 6-8 pounds additional compressed spring weight over the AR15. I found a warning on this site not to use AR15 springs in AR308 applications. Question is: Does the aforementioned buffer spring warning apply for the 243 Win chambering and my parts selection? If I am tuning the gas system with an adjustable gas block can I safely use a lighter AR15 buffer spring with the LR308 buffer without the buffer slamming rearward? Wouldn't that help reduce recoil even more while keeping the bolt that much cleaner from less gas use? Have fired these ARs/M16s for years but only started building them in the last year - Please enlighten me! Once I get this sorted out I plan to develop a handload using 95 grain SMK or TMK bullets for 800-1000 yard shooting. Greatly appreciate, Ty Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted May 17, 2017 Report Share Posted May 17, 2017 53 minutes ago, BIGTRUCKNUT said: Hey y'all, new to the forum and already picking your brains. Poked around, did a few searches, and read up here and on other sites but never got a definitive answer to an issue I had with the gas system/buffer assembly on my first time at the range with the new LR243. I had 3 goals last weekend on the range: 1. break in the barrel (shoot and clean, shoot and clean, etc etc), 2. get it to print on paper at 100, and 3. tune the gas system. I accomplished 1 and 2, failed on 3. Rifle is built with the following: - Aero Precision M5E1 upper and lower receiver and BCG - 24" X-Caliber barrel (8:1 twist) and compensator in .243 Win - SLR .875 adjustable gas block and rifle-length gas tube - Magpul Gen 2 PRS 308 stock - Aero Precision 308 rifle length buffer and spring This is my second LR build, the first being a pretty conventional LR308 from Aero Precision M5E parts. It shoots and operates fine. Tried to get sexy with this .243 though. As I said, wasn't able to tune the gas system completely. Since I was shooting cleaning, shooting cleaning and also trying to tune the gas block at the same time, I only loaded the magazine with 1 round each time to fire in order to tune it to get enough gas through to lock the slide to the rear - it never made it that far. The bolt came back far enough to eject the casing but not lock. Was shooting cheap American Eagle 75 grain varmint ammo and put 24 rounds through it in about a 2 hour period. When I got home I pulled the gas block off and confirmed that it was positioned over the gas port correctly. It felt like the 308 buffer spring was too strong. That said, after looking all over the internet I determined that the AR308 rifle-length spring has about 6-8 pounds additional compressed spring weight over the AR15. I found a warning on this site not to use AR15 springs in AR308 applications. Question is: Does the aforementioned buffer spring warning apply for the 243 Win chambering and my parts selection? If I am tuning the gas system with an adjustable gas block can I safely use a lighter AR15 buffer spring with the LR308 buffer without the buffer slamming rearward? Wouldn't that help reduce recoil even more while keeping the bolt that much cleaner from less gas use? Have fired these ARs/M16s for years but only started building them in the last year - Please enlighten me! Once I get this sorted out I plan to develop a handload using 95 grain SMK or TMK bullets for 800-1000 yard shooting. Greatly appreciate, Ty Can you make the bolt lock to the rear manually? If not, your buffer may be too long. Ask me how I know... LOL. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 17, 2017 Report Share Posted May 17, 2017 1 hour ago, BIGTRUCKNUT said: - Aero Precision 308 rifle length buffer and spring Check what Matt said, above - but I'd still pull the buffer out and measure it. If it's really a .308AR rifle buffer, it should be pretty close to 5.200" long. Quote Link to comment Share on other sites More sharing options...
BIGTRUCKNUT Posted May 17, 2017 Author Report Share Posted May 17, 2017 Yes, I can lock the bolt to the rear manually and yes, I verified that it is in fact a 308 buffer. As a matter of fact, I was using this complete lower, stock and buffer assembly included, with my 308 upper until about 3 weeks ago. Never a problem. Maybe I should try a regular gas block and see what happens? Appreciate! Ty Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 17, 2017 Report Share Posted May 17, 2017 (edited) 5 minutes ago, BIGTRUCKNUT said: Maybe I should try a regular gas block and see what happens? Definitely won't hurt - and very well worth trying. Something else to check when the gas block is off - gas port size in the barrel. Not many X-Caliber barrels have been through here (members here), but I do know of one of them that had a gas port that was too small... Had to be drilled up... Edited May 17, 2017 by 98Z5V Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 17, 2017 Report Share Posted May 17, 2017 The spring should definitely be the heavier .308 spring. I recommend the Armalite AR10 spring or the Tubb flat wire spring. It's not so much about absorbing the recoil, as much as it it is to drive the BCG back into battery. If the spring is too light, you'll get issues stripping a round from the mag and putting one in the pipe. Especially with a full/new mag. Quote Link to comment Share on other sites More sharing options...
BIGTRUCKNUT Posted May 17, 2017 Author Report Share Posted May 17, 2017 Roger, I get it. I'll check the gas port diameter as it compares to my functioning 308 barrel. About what diameter should it be? I'll also swap in a regular gas block and put the 308 buffer spring back in and see if that works. Thank you, Ty Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 17, 2017 Report Share Posted May 17, 2017 I'd go up to 0.099 and then depend on the adjustable gas block if needed. The gas block is at 0.125, so going to .099 still leaves plenty of room. #40 or #39 standard drill bit should suffice. A 7/64" should suffice if you can't find the others. Quote Link to comment Share on other sites More sharing options...
washguy Posted May 17, 2017 Report Share Posted May 17, 2017 (edited) Bigtruck The ar15 vs an ar308 is very different...its not the caliber you should be concerned with ....an ar15 spring with an ar308 buffer will cause coil bind among other things....the coil count is different and so is the length of the springs . the only time I ever had a bolt not catching was when I grabbed an ar15 spring off of my bench instead of an ar308...would not lock back. If you are wanting to reduce recoil get a Tubbs...you cant go wrong....then tune with the gas block....and a heavy buffer if you wish ....oh and measure that gas port ....x caliber has been known to not drill the right hole Wash the ar15 is the one on the bottom......look at the coil count and the diameter of the springs 308 car buffer Edited May 17, 2017 by washguy Quote Link to comment Share on other sites More sharing options...
Matt.Cross Posted May 17, 2017 Report Share Posted May 17, 2017 Tubb flat wound in conjunction with an SLR Sentry works really well, as several here can attest. I implemented that very combination on our last group shoot and it worked really well. Quote Link to comment Share on other sites More sharing options...
BIGTRUCKNUT Posted May 17, 2017 Author Report Share Posted May 17, 2017 Thanks for the input. I'll pull the gas block off again tonight and check the port diameter...and drill as necessary. Keeping my fingers crossed that it's that easy. Plan on test firing it again this weekend at the Quantico ranges if they are open. Will let you know how it works out. Ty Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 17, 2017 Report Share Posted May 17, 2017 5 hours ago, BIGTRUCKNUT said: Thanks for the input. I'll pull the gas block off again tonight and check the port diameter...and drill as necessary. Keeping my fingers crossed that it's that easy. Plan on test firing it again this weekend at the Quantico ranges if they are open. Will let you know how it works out. Ty A proper size wood dowel rod in the Barrel when drilling is a good safety stop for the drill bit . Also if you have them or barrow them , a drill index set will get you close to a measurement on what you have & also do one step at a time , till you get what works & it should not be more then the measurement Robocop stated. Just seeing what Gas Port size you have may give some answers to what is going on . Quote Link to comment Share on other sites More sharing options...
BIGTRUCKNUT Posted May 17, 2017 Author Report Share Posted May 17, 2017 1 hour ago, survivalshop said: A proper size wood dowel rod in the Barrel when drilling is a good safety stop for the drill bit . Also if you have them or barrow them , a drill index set will get you close to a measurement on what you have & also do one step at a time , till you get what works & it should not be more then the measurement Robocop stated. Inserting a dowel is a great tip, thanks. Quote Link to comment Share on other sites More sharing options...
shepp Posted May 17, 2017 Report Share Posted May 17, 2017 4 hours ago, BIGTRUCKNUT said: Inserting a dowel is a great tip, thanks. This ain't the first time the guys have coach somone thru with an Xcaliber barrel lol good luck! Quote Link to comment Share on other sites More sharing options...
BIGTRUCKNUT Posted May 18, 2017 Author Report Share Posted May 18, 2017 Well I pulled the gas block off to measure the gas port - it was .060". I dug through my drill bit collection to find a suitable bit to open it up a little. Ended up with a 3/32" bit (.094"). Before and after photos below. All back together with 308 rifle length buffer spring reinstalled; waiting to test fire this weekend. Quote Link to comment Share on other sites More sharing options...
Robocop1051 Posted May 18, 2017 Report Share Posted May 18, 2017 Give her a go! Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted May 18, 2017 Report Share Posted May 18, 2017 (edited) X-Caliber strikes again! Nice accurate barrels they just don't know Chit about gas ports....... Edited May 18, 2017 by jtallen83 clarity Quote Link to comment Share on other sites More sharing options...
washguy Posted May 18, 2017 Report Share Posted May 18, 2017 That gas port sizing is secret stuff You better not let them find out you gave out their secret Wash Quote Link to comment Share on other sites More sharing options...
shepp Posted May 18, 2017 Report Share Posted May 18, 2017 19 minutes ago, washguy said: That gas port sizing is secret stuff You better not let them find out you gave out their secret Wash Funny thing is our customer support trumps theirs Quote Link to comment Share on other sites More sharing options...
98Z5V Posted May 18, 2017 Report Share Posted May 18, 2017 (edited) 2 hours ago, BIGTRUCKNUT said: Well I pulled the gas block off to measure the gas port - it was .060". I personally don't know shiit about tuning a .243, but that gas port was WAY too small. 5.56 on a 16" carbine gas barrel is bigger than that! Edited May 18, 2017 by 98Z5V Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted May 18, 2017 Report Share Posted May 18, 2017 6 hours ago, shepp said: Funny thing is our customer support trumps theirs Their attempt at customer service was pretty good for me despite their arrogance. They were willing to keep paying the shipping back and forth till they got it right, they just didn't say anything that would give me the feeling they knew what to do. It was much easier to just follow the suggestions here on the forum and fix it myself. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted May 18, 2017 Report Share Posted May 18, 2017 This is some Port sizes for you to ponder for the 308 , which would be close to the 243 & are used for the 243 also . I guess if you had an 18" barrel with a Carbine Gas system , you might of been OK . Oh & these are secret , so you didn't see them ! DPMS LR-308 Style Rifle 18" rifle 0.308 0.0960 18" car 0.308 0.0635 16" mid 0.308 0.078 16" mid 0.308 0.081 16" car 0.308 0.07 16" car 0.308 0.073 16" car 0.308 0.076 20" rifle 0.308 0.0935 20" rifle 0.308 0.096 Quote Link to comment Share on other sites More sharing options...
BIGTRUCKNUT Posted May 18, 2017 Author Report Share Posted May 18, 2017 11 hours ago, survivalshop said: This is some Port sizes for you to ponder for the 308 , which would be close to the 243 & are used for the 243 also . I guess if you had an 18" barrel with a Carbine Gas system , you might of been OK . Oh & these are secret , so you didn't see them ! DPMS LR-308 Style Rifle 18" rifle 0.308 0.0960 18" car 0.308 0.0635 16" mid 0.308 0.078 16" mid 0.308 0.081 16" car 0.308 0.07 16" car 0.308 0.073 16" car 0.308 0.076 20" rifle 0.308 0.0935 20" rifle 0.308 0.096 So at 24" and rifle length gas system I guess that the suggested port size of .099" was spot on. Can't wait to test it Saturday if the ranges on Quantico are open. Quote Link to comment Share on other sites More sharing options...
BIGTRUCKNUT Posted May 22, 2017 Author Report Share Posted May 22, 2017 (edited) Took the .243 out for a test drive today and it performed flawlessly! Just 3 rounds to tune the gas block after opening up the gas port to .094" as suggested. Then the youngest daughter and I took turns tearing the center out of a target at 100 yards and busting clay birds on the berm at 300 yards. Can't wait to develop handloads for it and try it at 600 to 1000 yards. Thank you again for the help. Edited May 22, 2017 by BIGTRUCKNUT Quote Link to comment Share on other sites More sharing options...
washguy Posted May 22, 2017 Report Share Posted May 22, 2017 Way to go ! You will enjoy shooting it Wash Quote Link to comment Share on other sites More sharing options...
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