Been messing with a DPMS .22LR upper and have found out several things. Jewell trigger doesn't work,I
think a rimfire fireing pin needs a harder smack
than a centerfire.Rockriver NM works fine.Match
ammo doesn't seem to work ,some brands(Wolf match
extra)don't function well,some brands such as
fedral match function better but are not more accurate than high speed stuff.CCI Minimags are the
standard high reliability brand for me in any
semi auto and this has proved to be the case with
this upper.
I shoot in a 100yd prone rimfire weekly match which
is all about Anshutz match rifles and high power
high dollar scopes.
As a result of this match I test fire all my
rimfire rifles at 100yd .(just for fun!)
The Dpms upper with mini-mags was shooting 10shot
groops of about 2 1/2" hand held over a rest.This
is much better than most rimfire. My good 10/22T
will only shoot about 3" and I am happy with that
so I was pleased with the DPMS.I know 2 1/2-3"
doesn't sound great but try a rimfire with 10 shot groops at 100yd and I think you will see
as I have that this isn't bad.BTW all this was
with a Leupold vxIII 10 power.
Then I was messing  with a bunch of odd ammo and
I tried PMC ZAPPER---9 of 10  shots landed on a
1" orange target dot!! BINGO! I was able to repeate this several times.I have to get this
upper set up with a propper target sling and a
scope with more power-Look out!!
Bad part is this ammo has been hanging around my
stash for some time-I hope I can find some more
somewhere   NHSPORT

I have a new DPMS A22 sporting a Leupold Compact 3x9. So far it shoots CCI mini-mags pretty. Do you remember the price on those PMC ZAPPERs?

Hey- Mine is a heavy barrel-I got it from Brownells
I am not sure that DPMS actually makes this item,
but who cares. The thing that makes this really
nuts is that the PMC ZAPPER was like $18 a brick
and I bought a couple of dusty old bricks some
little local store was blowing out for $15. Come
to think of it I was useing Pmc Scoremaster in
my 10/22Target. It shot pretty darn good and was
only $17 or $18 a brick . This is standard vel
target stuff but I found wolf Match Target was the
very best and I bought a case (10 bricks) for $180. Around here now $28 a brick!!
None of this standard vel stuff functions my
standard 10/22 but It runs just fine in my
10/22 Target.
I have also found that the dpms upper is only
good for 150+- rounds and reliability goes out
the door untill it is completely cleaned.Mags,
trigger and upper all take a beating from all
the  junk that "blows back"
Trying to make this thing run well has taken
some time but I am so close I can taste it!!