Brand of Sabot Affects Velocity

Semisane · 02-01-2011, 04:25 PM

Interesting finding. Both loads were shot from my .45 GM/LRH Renegade.

The two different sabots loaded about the same. I could not push either one flush with the muzzle with my thumb. Both required a firm push with the short starter to seat flush with the muzzle, then a firm (but not difficult) push with the ramrod to seat on the charge. The bore was swabbed with both sides of one alcohol patch between shots.

I assume the velocity differences are a result of the different polymers used by the manufacturers.

Gm54-120 · 02-01-2011, 04:59 PM

The MMP also had a bit better deviation but there might be other factors. Ive used mostly MMP and sofar ive had good luck with them but Harvesters are the rage with the 45 SML crowd and they claim Harvesters give faster fps usually.

Sabotloader has always said he felt the MMPs remained more pliable at colder temps.

Grouse45 · 02-01-2011, 05:04 PM

The Harvester with stands heat and pressure alot better then the MMP sabot. But, i only see this in the 45cal Muzzleloaders.

sabotloader · 02-01-2011, 05:41 PM

Semisane

I can offer a partial explanation... The polymere formulas for the harvester and the MMP are different. It is my belief that MMP sabot is more pliable than the Harvester. Because of this the MMP molds itself to the lands and the grooves tighter than does the Harvester. Because of that I believe the MMP holds the compression a bit better.

The problem comes with HEAT... the Harvester polymere is less affected by heat than is the MMP and because of that appears to stand up to powder hot loads or warmer barrel better than the the MMP.

I made these same statement to Del Ramsey - he question my belief that the Harvesters could handle more heat, both heat of the load and the heat of the barrel and wanted to see pictures.

I sent hime these pictures because I felt that the MMP was on the verge of failure - he disagreed about the failure but did agree that the cups were showing signs of stress. These sabots were shot using 130 grains of T7.

Semi in my velocity comparisons I found pretty much the same velocity differences you are indicating.

Del did indicate that he was test a new formulation of MMP polymere as soon as time would become available. It has not happened as of yet.

I can not stand on a box and tell you that I got noticeably better accuracy from one sabot or the other - but I use the MMP 90% of the time.

Gm54-120 · 02-01-2011, 05:45 PM

I did find the higher end 45cal and especially 54x458cal loads were usually better with the Harvesters. My Accura 45 didnt like them though with most loads. The bore was a bit large and preferred the MMP.

cayugad · 02-01-2011, 06:30 PM

All that being said, my GMB seems to shoot a tighter group with the light blue (I believe this is a Harvester) then the tan sabot (MMP). The difference in velocity might not be a big factor since I only shoot them with 85 grains of powder.

oldsmellhound · 02-01-2011, 07:31 PM

Wow, I wouldn't have expected that much of a velocity. I've used both of those sabots, and find myself switching back and forth depending on the load/bullet combo. In general I've gotten better accuracy with the Harvestors at higher velocities, and better accuracy with the MMP's with moderate powder charges, but that's not a hard and fast rule. They both load about the same for me. I like to keep both on hand to try out with different loads. I've not noticed a difference when shooting in different temps, though I've never shot in temps above 60 degrees.

Semisane · 02-01-2011, 08:06 PM

Quote:

though I've never shot in temps above 60 degrees

That's funny StinkyPup, I seldom shoot in temps below 60 degrees.

.45muzzlenut · 02-02-2011, 05:32 AM

Quote:

Originally Posted by Semisane

That's funny StinkyPup, I seldom shoot in temps below 60 degrees.

You'll be able to today, Thursday, Friday, but Saturday it may be up to 60* F.

bronko22000 · 02-02-2011, 05:27 PM

Semi - Curious; did you shoot the mmp sabots first then the harvester? If that's the case it looks like you had a continuous drop in velocity from the first shot to the sixth (excluding #5). Seems to me it would have been just the opposite as any fouling would have generated more pressure which would increase velocity.
Also, I am wondering how consistant the powder charge was. Were they weighed out or volume measured? Sorry about all the questions. Its just my curious nature. The 144 fps from the first to the last shot is quite a difference. Almost approaching 10%.