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Hello.
I just tested my new built upper and it has a chamber issue I assume. I bought a Shilen 6.5 Grendel Barrel and head spaced bolt. the round fires but fails to eject and I have to tap the charging handle back with my small plastic mallet to get the spent round out. I don't see any real roughness or burs in the chamber and no visible marks on the brass from such an issue. I am thinking I should contact Shilen and just send them the whole upper to make it right? I am running Hornady Black 123gr ammo so I doubt it's an ammo issue but any advice is appreciated.
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My first thoughts are that there is not enough gas. Check that the gas port on the barrel is correctly aligned with the gas block. Measure the barrel gas port size (you can use a number drill bit shank in a pinch). If it has an adjustable gas block double check that it is open enough. Absolutely follow the manufacturers directions for warranty work, but if you did the assembly check that it was done correctly. Best of luck!
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If an unfired cartridge is not sticking in the lands and can be extracted by the charging handle then more than likely a gas issue. Here are some gas port sizes for various 6.5 Grendel barrel lengths. It wouldnt be the first time a barrel was shipped with an undersized gas port. Also look for gas leakage on the bolt carrier gas key and gas block.
6.5 Grendel gas port sizes
12 Faxon GB .068 CLGS.
16 Carbine G. 0625
16 Faxon GB .078 MLGS
16 Group Buy Green Mountain .076
18 Faxon GB .076 MLGS
20 Rifle LG .0935. same as 5.56/223
18 RLGS .094
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it's NOT undergassed after firing the charging handle CAN'T be pulled back by hand to extract the round. that's not an under gas that's a chamber grabbing the brass issue someplace. I am finding some info in other forums saying that Shilen barrels don't like Horandy brass I am wondering if this is my issue.
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Two things can be true at the same time. Extracting brass from a gun with the gas turned off can be quite difficult, combined with a marginally rough chamber and it would be worse. Post a good pic of the fired brass (cleaned with a solvent), that will give us guessers more data to work with.
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Separate your upper from your lower. Remove your charging handle and bolt carrier group from the upper. Put a factory round in the barrel and lightly tap the back of the cartridge with a finger into the chamber. Point the barrel up and the cartridge should fall free. If it sticks, you have a chamber or throat problem..A function gauge works best, "but in a pinch" using a well made factory round will work....
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Bretandry Wrote:Thank you nice trick
No problem. Make sure the chamber and throat are clean before you test it. Carbon and fouling can sometimes cause the cartridge to stick, giving a false reading...
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You guys were right I was wrong I was undergassed. Thank for all the help. I never would have thought that the case would grab the chamber that much but it does.
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Glad you got it sorted out. I have a 20 Shilen match profile 6.5 Grendel barrel and it shoots really good and Im usually the weak link.
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VASCAR2 Wrote:Glad you got it sorted out. I have a 20 Shilen match profile 6.5 Grendel barrel and it shoots really good and Im usually the weak link.
Same here. Never had an issue with the Shilen barrel and bolt.
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Almost every fte issue I have had after a dozen or so grendel builds are always a gas issue . Just my $.02
