Mike, I do see what you are saying NOW! (grin) Sorry about that partner! Shaft integrity is only as good as the muscle one puts behind it, the spine of the arrow has to be able to deal & hold up with this impact. In your photos where I see those broken shafts I see no problem with structural integrity! What I see is an arrow that penetrated only 4"-7" then broke off because rest of arrow was sticking out then sheared off by an elks leg, tree etc as it took off. I see too light of a setup that lacked penetration especially if those weren't leg bone or scapula/shoulder bone hits! If structural integrity of the arrow were the issue the shaft would have either broken near the 1/2 way point of shaft (weakest link) or the broadhead would have mushroomed the end of the arrow on impact on all of them. None of this is evident in those photos. It's only my observation.
Arrows in the 335grn range with 100grn heads just have no penetration value on elk sized animals. I know you can appreciate this now! Up that arrow spine to 340/300 & load up front end to a min of 175grn with the same flatliner brand shaft & you will see a world of difference in penetration. You will be in the 400grn total arrow wt. This same 400grn arrow will have close to the same penetration as a 475grn arrow with a 100grn head & standard 15grn aluminum insert, but, you will deliver that arrow with more speed which inhibits a flatter trajectory!
When guys come on here & say that a light setup doesn't work (again, define light) they are referring to setups with 400 spine & 100/125grn heads with poundages at or exceeding 70#, yep, they are undergunned, so they go to heavier which means they go up in spine! Thing is, you can get arrows in 340/300 spine from 6.7grn to 12/13grn per inch. This means you can shoot any wt range you'd like without sacrificing penetration. If a hunter really wants the best of both worlds choose a stiff spine the next number up on the arrow charts. (most charts are regulated for 100/125grn heads) This arrow will not oscillate nearly as much because of being underspined for the horse power delivered. This means that when the arrow meets its target it has a driving force because of the stored energy in that stiffer arrow & heavier head wt. Light arrow (underspined) & low head weight & the opposite effects are the outcome as your photos show & others experiences, you had lots of speed but no stored energy, the result is no penetration upon resistance.
As I mentioned earlier I have done some testing with this, I will do more & post photos of many comparisons. When I test I use 5/16" concrete board, I can easily put 2 & 3 together & it will stop most arrows. I've shot arrows as heavy as 710grns into this structure & not much can get through 3 layers. I will show what a aprox 400grn arrow with 175grn min head can do compared to a like arrow with a 100grn head but exact same arrow wt. Not all arrow wts are created equal! (grin)
This may fall on deaf ears but it sure is fun talking about it! (grin)
ElkNut1