Ruger AR15 BCG's are hot garbage

[leVieux]

"Hotdog in a hallway" is an interesting TDP to follow

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What means “TDP” ?

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[Dave Z]

Snap-Ring failure again?
(messing with you again)

Those are not snap rings, they are compression rings, similar to the ones in your car engine. When I disassemble my bolt carriers, I always make sure that the ring gaps don't line up with each other. I put a drop of oil on them then wipe off the excess. It goes back to what my Daddy always told me, "The best things in life are lubricated".

 

[zackmars]

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What means “TDP” ?

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Technical Data Package. All the info on how to build a military rifle, like an M4

 

[zackmars]

Those are not snap rings, they are compression rings, similar to the ones in your car engine. When I disassemble my bolt carriers, I always make sure that the ring gaps don't line up with each other. I put a drop of oil on them then wipe off the excess. It goes back to what my Daddy always told me, "The best things in life are lubricated".

You don't need to stagger the rings. An AR will work with just one ring, as the carrier will compress said ring.

And even if you align the gaps, they'll eventually stagger themselves.

 

[Sam7sf]

You don't need to stagger the rings. An AR will work with just one ring, as the carrier will compress said ring.

And even if you align the gaps, they'll eventually stagger themselves.

This.

 

[Gordo]

Those are not snap rings, they are compression rings, similar to the ones in your car engine. When I disassemble my bolt carriers, I always make sure that the ring gaps don't line up with each other. I put a drop of oil on them then wipe off the excess. It goes back to what my Daddy always told me, "The best things in life are lubricated".

Do your piston rings in your car engine, or any engine, have skinny spots right before the ends, like Snap Rings?
No...
They have the profile of a Snap Ring, just don't have the holes in the ends.
(cost less to make them without the holes)
Those thin sections of the AR SNAP RINGs is where they fail all the time, not only on the Ruger, but I've seen these failures on many other ARs.

Piston Rings:

Snap Ring:

AR 'GAS Ring' (LoL):

 

[easy rider]

While i consider Rugers AR's to be extremely substandard, by far the single worst component on them is their bolt carrier group.

I have seen so far 7 different Ruger AR's exhibit the same issue where a gas ring partially jumps the slot, and wedges the bolt partially out of battery over the past few years.

Fixing the problem involves pulling back the CH till the bolt locks about halfway back, separating the upper and lower until you can get a screw driver in the forward assist scallops, and driving it forward with a hammer till you can use the FA itself. Once it is in battery, you can fully remove the lower. Unlock the charging handle, have the upper in a vise (or have a buddy) hold it upside down, and stick a thick screwdriver against the back portion of the BCG, and hit it with a hammer. Hard.


With the carrier out, you should be able to remove the cotter pin and firing pin just fine. You will need to beat the bolt into its locked position by placing the BCG vertically and hitting it hard with a hammer. When that is done, you'll need to rotate the cam pin 90°. I've found a pair of needle nose pliers work the best. You'll then need to pull the cam pin out. Any slip joint pliers work well. You can then use a .30 caliber ram rod in the backside of the carrier to pop the bolt out. This beats up on ruger's cam pin pretty hard, and I would recommend replacing this part.

Typically it's only one of the 3 rings that has jumped, the other 2 are usually fine. Replacing all 3 rings will not solve the issue. Fortunately the AR really only needs one ring, so removing one of the rings will at least get you an extra mag or two of shooting if you really need it.

I believe 1 (or multiple) of 3 things are happening. Ruger's bolts are undersized, the carrier's bore is oversized, or the slot the rings sit in is too shallow.

The only real fix is to buy a higher quality BCG, Colt, BCM, DD, RRA, PSA, hell, even Anderson. These BCG's are also far easier to disassemble since the cut out for the cotter pin is properly shaped, unlike ruger who just cuts a flat spot.

You can always contact ruger for a new one, but it'll be a similar BCG to what you already have, from the same production line, with the same (at best) batch QC checks.

I'll see if I can add some pics later, but damn ruger. It's an AR BCG. The only thing that's easier to make is an A2 pistol grip.

I don't own any Ruger AR's, but good to know.

I was very impressed with Ground Zero Precision's 'Dead Bolt', so much so, I got them for all my AR's. They used to be, and maybe they still are, a sponsor here on TGT. Good Texas brand!

 

[leVieux]

Technical Data Package. All the info on how to build a military rifle, like an M4

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Thank you, again !

Another question: Could this be handled by carrying a spare “BCG”, or is the repair more complicated than just changing a part or parts ?

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[Gordo]

@easy rider
There is another possibility of the cause, that the grove in the bolt is a little too wide, allowing the rings to tilt, and get a head start on wedging between the bolt, and bore.

One of you guys should head over to a real machine shop, and ask them to measure the bore of the carrier, the OD, and grove width of the piston.
Then compare them to blue prints of those parts.

If you have dial, or digital calipers, you could get the piston info yourself, but the bolt carrier would be difficult due to the bore starting off larger, and then tapering down to the actual bore where the rings do their work.
You would need a small (.500"+ range bore micrometer), or a .501"-.625" gauge pin set.
My gauge pin set only goes up to .500", or I would offer to inspect the carriers. Some day...

Oh, and changing out to another brand of bolt carrier won't work on the Ruger 308, as it is completely different than a normal small frame bolt carrier.

 

[Gordo]

@zackmars
I think I have an extra McFarland ring around here.
I have went piston and my currant small frames, and will not use it any longer.
You could give it a try, if you like.

 

[zackmars]

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Thank you, again !

Another question: Could this be handled by carrying a spare “BCG”, or is the repair more complicated than just changing a part or parts ?

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Trying to clear the gun is a total PITA. The one i took a picture of wasn't as bad as all the others to strip.

A spare BCG should fix the issue. I don't trust a single part of a ruger BCG.

 

[Gordo]

Here is the Bolt Carrier tech drawing:

Calls out .500"+/-.001".
Pretty tight tolerances!

 

[zackmars]

@zackmars
I think I have an extra McFarland ring around here.
I have went piston and my currant small frames, and will not use it any longer.
You could give it a try, if you like.

Oh im good, thanks for the offer though, i had one a while back that was very unreliable, but i believe it was a part of a batch of undersized rings sold through Brownells iirc.

 

[leVieux]

Trying to clear the gun is a total PITA. The one i took a picture of wasn't as bad as all the others to strip.

A spare BCG should fix the issue. I don't trust a single part of a ruger BCG.

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Understood.

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[Gordo]

The bolt drawing I have shows ring section diameter at .488", but no tolerances.

 

[Sam7sf]

The bolt drawing I have shows ring section diameter at .488", but no tolerances.

When getting paid to make them I don’t recall much allowance. Between tool heat and the heat on a summer day and tool wear, I’d change the tool offset often to chase those specs.

It was a good newer haas tl series with good ceramic inserts. Still, would chase those specs and check about every 5 done.

 

[Gordo]

It may be that Ruger doesn't have operators that care that much, either on the bolt, or the carrier.
But only an inspection will tell.
It could also be that the 'snap' rings are just too soft.

 

[Sam7sf]

It may be that Ruger doesn't have operators that care that much, either on the bolt, or the carrier.
But only an inspection will tell.
It could also be that the 'snap' rings are just too soft.

My ruger mpr was made on a Monday with extra no shits given. I reconstructed most of the lower and tossed the bcg away.

Gas rings really aren’t an issue despite what’s been posted In this thread. Yes the bolt has little room for being out of spec but what’s actually the most important thing is where the carrier gets reamed. That’s where the magic happens and paying extremely close attention must be done by the machine operator.

 

[Lonesome Dove]

It may be that Ruger doesn't have operators that care that much, either on the bolt, or the carrier.
But only an inspection will tell.
It could also be that the 'snap' rings are just too soft.

I highly doubt that any of their AR parts are in house made. All sourced out to enable them to keeping their bread and butter firearms on a steady roll. Ruger has kept their shit together quite well unlike many other arms makers.

 

[zackmars]

It may be that Ruger doesn't have operators that care that much, either on the bolt, or the carrier.
But only an inspection will tell.
It could also be that the 'snap' rings are just too soft.

I've replaced them with colt and bcm rings and they still do the exact same things so it's not the rings