Why?

[mossie]

Why would a 300 grain Hornady xtp .452 in a short mmp sabot be much more accurate than 250 grain .452 in the same sabot? I would think the same diameter bullet would shoot with the same accuracy but they do not. Is there anything I can do to get the 250 grainers to shoot tighter groups? The barrel is Green Mountian 1/28 twist. I thought about a light paper patch around the bullet before I put it in the sabot to see if that might help some. Any ideas? I like that 250 grainer but I can't get it to shoot as well as I would like. The 300 shoots great but has a bit more recoil than I like for my 24" barrel and the trajectory is not as good as the 250.

 

[big6x6]

Why would a 300 grain Hornady xtp .452 in a short mmp sabot be much more accurate than 250 grain .452 in the same sabot?

Gun to gun variance. MANY 1 in 28 twist muzzleloaders prefer a 250gr bullet..

Is there anything I can do to get the 250 grainers to shoot tighter groups?

1. Try different powder charges.
2. Try different propellants(Goex, Pyrodex RS, Pyrodex P, Pyrodex Select, Triple Se7en, American Pioneer, Black Mag 3, etc)
3. Try a different sabot. MMP makes at least 3 different .452/50 sabots. Harvester makes them as well.
4. Try a DIFFERENT 250gr bullet. Choices are almost too many to list. A few of the best are Hornady .452 250gr XTP, Hornady 250gr SST, 240gr/.40 & 260gr/.429 Dead Centers, 250gr Barnes Expander, 245gr Barnes Spitfire....

 

[cayuga]

big 6x6 has the right idea here.

I shoot a 1-28 Green Mountain Stainless Steel Barrel in my Renegade and it too likes the 300 grain over the 250 grain projectiles. I have tried different sabots and different projectiels. I did find that if I dropped down to a smaller diameter bullet like a .430 I could get acceptable accuracy with lighter bullets.

Right now I am shooting some Speer Gold Dot 250 grain and they are doing all right but I have not pushed them hard enough and at long enough distances to be convinenced with them yet.

Another projectile that is showing a lot of promise is the Hornady .458 diameter 300 grain bullets. Since you want a lighter bullet have you considered some 200 grain Shockwaves?

Also try some different powders .. many times that can have a big difference.

 

[jaybe]

As to the original question, "WHY?", am I right in thinking that it might be due to the fact that it is a shorter bullet - and shorter bullets are often more difficult to stabilize?

IM jaybe

 

[cayuga]

Have you ever tried the 250 grain bullet in a .430 diameter? That might lengthen it enough that your rifle would shoot it well also... just offering suggestions.

 

[Spitpatch]

Why would a 300 grain Hornady xtp .452 in a short mmp sabot be much more accurate than 250 grain .452 in the same sabot?

Gun to gun variance. MANY 1 in 28 twist muzzleloaders prefer a 250gr bullet..

Is there anything I can do to get the 250 grainers to shoot tighter groups?

1. Try different powder charges.
2. Try different propellants(Goex, Pyrodex RS, Pyrodex P, Pyrodex Select, Triple Se7en, American Pioneer, Black Mag 3, etc)
3. Try a different sabot. MMP makes at least 3 different .452/50 sabots. Harvester makes them as well.
4. Try a DIFFERENT 250gr bullet. Choices are almost too many to list. A few of the best are Hornady .452 250gr XTP, Hornady 250gr SST, 240gr/.40 & 260gr/.429 Dead Centers, 250gr Barnes Expander, 245gr Barnes Spitfire....

The Barnes 245 Spitfire would be my first choice. If you don't like that try a compromise with the Barnes 285 Spitfire.

 

[scauper]

I shot the Barnes 285 gr spitfire (yellow sabot) out of my Knight MK-85... I used a 90+ Vol charge (weighed out on scale to 70 grs) I got a 3 shot group that measured 7/16" center to center.....basically one big hole. I swabbed between shots with damp patch. I didn't think recoil was excessive......you probably could get by with 70-80 grs if you are going to keep your range under 100 yds. I shot clear through a deer at 70 yds with a Barnes bullet & 80 grs 2F.

 

[Biff Mayhem]

The 1-28" twist will shoot a 240-300 grain bullet well. Yours just prefers the 300. The one built right after yours may prefer the 250. No strict guidelines when building MLs. Tolerances are much softer than your 30-06 or .243.

 

[Mountain Man]

As to the original question, "WHY?", am I right in thinking that it might be due to the fact that it is a shorter bullet - and shorter bullets are often more difficult to stabilize?

IM jaybe

No, longer bullets are harder to stabilize than shorter bullets, all else being equal (diameter, core/jacket densities, flatbase/boattail, nose profile, velocity, etc.). That's why a roundball gun will only have 1-in-66 rifling, whereas a conical shooter will have 1-in-32, 1-in-28, or even 1-in-24 twist.