• Post category:Lower Receivers
  • Post last modified:August 1, 2022
  • Reading time:13 mins read

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Best Polymer Lower

The lower receiver is the component that houses the hammer and trigger. The buffer tube assembly should be screwed in and the upper receiver needs to be connected to it at two takedown points. There are three main categories of lower receivers: billet, forged, and polymer.

Why do we need a polymer lower?

Usually, polymer lowers are copies of Mil-Spec forged Aluminum lower receivers. They are constructed from a high-impact composite polymer, which features to save a shape when most lowers bend or break.The typical polymer lower weighs half less than an aluminum billet lower receiver, and significantly less when comparing polymer to a forged lower receiver.

Best Pick

KE ARMS COMPLETE LOWER RECEIVERS AMBIDEXTROUS POLYMER

KE ARMS COMPLETE LOWER RECEIVERS AMBIDEXTROUS POLYMER

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The Lightweight monolithic polymer AR-15 ambidextrous lower receiver is compatible with all Mil-Spec fire control groups, and cassette-style match triggers.The hammer pin area is wider for long-lasting, but standard AR-15 hammer pins can still be used. The KE Arms mil-spec selector or Ambi selector makes removal easier.There is a great length of pull, and a light, crisp trigger with minimal take-up, clean break, and short reset.

Top 10 Polymer Lower

#1 JAMES MADISON TACTICAL POLYMER LOWER RECEIVER

JAMES MADISON TACTICAL POLYMER LOWER RECEIVER

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#2 KE ARMS STRIPPED LOWER RECEIVERS POLYMER

KE ARMS STRIPPED LOWER RECEIVERS POLYMER

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Specification

MAKE: AR-15
Style: Striped
Calibers: .223/5.56mm NATO, .300 Blackout, 6.5mm Grendel and 6.8mm SPC, not recommended for .458 SOCOM, .50 Beowulf or .50 BMG

This monolithic polymer AR-15 style lower includes such integral parts as the pistol grip, buffer tube, trigger, and a 13-inch (LOP) buttstock, as well as Pivot and Take Down Pins, KP-15 Selector Detent, Butt plate, and 5/64-in Roll Pin to Retain Buffer Detent. The KP-15 stripped lower receiver is crafted from injection molded, 30% glass-filled nylon, and available in Black or Flat Dark Earth finish. The item can be paired up with 9mm blowback systems with a minimum buffer weight of 5.4 oz (carbine). The lower uses a carbine buffer with spring, a standard bolt catch; it can’t accept the PDQ lever.

Pros
  • Lifetime warranty

  • Affordable price

  • Handy and lightweight

  • Put together very easily: no problem with fitting the roll pin horizontally to retain the buffer detent

  • Uses only standard carbine buffers and round springs or the JP SCSS in the KP-15

  • Sturdy all-in-one molded assembly

  • Great balance and sling attachment points

  • Fit with the lower and upper parts is precise and simple

  • Pre-drilled in front for QD socket inserts

  • Increased durability of the takedown and pivot pins with built-in detents due to the lack of spring and detent holes

  • Good ergonomics and length of pull

  • The FDE version had the same quality as the black one

  • Compatible with all Mil-Spec fire control groups, cassette-style match triggers and flared mag well

  • M-LOK Slots at the rear of stock for sling attachment

  • Fit, function, aesthetics, and utility are good

  • A safety from KE Arms is optimized for the KP-15

Cons
  • Receiver retainer pins, which must be inserted from the receiver’s left side, have a ball detent embedded in them allowing them to be easily pulled all the way out: they can be lost outdoor, hunting, or in any tactical situation

  • Detent that holds the safety selector in place is tiny: and easy to lose as well

  • Alignment of the two halves is not perfect

  • It seems that the casting and molding unit was not cooled correctly causing the deformity in the trigger well and upper pin area

  • Length of pull is a little shorter than expected

  • Some areas need a small screwdriver to get to and knock off

  • Have to file the space where the frontal pivot pin holds the upper receiver just to insert the front pivot pin

  • Included pin is entirely too short and does not seem to be fully supported or secure

#3 KE ARMS COMPLETE LOWER RECEIVERS AMBIDEXTROUS POLYMER

KE ARMS COMPLETE LOWER RECEIVERS AMBIDEXTROUS POLYMER

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Specification

Cartridge: 5.56 mm NATO
Style: Complete
Weight: 1.698 lbs

The monolithic polymer AR-15 ambidextrous lower receiver integrates the SLT-1 trigger (4.5-pound pull, sear link technology), Ambi selector, pistol grip, buffer tube, and a 13-inch (LOP) buttstock, flared mag well, and carbine buffer with spring. The SLT-1 will not hit the firing pin with enough force to fire it every time; to solve this issue a weaker spring could be used. The KE Arms KP-15 lowers are constructed from 30% glass-filled nylon (injection molded). The lower receiver can be paired with standard AR-15 uppers in calibers: .300 Blackout, .223/5.56mm NATO, 6.8mm SPC, and 6.5mm Grendel, as well as 9-mm blowback systems with a minimum 5.4 oz buffer weight (carbine). A standard bolt catch should be used, not the PDQ lever.

Pros
  • Ambidextrous Controls

  • Reasonably priced

  • Lightweight

  • Takedown and pivot pins come with built-in detents to improve durability by eliminating the spring and detent holes

  • Sling attachment due to the M-LOK slots at the rear of stock

  • Hammer pin area is wider for long-lasting, but standard AR-15 hammer pins can still be used

  • Pre-drilled in front for QD socket inserts

  • Fits all Mil-Spec fire control groups and cassette-style match triggers

  • The KE Arms mil-spec selector or Ambi selector make removal easier

  • Available in flat dark earth or black finishing

  • Excellent improvement on the original GWACS all polymer lower

  • Everything fits and works perfectly

  • Feel and length of pull are great

  • Trigger is wonderful: it is light and crisp with minimal take-up, clean break, and short reset

  • Fit and finish are well-executed

  • Seems very sturdy

  • Useful ability to actuate the safety without the hammer clocked

  • Grip has a decent amount of texture

Cons
  • Safety is a little mushy

  • Non-captive takedown pins can lose and the selector doesn’t have the firmest stop

#4 KE ARMS COMPLETE LOWER RECEIVERS MIL-SPEC POLYMER

KE ARMS COMPLETE LOWER RECEIVERS MIL-SPEC POLYMER

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Specification

Cartridge: 5.56 mm NATO
Style: Complete
Weight: 5 lbs, 3.7 ozs
Finish: Black, Flat Dark Earth

The KE Arms KP-15 is compatible with standard AR-15 uppers in calibers including .223/5.56mm NATO, .300 Blackout, 6.5mm Grendel, and 6.8mm SPC, it can be also paired with 9mm blowback systems, when used with a minimum buffer weight of 5.4oz (carbine).

The KP-15 lower receiver isn’t recommended to use for .458 SOCOM, .50 Beowulf, or .50 BMG.

The takedown and pivot pins with built-in detents allow enhancing durability by eliminating the spring and detent holes. The buffer detent is held in place with a 5/64 in roll pin. The KE Arms made the hammer pin area wider to provide longer service life, although standard AR-15 hammer pins can still be used.

The KP-15 lower receiver uses a carbine buffer, spring, and a standard bolt catch (not the PDQ lever). The safety selector spring and detent are loaded from the top, then the selector is slid over them. This Lower is legally classified as a receiver.

Pros
  • Lifetime warranty for normal use

  • Flared mag well

  • Competitive price

  • Paired with all Mil-Spec fire control groups, and cassette-style match triggers

  • M-LOK Slots at stock rear for sling attachment

  • Pre-drilled in front for QD socket inserts

  • Fits snugly without gaps or rattle

  • Standard trigger functions well

  • Sturdiness, affordability, and simplicity: it doesn’t feel like a forged lower with tons of adjustability, but it’s light and highly durable, with perfect pull length (so no adjustability needed)

  • Polymer composition is rigid and substantial

  • Fit between upper and lower is solid

  • Grip and grip angle are good

  • Finishing of the lower is good, without blemishes, defects, or obvious flashing from the molding process

Cons
  • Unsatisfied final inspection: bad-quality finishing of the fused mating surfaces at the top of the stock

  • The safety is a bit mushy

  • Every operation sounds and feels like it involves sandpaper

#5 POLYMER80 LOWER RECEIVER WITH JIG POLYMER

POLYMER80 LOWER RECEIVER WITH JIG POLYMER

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#6 POLYMER80 POLYMER LOWER RECEIVERS

POLYMER80 POLYMER LOWER RECEIVERS

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#7 POLYMER80 LOWER RECEIVER & JIG KIT

POLYMER80 LOWER RECEIVER & JIG KIT

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#8 HYBRID-80 POLYMER REINFORCED LOWER RECEIVER

HYBRID-80 POLYMER REINFORCED LOWER RECEIVER

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#9 BROWNELLS STRIPPED LOWER RECEIVER

BROWNELLS STRIPPED LOWER RECEIVER

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Specification

MAKE: AR .308, HECKLER & KOCH
MODEL: 417
CARTRIDGE: 308 WINCHESTER, 7.62 MM NATO
Style: Stripped

The BROWNELLS Lower Receiver is manufactured from original German HK417 forging, and anodized with a matte black, Type III.

Pros
  • The first-class forged lower

  • Everything fits snugly

  • Constructed under spec and assembled perfectly

  • Selector markings with color-filled pictograms

  • Sturdy build

Cons
  • The HK mags only hold 20 rounds but marked 30, which doesn’t match real capacity

#10 BROWNELLS – BRN-10 LOWER RECEIVER

BROWNELLS - BRN-10 LOWER RECEIVER

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Specification

MAKE: BROWNELLS
MODEL: BRN-10
CARTRIDGE: 308 WINCHESTER
Style: Stripped

The BRN-10 Lowers are only compatible with the BRN-10 Upper Receivers, not with other 308 pattern receivers. The BRN-10 Aluminum (7075-T6) Lower Receiver allows building out a unique AR-10 clone, including the proprietary components, such as the safety selector, takedown pins, and magazine release. The buffer tube fits any standard AR-15/308 buffer tube and stock.

Pros
  • Made in the USA

  • Compatible with standard AR-15 trigger parts

  • Easy To Install

  • Durable anodized Matte Black finish

  • Aesthetically Pleasing

  • Tight fit with the BRN-10 upper receiver

  • High-quality machining

  • Comes with all “special” retro parts to complete the 1950’s appearance

  • All small components fit well

  • No burrs, dings, or scratches

Cons
  • Bolt hold open, however, doesn’t work without an inserted mag

  • Limited Function

  • Doesn’t come with the buffer retainer or spring

  • Safety selector is much more difficult to actuate than a standard AR-15 one

Conclusion

Customers prefer polymer lowers as they are more affordable than metal lower receivers, despite less toughness. Most polymer lower receivers are largely Mil-Spec compatible. Low-cost and lightweight make the polymer lower receivers more and more popular and commonly used, becoming a workable option for training.

Tags: #best polymer lower / #best polymer ar lower / #best polymer 80 lower / #best polymer ar 15 lower / #best 80 polymer lower

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