Feeding issues

IAMDEATH · January 5, 2018, 10:26 PM

I recently finished AR in 300 blackout and had a issue when I took it to the range. I bought a box of Remington 120 grain and the first round chambers fine, bolt comes back and grabs the next round fine but when round goes into the chamber it's not allowing the bch and round to go all the way in. I try to eject that round and the round is jammed in and takes a good bit of force to eject. I'm fairly new to AR's and not sure on what to look for to fix my issue, any help would be appreciated.

ms6852 · January 5, 2018, 10:37 PM

Since this are factory rounds, measure each of the rounds and ensure that the maximum case length for each cartridge is between1.350- 1,360. If any of the cartridges exceed this length the shoulders are causing the round to jam and possibly putting the bullet in the lands. Since you are new to AR's are your sure your upper is a 300 blackout and not a regular .223/5.56? Some of the manuals will will say 1.400 max but can be too long. Check the saami specs.
http://www.saami.org/PubResources/_C...20Blackout.pdf

Slamfire · January 5, 2018, 10:37 PM

Did you use cartridge head space gages in setting up your sizing dies?

These are examples. The Wilson type only measures base to shoulder distance, it is cut wide between the base and shoulder.

The Sheridan is cut to a SAAMI minimum chamber and has a neat port.

The most common problem for new shooters reloading for gas guns is not full length resizing, notsetting up their dies with cartridge head space gages, and using ammunition fired in another rifle.

I do recommend small base dies for gas guns, if you can find them for your cartridge you might try them.

IAMDEATH · January 5, 2018, 10:52 PM

I measure factory rounds and case measures 1.358 and C.O.A.L is 2.150.

Charlie98 · January 5, 2018, 11:22 PM

Is the round jamming in the chamber, or is the bolt hanging up in the bolt recess?

IAMDEATH · January 5, 2018, 11:31 PM

The round appears to be jamming in the chamber.

ms6852 · January 6, 2018, 01:11 AM

Get a bore light and check for any imperfections on the chamber or debris. If it looks good you might have to do a chamber casting using cerrosafe. Videos in youtube will show you how to do it.

Theohazard · January 6, 2018, 01:21 AM

It’s possible that your rifle is simply under-gassed. The BCG might be traveling just far enough back to strip the next round off the mag, but not far enough back to build up enough momentum to completely chamber it.

Try the lock-back test: Load one round into the chamber with an empty magazine inserted. If you fire the round and the BCG doesn’t lock back on the empty magazine, that’s a sign of under-gassing.

Mobuck · January 6, 2018, 08:17 AM

"Try the lock-back test: Load one round into the chamber with an empty magazine inserted. If you fire the round and the BCG doesn’t lock back on the empty magazine, that’s a sign of under-gassing."

I, for one, simply don't understand why AR makers don't put a bit of info in the package to let new owners know about such things. Or maybe new owners simply don't take the time-no reflection on the OP intended. Really, how much paper would it take to give the "full start up" regimen?

stagpanther · January 6, 2018, 09:05 AM

I think ms682 has it.

Assuming you did a complete clean and check of the weapon before first operating it (as opposed to opening the box and running off to the range and start emptying magazines) my guess is you have an obstruction in the chamber hanging the case up--in my experience the 300 BO is one of the easiest and most reliable cycling AR cartridges there is.

It is also true that it tends to be over-gassed--it's possible that you may be getting some interference from the spent case if the cycling is "violent" enough that the spent case somehow is interfering with the cycling--do your spent cases show signs of excessive damage--like crushed mouths or huge dents?

T. O'Heir · January 6, 2018, 01:03 PM

An obstruction in the chamber would cause the first round to not chamber as well. So would any case size related issues. It's factory ammo, not reloads. So cartridge head space gaUges(that are not necessary for doing anything. Particularly for setting up the dies) don't apply.
99% of feeding issues are magazine related. I'm thinking the round is not coming out of the mag correctly and gets jammed in at an angle by the bolt. Very much a guess though. Might not be sufficient gas or it might be the mag lips are bent in a tick. Might be the return spring is too light.

Charlie98 · January 6, 2018, 02:55 PM

That's why I axed if maybe the bolt was hanging up... if the first round chambers and fires, there is no reason the second one wouldn't... unless there is an obstruction, particularly with factory ammos.

T. O'Heir · January 7, 2018, 02:41 PM

Why you what?
It's not an obstruction if the first round chambers and fires with no fuss. Nor is it ammo related.

January 5, 2018, 10:26 PM	#1
IAMDEATH Member Join Date: May 17, 2012 Posts: 28	Feeding issues I recently finished AR in 300 blackout and had a issue when I took it to the range. I bought a box of Remington 120 grain and the first round chambers fine, bolt comes back and grabs the next round fine but when round goes into the chamber it's not allowing the bch and round to go all the way in. I try to eject that round and the round is jammed in and takes a good bit of force to eject. I'm fairly new to AR's and not sure on what to look for to fix my issue, any help would be appreciated.

January 5, 2018, 10:37 PM	#2
ms6852 Senior Member Join Date: April 3, 2010 Location: Texas Posts: 1,394	Since this are factory rounds, measure each of the rounds and ensure that the maximum case length for each cartridge is between1.350- 1,360. If any of the cartridges exceed this length the shoulders are causing the round to jam and possibly putting the bullet in the lands. Since you are new to AR's are your sure your upper is a 300 blackout and not a regular .223/5.56? Some of the manuals will will say 1.400 max but can be too long. Check the saami specs. http://www.saami.org/PubResources/_C...20Blackout.pdf __________________ ONLY TWO DEFINING FORCES HAVE GIVEN UP THEIR LIVES FOR YOU. ONE IS JESUS CHRIST FOR YOUR SOUL AND THE OTHER IS THE AMERICAN SOLDIER FOR YOUR FREEDOM. Last edited by ms6852; January 5, 2018 at 10:54 PM.

January 5, 2018, 10:37 PM	#3
Slamfire Senior Member Join Date: May 27, 2007 Posts: 5,261	Did you use cartridge head space gages in setting up your sizing dies? These are examples. The Wilson type only measures base to shoulder distance, it is cut wide between the base and shoulder. The Sheridan is cut to a SAAMI minimum chamber and has a neat port. The most common problem for new shooters reloading for gas guns is not full length resizing, notsetting up their dies with cartridge head space gages, and using ammunition fired in another rifle. I do recommend small base dies for gas guns, if you can find them for your cartridge you might try them. __________________ If I'm not shooting, I'm reloading.

January 5, 2018, 11:22 PM	#5
Charlie98 Senior Member Join Date: September 6, 2006 Location: Great state of Texas Posts: 1,077	Is the round jamming in the chamber, or is the bolt hanging up in the bolt recess? __________________ _______________ "I have this pistol pointed at your heart!" "That is my least vulnerable spot."

January 6, 2018, 01:11 AM	#7
ms6852 Senior Member Join Date: April 3, 2010 Location: Texas Posts: 1,394	Get a bore light and check for any imperfections on the chamber or debris. If it looks good you might have to do a chamber casting using cerrosafe. Videos in youtube will show you how to do it. __________________ ONLY TWO DEFINING FORCES HAVE GIVEN UP THEIR LIVES FOR YOU. ONE IS JESUS CHRIST FOR YOUR SOUL AND THE OTHER IS THE AMERICAN SOLDIER FOR YOUR FREEDOM.

January 5, 2018, 10:52 PM	#4
IAMDEATH Member Join Date: May 17, 2012 Posts: 28	I measure factory rounds and case measures 1.358 and C.O.A.L is 2.150.

January 5, 2018, 11:31 PM	#6
IAMDEATH Member Join Date: May 17, 2012 Posts: 28	The round appears to be jamming in the chamber.

January 6, 2018, 01:21 AM	#8
Theohazard Senior Member Join Date: April 19, 2012 Location: Western PA Posts: 3,829	It’s possible that your rifle is simply under-gassed. The BCG might be traveling just far enough back to strip the next round off the mag, but not far enough back to build up enough momentum to completely chamber it. Try the lock-back test: Load one round into the chamber with an empty magazine inserted. If you fire the round and the BCG doesn’t lock back on the empty magazine, that’s a sign of under-gassing. __________________ 0331: "Accuracy by volume."

January 6, 2018, 08:17 AM	#9
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	"Try the lock-back test: Load one round into the chamber with an empty magazine inserted. If you fire the round and the BCG doesn’t lock back on the empty magazine, that’s a sign of under-gassing." I, for one, simply don't understand why AR makers don't put a bit of info in the package to let new owners know about such things. Or maybe new owners simply don't take the time-no reflection on the OP intended. Really, how much paper would it take to give the "full start up" regimen?

January 6, 2018, 09:05 AM	#10
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,784	I think ms682 has it. Assuming you did a complete clean and check of the weapon before first operating it (as opposed to opening the box and running off to the range and start emptying magazines) my guess is you have an obstruction in the chamber hanging the case up--in my experience the 300 BO is one of the easiest and most reliable cycling AR cartridges there is. It is also true that it tends to be over-gassed--it's possible that you may be getting some interference from the spent case if the cycling is "violent" enough that the spent case somehow is interfering with the cycling--do your spent cases show signs of excessive damage--like crushed mouths or huge dents? __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

January 6, 2018, 01:03 PM	#11
T. O'Heir Senior Member Join Date: February 13, 2002 Location: Canada Posts: 12,453	An obstruction in the chamber would cause the first round to not chamber as well. So would any case size related issues. It's factory ammo, not reloads. So cartridge head space gaUges(that are not necessary for doing anything. Particularly for setting up the dies) don't apply. 99% of feeding issues are magazine related. I'm thinking the round is not coming out of the mag correctly and gets jammed in at an angle by the bolt. Very much a guess though. Might not be sufficient gas or it might be the mag lips are bent in a tick. Might be the return spring is too light. __________________ Spelling and grammar count!

January 6, 2018, 02:55 PM	#12
Charlie98 Senior Member Join Date: September 6, 2006 Location: Great state of Texas Posts: 1,077	That's why I axed if maybe the bolt was hanging up... if the first round chambers and fires, there is no reason the second one wouldn't... unless there is an obstruction, particularly with factory ammos. __________________ _______________ "I have this pistol pointed at your heart!" "That is my least vulnerable spot."

January 7, 2018, 02:41 PM	#13
T. O'Heir Senior Member Join Date: February 13, 2002 Location: Canada Posts: 12,453	Why you what? It's not an obstruction if the first round chambers and fires with no fuss. Nor is it ammo related. __________________ Spelling and grammar count!