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Posted: 11/15/2009 12:02:54 PM EDT
| I have one of these I purchased some years back, never used. Never. Bought a Spike's .22 upper, which at some point I will use as part of a dedicated build, with one of the lower kits I have floating around. Back to the DPMS-gave it to a friend of mine, and he reported significant function issues with as many varieties of .22 ammo I could find and use. FTF, FTE, you name it. Any guesses as to why or a reasonable fix? I understand DPMS discontinued their .22 upper for re-design, which I do not believe has come to pass. And let's not use this as a foundation for a DPMS bashing thread, okay boys and girls? |
I have two DPMS dedicated uppers which I have been very pleased. One common problem on any 22 semi auto is they may require a break in period. Dedicated 22 rimfires can also be little fussy when it comes to the strength of hammer springs. My 22 pistols and rifles refuse to work with current Remington rimfire ammo but I have a lot better luck with Federal, CCI and Aguila. Check the chamber end of the barrel to ensure the firing pin has not peened the top edge of the barrel. This peening can obstruct the chamber and firing of cartridges. If your chamber is not peened you might try the DPMS upper on a different lower. On a new DPMS rifle I've found they work better wet with lube and I personally use break free CLP. I also make sure the recoil spring guide on the left side of the bolt is well lubed. Usually with trial and error you can get your dedicated uppers to run. Its also possible you have a bad magazine. Try to mark your mags so you will know if you have one individual mag which is causing the problem. Some conversion kits and dedicated upper bolts can snag on notched hammers or drag on bolt catches. Make sure none of these parts have rub marks and the bolt moves freely. If problems persist you might considering converting your DPMS dedicated upper to use a Ciener/CMMG style of conversion bolt. With this bolt you can use the high capacity mags which are manufactured by Black Dog Machine and CMMG. I just converted my M-4 DPMS upper to use the Ciener bolt last week. I bought a barrel collar for the conversion bolt from CMMG. I removed the chamber insert and attached the collar to my Ciener. The CMMG collar fits the DPMS barrels. The only issue is you have to file the extractor groove opening slightly on the ejection port side of the barrel where the Ciener extractor will seat. The DPMS bolt uses two extractors one at 9 O clock and the other at 2 O clock. The Ciener extractor sits at 3 O clock so the DPMS barrel has to be modified slightly. CMMG uses a smaller barrel than Spikes and Model 1 sales and as far as I know is the only barrel collar to work with the DPMS. I hope this helps and if you still have problems try to be specific in what is going wrong and usually someone on this sight help you sort out the problem.
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Vascar knows!
My DPMS M-4 ran fine, except if you used the mag for a palm rest it bound the bolt. It DID require a custom, non-rotating firing pin to run with my JP trigger. I was one of the first to modify a Ciener chamber adapter for the DPMS so I could use Ciener mags right after the AWB sunset. In ?'94. The aspect of the CMMG is GREAT news, since you don't need lathe access to enable use of BDM/Atchisson mags with this barrel, which has a reputation for good accuracy. |
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