Odd observation: my 1P sling carries "heavier" than my 2P slings?

[HeavyDuty]

I'm new to the concept of tactical slinging. I've used carry and accuracy slings in the past, but not tactical.

After doing a lot of reading here and elsewhere I recently ordered a variety of Boonie Packer slings to start getting a feel for what I like and dislike about various modes of slinging with an emphasis on single point and two point.

Two of my carbines have ASAPs, MOE handguards with home-made HK loops at the rear and MOE buttstocks. The third is an A1 retro with an M4-type barrel band side sling loop in front and a CAR buttstock with no other sling points. (The last has an ASAP, ACS QD and is still in the process of getting both front QD and HK loop points so hasn't been part of the experiment.)

The slings I ordered were:

* A 2P-TQA 1.25" two point (on the A1 retro);
* A 2P-TQA 1.5" two point with an HK hook on the front and their M4 buttstock connector (on one of the MOE carbines); and
* A 1P 1.5" single point (on the other MOE carbine).

The two MOE carbines are substantially identical except for chambering (one is 5.56, the other .22LR) and weigh within a few ounces of each other. The retro is about a half pound lighter.

I've noticed something odd. Both of the two points carry very light, but for some reason the single point feels like a ball and chain! Note the single point uses 1.5" web over the shoulder just like the two point so that's not it. I've even switched the two point and the single point around between carbines with the same result.

I can't immediately come up with a good reason for this difference. Does anyone have any ideas? Could it be due to unrestrained mass hanging from a single point versus controlled mass with the two point?

[SW-Shooter]

Simple physics. Hold a rifle with one hand, than hold it with two. Which one feels like it weights less? Same basic principle applies to the sling when it's used.

[HeavyDuty]

I don't know if that's a valid analogy - both use a single strap for contact with the body.

[HeavyDuty]

When you put it that way it makes more sense to me - some of the weight may be carried transversely across the back through the lower sling point instead of up and over the shoulder. Interesting - this wasn't something I expected!

This is turning into a real learning experience.