I have begun working up loads for hogs with my AR15 6.5 Grendel build. The problem I have been having is after I fire a round, the case fails to eject. I have an adj. gas block which is basically wide open at this point. Barrel is a 22" with a rifle length gas system. I began working up reloads using 26grs of Alliant Power Pro Varmint using 123gr Hornady SST's. My heaviest charge is 28grs. For each 5 shot string, I inspected each case for signs of hi pressure. (Saw no indications with excessive pressure).
The issue I have is not 1 single case was ejected after the shot. In many cases, I had to really pull hard on the charge handle in order open the chamber and remove the spent brass. I finally had a friend watch the BCG while I took a shot down range to see if the BCG was moving at all. He said after watching me take 8 or so shots, the BCG did not move at all or moved back very little. (My guess is it may be related to head space issues...)
I have built 15+ AR's mostly .223 with 1 rifle chambered for for .204 Ruger, and 2 AR10's (1 chambered in .308 and the other, 6.5 Creedmoor) and everyone of them ran flawlessly.
Any ideas on a course of action to figure this out?
Speed is Fine, Accuracy is final....but accurate hits at extremely high speed is final much faster.
I don't think you understand, these boys killed my dog!
Taking the gun off safe increases the velocity by 100%
I just pulled the handguard and gas block and noticed the port on the gas block did not perfectly align up with the gas port on the barrel. I believe that should solve my problem and will let you know after I have a chance to go to the range and shoot it later this week. Thx for the reply's!
Speed is Fine, Accuracy is final....but accurate hits at extremely high speed is final much faster.
I don't think you understand, these boys killed my dog!
Taking the gun off safe increases the velocity by 100%
I got a chance to sneak away from work this afternoon and chrono some loads for my hog hunt down in Tx this January. On a positive note, all of my loads grouped 1 MOA or less. The BCG is still not coming out of battery enough to eject the spent shell casing. (Adj gas block cranked wide open). I asked a fellow shooter to video the action while I took a shot down range and just watched the vid. As I stated, the action is opening. I went through the vid frame by frame and estimate the action opens approx. 1.35-1.4". I live about 40 miles south of JP Enterprises and plan on making a trip up to their offices (Silent Captured Spring in tow) and asking them if they can break it down reducing the weight of it and seeing if that will make a difference...
Speed is Fine, Accuracy is final....but accurate hits at extremely high speed is final much faster.
I don't think you understand, these boys killed my dog!
Taking the gun off safe increases the velocity by 100%
11-04-2021, 08:12 AM (This post was last modified: 11-04-2021, 08:27 AM by montana.)
It can be many reasons why your rifle is failing to eject. First thing is to check your chamber to make sure it will pass a go- no go gauge. A tight chamber can cause excessive pressures resulting in function issues. More than likely it is a gas issue. The best way to check the gas block- barrel port alignment is with a bore scope and a lighted gas tube. Check the gas block barrel journal fit for excessive gas leakage. Then move back from there by checking the gas block- gas tube interface and check for excessive gas leakage, check the gas tube for any cracks or leaks, check the gas key-gas tube interface. Using a pin gauge the gas key I.D. should be .180 to.182. A Mark Brown custom gas tube gauge checks the button on the end of the gas tube for excessive wear, that can cause excessive gas leakage. Most gas leaks occur between the gas key and the bolt carrier. The gas key screws may look fine but can have a broken screw or be loose. The gas key screws should be tightened to 55 to 58 inch pounds. Mill spec requires a gas sealant between the gas key and carrier, but many companies do not do this. The inside of the bolt carrier has three bores that may or may not be gas efficient, especially between the bolt tail and bolt tail bore. Do the gas ring test on your bolt carrier group. If all else fails, then it may be necessary to open the barrel's gas port. One area I always check, "especially with the Grendel bolt" is the extractor. If the extractor has the rubber O-ring, I will remove the O-ring if the extractor spring is strong and the extractor spring has the black plastic insert, see if this helps. Too much extractor force can cause function issues.. If you have a JP SCS with tungsten weights, it is very easy to take apart and change weights. JP has a video on how to do this..There can be other problem areas such as barrel clocking in the upper, buffer tube alignment and depth, fire control group problems, etc. Good luck...
JP Silent capture spring. (Same setup that I have used on 5 other AR15 builds). Lugs are tight on the BCG. Broke down the BCG and the rinks function/appear as new.
I spent over an hour with Dustin (with JP Enterprises) ad he systematically walked through potential problems. I've decided to tap a friend who owns a machine shop and open up the gas port on the barrel a few thousands and see if that solves my problem. (I'm using an adj. gas block on the build).
I have to say Dustin spent way more time with me on the phone that I deserved helping me diagnose my problem! GREAT CUSTOMER SERVICE!!!
Speed is Fine, Accuracy is final....but accurate hits at extremely high speed is final much faster.
I don't think you understand, these boys killed my dog!
Taking the gun off safe increases the velocity by 100%
Stugotz Wrote:JP Silent capture spring. (Same setup that I have used on 5 other AR15 builds). Lugs are tight on the BCG. Broke down the BCG and the rinks function/appear as new.
I spent over an hour with Dustin (with JP Enterprises) ad he systematically walked through potential problems. I've decided to tap a friend who owns a machine shop and open up the gas port on the barrel a few thousands and see if that solves my problem. (I'm using an adj. gas block on the build).
I have to say Dustin spent way more time with me on the phone that I deserved helping me diagnose my problem! GREAT CUSTOMER SERVICE!!!
I have a Faxon barrel that needed the port opened. It is important to incrementally open the port and try the rifle ammunition combination you are planning to use. Be careful the drill bit does not go too far and damage the bore opposite the port hole. An adj gas block will only restrict the gas port pressure and will work if a port has excessive pressure, but it is best to find the sweet spot. A 22" barrel should be a soft shooter to begin with, so be very careful opening the port. Good to hear JP was so helpful, I also use the JP SCS in most of my builds. Good luck and let us know how it works out..
montana Wrote:It can be many reasons why your rifle is failing to eject. First thing is to check your chamber to make sure it will pass a go- no go gauge. A tight chamber can cause excessive pressures resulting in function issues. More than likely it is a gas issue. The best way to check the gas block- barrel port alignment is with a bore scope and a lighted gas tube. Check the gas block barrel journal fit for excessive gas leakage. Then move back from there by checking the gas block- gas tube interface and check for excessive gas leakage, check the gas tube for any cracks or leaks, check the gas key-gas tube interface. Using a pin gauge the gas key I.D. should be .180 to.182. A Mark Brown custom gas tube gauge checks the button on the end of the gas tube for excessive wear, that can cause excessive gas leakage. Most gas leaks occur between the gas key and the bolt carrier. The gas key screws may look fine but can have a broken screw or be loose. The gas key screws should be tightened to 55 to 58 inch pounds. Mill spec requires a gas sealant between the gas key and carrier, but many companies do not do this. The inside of the bolt carrier has three bores that may or may not be gas efficient, especially between the bolt tail and bolt tail bore. Do the gas ring test on your bolt carrier group. If all else fails, then it may be necessary to open the barrel's gas port. One area I always check, "especially with the Grendel bolt" is the extractor. If the extractor has the rubber O-ring, I will remove the O-ring if the extractor spring is strong and the extractor spring has the black plastic insert, see if this helps. Too much extractor force can cause function issues.. If you have a JP SCS with tungsten weights, it is very easy to take apart and change weights. JP has a video on how to do this..There can be other problem areas such as barrel clocking in the upper, buffer tube alignment and depth, fire control group problems, etc. Good luck...
Hey Mt! I looked for signs of gas leaks at the point where the gas block attaches to the barrel, and where the gas tube is inserted into the gas block (no cracks/leaks and I do have a rubber O-ring) as well as the chamber where the gas exhausts into the port of the BCG while attempting to cycle it. The only signs of spent powder residue is in the chamber in addition to the coating of residue in/on the BCG. If opening the gas port on the barrel fails to solve the problem, I will look at the Grendel bolt extractor. Thanks again Mt!
Speed is Fine, Accuracy is final....but accurate hits at extremely high speed is final much faster.
I don't think you understand, these boys killed my dog!
Taking the gun off safe increases the velocity by 100%
11-05-2021, 12:17 AM (This post was last modified: 11-05-2021, 12:28 AM by montana.)
Stugotz Wrote:Hey Mt! I looked for signs of gas leaks at the point where the gas block attaches to the barrel, and where the gas tube is inserted into the gas block (no cracks/leaks and I do have a rubber O-ring) as well as the chamber where the gas exhausts into the port of the BCG while attempting to cycle it. The only signs of spent powder residue is in the chamber in addition to the coating of residue in/on the BCG. If opening the gas port on the barrel fails to solve the problem, I will look at the Grendel bolt extractor. Thanks again Mt!
Mt, I will throttle back and follow your advice. Plenty of time between now and when I leave for my hog hunt down in Tx.
Speed is Fine, Accuracy is final....but accurate hits at extremely high speed is final much faster.
I don't think you understand, these boys killed my dog!
Taking the gun off safe increases the velocity by 100%
I believe I found the root problem. I measured the distance between the edge of where the hole was bored through the barrel allowing the gas to vent into the gas block and to port in the gas block. If I seat the gas block against the the shoulder of where the gas block seats against the barrel the gas block port extends beyond the barrel port by approx. 1mm. (Please see the attached pix.) I tightened down the gas block 1mm prior to where it engages the shoulder of the barrel and it centers over the port on the barrel perfectly. So who is at fault? The gas block manufacturer for incorrectly drilling the port in the block, or the barrel manufactured for incorrectly drilling the gas port in the barrel 1mm further down the barrel (closer to the muzzle of the barrel?!?[ATTACH=CONFIG]18346[/ATTACH]
Speed is Fine, Accuracy is final....but accurate hits at extremely high speed is final much faster.
I don't think you understand, these boys killed my dog!
Taking the gun off safe increases the velocity by 100%
Stugotz Wrote:I believe I found the root problem. I measured the distance between the edge of where the hole was bored through the barrel allowing the gas to vent into the gas block and to port in the gas block. If I seat the gas block against the the shoulder of where the gas block seats against the barrel the gas block port extends beyond the barrel port by approx. 1mm. (Please see the attached pix.) I tightened down the gas block 1mm prior to where it engages the shoulder of the barrel and it centers over the port on the barrel perfectly. So who is at fault? The gas block manufacturer for incorrectly drilling the port in the block, or the barrel manufactured for incorrectly drilling the gas port in the barrel 1mm further down the barrel (closer to the muzzle of the barrel?!?[ATTACH=CONFIG]18346[/ATTACH]
You are at fault if the gas ports don't line up Not all gas blocks sit flush to the barrel journal shoulder. I take a measurement from the edge of the gas block to the port center and take a measurement from the shoulder of the barrel journal to the barrel port center to get perfect alignment. Then I verify my alignment with a bore scope and gas tube light. If you have a bottom set screw type gas block, the SLR barrel dimpling jig does a good job lining the ports for proper dimpling..
I have this cheaper one that worked OK and is better than nothing if cost is an issue. https://www.amazon.com/dp/B096Y93TPX but I would recommend the other..
I already own a Teslong bore scope and went halves with a friend on a Lyman. (The Teslong is the better of the 2). I confirmed with a friend regarding the issues of the offset that is referenced in the Brownells ling post by mdram. Quite aware with not having measured to make sure the 2 ports did not line up that I am ultimately at fault, I just have never run into this issue before. In my personal collection I have built 9 AR uppers and have built/assisted a few of my friends in another 12 or so builds. Totally un-expected find reguarding the repositioning of the gas block on the barrel... Live and Learn!
I will be out shooting this rifle tomorrow verifying this solved the problem.
Speed is Fine, Accuracy is final....but accurate hits at extremely high speed is final much faster.
I don't think you understand, these boys killed my dog!
Taking the gun off safe increases the velocity by 100%
Speed is Fine, Accuracy is final....but accurate hits at extremely high speed is final much faster.
I don't think you understand, these boys killed my dog!
Taking the gun off safe increases the velocity by 100%
It sure would have been nice if Criterion had pointed out this fact in the paperwork I received with the barrel... The good news is this barrel is crazy accurate with all of the loads I have worked up to day.
Speed is Fine, Accuracy is final....but accurate hits at extremely high speed is final much faster.
I don't think you understand, these boys killed my dog!
Taking the gun off safe increases the velocity by 100%
Not all gas blocks sit flush to the barrel journal shoulder. I take a measurement from the edge of the gas block to the port center and take a measurement from the shoulder of the barrel journal to the barrel port center to get perfect alignment. Then I verify my alignment with a bore scope and gas tube light. If you have a bottom set screw type gas block, the SLR barrel dimpling jig does a good job lining the ports for proper dimpling..