Ar not going into battery

[Mo Zee]

Hi Guys,

I am pretty new to the 3 gun equipment. I have an oldish type AR-15. I recently fitted a flat top receiver and an adjustable stock. This is the type of stock that was purchased and fitted Adjustable Stock with Pic

After fitting, I am finding it difficult for the bolt/action to go back into battery. After the shot is fired, the bolt sort suspends at the open position, with or without the mag inserted. The only way to get it back to battery is either to shake the living daylights out of it or actually hitting it on the side.

Is the problem with the flat top or the stock. My guess is the stock and I have no idea what to adjust and/or check. Can anyone assist???

[Derek45]

Take the bolt out of the carrier, slide the carrier into the upper receiver to see if the gas key is properly aligned with the gas tube.

If you replaced the upper, and the gas tube isn't aligned, it can cause the bolt carrier to hang up when going forward.

[kurtm]

I am betting there is a missalignment of the upper receiver and the stock tube causing the bolt carrier to bind on the tube. Pull the carrier and look for marks on the top of the carrier near the gas key. The other problem might be the wrong or to short buffer being used, look for marks on the lower receiver where the top of the carrier would hit it. It will look like two verticle lines being hammered into the top of the lower receiver where the stock tube comes through. If y ou have a "big pin" lower you need to run an adapter. This also will cause the trouble you are having. KurtM

[gotm4]

Check you buffer spring length. It should be for a carbine 10 1/16" to 11 1/4"

[Mo Zee]

Thanks for all of the responses - Much appreciated.

I am betting there is a missalignment of the upper receiver and the stock tube causing the bolt carrier to bind on the tube. Pull the carrier and look for marks on the top of the carrier near the gas key. The other problem might be the wrong or to short buffer being used, look for marks on the lower receiver where the top of the carrier would hit it. It will look like two verticle lines being hammered into the top of the lower receiver where the stock tube comes through. If y ou have a "big pin" lower you need to run an adapter. This also will cause the trouble you are having. KurtM

Kurt - I am not sure what type of lower I have BUT when I fitted the Upper I needed an offset pin. This I would assume makes my lower a "big pin" lower as you put it because the upper had a smaller hole than the lower. Other than the offset pin, what other adapters to I need to have in order to solve the problem?

Check you buffer spring length. It should be for a carbine 10 1/16" to 11 1/4"

Gotm4 - This is a rifle length AR. What length am I looking at for this rifle in comparison to the carbine length

[gotm4]

Gotm4 - This is a rifle length AR. What length am I looking at for this rifle in comparison to the carbine length

Rifle 11 3/4" to 13 1/2" (for rifle stocks only regardless of the length of the upper).

Carbine 10 1/16" to 11 1/4" (for carbine stocks only regardless of the length of the upper).

[Mo Zee]

Gotm4 - This is a rifle length AR. What length am I looking at for this rifle in comparison to the carbine length

Rifle 11 3/4" to 13 1/2" (for rifle stocks only regardless of the length of the upper).

Carbine 10 1/16" to 11 1/4" (for carbine stocks only regardless of the length of the upper).

Ok - Now I am confused. :-)

This stock is adjustable. And can be used in Rifle and Carbine length. How would I know what to use.

[gotm4]

Gotm4 - This is a rifle length AR. What length am I looking at for this rifle in comparison to the carbine length

Rifle 11 3/4" to 13 1/2" (for rifle stocks only regardless of the length of the upper).

Carbine 10 1/16" to 11 1/4" (for carbine stocks only regardless of the length of the upper).

Ok - Now I am confused. :-)

This stock is adjustable. And can be used in Rifle and Carbine length. How would I know what to use.

Can you post a pic of your stock one just like it?

Most 'adjustable' stocks have carbine length buffers and springs.

[Mo Zee]

Gotm4 - This is a rifle length AR. What length am I looking at for this rifle in comparison to the carbine length

Rifle 11 3/4" to 13 1/2" (for rifle stocks only regardless of the length of the upper).

Carbine 10 1/16" to 11 1/4" (for carbine stocks only regardless of the length of the upper).

Ok - Now I am confused. :-)

This stock is adjustable. And can be used in Rifle and Carbine length. How would I know what to use.

Can you post a pic of your stock one just like it?

Most 'adjustable' stocks have carbine length buffers and springs.

I have this exact one -

If I do in fact have the carbine length spring can I use the standard spring that came with the gun to see if that works??? The gun came with the standard Ar-15 stock. Non adjustable one.

[gotm4]

I have this exact one -

If I do in fact have the carbine length spring can I use the standard spring that came with the gun to see if that works??? The gun came with the standard Ar-15 stock. Non adjustable one.

You can't use the longer rifle spring because the internal dimensions of the carbine and rifle tubes are different.

[Mo Zee]

I have this exact one -

If I do in fact have the carbine length spring can I use the standard spring that came with the gun to see if that works??? The gun came with the standard Ar-15 stock. Non adjustable one.

You can't use the longer rifle spring because the internal dimensions of the carbine and rifle tubes are different.

OK - So I assume the spring that came with the adjustable stock is for the carbine length. Is there a rifle length buffer as well?

[gotm4]

I have this exact one -

If I do in fact have the carbine length spring can I use the standard spring that came with the gun to see if that works??? The gun came with the standard Ar-15 stock. Non adjustable one.

You can't use the longer rifle spring because the internal dimensions of the carbine and rifle tubes are different.

OK - So I assume the spring that came with the adjustable stock is for the carbine length. Is there a rifle length buffer as well?

Yes. They look like this:

[photog]

Sounds like the buffer tube is cross threaded.

Test: Pull the upper off the Carbine. check the bolt and carrier while it is separate. It should slide freely and the bold should lock up into the lugs with MINIMAL force. (one finger should get the bolt to fully engage with no ammo present. If it does not, most likely its the gas tube or gas key not in aligmnet. If they are ok, check the locking lugs for burrs. If they are ok, your upper may be bent (highly unlikely) or the charging handle may be bent (more likely). It pretty hard to ruin a carrier or bolt, but it could happen.

If the bolt and carrier move freely when dissaembled from the lower, reassemble the carbine after you have removed the buttstock, the buffer stop pin and buffer tube. Pull the carging handle. the bolt and carrier should 1. cock the hammer and 2. pull right out of the carbine without much force. Slide the carrier back into the buffer tube hole and repate the above. If you feel any resistance, there is a problem in the lower, maybe the bolt catch, maybe the hammer.

If the carrier and bolt operate smoothly with the butt stock removed, teh problem is going to be the butt stock. With the buffer and spring removed, slide the carrier into the buffer tube. It should move freely through the tube. If it does not, find the burr and remove it. If it does move freely, check the threads on the lower receiver, as they are probably mangled. The buffer is steel, the receiver is aluminum; steel wins.