Operations Manual

AMMUNITION WARNING
Due to a number of calls and comments concerning AR-type rifles, we have incurred
feeding problems with the following:
A) 1. Israeli ammunition
2. Korean ammunition
We have heard and reviewed several reports of problems with many manufacturers’ rifles
using this ammunition. The problem appears to be the bullet contour and the overall
length of the cartridge, which is contacting the rifling before firing. This is creating a gas
port pressure and chamber pressure higher than recommended, therefore causing
feeding and extraction problems due to the increased bolt carrier velocity. In addition,
there is accelerated fatigue on internal parts.There are also indications that brass may be
oversized, which could create an unsafe condition.
B) 1. PMP
2. South African produced surplus
We have used this ammunition in the past for testing purposes and found that the brass
is extremely soft and can “flow” into microscopic pores and grooves in the chamber,
creating “sticky” extraction. This had been reported in many types of rifles, but is more
prevalent in semi-automatic weapons.
C) Lacquer Coated Ammunition or Steel-cased, lacquer coated ammunition
The problem with this ammunition is the lacquer coating on the case.As the barrel heats
up, the lacquer turns to a soft, varnish substance and upon cool down, becomes very solid
and difficult to remove. This effectively creates an undersized chamber and creates
understandable problems.
DPMS recommends the use of high quality, domestically produced ammunition for best
results and highest accuracy. For plinking and practice, we recommend only domestic,
commercially manufactured ammunition or high quality surplus NATO specification
ammunition. Please note that the use of re-loaded ammunition voids the factory
warranty as well as the use of the above-mentioned types of ammunition.
Your rifle is an investment and it only makes sense to choose quality ammunition for a
quality rifle!
BARREL INFORMATION
To achieve the best results for accuracy you should clean the chamber and bore after every
round for the first 25 rounds and then every 10 rounds up to 100 rounds. It usually takes
about 200 rounds per barrel for optimum accuracy. Please keep in mind that our barrels are
production barrels not custom barrels. Accuracy is dependent upon many factors such as
bullet weight, powder load, rifling twist, rifling lands, operator technique, etc. Our produc-
tion barrels have achieved anywhere from 1/8” to 1 1/2” M.O.A. Obviously, we would hope
that every production barrel would shoot 1/8” M.O.A., but with all of the above factors, we
cannot guarantee a specific group size.
37