Twist Rate Question

Discussion in 'Firearms & Ammunition' started by PHOENIX PHIL, Jun 10, 2012.

  1. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    Gents,

    I have never been able to get either the TSX or TTSX in 180gr to shoot well in my Tikka T3 in .300 Win Mag. That rifle will shoot just about anything else at MOA or better. I did get loads that were accurate enough for hunting at reasonable distances, but really it would be better to in that rifle with A-Frames, Partitions or AB's.

    Today at the range with my M70 in .300 Win Mag, I shot some TSXs and TTSX's, 3 of each. I loaded them up just for giggles to see how they'd do. Well the TTSX load was under MOA and the TSX just a smidge over. This was the first loads in these bullets fired in this rifle so who knows with a bit more work just how accurate these could be made?

    Now obviously these are two different rifles and the M70 has a 26" barrel versus the T3's 24" barrel. But I couldn't help but wonder if the difference was in the twist rate. The M70 has a 1:10" versus the Tikka's 1:11".

    So what do you think, is it the twist rate?
  2. sestoppelman

    sestoppelman SILVER SUPPORTER AH Legend

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    Not enough barrel length or twist to make any difference. Purely barrel/bullet preference. And with different powder combinations you will probably get the opposite result.
  3. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    I tend to agree with you ses. But never one to leave well enough alone....I did some more research and came across a website dedicated to ballistics.

    Here's the home page: JBM

    But of more interest is the stability calculator: JBM - Calculations - Stability

    I measured the 180gr TTSX's in .308 and came up with 1.48". I then put that along with 2972 fps per the Barnes manual and ran the calculator for 1:10" and 1:11" twist rate. The result came out 1.628 for the 1:10" well into the range it recommends for stability. The result came out to 1.341 for the 1:11" rate, at the low end of the recommended range.

    Does this mean anything? I don't know but it sure makes for fun and games with this engineer! :crazylol:
  4. sestoppelman

    sestoppelman SILVER SUPPORTER AH Legend

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    Dont mean nuttin. The diff between 10 and 11 is miniscule. There are all sorts of formulas for optimal twist rate for bullets based on length and or weight. Generally we like in .30 cal, the 1-10 twist as the best overall rate especially with heavier bullets. I had a Rem PSS in .308 that shot its best groups with Sierra 175's, with a 1-12 twist. Some of the Palma shooters use like a 1-15 twist in their barrels for those 155's they shoot. I approach it like this. If a given bullet wont shoot to my satisfaction, I try another one. It never fails.
  5. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    Well if you want to make it simple and uncomplicated and maintain your sanity and hair color, I guess that would be preferable. :rolleyes:
  6. 35bore

    35bore AH Legend

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    Tend to agree with sest here, (in a big way), I shoot nothing but factory loads... That's it, I have found that modern "quality factory loads" get as close if not better than hand loads. That being said, some rifle barrels like certain bullets/speed. My Savage loves the Sierra game king, all of my 700's love mostly Remington ammo (any given breed. Most of the time if its Remington, it shoots Remington ammo better than any other. Contrary to my experience thus far, when my grandfather passed away, I received an old Winchester model 88 in 308win, it shot all, I mean ALL of the Winchester ammo like crap, put some 150gr. Core Lokt bullets down the tube and wow, shot and grouped like a dream.

    All this aside, I say if you tinker with your load long enough you can get the 180's to group, BUT, you may not get the velocity you want , but it would group. Good luck Phil, you may be better off choosing another Quality bullet for your venture.

    BTW, I do enjoy reading the handloading post's, and again, not sure the twist rate would matter as much as one would think.
  7. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    Love my Winchester rifles, but I've never had much luck with their ammo before I started reloading. What inspired this thread was getting a good load first time out with the TTSX in this M70. Roughly a 0.75" 3 shot group. I'll need to shoot it a few more times to make sure it's repeatable.

    But that bullet will never see the barrel of my Tikka again. I don't know how many different combinations of powder, seating depth, primers I tried. You can only throw so many $$$ at a problem before you give up.
  8. 35bore

    35bore AH Legend

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    :thumb::thumb:
  9. huntingbigun

    huntingbigun AH Veteran

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    My 300 Rum did not like TTX but loved the TTSX, I think it is more the Ogive of a bullet, sometimes, the list is long on why one guy will shoot a load better than another but it is the chase that is sweet lol, glad they shot well for ya
  10. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    Feeling so spry after this, I may just give the Scirocco a go in this rifle. Never got it to shoot well either in the Tikka. I can't help but wonder if the IMR 7828 hasn't a lot to do with this.
  11. Cliffy

    Cliffy AH Elite

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    I shoot a 338/06 1/10 twist. 225 Partitions and 225 Accubonds do 1 MOA, 225 Hornady do 4+MOA with the same brass, same primer and powder. Go figure. Have never had any Barnes shoot well in this rifle. AND, NO 210 gr bullets shoot worth a damn. Like was said, if it don't like one bullet, try another,
  12. gillettehunter

    gillettehunter AH Fanatic

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    I also have a T-3 in the .300WSM. The 180 gr TTSX's don't shoot well in that gun either. Try the 150's. My gun just loves those. 1 1/2 inches at 300 yards. You can zip that bullet right along. I've killed several elk w/ that load and it works great. I'll bet it works in your gun too. Bruce
  13. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    You I bet those 150's do a good job on elk. I've seen numerous elk taken with 150gr cup-n-cores out of a .270. I'm going to try them on my son's .308 and perhaps the Tikka, we'll se how it works out.

    This would of course suggest the twist rate and bullet length/weight are correlating if they shoot accurately.
  14. BryceM

    BryceM AH Veteran

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    My (limited) experience with twist rates suggests that it's pretty rare to see true instability. When bullets actually do de-stabilize the results are ususally very dramatic - on the order of 1 or 2 foot groups at 100 yards with oblong or key-hole holes in the paper. Barnes puts warning labels on their long-for-caliber bullets such as the .308" 180gr TTSX, but so far I've had no problems with it and I shoot that particular bullet in .300 WBY as my main go-to hunting round. I think the twist-rate warning labels from Barnes include a certain margin of safety.

    You have a ton of options in .308 if you like the TTSX (my personal favorite bullet). The 168gr is a good one to consider and its performance on game will probably be virtually identical to the 180.

    I love the TTSX, but I wouldn't use it if I couldn't find a primer/power/bullet/OAL combination that would get me <1 MOA. We live in an era where that level of accuracy should be mandatory in a standard bolt-action, mid-caliber rifle. A terrible bullet in the right place is better than a TTSX in the guts any day of the week. My 1970s era MkV Weatherby loves 80.0gr of H4831-SC, Federal 215s, and 180gr TTSX and will print 5/8" groups at 100 yards all day long if I do my part. The level of confidence that comes from that is a huge benefit when the shot has to count.
  15. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    I think there's a line between instability resulting in dramatic results as you pointed out and stability required to be accurate. If you check out the calculator, one of the inputs is velocity. Your WBY may with that extra velocity over the Win Mag may be the difference.

    My problems with the Tikka shooting that bullet were discovered only after I got back from my safari and started checking out how well they'd shoot at 400 yards. Now I won't claim to be a sniper than can hold 1" groups at that distance, but I will never forget the look on my son's face when I saw the first flyer. I had him looking through the binoculars at a rock I was shooting at lasered at that range to let me know if I hit or how badly I missed. With shooting that far I usually can raise my head off the gun and/or stay on the scope well enough to at least guess how it turned out. To say the least I was shocked with what I saw and looked to him for confirmation. It was almost funny because he wasn't sure if he messed up and missed it or if he really saw the bullet hit some estimated 8-10 feet off to the right! As I said I'm no sniper, but I don't miss that badly.

    Was it just one round? Nope. I repeated that feat a few more times. The strange part of this was that the groupings at 100 yards would not have suggested anywhere near this kind of long range error. Funny part was I hit that rock (relatively small, about 8" wide/tall) several times with other near misses, but also with plenty of "what was that" thrown in.

    This will be fun to see how this works out with the 150's.
  16. BARTFRNCS

    BARTFRNCS AH Enthusiast

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    Have you bore scoped your barrel? sounds like a hardwaer problem.
  17. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    No, it's practically a new barrel. It could still have issues of course, but it hasn't with other bullets.
  18. BARTFRNCS

    BARTFRNCS AH Enthusiast

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    How many rounds have been down the tube? I've seen barrles go during breakin. If its factory weatherby then expect about 500 to 800 rounds before its gone in the first third of the barrel. Most people dont shoot enough to notice.
  19. Second Wind

    Second Wind AH Enthusiast

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    Phil.
    Tell you what, if you come up with the answer to this riddle the drinks are on me

    I have so often seen two or three guns of the same style, caliber and manufacturer that will
    shoot one bullet well but horrible with another

    All things being equal, which they never are, I have yet to see anyone render a really spot on explanation
    for this

    Rifle barrels are a lot like women, they don't all go for the good looking, witty and charming blokes like me, some actually prefer something different

    I know, hard to understand isn't it
  20. PHOENIX PHIL

    PHOENIX PHIL AH Legend

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    Not a Roy, the rifle that won't shoot the 180gr TTSX is a Tikka, therefore a Sako barrel. The rifle that will shoots the TTSX is my M70 that I've only had a couple hundred rounds through. The Tikka does have a few hundred through it, but it exhibited the behavior at long range when it was really new. Since then all of the rounds have been for load dev't and all but the Scirocco have shot well.

    The Scirocco from what I've read has been a tough bullet to get a load for.

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