MP5 FRT Lower - LS5
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The Lee Sporting LS5 is the ergonomic upgrade your MP5 has been waiting for. This billet aluminum lower moves your firing hand 0.6" forward and 0.4" up toward the bore axis, transforming the dated MP5 grip geometry into a modern, AR-like feel — and it accepts AR-pattern fire control groups, opening the door to a genuinely great trigger pull on your roller-lock. Available in Full-Size Semi-Shelf and K Push-Pin configurations — select yours in the dropdown.
MARC FRT Ready — Free Insert Included
Free MARC / MARC II Compatibility Insert — every LS5 lower from Copperhead Safety ships with a free compatibility insert for the MARC and MARC II Forced Reset Triggers. Your LS5 is MARC-ready right out of the box.
Professional MARC Installation Available — want it running on arrival? Select the MARC installation option in the dropdown box and we'll install a MARC FRT in your LS5 before it ships — professionally fitted, function-checked, and ready to drop onto your host.
Product Features
- Billet Aluminum Housing — precision CNC-machined, not polymer
- AR-Pattern Trigger Compatible — run the trigger you already love, including the MARC / MARC II FRT with the included free compatibility insert
- Improved Ergonomics — hand sits 0.6" forward and 0.4" closer to bore for faster, flatter follow-up shots
- CNC-Machined 4140 Alloy Steel Ejector Lever — nitride coated for wear resistance
- Two Attachment Systems — Semi-Shelf clamps onto HK/PTR-pattern receivers; Push-Pin pins directly to MKE-pattern receivers
- Ambidextrous Laser-Engraved Pictograms — clean markings on both sides
- AR Grip Compatible — accepts popular AR grips (Magpul MOE-K and similar compact-pattern grips recommended)
Specifications
K Push-Pin (LS-LS5-KPP) · approx. 7 oz · pins directly to MKE-pattern receivers · no shelf inserts required
Billet aluminum housing · 4140 steel nitride-coated ejector lever · AR-15 pattern fire control groups · Made in USA by Lee Sporting
Trigger, safety, and grip sold separately unless added via the dropdown. This is a firearm accessory, not a serialized part — ships directly to you, no FFL required.
Which Model Fits Your Host
Lee Sporting builds the LS5 in a 2×2 matrix — size (Full-Size vs K) × attachment (Semi-Shelf clamp vs Push-Pin). Copperhead Safety stocks the Full-Size Semi-Shelf (FSS) and the K Push-Pin (KPP). Match your host below before ordering — the two axes are independent, and "AP5" alone doesn't tell you which one you need.
| Your Host Gun | Receiver Pattern | LS5 Model | Notes |
|---|---|---|---|
| HK SP5, 94 | Full-size, shelf | FULL-SIZE SEMI-SHELF | Use the larger included shelf insert |
| PTR 9C, 9CT, 9R, 9RS, 9CL | Full-size, shelf | FULL-SIZE SEMI-SHELF | Use the smaller included shelf insert |
| Dakota Tactical D54-N, D54SD, D54R-N | Full-size / reverse-stretch, shelf | FULL-SIZE SEMI-SHELF | Reverse-stretch builds fit as long as there's no front push pin |
| Century AP5-P · MAC-5K · Zenith ZF5-T / ZF5-K / ZF5-P | K-size, MKE push-pin | K PUSH-PIN | Pins directly to receiver — no shelf inserts. ZF5-K and MAC-5K can run tolerance variance; if the trigger group binds, contact us before modifying anything |
| Century AP5, AP5SD · POF-5 · MAC-5 · Zenith ZF-5, ZF-5L | Full-size, MKE push-pin | NEITHER STOCKED MODEL | These take Lee Sporting's Full-Size Push-Pin variant. Contact us and we'll help you source it |
| HK SP5K, SP5K-PDW, SP89 · PTR 9KT · Dakota Tactical D54K-N | K-size, shelf | NEITHER STOCKED MODEL | These take Lee Sporting's K Semi-Shelf variant. Contact us and we'll help you source it |
| POF-5PK | Conflicting published info | ASK FIRST | Lee Sporting's own pages disagree on the fit — email us and we'll confirm before you order |
| HK53 / HK33 / HK91-pattern (.223 / .308) | — | DOES NOT FIT | The LS5 uses a proprietary 9mm ejector lever; .223/.308 levers are not shipping yet |
| .40 S&W / 10mm hosts (MP5/10, MP5/40) | — | NOT SUPPORTED | No published LS5 fitment for non-9mm calibers — treat as incompatible unless Lee Sporting confirms otherwise |
Quick pattern check if your host isn't listed: look at the front of the trigger housing. A push pin hole through receiver tabs = push-pin pattern (MKE-style). A shelf block welded to the receiver with no front pin = shelf pattern (HK/PTR-style). Then match size: 8.9" barrel class = full-size, 4.5"–5.8" stubby = K. Still unsure? Email team@copperheadsafety.com a photo of the front of your trigger housing area and we'll match you to the right model.
Keep the Host Running Right
Two things solve nearly every roller-lock reliability question: matching the correct locking piece angle to your barrel/suppressor/ammo setup, and checking bolt gap with a feeler gauge. Both live in the gun's upper/bolt group — your choice of trigger group (including the LS5's AR-pattern trigger) doesn't change them.
Locking Piece Quick Reference (Semi-Auto Reliability Tuning)
Roller-delayed guns time their breech opening with a wedge-shaped locking piece. HK made different angles for different host configurations. Running the wrong angle shows up as extraction and cycling problems, not danger-to-clear malfunctions, but the factory rule is firm: match the piece to the configuration, and never mix pieces between dissimilar setups.
| Your Host Configuration | Factory Locking Piece |
|---|---|
| Full-size 9mm, 8.9" barrel, unsuppressed (MP5/HK94/SP5 pattern) | 100° (unmarked, HK P/N 201599) |
| K-size 9mm, short barrel, unsuppressed (MP5K/SP5K pattern) | 110° (marked "16") |
| SD ported-barrel hosts (MP5SD pattern) | 115–120° (early pieces marked "5") |
| Suppressed 9mm + 147gr or heavier ammo (HK's own MP5K-PDW spec) | 80° (marked "80E" / "#28") |
Ammo rule of thumb: 115gr and 124gr standard-pressure run fine on the factory angle for your host. Going suppressed and/or shooting 147gr/+P consistently is what pushes a 9mm host toward the 80° piece — that's HK's own published pairing, not gunsmith folklore.
Bolt Gap — The 60-Second Health Check
How: let the bolt snap closed on an empty chamber, drop the hammer, turn the gun over, and slip a feeler gauge through the magwell between bolt head and carrier until you feel firm drag
Fixing it is a roller job, not a locking-piece job — rollers come in 7.96 / 7.98 / 8.00 / 8.02 / 8.04 mm sizes and set the gap
Re-measure after any locking piece change — swapping angles moves the measured gap. Angle first, then rollers
Does the LS5's AR Trigger Change Any of This?
No. Locking piece angle and bolt gap are upper/bolt-group variables — tune them exactly as you would with the factory trigger group. The one LS5-specific fitment note is travel, not timing: the AR hammer pivots closer to the bolt, so full-size and reverse-stretch hosts use the included silicone buffer (short-stroke) to keep the carrier from riding past the hammer; K-size hosts don't need it. Some AR hammers also like a light 27–30° polish on the top front edge for smooth carrier glide — both steps are in Lee Sporting's install instructions.
Both LS5 models are in stock and ready to ship from Copperhead Safety — with a free MARC / MARC II compatibility insert in every box.
Questions on fitment? Contact: team@copperheadsafety.com
