Ejector spring problem?

308Loader · March 23, 2019, 05:55 PM

I recentally built a 300 acc upper and finally got to test it today. it is a 16" with a pistol length gas tube.The lower and bolt is an Olympic arms that has run flawlessally in 556 for years. Fit and from lower to upper is pretty good, verry little slop. I ran into an issue with it cycling, it will fire, grab the next round and feed it into the chamber, but the spent round will stove pipe behind the new round causing a malfunction. Looks like the new round begins to chamber when the case head of the spent round gets between the bolt and new round. The first box of 20 federal 150gr would literally turn it into a single shot, had to clear the spent case and advance the bolt on the live round in the chamber. the second box of Remington 125gr had the same issue but only 1 in 4 rounds, not every time.
So this leads me to believe that the ejector isn't slinging the case out of the action properly? could this be a weak spring? is the spent case dwelling in action area too long and getting caught up when the bolt is returning into battery, or is it bouncing back into the action? when it runs correctly the cases fly to the 2-3 o'clock position.

As always thanks for any input.

**4V50 Gary** · March 23, 2019, 07:33 PM

Could be the bolt is moving too slow too. That would delay the extraction and reduce the time for the ejector. How's the chamber? Gas port timed? If not, reduced gas entering into the action to push the bolt carrier back.

Or it could be hyperfunction. Too much gas, gun unlocking too fast for the ejector to work.

Check the ammo too.

Try different magazines. Drag on the bolt & bolt carrier can slow down the action. Mag spring too strong?

It could also be the gun needing a break-in.

Mobuck · March 24, 2019, 06:49 AM

What do the rims of the fired cases look like? Dings from the extractor being ripped past the rim?

FrankenMauser · March 24, 2019, 01:46 PM

Many modern smart phones have "high speed" / "slow motion" recording capability. You might try recording a few shots to see if you can identify - or at least get a better idea of - the mode of failure.

Will the ejector cleanly and assertively fling a cartridge clear if you hold the BCG in your hand, insert a loaded cartridge with your other hand, hold it in place with your finger tip, and let it fly?
If it tosses the cartridge with authority, the ejector probably isn't the problem.
If the cartridge just kind of 'flops' out, then the spring may be weak, or the plunger binding or slowed (by debris, carbon build up, sticky oil residue, or damage).

If you do pull the BCG for any reason, take a moment to see if cases hang up on the extractor. Cases being ejected should be able to cleanly "roll" or pivot over the extractor hook, with no snags or bobbles. If it hangs or snags at all, the extractor was cut wrong or has been damaged.

On the timing front:
Are you running a special bolt carrier? (Extra light / extra heavy?)
Anything non-standard in the buffer tube? (Heavier buffer, special spring, etc.?)

308Loader · March 25, 2019, 04:44 PM

no special bolt or buffer, case heads look normal. gas block seems to be timed ok. I will try to video the problem next range trip. I also have another lower I could try out.

308Loader · March 31, 2019, 03:48 PM

After the last range trip I cleaned the BCG and lubed it up, also cleaned up the buffer tube, buffer, and spring. They weren't clean but not crusty, added an extra drop of oil to the BCG since it is above freezing finally. On close inspection the gas block seemed a little crooked compared to the key mod handguard slots but gas tube was parallel with the upper reviver walls. I removed the setscrew and checked its alignment with the setscrew dimple, all was well. By best gestement the gas hole in the barrel and gas block seem to align well. Alignment with gas hole in the block and gas tube were spot on. Cleaned and oiled everything and reassembled, went and shot it this this Sunday. Didn't have as much of an issue, but still had cases landing in the action with their mouth or head between the bolt and next chambered cartage. Tried a steel GI mag towards the end of the range trip, might have helped a little, but ran out of ammo before I could confirm any appreciable difference.

couldn't keep the phone lined up with the action one handed to take video of the event. will need to take tripod or wife on the next trip.

edit: Cases fling out of the action just fine when running the charging handle. so weak spring is out I guess?

March 23, 2019, 05:55 PM	#1
308Loader Senior Member Join Date: August 24, 2014 Location: Minnesota Posts: 639	Ejector spring problem? I recentally built a 300 acc upper and finally got to test it today. it is a 16" with a pistol length gas tube.The lower and bolt is an Olympic arms that has run flawlessally in 556 for years. Fit and from lower to upper is pretty good, verry little slop. I ran into an issue with it cycling, it will fire, grab the next round and feed it into the chamber, but the spent round will stove pipe behind the new round causing a malfunction. Looks like the new round begins to chamber when the case head of the spent round gets between the bolt and new round. The first box of 20 federal 150gr would literally turn it into a single shot, had to clear the spent case and advance the bolt on the live round in the chamber. the second box of Remington 125gr had the same issue but only 1 in 4 rounds, not every time. So this leads me to believe that the ejector isn't slinging the case out of the action properly? could this be a weak spring? is the spent case dwelling in action area too long and getting caught up when the bolt is returning into battery, or is it bouncing back into the action? when it runs correctly the cases fly to the 2-3 o'clock position. As always thanks for any input. __________________ Just a dude with stuff.

March 23, 2019, 07:33 PM	#2
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,832	Could be the bolt is moving too slow too. That would delay the extraction and reduce the time for the ejector. How's the chamber? Gas port timed? If not, reduced gas entering into the action to push the bolt carrier back. Or it could be hyperfunction. Too much gas, gun unlocking too fast for the ejector to work. Check the ammo too. Try different magazines. Drag on the bolt & bolt carrier can slow down the action. Mag spring too strong? It could also be the gun needing a break-in. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

March 24, 2019, 01:46 PM	#4
FrankenMauser Senior Member Join Date: August 25, 2008 Location: In the valley above the plain Posts: 13,424	Many modern smart phones have "high speed" / "slow motion" recording capability. You might try recording a few shots to see if you can identify - or at least get a better idea of - the mode of failure. Will the ejector cleanly and assertively fling a cartridge clear if you hold the BCG in your hand, insert a loaded cartridge with your other hand, hold it in place with your finger tip, and let it fly? If it tosses the cartridge with authority, the ejector probably isn't the problem. If the cartridge just kind of 'flops' out, then the spring may be weak, or the plunger binding or slowed (by debris, carbon build up, sticky oil residue, or damage). If you do pull the BCG for any reason, take a moment to see if cases hang up on the extractor. Cases being ejected should be able to cleanly "roll" or pivot over the extractor hook, with no snags or bobbles. If it hangs or snags at all, the extractor was cut wrong or has been damaged. On the timing front: Are you running a special bolt carrier? (Extra light / extra heavy?) Anything non-standard in the buffer tube? (Heavier buffer, special spring, etc.?) __________________ Don't even try it. It's even worse than the internet would lead you to believe.

March 25, 2019, 04:44 PM	#5
308Loader Senior Member Join Date: August 24, 2014 Location: Minnesota Posts: 639	no special bolt or buffer, case heads look normal. gas block seems to be timed ok. I will try to video the problem next range trip. I also have another lower I could try out. __________________ Just a dude with stuff.

March 31, 2019, 03:48 PM	#6
308Loader Senior Member Join Date: August 24, 2014 Location: Minnesota Posts: 639	After the last range trip I cleaned the BCG and lubed it up, also cleaned up the buffer tube, buffer, and spring. They weren't clean but not crusty, added an extra drop of oil to the BCG since it is above freezing finally. On close inspection the gas block seemed a little crooked compared to the key mod handguard slots but gas tube was parallel with the upper reviver walls. I removed the setscrew and checked its alignment with the setscrew dimple, all was well. By best gestement the gas hole in the barrel and gas block seem to align well. Alignment with gas hole in the block and gas tube were spot on. Cleaned and oiled everything and reassembled, went and shot it this this Sunday. Didn't have as much of an issue, but still had cases landing in the action with their mouth or head between the bolt and next chambered cartage. Tried a steel GI mag towards the end of the range trip, might have helped a little, but ran out of ammo before I could confirm any appreciable difference. couldn't keep the phone lined up with the action one handed to take video of the event. will need to take tripod or wife on the next trip. edit: Cases fling out of the action just fine when running the charging handle. so weak spring is out I guess? __________________ Just a dude with stuff. Last edited by 308Loader; March 31, 2019 at 04:06 PM.

March 24, 2019, 06:49 AM	#3
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	What do the rims of the fired cases look like? Dings from the extractor being ripped past the rim?