Twist Rate and Greener Formula

[John C]

I have a T/C Impact inline rifle in .50 caliber. It has a twist rate of 1:28. I tried using Buffalo Ball-ets, at 245 grains, will less-than-expected results. I tries some sabots with 250 grain .45 bullets, with similar results.

I put my data into the Greenhill formula, and it calculates that I need a projectile 1.4 inches long to stabilize. Does anyone have suggestions on longer bullets? I see the T/C Maxi Ball at 378 grains, and the Hornady Great Plains bullet at 385 grains. Are there any other good choices? What has worked for others?

 

[entropy]

I use the Hornady 385 Gr. bullet, works well in my 1:48 Traditions Hawken.

 

[John C]

Entropy;

Thank you. Would you happen to have one of those bullets handy that you could measure for length? It would put my mind at ease before I plunked down and bought some.

 

[stringnut]

Twist rate should be fine for what you want. With shorter bullets they are actually being spun faster than needed. This is not the problem everyone thinks it is. Overstabilization is only an issue if your bullets are out of balance. Then it magnifies that out of balance condition. Only for specialized circumstances do you have to have exactly the right twist. Bench shooting would be an example.

What kind of groups are you getting? My t/c strike is fussy about powder. Jim Shockey gold was around 8 inches at 100 yards with everything. Tried some triple 7 and 250 gr Hornady SST now go 2 inches or a bit less. Going to try some Bighorn 209 when the weather warms up.

 

[rodwha]

I have a T/C Impact inline rifle in .50 caliber. It has a twist rate of 1:28. I tried using Buffalo Ball-ets, at 245 grains, will less-than-expected results. I tries some sabots with 250 grain .45 bullets, with similar results.

I put my data into the Greenhill formula, and it calculates that I need a projectile 1.4 inches long to stabilize. Does anyone have suggestions on longer bullets? I see the T/C Maxi Ball at 378 grains, and the Hornady Great Plains bullet at 385 grains. Are there any other good choices? What has worked for others?

Did you try reducing your powder charge with those? I see that's how people get a patched ball to work in a fast twist. In ess ice it gets the RPMs in a similar range.

 

[Noz]

I have a 20" barrel TC 50 cal, 1 in 48, and it will ONLY shoot a 385 MaxiHunter. It shoots clover leafs with that bullet but 24 to 36 inch groups with anything else.

 

[rodwha]

I have a 20" barrel TC 50 cal, 1 in 48, and it will ONLY shoot a 385 MaxiHunter. It shoots clover leafs with that bullet but 24 to 36 inch groups with anything else.

Wow!

I bought a 1:48" blues Lyman Deerstalker with the deeper grooves hoping to have a rifle capable of 100-125 yd medium game ability with a patched ball on calm days.

I've merely just shot it quite a bit (~200 shots) to break it in not really working with variables and getting 3-4" groups at 50 yds. I'm fairly certain it will do much better, and one variable has been addressed (20/40 vision). But I'm hoping for less than that at 100 yds as this is meant to be a stalking rifle able to hunt from a blind.

I had to buy some cast .50 cal 320 grn Lee REALs, and reading these typically need wads punched some, and the two I tried with my typical 70 grns of 3F produced two nearly touching holes at 50 yds. Bought the mold after that and have wondered if mine will just prefer conicals. I hope not but won't cry much if it does.

 

[alsaqr]

I tries some sabots with 250 grain .45 bullets, with similar results.

The TC Impact rifle was designed for use with sabots. It will shoot them very well.

 

[entropy]

Entropy;

Thank you. Would you happen to have one of those bullets handy that you could measure for length? It would put my mind at ease before I plunked down and bought some.

Sadly, I'm out right now, as my son shot up the last few I had. If I took a SWAG, I'd say they approached an inch in length. Stringnut and Rodhwa both have good advice. Powder selection and charge can cure accuracy problems. I use Pyrodex 'P' , 83 gr. with the 385 Hornadys. I sight at 50 yds. I took a doe at 125 with it aimed 6" above the aorta, hit just above the aorta, through both lungs. Ironically, the longest shot I've ever taken a deer at.

 

[John C]

Thanks, gentlemen, for your replies.

I was using FFg Goex and Blackhorn 209 powder. It very likely could be my loading technique: I'm new to muzzleloading rifles and inlines specifically. The sabots I was using were cheap ones that I put in 250 gr cast bullets. I also heard that these shoot best around 100 gr of powder, but I could only get to 70 grains due to scope bite. I need to address that issue, and get back to shooting. I have some RB, I'll try them with low charges.

 

[stringnut]

Cast bullets are ok if they have a flat base. If the base is beveled forget it. I have seen bevel base bullets keyhole at 50 yards. Don't know why and don't care. When I had my first in line a couple of guys told me results would be poor. They were right.

 

[rodwha]

Cast bullets are ok if they have a flat base. If the base is beveled forget it. I have seen bevel base bullets keyhole at 50 yards. Don't know why and don't care. When I had my first in line a couple of guys told me results would be poor. They were right.

That's seems odd as most bullets made for sabots have a beveled base. Flat base bullets generally (from what I've read) don't seat properly in the sabots.

 

[RecoilRob]

Thanks, gentlemen, for your replies.

I was using FFg Goex and Blackhorn 209 powder. It very likely could be my loading technique: I'm new to muzzleloading rifles and inlines specifically. The sabots I was using were cheap ones that I put in 250 gr cast bullets. I also heard that these shoot best around 100 gr of powder, but I could only get to 70 grains due to scope bite. I need to address that issue, and get back to shooting. I have some RB, I'll try them with low charges.

Depending on the chamber design....some rifles won't shoot with low charges worth a darn. If there's a pocket for the powder....a light charge can be loose in it despite the ball being rammed down tight as it'll go and you'll get widely varying velocities which play hell with accuracy. The Kodiak 72 caliber is like this and needs at least 100 grains to start shooting well and it seems that most find about 120 the sweet spot. A strong light down the barrel might let you see what the chamber looks like and some experimentation with varying powder charges to be sure the ball is compressing it like you want could help with the accuracy.

 

[stringnut]

Checked some older Knight lead bullets and sabots I had kicking around and the bases are very flat. The radius is very slight and is just enough so the mould wouldn't have a right angle in it. Hornady SST are flat as are handgun bullets that come with some sabots. The cast bullets that I tried were very beveled having a wide angle instead of a radius. Also they had a grease groove. Whatever was wrong the guys who told me they wouldn't shoot accurate were right. The same sabots with swaged lead flat base bullets shot groups about 1/4 the size. Also none of the bullets went thru the target sideways. Always a plus.

 

[rodwha]

Checked some older Knight lead bullets and sabots I had kicking around and the bases are very flat. The radius is very slight and is just enough so the mould wouldn't have a right angle in it. Hornady SST are flat as are handgun bullets that come with some sabots. The cast bullets that I tried were very beveled having a wide angle instead of a radius. Also they had a grease groove. Whatever was wrong the guys who told me they wouldn't shoot accurate were right. The same sabots with swaged lead flat base bullets shot groups about 1/4 the size. Also none of the bullets went thru the target sideways. Always a plus.

Very interesting I must say. Certainly goes against what I've read said.

 

[stringnut]

rodwha, we may be talking about two different style of bullets. The ones I tried had an extreme bevel and grease groove. They were also lubed and ready to be loaded. Between the bevel and the grease groove the sabots may not have been able to grip the bullet properly. The lube probably didn't help either. This is interesting. Could you send pictures of the cast bullet and sabots combo you have had good luck with? Just like handloading slight differences in loading can make big differences in accuracy at times.

 

[rodwha]

rodwha, we may be talking about two different style of bullets. The ones I tried had an extreme bevel and grease groove. They were also lubed and ready to be loaded. Between the bevel and the grease groove the sabots may not have been able to grip the bullet properly. The lube probably didn't help either. This is interesting. Could you send pictures of the cast bullet and sabots combo you have had good luck with? Just like handloading slight differences in loading can make big differences in accuracy at times.

Saboted bullets are one thing I've yet to try but have been a bit interested in as I'd like an additional barrel either with peep sights or a Malcolm style scope for hunting fields with where shots can easily be 200 yds.

 

[Loyalist Dave]

Are there any other good choices? What has worked for others?

Not trying to be a "smart-butt", however, what does TC say in their manual you should be using for a sabot and powder load?
TC has a vested interest in their product being as accurate as possible, rather than it getting a bad rep, and perhaps all of their products getting a bad rep. I've found that manufacturers normally can steer you to a good combination. At that point, you can look for a similar projectile, perhaps cheaper than the recommended (and often "brand name" one), that preforms as well, or better.

LD