224 Valkyrie New AR-15parts.com 24" Bull Barrel AR15 Upper load issue

[fkimble@charter.net]

Sounds like a no gas situation. Take a spray can of something like carb clearer brake cleaner etc. With the action open, stick the red straw in the rear end of the gas tube. Give it a shot. If the tube or gas block is stopped up, it should all come flying back out the rear end of the tube. If not stopped up about half will enter the barrel. keep it pointed down. If non runs out the end of barrel, you have it narrowed down to gas tube, gas block or gas block to gas port alignment. It does have a gas port in the top of the barrel? If above is ok, then take the red straw and stick it the front of the gas key. Another shot of spray. Most will come back out the front but some should enter the bolt if all is good. Gas key could be blocked, no hole or mis-aligned with bolt. Follow the gas path, somewhere there is a big problem. 50K psi of gas should at least show some movement of the bolt even if there was a partial blockage of the gas.

Frank

 

[searcher]

Because your brass is chambering but extremely difficult to extract - I'd now swerve away from this being a gas problem and more of one which is a brass problem brought on by pressure. Because you are using "new" brass - I'd also rule out the likelihood of needing a short-base die because it appears your brass expansion is occurring with your rifle - again pointing to high pressure. Lots of indicators you are running a load that is a bit hot for your rifle. As you noted - reducing load 1 grain helped but did not cure. If your head spacing is correct, not jamming bullets (if they fit in mag - they probably aren't) and your powder charge is not excessive - your fired brass should easily extract even if the gas port was completely blocked by the gas block. Good luck!

 

[fkimble@charter.net]

Searcher, his last range trip with the reduced powder charge, he says "Fires fine and the case doesn't stick in the chamber now with 1 grain less power in this (2nd) load".

Even a marginal working gas system should at least be moving the bolt/BCG a little? I think.

The fix will probably be real logical when found!

Frank

 

[mudduck]

Gas tube is to short!!! Show some pics of tube though the upper.

 

[Linko]

I ordered a new gas block and tube. When it arrives we will see.

I will stick the original back in the upper and get a photo in the mean time.

 

[cmillard]

May I ask what brand upper receiver group it is? Hopefully it's not an AR-Stoner or Bear Creek Arsenal. You put the upper on a S&W lower right? I will say this, the two brands listed above, I have done work on both of those brands this week from co-workers I told to stay away from them. I am not seeing ejector marks on the brass which can be indicative of pressure. I would check all the above recommendations and also check the carrier key to make sure it's not loose.

 

[Linko]

ar15parts.com

key not loose.

picture coming soon, sorry delayed

 

[Linko]

Here is the gas tube

 

[jelenko]

The key can be leaking gas AND not be loose.
The test is to liberally apply water with detergent all over the gas key. Then, blow compressed air into the key. If it's leaking, you'll see bubble around the base of the key where it's mounted on the carrier.

 

[Linko]

The key can be leaking gas AND not be loose.
The test is to liberally apply water with detergent all over the gas key. Then, blow compressed air into the key. If it's leaking, you'll see bubble around the base of the key where it's mounted on the carrier.

Nice test.

will do

thanks

 

[cmillard]

It looks like you have a bunch of carbon buildup. Unless my eyes are mistaken. That carbon, if left to build up, can turn hard like a rock and can cause numerous issues. I had a coworker that was having malfunctions in his AR-15 and in order for the bolt to close all the way, the forward assist had to be used. He had other issues along with that. When I took a look, there was so much carbon in it, I had to soak it in kroil for 2 days. After considerable effort, I got out all the rock like pieces (in the chamber and upper receiver near gas tube, and inside bolt carrier), his rifle ran flawlessly. When I returned the rifle, a sermon on rifle cleaning ensued.

 

[Linko]

new gas block and tube with factory Federal ammo = same result, no eject

sent upper and BCG back to supplier.

 

[5spd]

I had similar issues and after checking everything I got a set of small base dies bam no issues since.

 

[Linko]

small base die did not help.

 

[searcher]

Look - there is NOTHING in the gas system that is going to cause high pressure leading to difficult extraction. The A/R gas system is not a gas relief valve of sorts - it merely diverts a rather insignificant amount of gas to operate the bolt. So - if you have difficult extraction - I'd focus on what causes it. That will be one of two things 98% of the time in an A/R. It will be because the load is too hot for the rifle or excessive headspace is in play.

If I understand correctly, the problem loads were neck sized? Does this mean other loads full length sized worked OK? An AR is not a weapon I would use a necksizer on. It needs to be full length sized to insure the .200 area of the case is resized enough to freely chamber and eject. Also sounds like your neck sizing is way to tight. Using such a tight bushing may also cause the neck to force the body/shoulder junction to expand outward causing a tight or even no go situation. Same as when a seating die body is screwed down too much and is hitting the end of the case swelling the body/shoulder junction.
So please verify, are full length sized brass loads working? Also some fast powders do not produce enough gas to correctly operate an AR's gas system. I know Accurate 2220 is one of those. Did you by chance measure the diameter of the gas port?

Frank

Neck sizing dies are the PREFERRED way to go for the most accurate A/R ammo - though, of course, they should be FULL LENGTH resizing dies, as the writer is using. The problem using them with heavy bullets and no crimp (if that be the case) is that those heavy bullets carry a lot of inertia when loading and can often slide forward when the round chambers. That requires using a smaller bushing than would be used with, say, a 55-grain bullet. I quit using coatings on my .20 caliber bullets because I couldn't completely stop them from sliding no matter the bushing size. Allowing the charging handle to snap forward and strip a round off the magazine and then extract it and measure OAL will show if this is occurring - something that happens much more than most folks realize. If one uses a bushing so small as to affect the dimensions of the brass adversely - such as the neck collapsing into the shoulder (which is what usually happens to some degree), a round will either not properly load or extract - or it creates excessive headspace problem which the writer suggests does not exist. Both of these conditions are readily apparent before firing a live round by measuring OAL (after ejecting an unfired round) and headspace measurement. Gas leakage around any such distorted brass could cause the brass to further distort, though any condition of such magnitude would be readily measured as being present before the round is even chambered, let alone fired. The fired brass would also show clear signs of gas slipping past the neck as well in the form of carbon streaking. While fast powders can present problems for extraction - it occurs when the mainspring is too heavy for the lighter load to push the bolt all the way back to where it can strip off another round from the clip, resulting in a "short stroke". A mere mainspring changeout to a light (like a Wolff) mainspring re-tunes to proper operation. Most rifles and uppers are equipped with mainsprings designed for use with what "most people" will likely shoot - which is typically 55-62 grain commercial ammo. This explains why most factory small-bullet varmint ammo doesn't shoot so well - as the manufacturers had to use those powders which would cycle the bolt on commercial guns - and not be able to use those which may exhibit the best accuracy characteristics when firing the small bullets (usually 40 grain and under). When using the small bullets and the powders that shoot best for particular small vermin applications - the cycling problems often pop up till the rifle is re-tuned. Regardless - even a gas block completely rotated to shut off ALL gas would merely turn the rifle into a rifle which would still allow simple ejection from manual charging handle cycling. Lack of gas alone would cause no pressure or case distortion issues. It is very possible the problem is just the opposite - as the combination of slow powder and heavy bullets may allow enough residual pressure to remain in the tube in the tube when the bolt begins to rotate out of battery to cause a problem. If the problem did not completely go away after backing off the load charge (and still getting reasonable velocity) and my brass and neck tension specs were all good, I'd be inclined to replace the mainspring with a heavier one. Sometimes it is the simplest and least expensive fix. Sometimes folks just need to fire a few rounds of factory ammo to test for function to show them the issue is with their load and not the rifle. Of course - it should be heavy bullet ammo - which could also dispel needing a heavier spring possibly. While writers' buddy sent the upper back - they may very well send it right back or another one just like it - as there may be nothing wrong with either. If the factory function tests the upper - I doubt they will use 80 grain bullet ammo.

 

[Linko]

Received information from the supplier's gunsmith. Chamber is out of spec, they are replacing the barrel. We shall see....

 

[Linko]

Further update. Supplier also reports they found that the gas key had the reamer broken in it.

 

[Linko]

 

[Jeff Porter]

Well that explains a lot of issues.

 

[Culater]

Should have went with Craddockprecision.com I love my 224 Val. Shoots 1/2 moa at 100 yards. Dose very well at 1000 yards. They use Barlein barrels I went with a 1-6.5 twist.