Ever wonder why a Colt LE6920 sells for over $1k while an Olympic Plinker sells for under $600 on occasion? One reason is that there are dozens of places to change parts away from the specifications military contractors must provide to cheaper parts and practices that may not be necessary for commercial ARs. Not all of these changes are bad. Many of them will never be noticed by 99% of shooters; but some of them can effect function and I think it is important that a buyer understand what type of trade they are making when purchasing a rifle. For an easy to follow shorthand, I've set up the following reference system (reflecting only my own opinions): * Most likely will not make a difference for all but the most demanding shooters who put their rifles to hard use. ** Unlikely to make a difference for the vast majority of recreational shooters, may see occasional issues among those who train frequently. *** Known to effect reliability for all users, though it may still not be an issue if you don't shoot that much. 1. Use cheap extruded or cast charging handle instead of proper forged charging handle.** 2. Cheap shot-filled or plastic buffer instead of correct military rifle or carbine buffer.*** 3. 4140 barrel steel instead of 4150 MIL-B-11595.* 4. Don't proof test the barrel or bolt.* 5. No need for magnetic particle inspection of barrel or bolt.* 6. Don't test-fire the rifle prior to selling it.*** 7. Replace heat-shielded handguard with lower grade plastic and no heat shield handguards.** 8. Use the same front sight base for every model instead of F-marked front sight base for flattops.* 9. Cast front sight base instead of forged.* 10. Cast upper and lower receivers.** 11. Plastic upper and lower receivers.** 12. Have a bunch of uppers that don't quite meet the Picatinny spec? We'll take them at a discount!** 13. Torquing and staking the gas key is something the customer can do.*** 14. No chrome-lining.* 15. Why buy chrome-silicon springs designed for the weapon when we can use a cheaper steel and cut them to fit?*** 16. That part is only a little out of spec. We can make it work with a little grinding and save money on parts too!*** 17. Why use trained monkeys for assembly when regular monkeys work for half and can do the job almost as well?*** 18. Make so many exceptions to your "lifetime warranty" that it will be impossible for anyone to ever make a valid claim against your "warranty." 19. Nobody will ever notice a few .001" difference on that part.** 20. Our patented spray-paint finish is much better than anodizing.** 21. Shipping every rifle with an HBAR profile to save machining costs, even if it is an entry rifle/"lightweight" carbine.* 22. Replace metal parts with plastic -plastic magazine release, trigger guard or delta ring.** 23. Use an Unmarked/mismarked A2 Elevation Adjustment Knob for the rear sight.** 24. Plastic A2 trapdoors in the butt of the rifle stock.** 25. Replace forged AR15 hammer with cast hammer.** 26. No drain hole in stock screw.** 27. Dremel cut feed ramps instead of feed ramps cut prior to anodizing.*** 28. Use cheaper cast/extruded receiver extension instead of military extension (different diameter also).** 29. No parkerizing under the FSB.* 30. Straight pins or even roll pins instead of taper pins in FSB.*** 31. Using A2 windage drums on detachable carry handles.** 32. Don't mark the barrel with chambering or twist rate.** 33. Don't stake the castle nut in place.** 34. Don't shot-peen the bolt during manufacturing.* Note that there is often disagreement about how crucial some of these issues are and likely people will disagree with some of the arbitrary judgements I've made just to simplify it for those who don't want to read through a discussion on each of the 34 points. Also note that you can often learn more about any one of these subjects using a quick search in the rifle forum. Thanks to the members of AR15.com who helped me flesh out and condense this list.