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+--- Thread: DIY Build short stroking?? (/showthread.php?tid=21167)
DIY Build short stroking?? - plt228 - 05-03-2020
I built an upper with an 18" Wilson Combat Recon barrel with rifle gas system for a friend (he wanted get his first AR for hunting, I sold him on the Grendel). This is my 3rd Grendel and 5th AR build. He was excited on how it looked and balanced for him. When I built the upper I used the same steps as before. Measure the gas port from the shoulder, measure the offset on the gas block. I ordered the gas block, tube and barrel all from Wilson. Figure that was the best bet for a proper fit. I used a pencil to mark the barrel and gas block with a reference line. The barrel is also dimpled from the factory. The dimple and all of my marks lined up.
We take it to the range for the first time and it will shoot any where from 4 to 15 rounds before having a jam. All cases are being ejected. I swapped lowers and BCG from a known good rifle. I put the new lower and BCG on a 16" group buy barrel, mid gas system. The lower and BCG worked mine with the 16" upper, used fully loaded elander mags, 1-10 and 2-17 with no problems. The known good lower and BCG had the same jams as the new lower. It took me a 5 or 6 jams before I realized what was happening. Both lowers are using a standard carbine buffer. Which is what Wilson recommends. We were using 123 gr Hornady AG factory ammo.
I told him I would take a look at it and get it corrected before giving it back. I started disassembling the upper to confirm the gas port size, gas block alignment and anything else I can find. When I attempted to pull the gas block and tube from the upper, the tube will not come out of the upper. It's stuck at the very end of the tube still in the upper. I'm still newer to ARs but I've never seen this before.
Since I can't complete the disassembly I'm just going to clean and lube everything and give it another shot at the range tomorrow with both Grendels and an additional lower running an A5 buffer. I plan on calling or emailing Wilson on Monday. I feel bad that I sold me friend on the Grendel and on the fact building is better than buying so you can get exactly what you want. I'm open for any suggestions?
DIY Build short stroking?? - FRB6.5 - 05-03-2020
Possible gas tube misalignment with the key that peened the end of the tube larger? If you put the gas block and tube back in position and slide just the carrier without the bolt back and forth over the tube do you feel any resistance? Is the end of the gas tube inside the receiver misshapen?
DIY Build short stroking?? - plt228 - 05-03-2020
Once I pulled the bolt and slid the carrier in the upper I felt it bump against the gas tube. I tried the carrier in another rifle and it had no resistance and was smooth. I loosened the hand guard nut and I could notice a change in the alignment of the gas tube. The carrier will now slide in with no issues. I was also able to pull the gas tube out of the upper. Thanks for the answer. I'll wait till morning on trying to get it all back together again.
DIY Build short stroking?? - A5BLASTER - 05-03-2020
plt228 Wrote:Once I pulled the bolt and slid the carrier in the upper I felt it bump against the gas tube. I tried the carrier in another rifle and it had no resistance and was smooth. I loosened the hand guard nut and I could notice a change in the alignment of the gas tube. The carrier will now slide in with no issues. I was also able to pull the gas tube out of the upper. Thanks for the answer. I'll wait till morning on trying to get it all back together again.
Your going to need a new gas tube.
DIY Build short stroking?? - plt228 - 05-04-2020
Ordered 2 this morning. Hopefully that will get the rifle running correctly.
DIY Build short stroking?? - LRRPF52 - 05-11-2020
A key step in gas tube and block installation is aligning it with the carrier key.
Place a stripped carrier with key inside the upper receiver with the upper upside-down.
Slide the gas tube and block over the barrel onto the journal after having taken your measurements for gas port alignment, and then slide the gas block with tube into position, ensuring that the carrier key does not bind.
The inverted upper will simulate magazine cartridge stack pressure up against the bottom of the carrier, pushing it to its maximum height inside the raceway in the upper, and therefore replicate correct position of function for interface with the gas tube.
Gas tube binding is a problem if assembled incorrectly, and it sounds like you had rotational binding with the barrel nut against the side of the gas tube as well.
DIY Build short stroking?? - FLshooter - 05-12-2020
I was using a Sampson hand guard which requires an insert that fits over the barrel nut.It pushed my gas tube a little bit to the side Causing it to bind w/carrier.I noticed it before ever taking it to the range.So,I fixed it.But you need to find out whatÂ’s causing it to misalign w/carrier.
DIY Build short stroking?? - Klem - 05-12-2020
plt,
You say in Post 30 that when you undid the barrel nut the gas tube alignment changed. This sounds like the barrel is a loose fit in the receiver and even though you line everything up carefully, as you finally screw up the nut tight the barrel rotates slightly clockwise with the nut taking everything out of alignment. Do you think this might be the case?
What sort of barrel nut do you have? Is it the traditional MILSPEC type with multiple teeth that you have to line up with the gas tube hole, or is it a proprietary nut that comes with a particular handguard and has flats (so there's no teeth getting in the way of the gas tube).
DIY Build short stroking?? - plt228 - 06-05-2020
First thanks to everyone that responded. Everyone was on the money and pointed out a hole in the little bit of knowledge I did have on AR assemblies. I've added a step to check alignment before taking a rifle to the range.
As for the rifle build. It was an Aero Upper with a Seekins SP3RV3 handguard. With it being a standard upper you do have to time the 2 nut assembly to get the holes for the gas tube to line up. I guess I got lucky on the 556 I used on my first build using this type handguard. I decided that when I took the rifle apart I would switch the upper to a BCM blem. Had to thermo fit but I think I'll just make those uppers my standard now. I got the rifle back together and ran to the range just for function testing. I used 3 ten round elanders with 90, 107, and 123 gr factory ammo. 60 rounds with no malfunctions of any type. Ejection was at 3:30-4:30.
DIY Build short stroking?? - A5BLASTER - 06-05-2020
plt228 Wrote:First thanks to everyone that responded. Everyone was on the money and pointed out a hole in the little bit of knowledge I did have on AR assemblies. I've added a step to check alignment before taking a rifle to the range.
As for the rifle build. It was an Aero Upper with a Seekins SP3RV3 handguard. With it being a standard upper you do have to time the 2 nut assembly to get the holes for the gas tube to line up. I guess I got lucky on the 556 I used on my first build using this type handguard. I decided that when I took the rifle apart I would switch the upper to a BCM blem. Had to thermo fit but I think I'll just make those uppers my standard now. I got the rifle back together and ran to the range just for function testing. I used 3 ten round elanders with 90, 107, and 123 gr factory ammo. 60 rounds with no malfunctions of any type. Ejection was at 3:30-4:30.
Glad to hear you got it figured out sir.
DIY Build short stroking?? - Bronz - 06-08-2020
Gas block not aligned or gas tube