The old contention about synthetics is they will melt onto the bore. Since the Bevel Bros did not experience this, I can only assume they use what we think of as normal, snug loads. If not
well, they're findings are very interesting- of course the question arises, were the patches the same thickness compressed?
If getting blowby and scorched or burned patches already, the use of the same thickness of a synthetic blend may indeed melt onto your bore - or more likely will melt onto the bore's fouling, but
not the steel itself as it will be dirty/protected with fouling), perhaps making it harder, or chunky.
Taylor had some (low %) synthetic/cotton blend that measured .022". It shot just fine with low powder charges, like 85gr.2F in his Virginia rifle using .495" pure lead balls. If he raised the charge
to 100gr.2F, the patches experienced burn-through on the grooves.
Straight denim at .021" or .022 did not burn with the 100gr. charge, but did show some minor scorching as the deep Rice grooves were not filled hard enough, - but - the 100% cotton did not
burn. I took this to likely mean that the somewhat too-loose combination burned through due to the synthetic burning or melting with the higher pressures, while the 100% cotton was more
resistant to burning.
The accuracy was still good with the cotton, though not as good due to burn-through with the synthetic. Even though he/we got burn through and scorching, no wiping was necessary with either
patch material.
One other characteristic I noted with this partial synthetic material, was it was much stiffer than properly washed cotton.
The same day of those tests, we tested that same partial synthetic material with a .508" ball and experienced no burning nor melting. Go figure. Makes sense to me.
edited to change .594" balls, to .495".lol