Posted 11 May 2020 Finally took out the mac 10 with Lage upper yesterday. The firing rate was erratic and I got a lot of blown out casings. I was using Federal 150 grain with the synthetic jacket. Could this cause the problems or is it the upper itself? Share this post Link to post Share on other sites
Posted 11 May 2020 DEAN, next time you take that "mac" out be sure to have the original upper along. just in case. a quick switch back to the original upper and you would know if it was the ammo or the change. I try to have a good asst of my "proven" parts / mags/ ammo along anytime something new is tried. while the net can be a big help, there are just too many variables. its certainly better to use a "PROVEN" set or combination of parts . I only accept postal money orders. contact me DIRECTLY before sending any funds email myoldiron@outlook.com Share this post Link to post Share on other sites
Posted 12 May 2020 19 hours ago, Dean said: Could this cause the problems or is it the upper itself? Yes... all is possible. I take it one thing at a time. Ammo first! Share this post Link to post Share on other sites
Posted 14 May 2020 Sounds like the ammo is reloads with too much powder. Not many other causes for blown casings. Share this post Link to post Share on other sites
Posted 15 May 2020 GAFFSHOT, ammo is stated to be FEDERAL I would take that as a factory loads , many sub machine guns fire well b-4 a round is fully chambered. known as "preignition" its a necessary part of any blowback action and the cases will show the effect. when things go wrong and fire even sooner, it will be much more obvious as in this case. I only accept postal money orders. contact me DIRECTLY before sending any funds email myoldiron@outlook.com Share this post Link to post Share on other sites
Posted 15 May 2020 Called Lage and they guessed ammo because it was 150gr vs 115gr. Plus the synthetic bullet itself. Will try some round nose jacketed lead rounds. Share this post Link to post Share on other sites
