Winter Spare Parts Build Part 1

[jeff]

This might not be y’alls bag but… I had all the spare parts minus the brace and lower. The lower I picked up at a gun show because the vendor is a local.

I’m a little curious about muzzle flash and pressure. Better use foamies under the ear pro.
…

Winter break builds, Part 1. While it’s been damn cold, wet, and icy, the range has been closed. I’ve been collecting some parts here and there and finally put something together.

As the weather is warming, I wil get a range report later this week.

2026 AR Pistol
Spare Parts Build

Lower: Panther City Tactical, Ft Worth TX (supporting the homies)
Controls: Sons of Liberty Gun Works Blaster Kit, 90° Selector
Receiver Extension: Maxim Defense, Pistol Spring/Weight
Stock: Maxim Defense
Fire Control Unit: Mil-Spec
Grip: Magpul MOE

Upper: Unknown
Charging Handle: Unknown
BCG: Unknown
Dust Cover: Mil-Spec
Forward Assist: Mil-Spec
Barrel: Unknown 7.5, pistol length gas
Gas Block: Unknown
Muzzle Device: Unknown
Handguard: Made in USA

Optic 1: Vortex Strikefire II

 

[jeff]

50rd range report:

Hit the local indoor range for test firing. Several problems arose. Started with single rounds in a mag. Then 3, then 5. Deliberate slow fire to function and safety check.

• Multiple failures to feed. First rounds from magazine, middle rounds
• Failure to bolt lock on last round in magazine
• When the bolt did lock, pressing the mag release to drop empty would cause the bolt to drop.
• Case ejection at 1 to 2 oclock.
• Holy god of 556 is this loud.

Did troubleshooting after dinner.

• Swapped out bolt catch. No change in that locking the bolt on an empty mag. Pressing the mag release would drop the bolt. I tried Pmags, steel, and aluminum mags.
• Swapped out the bolt carrier group, charging handle, and backed off two turns on the mag catch. No change, same issue
• Put the complete pistol upper on another lower (from my part 2 build). No issue. hmm.

My current hypothesis, is I ordered the wrong buffer and spring. I read the description several times and thought what I was ordering was a buffer and spring for a 556 pistol length gas system. What I actually ordered was a buffer and spring for a pistol caliber.

My thought, and research are leading me to the pistol caliber buffer and spring are too light. Which might explain all the feeding issues and the ejection pattern. It might also explain why the bolt drops when the mag release is pressed. The light spring doesn’t have enough tension to keep the bolt lock engaged.

I’ve ordered an H3 buffer and spring set for the Maxim Defense brace. These short barreled AR’s are more likely than not to be overgassed and with a light buffer spring the bolt speed is too fast. I went heavy and in a few days we’ll try again.

I’m also ordering a muzzle device that works with my suppressors. I had to wear foam ear plugs under my ear pro and it wasn’t enough

My part 2 build is 99% complete but not reveal ready.

 

[The Black Colin Jones]

50rd range report:

Hit the local indoor range for test firing. Several problems arose. Started with single rounds in a mag. Then 3, then 5. Deliberate slow fire to function and safety check.

• Multiple failures to feed. First rounds from magazine, middle rounds
• Failure to bolt lock on last round in magazine
• When the bolt did lock, pressing the mag release to drop empty would cause the bolt to drop.
• Case ejection at 1 to 2 oclock.
• Holy god of 556 is this loud.

Did troubleshooting after dinner.

• Swapped out bolt catch. No change in that locking the bolt on an empty mag. Pressing the mag release would drop the bolt. I tried Pmags, steel, and aluminum mags.
• Swapped out the bolt carrier group, charging handle, and backed off two turns on the mag catch. No change, same issue
• Put the complete pistol upper on another lower (from my part 2 build). No issue. hmm.

My current hypothesis, is I ordered the wrong buffer and spring. I read the description several times and thought what I was ordering was a buffer and spring for a 556 pistol length gas system. What I actually ordered was a buffer and spring for a pistol caliber.

My thought, and research are leading me to the pistol caliber buffer and spring are too light. Which might explain all the feeding issues and the ejection pattern. It might also explain why the bolt drops when the mag release is pressed. The light spring doesn’t have enough tension to keep the bolt lock engaged.

I’ve ordered an H3 buffer and spring set for the Maxim Defense brace. These short barreled AR’s are more likely than not to be overgassed and with a light buffer spring the bolt speed is too fast. I went heavy and in a few days we’ll try again.

I’m also ordering a muzzle device that works with my suppressors. I had to wear foam ear plugs under my ear pro and it wasn’t enough

My part 2 build is 99% complete but not reveal ready.

What is the stock, buffer, and spring situation on the lower that run flawlessly?

 

[jeff]

What is the stock, buffer, and spring situation on the lower that run flawlessly?

It’s just another lower I have built. A Colt M4 with carbine buffer and spring.

My “testing” consists of trying to replicate the same behaviour seen at home in the lower pictured. With an empty mag in place and the bolt locked back. Does pressing the mag release drop the mag and the bolt?

Live fire would be the only true test I just won’t have time until this weekend.

If you have any ideas, I’m all ears. Thanks for reading.

 

[The Black Colin Jones]

It’s just another lower I have built. A Colt M4 with carbine buffer and spring.

My “testing” consists of trying to replicate the same behaviour seen at home in the lower pictured. With an empty mag in place and the bolt locked back. Does pressing the mag release drop the mag and the bolt?

Live fire would be the only true test I just won’t have time until this weekend.

If you have any ideas, I’m all ears. Thanks for reading.

Let me know how things work out with the H3. If that doesn’t work, I think I have an extra hydraulic buffer that fixed a similar problem in the past.

 

[jeff]

Let me know how things work out with the H3. If that doesn’t work, I think I have an extra hydraulic buffer that fixed a similar problem in the past.

Thanks man. I’ll update when the new parts arrive.