Of course they do! They say such things because another expert with another slant on the VIRTUAL possibilities of a their subject might have an opposite view. Stick the word 'expert' next to anyone's name and we're supposed to believe everything they tell us? For every statistic, there will be another that is equal to but opposite from what we are trying to prove. Whether or not a .22 with a silencer would yield ANY drawback is open to debate - it was never tested. Virtually is not a certainty.
The expert testified that it was a vurtial certainty the location of the wound and fact it was either a contact shot or fired within 1-2mm from the weapon (based on sooting etc such was determined) that if the suppressor were not attached then it would be a virtual certainty there would have been drawback into the muzzle. So he said in laymen terms that Sheila's blood would have been found in the rifle if the fatal shot was delivered without the suppressor attached.
Hence why planting the evidence required:
1) knowledge that the wound in question would cause spatter
2) knowledge that it was necessary to eimlinate the spatter from the rifle
3) knowledge of what blood type to plant and securing such blood
4) knowledge of how to plant it so that it would mimick back spatter by spraying it inside with some sort of device as opposed to dripping it in with a dropper or pouring it from a vial.
Which is why the only person on Bamber's side who ever thought about these points long and hard concluded it had to be the lab that conceived the plan to plant the evidence and carrie dit out and used others to try to help conceal their actions.
Breaking the golden rule and involving a wide array of people in the conspiracy as opposed to keeping it as narrow as possible.
While accurate that is how it would have to go down to be true, he missed the most important thing of all evidence to establish this actually happened.