![]() To make up the extra weight they used a 5.6 oz. ![]() They managed to make the bolt 15.9 oz., so they needed 5.6 oz. Greater bolt velocity would batter the system and accelerate wear and parts damage. I think it’s reasonable to assume that the engineers at Colt were trying to keep the rearward bolt velocity of the 9mm bolt about the same as the 5.56mm design. (source), almost exactly what we get for the calculated Colt 9mm SMG bolt velocity with 9mm NATO (see here) when using 21.5 oz. Using a standard buffer, the gas-operated 5.56mm bolt velocity is about 18 ft/sec. The Colt 9mm AR was developed from the 5.56mm AR, so the durability of the 5.56mm design is important to consider. There may have been several reasons, but one thing I noticed does stand out. Ruger PC9, closed bolt semi-auto, bolt = 23.7 oz. UZI 9×19, closed bolt semi-auto, bolt = 22.80 oz. UZI 9×19, open bolt full auto, bolt = 24.20 oz. STEN MKII 9×19, open bolt full auto, bolt = 22.39 oz. Stribog SP9A1, closed bolt semi-auto, bolt = 23.1 oz. seems to be a common total reciprocating mass for many 9mm blowback designs using factory ammo.ĬZ Scorpion, closed bolt semi-auto, bolt = 22 oz. I am not an expert on Colt history, but from what I have found in my research, the sequence of events seems to have generally gone as follows…Ĭolt “invented” the 9mm AR in the 1980’s by minimally adapting (ostensibly for cost savings) their 5.56mm AR carbine to fire 9mm pistol ammo using simple blowback operation.įor simple blowback to operate safely, they had to increase the weight of the bolt and buffer (a.k.a. Why is 9mm the only AR chambering where solid buffers are commonly used? Do a search in YouTube for videos to see bolt bounce in a gas operated 5.56mm AR. The internal weights slam forward a fraction of a second later, helping to cancel out the bounce.īolt bounce affects practically all AR platform chamberings, gas operated and blowback. In a 9mm blowback, this may cause an out-of-battery (OOB) discharge of the cartridge (very bad!).Ī buffer with sliding weights inside acts like a deadblow hammer. If bolt bounce is combined with fully automatic fire, fast triggers, or simply a very quick trigger finger, the hammer may strike the firing pin just as the bolt bounces backwards. The bounce happens too fast for the naked eye to see. The bolt then slides forward again under recoil spring pressure. Why do they have sliding weights inside the buffer?īolt bounce happens when, after firing a round, the bolt returns to battery and literally “bounces” off of the chamber face, partially extracting the chambered cartridge in the process. Disassembled AR buffer with internal weights, rubber cushion disks, and polymer bumper cap. buffers with an aluminum body and 3 internal sliding steel weights have been used in the 5.56mm AR carbine since early in it’s history. Since the 9mm AR is a modification of the 5.56mm AR, let’s start there.ģ oz. buffer are almost universally a good selection. If that’s still too much TL DR, a Wilson Combat flatwire carbine spring and a KAK Industries gold top 8.4oz. ![]() The accuracy of this information is not guaranteed or warranted.Ĭlick here to skip the TL DR history and details and go to the buffer selector. Do not perform any action based on any of the following information. This information is intended solely for entertainment purposes only. NOTE: None of this applies to the CMMG Banshee. Let’s look at a little quick history and then get to what works best for most typical 9mm ARs.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |