bradys555 said:

Is this assumption correct?

No

There are a lot of factors that influence the behaviour of a penetrator during impact. There are also different APDS and APCR designs. So its virtually impossible to make such broad assumtions with any degree of reliability.

Specifically, I am thinking of 6 pounder APDS and 17 pounder APDS vs German APCR rounds from ww 2.

 

bradys555 said:

Specifically, I am thinking of 6 pounder APDS and 17 pounder APDS vs German APCR rounds from ww 2.

And what would make you think that?

The APDS is in concept a further improved APCR. Its superiour in any way except deviation due to sabot seperation.
WW2 era tungsten in general is rather brittle compared to modern alloys. But the chance of a tungsten carbide penetrator shattering when impacting a steel target of the time are rather low anyway. Which nation had the better tungsten penetrator material during WW2 I don't know. Regardless this is not related to the type of ammo used. Its a material property of the penetrator and thus would affect APCR and APDS of a nation.

Both type of rounds also will have similar behaviour if impacting at an angle. If and how a shell ricochets depends on the exact details. Penetrator shape and weight, presents and shape of a cap, armor hardeness, armor thickness and impact angle etc. If the penetrator and the cap are the same there will be no difference between an APDS and an APCR everything else being equal too. If they differ their behaviour will differ. Just as different APCR or APDS designs differ to one another.

I think my assumption was that the APCR round having a greater mass on impact would be able to better deliver the penetrating dart against angled armor, that is it would in effect ensure that the penetrator was able to do just that penetrate the armor, and that the Dart from APDS would be more likely to bounce or shatter if it arrived at an unfavorable angle.

but if I'm understanding you correctly it doesn't sound like you're suggesting that there really was all that much difference between the two and that they more or less performed in the same way with regard to angled armor?

bradys555 said:

and that the Dart from APDS would be more likely to bounce or shatter if it arrived at an unfavorable angle.

APDS doesn't have a dart. Its basically a sub caliber APCBC fired with sabots. APDS penetrators tend to be made from tungsten but this is not a requirement. There are example which are not. With APCR using a denser and harder material for the penetrator technically isn't necessary either but such ammo only really makes sense with a heavy penetrator.

bradys555 said:

but if I'm understanding you correctly it doesn't sound like you're suggesting that there really was all that much difference between the two and that they more or less performed in the same way with regard to angled armor?

Yes.
If you look a drawings showing the construction of APDS and APCR ammo you will notice that they look allmost identical. The difference is that APDS drops its sabot on the way and APCR doesn't. The penetrator design and the caps and ballistic caps are more or less the same.
The only meaningfull difference is the better KE retention of APDS due to the smaller cross section during flight.

Thanks for that.

So APDS will pen more at range, but be less likely to hit ( WW2 ), and APCR is more accurate overall, but the differences in pen at close and intermediate ranges would be negligible all things being equal. 

bradys555 said:

So APDS will pen more at range, but be less likely to hit ( WW2 )

Not necessarily.
The flatter trajectory of APDS does improve hit propability because it makes range finding errors less problematic. The increased deviation on the other hand does negatively impact hit propability. It depends on the situation.
The deviation problem has been solved during WW2 to a satisfying degree allready. But this was not implemented by all users.

APCR for example suffers more from cross winds. While in theory its deviation should be comparable to that of APCBC.

So there could be situations where APDS is effectively more accurate than APCR.

bradys555 said:

but the differences in pen at close and intermediate ranges would be negligible all things being equal.

That depends on how you define intermediate. Usually APDS allready outperforms APCR at the combat ranges common during WW2. (500-1000 m)

Is there some sort of link to a Range test that supports these findings, specifically about the angles of impact and penetration being more or less the same under similar  situations?

Well, there is data of tests of APCR and APDS.
But I don't know any comparisons of the same penetrator being used in APDS and APCR. Of course you can compare the test results of actually made and used ammo. But this will not give you the answers you are looking for as there are too many variables that differ.

There are also no reports from WW2 that suggest the behaviour you asked about in the amunition types used.

We know the penetration capability of APCR has been superiour to APCBC and APDS has been superiour to APCR. We also know that some early ADPS has had problems with deviation. Which where not severe enough to prevent its use though.
Everything suggests that APCR and APDS worked as intended and did so reliable. So both have been concidered an improvement over APCBC.
APDS was the generally superiour concept and was widely adopted after the war. Mostly replacing APCBC and APCR. The latter only remained for specific uses usually in medium or small caliber weapons.
Given the lack of any evidence or sugestion that you theorie is true there really is no other way than concidering it false. At least until evidence appears.

As a general comment I would add that its of little value to look at isolated statistics or performance data. Even if something like your theorie would be found during testing the question if it matters on a battlefield is an entirely different matter. There are simply to many variable and details different during each incident.

Ok, so in a nutshell the absence of any statements in any known references indicating that APCR was inferior to APDS in dealing with angled armor suggests it was not, or should not be by default considered inferior in that regard, because at it's (Literal) core it was essentially identical to APDS.