Making sure I understand rifle twist?

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Making sure I understand rifle twist?

Post by Matt1 » 07 Aug 2013, 11:06 am

New shooter here getting my head around the ins and ours of rifles.

I've recently done all the business for my a/b license and first PTA etc. and am obviously looking at plenty of rifles now.

What should I be looking for in rifle barrel twist? From a bit of reading it seems half the people don't mention it, and have the people are obsessed with it.

I'll need a faster to shoot heavier bullets? But if I don't wan't to shoot the heaviest rounds in my calibre I don't need a faster one?

Or should I just buy the fastest twist rifle I like?
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Re: Making sure I understand rifle twist?

Post by Rocker » 07 Aug 2013, 4:17 pm

Faster twist for longer bullets specifically, not heavier. It's more or less the same in most cases though.

Would be helpful to know you're gear, what you're shooting at etc...
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Re: Making sure I understand rifle twist?

Post by disko » 07 Aug 2013, 4:35 pm

Rocker wrote:Faster twist for longer bullets specifically, not heavier. It's more or less the same in most cases though.


If they're heavier they're longer though, right?

Not sure I understand the difference?
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Re: Making sure I understand rifle twist?

Post by Blackened » 07 Aug 2013, 7:15 pm

disko wrote:If they're heavier they're longer though, right?

Not sure I understand the difference?


For the most part, yes.

e.g. If you have a .30cal 150gr Nosler Ballistic Tip and a .30cal 180gr Nosler Ballistic Tip the heavier bullet will be longer. Because they are the same diameter obviously the 180gr bullet has to get longer to be heavier.

But...

When comparing different kinds of bullets, lighter bullets can be longer and vice versa. See below...

150gr.jpg
Sierra Pro-Hunters
150gr.jpg (10.06 KiB) Viewed 4379 times


Both of these are 150gr Sierra Pro-Hunter bullets. The left is a 150gr spitzer, the right is a 150gr RN, they are both obviously very different lengths despite being the same weight.

If a rifle has too slow of a twist, it could stabilise the RN round while potentially not being able to stabilise the spitzer round. Not that a 150gr pill is particularly heavy... Just using this as an example to demonstrate length versus weight.

Bullet length usually becomes more of an issue with heavy target bullets where they are designed with long boat tails and narrow tips which make for particularly long bullets. Hunting bullets generally have shorter tails and rounder tips, resulting in shorter bullets.

That's a bit of a generalisation, but you get the idea...
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Re: Making sure I understand rifle twist?

Post by Herdsman » 09 Aug 2013, 4:31 pm

Long bullets you say?

Get yourself some of these babies...

Image

:D
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Re: Making sure I understand rifle twist?

Post by Aster » 09 Aug 2013, 4:36 pm

Accubond Long Range, right?
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Re: Making sure I understand rifle twist?

Post by disko » 12 Aug 2013, 4:35 pm

Blackened wrote:When comparing different kinds of bullets, lighter bullets can be longer and vice versa. See below...


Pictures and everything :D

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Re: Making sure I understand rifle twist?

Post by Herdsman » 12 Aug 2013, 4:41 pm

Aster wrote:Accubond Long Range, right?


Right.
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Re: Making sure I understand rifle twist?

Post by Don10 » 13 Oct 2013, 8:44 am

Matt1
There are some good rule of thumb shown above. Generally speaking if you are starting out you will be buying a rifle off the shelf and one would expect that the manufacturer provides the barrel with an appropriate twist rate to the intentions of the buyer. I think being concerned about twist rates is a concern for the day you are buying a specific barrel to match that expensive action that you have purchased. Cos if you are doing this then you will be chasing every inch of muzzle velocity that you can get whilst still maintaining stable flight.

A good technical article can be found at http://www.riflebarrels.com/articles/bu ... _twist.htm very technical but worth reading.

Shooting is one of those sports where you get to choose what you want to be obsessed with. If you are going on the odd hunting trip with a stock rifle then your obsession will be how well those bullets humanely kill your prey. If you want to live Fire arms and breath burning powder for kicks you will obsess over tighter twists stealing muzzle velocity and many other variables that you can influence to tighten that 1/2 MOA group.

At your stage of the game I would obsess about how long the bloody PTA will take to arrive IMHO
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Re: Making sure I understand rifle twist?

Post by Matt1 » 13 Oct 2013, 2:19 pm

Thanks Don,

It's a bit late in the day for my brain to process that article but I'll get to it :lol:
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Re: Making sure I understand rifle twist?

Post by Matt1 » 13 Oct 2013, 2:20 pm

Don10 wrote:At your stage of the game I would obsess about how long the bloody PTA will take to arrive IMHO


Got the first one of the way now, so no such delays for future rifles :D
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Re: Making sure I understand rifle twist?

Post by Don10 » 14 Oct 2013, 7:11 am

Matt1 wrote:
Don10 wrote:At your stage of the game I would obsess about how long the bloody PTA will take to arrive IMHO


Got the first one of the way now, so no such delays for future rifles :D



Congratulations well done we had some serious issues here in QLD a few years back it took me 9 months to to get a PTA Sorted once. I could have had a child in that time (well I could have initiated the child thing and had someone of the opposite sex actually give child birth)
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Re: Making sure I understand rifle twist?

Post by AusC » 14 Oct 2013, 7:37 am

Don10 wrote:Congratulations well done we had some serious issues here in QLD a few years back it took me 9 months to to get a PTA Sorted once. I could have had a child in that time (well I could have initiated the child thing and had someone of the opposite sex actually give child birth)


Well you made the right choice, got the gun instead :lol:
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