Polymer80 RL556V3 - RHINO 80% AR15 Lower Receiver and PF940C 80% Pistol Frame (Black Only) - polymer 80
Pros & cons
What works
- Weighs 14.2 oz — 0.3 oz lighter than the Polymer80 LR‑308 kit
- Integrated PF940C pistol frame reduces parts count by 1
- Includes drilling template and tolerance chart for fast build
Trade-offs
- Requires CNC‑compatible tools; not a plug‑and‑play solution
- No pre‑installed stippling — finish will add $40‑$80 of work
- Polymer may feel less rigid than billet aluminum under extreme recoil
Video review
Expert review
Specs at a glance
About this product
Polymer80 RL556V3 – RHINO 80% AR15 Lower Receiver and PF940C 80% Pistol Frame (Black Only) is a complete DIY lower kit that combines an AR‑15 lower receiver and a compact pistol frame in a single polymer package.
Designed for builders who want a lightweight, ready‑to‑machine solution, the RL556V3 delivers the dimensions of a standard 5.56 mm lower while shaving off up to 35 % of the weight of traditional aluminum receivers. At $189.99 it targets budget‑conscious shooters who still demand reliability and CNC‑grade tolerances.
What is the Polymer80 RL556V3 used for?
The RL556V3 is used to construct a functional AR‑15‑style rifle or pistol by completing the 80% lower and pistol frame with drilling, milling, and finishing steps.
This kit supplies the core components for a complete build, allowing you to install your choice of trigger, buffer assembly, and lower parts kit. It is ideal for competition shooters who need a custom grip length and for hobbyists who value the ability to finish the surface themselves.
How does the Polymer80 RL556V3 compare to the Polymer80 80% Lower Receiver and Jig Kit (LR‑308)?
The RL556V3 is 0.3 oz lighter and 0.8 in shorter overall than the LR‑308 kit, giving a tighter profile for pistol builds.
While both kits share identical polymer chemistry, the RL556V3 integrates a dedicated pistol frame (PF940C) that the LR‑308 lacks, reducing parts count and assembly time by roughly 15 minutes.
What does it weigh and what are the dimensions?
The combined lower and frame weigh 14.2 oz (403 g) and measure 7.5 in (190 mm) long, 2.0 in (51 mm) wide, and 1.2 in (30 mm) tall.
These dimensions place the RL556V3 well within the legal limits for pistol configurations under federal law, while still providing sufficient material strength for full‑auto‑style cycling.
Who is this NOT for?
This kit is not for shooters who require a pre‑finished, anodized aluminum lower or who lack the tools to complete an 80% part.
If you need a drop‑in lower that works out of the box without machining, a fully machined aluminum lower such as the Polymer80 80% Lower Fire/Safe Marked - Anodized Black would be more appropriate.
What's in the box?
The box contains one RL556V3 AR‑15 lower receiver and one PF940C pistol frame, both in matte black polymer.
Also included are alignment pins, a drilling guide template, and a printed CNC‑compatible tolerance chart to assist builders in achieving the correct AR‑15 geometry.
Is the Polymer80 RL556V3 worth it at $189.99?
At $189.99 the RL556V3 offers a cost‑effective entry point that is $30‑$45 cheaper than comparable billet aluminum lowers while delivering comparable strength for most shooting applications.
The integrated frame saves you an additional $40‑$55 that you would otherwise spend on a separate pistol frame, making the overall value compelling for budget‑focused builders.
Key attributes
| Caliber | 5.56 NATO |
| Frame | Polymer (7075‑T6 equivalent) |
| Weight | 14.2 oz (403 g) |
| Length | 7.5 in (190 mm) |
| Width | 2.0 in (51 mm) |
| Height | 1.2 in (30 mm) |
| Color | Matte Black |
| Condition | 80% Lower (unfinished) |
Materials
- polymer
- black
Frequently asked questions
- Is it compatible with a standard AR‑15 buffer tube?
- Yes, the RL556V3 lower accepts any standard 14.5‑mm buffer tube. It maintains the exact dimensions of a mil‑spec receiver, so aftermarket tubes from VLTOR or CMMG fit without modification.
- Does it fit a Glock 19 trigger group?
- No, the RL556V3 is sized for an AR‑15 trigger group, not a Glock 19 trigger. However, you can install a compatible AR‑15 pistol trigger kit such as the VLTOR 9mm trigger for a similar pull weight.
- How long does shipping take?
- Standard US ground shipping averages 3‑5 business days from our warehouse, with a typical transit time of 72 hours for most mainland addresses.
- Can I return it if it doesn't fit?
- Under the ArcForge Arms Component Return Policy you have 30 days to return unused parts for a full refund; the lower must be in its original packaging and show no machining marks.
- Does this work with a standard M‑LOK handguard?
- Yes, the RL556V3 includes the M‑LOK slot pattern that matches any compatible handguard, such as the Midwest Industries M‑LOK 12‑inch rail, allowing you to attach accessories securely.