Adjustable Gas Block and Ding on Spent Casing

[Ranchmanager]

Everyone

Went to the range with the new gun today, followed their break in procedure ( shoot 5 clean - 4 times). Came home did a thorough cleaning went back. Not Sub MOA but couldn't get Sub MOA with my AR in 556 that is sub MOA. Guess I wasn't holding my mouth right. Hoping I'm not going to have to go down the reloading rabbit hole!

The new gun has an adjustable gas block which I have never had. There is a video online on how to adjust it. I have a few questions for those with more expertise than I.

1. Will the adjustment of the gas block affect accuracy?
2. How do you know if a gun is over gassed? ( I understand if under gassed it wont cycle properly)
3. If over gassed will it harm the rifle over time.
4. See attached picture of shell casing. What is causing the small indentation.

Thanks in advance for your support and answers, I've opened up a new can of worms with this caliber and want to get the most out of it for deer and hog hunting.

Sincerely

Ranch Manager ( Chris )
P.S. I'm not a ranch manager but that title is a whole different story!

Thanks Again

[CJW]

[Klem]

Chris,

In answer to your questions;

1. Will the adjustment of the gas block affect accuracy? Maybe. It won't affect precision but may affect accuracy with harsher recoil influencing flinching and jump.

2. How do you know if a gun is over gassed? You can use the ejection pattern as a guide. Look where the cases are ejecting relative to the muzzle which is 12 O'clock. Normal ejection is about 4 O'clock, but cases ejected further to the front of the rifle is a sign you are overgassed. Or, you can almost close the gas off and fire single rounds as you open the gas one click at a time, until it locks back on last round. Then go one more click for good measure and stop. Obviously some factory loads have more oomph than others so you can fine-tune the AGB for the ammo you are using.

3. If over gassed will it harm the rifle over time. Maybe - if it is good quality you can hammer it while overgassed and nothing will break, but it is unpleasant to shoot. Everything wears out eventually and you will never know if whatever needs replacing is a result of being overgassed, so best not to do this in the first place.

4. See attached picture of shell casing. What is causing the small indentation. That 45 degree little ding? Unsure. Is it on every spent case or just a few, or only one?

Klem

[VASCAR2]

https://www.youtube.com/watch?v=YbXBDe1argo

[Ranchmanager]

Klem, Vascar2

Thanks for your prompt replies.

The shells are ejecting about the 4 o'clock position. So it must be set properly. The gentleman I spoke to said they would adjust it prior to shipping since I had never adjusted it before. There is minimal if at all any recoil in the gun. It shoots very nicely.
The ding is on most of the shells, I did notice a brass smudge/scratch in the area where the shell casing are hitting the deflector. Thought to myself "Damn scratched a brand new rifle the first day!" the paint is gone on a very small section of the deflector!

Will have to have my favorite AR looked at as it throws the shells forward not backward ( a buddy helped me build that one). Will have to take the others to the range next trip to check them ( factory builds).

LOTS of great information. Thanks a million.
Sincerely
Chris

[Klem]

Chris,

Sounds like it's squared away and just needs some fine-tuning.

On the adjustable gas block can I suggest you regularly open and close the adjuster screw. This cracks the build-up of carbon after each shooting session and keeps it from seizing up. You may as well do this just prior to cleaning by screwing it right in (closed), to stop solvents going into the gas system. Then don't forget to open it again counting the clicks or revolutions to the right setting. If it does seize up from carbon then you might have to pull it apart to clean it. If the block is under the handguard then that has to come off as well, so best to prevent this by keeping everything moving regularly.

The 4 O'Clock ejection pattern sounds perfect, but why don't you close it one click in and see if it still functions flawlessly. Then keep doing that until it fails to function and then you know the threshold. Then maximise its benefits by opening one click.

Vas is on the money with the dents in spent Grendel cases. Grendel is shorter than 223 so gets flung around to the deflector. Velcro is one solution; or cutting a couple of coils off the ejector spring is another. There are threads on this on the Forum.

As for wearing the paint off the deflector what can I say - par for the course.

Happy shooting.

K

[grendelnubi]

I had experienced a short stroking issue during hotter temps with my 129 ABLR AR Comp load and made an adjustment to correct it. I always had case mouth dents on this platform but after increasing the gas the dented case mouth went away. Make a gas adjustment and share the results. It could be another data point in improving cycling timing

[DHD]

An AR can be rough on brass for sure. One of the best tricks I've done to help keep dents to a minimum was to cut a coil ot two off of the ejector spring (like was previously mentioned by Klem). My pair of Grendels don't have the brass deflector wart but the rear of the ejection port did put a quarter moon on brass until I shortened the spring. Keeping the gas tuned down (but still operating 100%) helps too.

The brass battering I will not tolerate are the gouges on the case necks from the sharp edges of the barrel extention (2 lug recesses at 3 O'clock). I make a point to smooth them up before assembly. Shortening the ejector spring helps with this too. Grendel brass is expensive so I try to take care of it as best I can.

Klem also gives good advice about keeping the adjustable gas block operating. I will give all of mine a quick squirt of Free-All down the gas tube before cleaning and turn in and back out a few turns (all SLR gas blocks here) then let them sit muzzle down. Everyone has their own tricks to keep these rifles running....

[Happy2Shoot]

Everyone

Went to the range with the new gun today, followed their break in procedure ( shoot 5 clean - 4 times). Came home did a thorough cleaning went back. Not Sub MOA but couldn't get Sub MOA with my AR in 556 that is sub MOA. Guess I wasn't holding my mouth right. Hoping I'm not going to have to go down the reloading rabbit hole!

Not sure if joking or not. A proper and consistent cheek weld is very important to accurate shooting. I always make a point to align my teeth and slightly clinch my jaw.

The new gun has an adjustable gas block which I have never had. There is a video online on how to adjust it. I have a few questions for those with more expertise than I.

1. Will the adjustment of the gas block affect accuracy?

Not likely.

2. How do you know if a gun is over gassed? ( I understand if under gassed it wont cycle properly)

If the brass, when ejected, is going forward it is over gassed.

3. If over gassed will it harm the rifle over time.

Not likely. All AR's are over gassed for civilian use.

4. See attached picture of shell casing. What is causing the small indentation.

100% normal ejection ding from hitting the brass deflector. Have you not seen this with your 5.56 as well?

Thanks in advance for your support and answers, I've opened up a new can of worms with this caliber and want to get the most out of it for deer and hog hunting.

Sincerely

Ranch Manager ( Chris )
P.S. I'm not a ranch manager but that title is a whole different story!

Thanks Again

I think adjustable gas blocks are really good to have for a reloader.