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Posted: 3/29/2015 9:42:29 PM EDT
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So this is my first build and first time posting, so please be patient and gentle...
Here are the details of the build: Spike's lower CMMG LPK Odin pistol buffer tube Pistol spring Heavy Buffer 7.5" Odin 223 Wylde barrel BCM Upper AAC BCG and Charging handle Odin adjustable gas block AAC Brakecomp 2.0 muzzle device Symptoms: I tuned the gas block, or so I thought, i intermittently experienced one of two failure mechanisms. The first was a failure to load the next round, I am pretty sure this is short stroking. The second was a light strike on the primer, I am pretty sure this is related to short stroking. When this would happen the round was a pain to get out. I had to use a mallet on the charging handle once. This still happened even after I open the gas block all the way. Debug so far: 1.) My first suspect was my ammo, since I started with a clean gun. I was using my reloads and Tulammo steel case 223. The steel case stuff is what it is, so I suspected my reloads (trimmed once fired 5.56 from my rifle, 55gr FMJ BT, 24.6gr CFE223 Hodgdon powder, CCI small rifle primer) but I have fired several hundred of these through my other AR and never hand any issues, but to be sure I used a micrometer and Dillon case gauge on about 50 rounds to double check. All within SAAMi spec. 2.) My next suspect was the gas block, so I stripped it down and check and I couldn't hav aligned it better if I wanted to. Next step: I replaced the heavy buffer with a carbine buffer, cleaned and lubed everything, scrubbed the chamber. Looking at picking up a low mass BCG. Any suggestions? |
| Double check your gas block,take a look at the carrier,make sure the key is tight, check that the hammer and trigger springs are installed correctly. also did you allow a small space between the gas block and the shoulder on the barrel? It is the width of a hand-guard cap. |
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It appears to me that you have two problems.
#1 short stroking. Not enough gas to operate the action reliably. You need to open up the adjust to let more gas in, OR add more powder to your reloads. #2 Improperly resized casings on your reloads. Are you using small based dies? You need to make sure that the casing are fully resized. The chambers of all guns of the same caliber are not all the same finish size. The fact that rounds fired out of another 5.56mm gun, and reloaded sometimes do not fully chamber, and are hard to extract from your new gun is not a surprise (while they work without a problem on the gun that they were fired from before). Personally, I didn't think that steel casing were even worth reloading. Once fired Lake City bras is available cheap. I know that that steel casings will not last as long as brass casings, as steel ones are more brittle. And, I've heard that they will wear your dies out faster. |
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Did you check headspace?
Did you check BCG travel? Reloads sized at the high end of the tolerance range may be “in spec” and still cause problems. Use known good ammo like XM193. Load one round in the mag, the BCG should lock back when fired. What do you mean by light primer strike? Barely a mark on the primer or something more substantial? |
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Just to clarify, the reloads were LC brass. Checked the headspace, and the travel. I am on the top end of the headspace, so I may need to check the settings of my dies. I am going to pick up some factory XM193 and 223 Remington to try out. BCG travel is good, not impinged at all. The light primer strike was barely a mark on the primer, but if I locked the bolt back and let it slam home the round would fire just fine. If light primer strike happens with the factory ammo, I will take a picture. I think this may be a combination of reloads at the high end of the spec and the slightly smaller chamber of the 223 wylde barrel. |
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If you are not sizing enough or are over crimping you can cause the round to chamber hard and make an unfired round hard to extract. Also if you are not seating the bullet deep enough you could be forcing the bullet into the lands, which can also cause sticky extraction of unfired rounds. Plus, improperly sized cases, over crimped cases, and long bullets can cause the bolt not to completely lock up, hence the 'click' and the only mark on the primer being the inertial peck.
Size a case with no primer. It should extract effortlessly. Seat a bullet with NO crimp (no powder or primer). Adjust so it extracts effortlessly. Then crimp if you so desire. If it hangs then, back off on the amount of crimp. Also make sure your cases are trimmed to the correct length. |
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So here is an update... I received my go/no-go headspace gauge yesterday. I pulled the extractor and ejector out of the bolt, dropped the go gauge in and tried to close the bolt. Wouldn't close... After about 20 minutes of checking the PTG 5.56 go gauge specs and checking it with a micrometer, I turned my attention to the chamber. Go gauge wouldn't close with 2 different BCGs, so I shined some light into the chamber and it was pretty dirty (only fired 80 rounds). After scrubbing the chamber with a chamber brush, this sandy material starts running out the barrel. It appears to be partially burnt powder. After scrubbing the chamber and giving the pistol a complete cleaning, the go gauge checks out. The sandy looking partially burnt powder appears to be from the tullammo 223 I was firing. So I will never use those again... I still have to tweak my dies for reloading as I am on the top end of some of the SAAMI specs, but I think the catalyst for all of this was cheap ammo. |
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Quoted:
So this is my first build and first time posting, so please be patient and gentle... Here are the details of the build: Spike's lower CMMG LPK Odin pistol buffer tube Pistol spring Heavy Buffer 7.5" Odin 223 Wylde barrel BCM Upper AAC BCG and Charging handle Odin adjustable gas block AAC Brakecomp 2.0 muzzle device Symptoms: I tuned the gas block, or so I thought, i intermittently experienced one of two failure mechanisms. The first was a failure to load the next round, I am pretty sure this is short stroking. The second was a light strike on the primer, I am pretty sure this is related to short stroking. When this would happen the round was a pain to get out. I had to use a mallet on the charging handle once. This still happened even after I open the gas block all the way. Debug so far: 1.) My first suspect was my ammo, since I started with a clean gun. I was using my reloads and Tulammo steel case 223. The steel case stuff is what it is, so I suspected my reloads (trimmed once fired 5.56 from my rifle, 55gr FMJ BT, 24.6gr CFE223 Hodgdon powder, CCI small rifle primer) but I have fired several hundred of these through my other AR and never hand any issues, but to be sure I used a micrometer and Dillon case gauge on about 50 rounds to double check. All within SAAMi spec. 2.) My next suspect was the gas block, so I stripped it down and check and I couldn't hav aligned it better if I wanted to. Next step: I replaced the heavy buffer with a carbine buffer, cleaned and lubed everything, scrubbed the chamber. Looking at picking up a low mass BCG. Any suggestions? Low bolt carrier velocity (short stroking) is not directly related to light primer strikes. Low bolt carrier velocity is most often caused by too heavy a bolt carrier/buffer combination, too small a gar port, or both (there can be other reasons, but since this is new, we can rule out dirt, along with worn gas rings). Since your gas block is adjustable, and open all the way and you already put in a standard buffer, open up the gas port (one drill size at a time). Also, just to be thorough, check the gas key for security, gas tube for bends/dents that might restrict flow, proper installation of the tube, and clean passages in the bolt carrier. Tula seems to use a really fast powder so the gas port pressure is lower that usual leading to this sort of problem Light primer strikes are caused by weak hammer springs, improperly installed springs, light hammers, sticky pins, burred hole in the bolt face, pin binding in firing pin passage, and a short firing pin. Since this is a "construction première", check that bolt of the legs of the hammer spring are over the trigger pin. |
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Light primer strikes can be from your trigger if you are using a non-mil spec trigger system. Those wolf primers are hard and a high primer can make things tough too. Most AR issues are caused by lube issues, ammunition and or magazines. These don't sound like magazine issues. A properly running AR needs only to be kiind of clean but if your getting all that crud from ammo running out of the gun then that's a no go. Is there any possibility that that sandy stuff has clogged up the gas system? Could it be possibly tumbling media? Just some thoughts.
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| So here is the verdict. It was actually two different problems causing the same thing. The tulammo would clog up the chamber with so much un-burnt powder that no ammo could chamber. I showed this with a before and after test with the case gauge and a thorough cleaning of the gun. The second problem is my reloads. While they are wishing SAMMI, they are on the top end. This is too tight for the 223 Wylde chamber, but they run just fine in my M&P15, so all is not lost. First I will never use tulammo again, second I am going to tweak my reloading setup and try in pull in the dimensions. Thank you all for your input, it was a fun build. |
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