Share Deals on Guns Ammo Accessories Here

[Emptymag]

As near as I can figure, these are the two DPMS rifles you mentioned.
Unfortunately DPMS website isn't a wealth of knowledge either, but...

Differences as noted from specs:

DPMS AP4 Carbine
4150 Chrome Lined
Mil-spec A2 detachable carry handle
(stock) AP4, Com. Tube
Weight: 7.15 lbs

DPMS ORACLE
Lightweight 4140 Chromemoly
Railed Gas Block / Optics Ready
(stock) Pardus, Com. Tube
Weight: 6.4 lbs


Looks like the biggest difference is that the ORACLE has a lightweight barrel.
I don't know what the difference is between 4140 and 4150 for the barrels.
The Oracle has that goofy looking stock. (but that's just my opinion)
Both have commercial sized tubes/stocks (something to consider if you plan on swapping out, but many stocks are available in either commercial or milspec)

Aside from that, you need to weigh how you would like to outfit it with optics.

[Berncly]

Thanks EM.
They won't let me rep you twice.

[Berncly]

Looks like the biggest difference is that the ORACLE has a lightweight barrel.
I don't know what the difference is between 4140 and 4150 for the barrels.

I am no expert, but from what I have read 4140 vs 4150 steel relates to the carbon content in the steel, the heavier steel being stronger and able to take more heat.
But it is complicated and also involves a lot of other factors.
I do tend to prefer to buy rifles with the heavier barrels.

Here are a few nuggets from http://www.eng-tips.com/viewthread.cfm?qid=85420

[Start Quote]
Shafts: 4140 vs 4150?

NickE (Materials)
27 Jan 04 12:51
the only difference I see in these two steels chemistry is the carbon content: 0.38-0.43 vs 0.48-0.53 for an nominal increase in carbon of .1%wt. The differences btw the steels in service is: additional carbon causes: less machinable, stronger, better quenching response (hardneability), harder martensite,lower corrosion resistance.
Obviously as the difference in carbon content gets bigger the differences btw the steels will be greater also.
Nick
I love materials science!

NickE (Materials)
27 Jan 04 13:43
I guess I have to say it all depends. If the material as specd from the producer at 110ksi UTS then thats its strength. Usually from lot/heat testing. Teh strength difference I mentioned is in the quenched and tempered condition. (same for each chemistry). The only good physical indicator of fatigue life is ultimate tensile strength since thats what governs the crack propagation speed. (Surface finish and geometry are really important too just not a result of chemistry/heat treat).
<opinion follows>
If you are'nt concerned about heat treated shaft then there wont be a significant difference in these materials. The additional carbon really plays a role when Quenched and tempered.
nick
(keep the wheels in the dirt you mean)
Viva Pro-Le-Ralliatterials science!

MOB1 (Materials) 30 Jan 04 01:31
For a shaft of 12 inch diameter I believe that you would be better served using a higher alloy steel such as 4340 or better. This steel has superior hardenability response during heat treatment compared to either 4140 or 4150, that is, it will give superior tensile&yield strengths and other mechanical properties in larger diameters. This is important if you are doing considerable machining after final heat treatment.
There is some argument that the leaner alloy steels such as 4140 and 4150 give desirable compressive surface stresses after quenching and tempering. I have doubts about this because of the generally high tempering temperatures to bring these steels back to the strength level required for optimum machinability and fatigue resistance. The tempering acts as a stress relief and any benefits from compressive surface residual stresses are negated.
[End Quote]

[ungawa]

I've taken all these courses but it was some time ago. Machine parts are Noah_Zark's dept. My department is materials for vessels and piping, which is simpler.

[fallenleader]

my understanding is that chromemoly is a high chrome content steel, where chrome lined is where they coat the inside of the barrel.
chromemoly maybe cleaner bore cuts and chrome lined more durable long term.
not like i'd let that affect my decisions with the prices we're seeing now a days.

I've taken all these courses but it was some time ago. Machine parts are Noah_Zark's dept. My department is materials for vessels and piping, which is simpler.

a barrel is a pipe, a twisty one.

[ExFlyinguy]

I stayed at a Holiday Inn one night & watched a YouTube video that said that most civilians will never out shoot the life of a 4140 barrel where they would have been better suited to buy a 4150. All joking aside I kind of believe that, but I am NO expert, and for only $40 bucks why not go the higher grade.

I'm still baffled why some AR's are made with commercial buffer tubes though. Make them all with mil-spec tubes- damn.

[ungawa]

my understanding is that chromemoly is a high chrome content steel, where chrome lined is where they coat the inside of the barrel.
chromemoly maybe cleaner bore cuts and chrome lined more durable long term.
not like i'd let that affect my decisions with the prices we're seeing now a days.

a barrel is a pipe, a twisty one.

I don't use carbon vanadium steel when I am worried about heat and corrosion But, then again, I don't have a bullet going through my pipe.

I'm not even going to bother when Noah can square you away on this, just PM him with a link to the post.

[fallenleader]

bah im just teasing and dont care what a barrel is made from. precisely the above,you wont wear it out and if you get bored.soon a new one will be $100
iwwnt nitride but only because core was all milspec milspec milspec.
im hoping there isnt any special proprietary parts.
which is probably where commercial originated. a way to make the first one special and more expensive to repair, replace or modify.

[ungawa]

bah im just teasing and dont care what a barrel is made from. precisely the above,you wont wear it out and if you get bored.soon a new one will be $100
iwwnt nitride but only because core was all milspec milspec milspec.
im hoping there isnt any special proprietary parts.
which is probably where commercial originated. a way to make the first one special and more expensive to repair, replace or modify.

Oh, I've worn them out. It's not just the round count but also the duty cycle.

[fallenleader]

Oh, I've worn them out. It's not just the round count but also the duty cycle.

lol ok, well theyre almost cheap enough to strip for parts toss the barrel and just buy another ar. <- when the barrel wears out
now you got a new one and spare bits.