Ejector roll pin failure

[LMT/556]

Ejector roll pin broke on a new LMT MRP upper that shut it down. Ejector lost in the stones, spring found mangled from the bolt slamming home. Anyone else experience this exact failure? Yes I searched titles...

[Iraqgunz]

Yes. I have seen it on shoddy assembled bolts and where someone has replaced the spring and re-used the roll pins.

[opngrnd]

IG- What specific punches would you recommend for bolt maintenance and where do you source the individual parts?

[alx01]

IG- What specific punches would you recommend for bolt maintenance and where do you source the individual parts?

Bolt vise (something like this https://www.midwayusa.com/product/231625/schuster-ar-15-bolt-extractor-and-ejector-disassembly-tool) and a 1/16" roll pin punch are needed to disassemble the ejector and ejector spring. Some people manage to do it using a spent shell case and a regular vise.


@LMT/556 i suspect it was probably a bad ejector pin, but I've never seen anyone reporting of this happening especially on a new or high mileage quality part like LMT.
Not sure about LMT and what pin they use in their bolts - from what I've seen typically ejector pin is a spring pin (c-shaped also called a slotted pin) and not a roll pin (i.e. coiled pin). Spring pins can often be re-used if not damaged, roll (coiled) pins should not be reused.

Brownell's recommends replacing ejector pins as well when re-assembling the ejector.

[LMT/556]

Brand new L7D3 purchased with the upper 3/24/2018 with approximately 300rnds run through it, mixed 5.56, LC XM193 IMI 69OTM, CBC 77OTM. Not had any time to examine the bolt beyond the ejector is missing, the spring came out, and it looks like part of the spring pin is still in the bolt. I have spares, just didn't expect this, and yes I'm sure Mr. Swanson will take care of it.

Thanks for the help and alx01 for the clarification on the pin type (and correct name). 1/16x3/8 https://www.mcmaster.com/#97855A120

[Iraqgunz]

From Brownells-

939-000-003WB
AR-15/M16 Bolt Ejector Tool
Mfr Part: YM023

827-525-780WB
Starrett Pin Punch 1/16"
Mfr Part: 52578

080-685-062WB
#1 - 1/16"(1.6mm) dia, 4-1/2"(11.4cm) O/A Length

230-100-001WB
#1 Roll Pin Punch
Mfr Part: 25000939


IG- What specific punches would you recommend for bolt maintenance and where do you source the individual parts?

[LMT/556]

Turns out LMT uses a true coiled roll pin. They requested I send in the bolt so it's on the its' way.