As Del has suggested and since he is one of the folks that makes and tests them:
Back in 1985 we introduced the 50 X 44 green sabot. At the time 44 caliber bullets was a no brainer decision for me. If I recall correctly there were two 45 caliber pistol bullets readily available and nine 44 caliber pistol bullets available that we determined were suitable for deer size game. Some 4 years later a better selection of 45 caliber bullets began to show up.
During development of the 50 X 45 sabot we also experimented with the broader selection of polymers that were becoming available.
I went through a large learning curve during those first 5 years of making sabots.
Comparative accuracy between 44 and 45 caliber bullets in 50 caliber rifles....the 45 caliber bullet gets the nod based on 25 plus years of shooting sabots. However, it is a small statical advantage and has little or nothing to do when it comes to "minute of deer". I have also shot a few 50 cal rifles that preferred 44 over 45 cal bullets.
Plastics manufacturers continue to improve and expand their product lines and we test formulations that may be suitable, often with success.
We continue learning as we go and hopefuly progressing. I believe I learned more from customers over the years than any other source. Del
"Forgive me if this has been discussed numerous times in the past but somewhere long ago I read that for .50 cal ml, the .45 cal bullet was favored over the .44 cal bullet because it's thinner walled sabot would grip into the rifling grooves better to impart spin."
Imparting spin or sabot/bullet rotation requires very little in interference fit. A proper loaded diameter sabot/bullet combination will impart spin. Thicker or thinner sabot wall will not contribute in any way to the process of imparting spin.
A thinner walled sabot opens at the muzzle and separates from the bullet quicker than a thick wall. IMHO clean quick separation contributes to accuracy
With the last statement being the key statement and also the statement that I have found to be more often true. Certainly not always but for the most part correct.
I have shoot a lot of 44 cal bullets in a 50 ML and again
for the most part and for me they ARE accurate but in most cases a 45 cal or even a .458 has proven to have the most consistent accuracy over all.
I suppose one reason for that might be you have a selection of many different sizes of 45-50 cal sabots and if or when you find the correct one for your barrel - accuracy is the winner - as not all barrels are created equal. You really do not have the wide selection of sabots with the 44-50's.
I think one other reason that this accuracy may increase with the 45/.458 and one that Del does not mention in his posts, the 50 and the 458 both went through an engineering design change in and manufacturing that increases their physical strength yet allows them to get off the bullet quickly and smoothly.
You can sometimes even see this if you are able to watch as a by-stander the flight path of a 44 cal sabot as it leaves the bullet. I think you will see that there are times that you will see a 44 sabots take a really weird path as it leaves the bullet and in most cases the 50 or 458 sabot remains musch more uniform..