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Can't decide on twist rate, help please


fieldwanderer
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Callibre's .22-250 rem

 

Border barrels 28" stainless barrel (not sure if that's bolt face to muzzle or throat/reciever to muzzle), I won't be getting it hot as I cant see me firing more than 2-3 shots consecutively except when zeroing but even then I'll be pausing between shots to make sure the zero's correct for a cold barrel so, heat's not really a concern. Given the barrel length and that I'll be loading my own, I gather I can probably "up" the velocity slightly - higher velocity resulting in higher rpm for a given twist rate.

 

Knowing the permissions I intend to use the rifle on, I want reasonable wind resistance and the flatter it shoots the better but it's not really that simple :/ I've read so much about the subject but the more I read, the more questions I come up with and I think I'm over complicating things to be honest. Some figures though;

 

75gr AMAX is an awsome round, needs a 1:9 twist or faster. At 300yds my ballistic calc thing says 5.01" drop, 6.14" drift (10mph wind at 3-9o'clock) and still has 1177ft/lbs - However, I've read that pushing the barrel like that will result in a barrel lasting about 1200 shots tops :oops:

 

Hornady also make their 50gr superformance which, again according to my calc thing= 4.18" drop, 8.8" drift and 808 ft/lbs (300 yds etc as above) and would be fine even in a 1:14twist but is also known as a barrel burner.

 

The 62gr Barnes tsx looks good to me; 5.31" drop 8.5" drift and 853 ft/lbs, is probably the easiest of the three on the barrel and probably among the most expensive - seems it would be o.k. with a 1:10 or 1:11 twist.

 

I think anywhere between 55gr and 69gr would suit what I'm looking for the best and a 1:10 twist looks about right to me but, it's a lot of money and I want to be absolutely sure I get it right, I don't know if a 65gr bullet in a 1:10 twist is better for the barrel than a 75gi in a 1:9 for example, I'd imagine so though.

 

The rifle's mostly for foxes but would include the odd long range hare, legal deer (including scottish roe if the opportunity arose) and anything else that's legal if I feel like blowing stuff up (should get my certificate back with a.o.l.q. on it). So a twist rate that's versatile is also important, any thoughts?

 

 

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Forget about burning out the barrel based on the bullet. The amount of powder and hot hot you get the barrel while shooting will be what determines it. Since you are already set on a cartridge, the powder volume is basically fixed.

 

Given that you are going with a looong barrel, i would set it up for heavy bullets and slow powder. In that case i would look at either a nine or eight twist depending on the specific bullet you want. For the 75 amax go an eight twist and call it a day.

 

Rick

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Granted, but I gather a heavier bullet through a tight twist needs more of a push one way or another which results in higher pressure and more heat - if that's total codswallop, by all means enlighten me; I've read so many peoples views and experiences over the last week or so I'm more confused than before I started :rolleyes:

 

 

I asked the barrel maker and got; 1:10 twist up to 60gr and 1:9 twist up to 75gr, little bit vague really

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I'm not saying the amax's at all - I believe the norm's to shoot 50 or 55gr bullets (very approximately), all I'm saying is I'd like to go a bit heavier - so more like thinking of 55 as the lower end.

 

The figures were there more for a guide than anything, it shows the 62gr Barnes is a good compromise - pretty flat, reasonable in the wind and holds on to it's power quite well. I've no idea about price, availability or how they perform on foxes / small deer - but the weight and b.c. do some good, and my guess is they'd be pretty happy in a medium sort of a twist.

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I know what you're getting at al4x- I've not had any centrefires before, and I'll likely be surprised at how well they handle the wind after all the years of rimfires.

 

But

 

Seeing as I'm building one to try to get some sort of "ideal" what I'm trying to do is tailor the end result to what I want from it - simply because I can and because its likely to be the last rifle I buy for quite a while. So, just trying to make informed decisions each step of the way

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The best decision would be to stop reading so much and get one in a factory twist and shoot it. Any 22-250 will shoot foxes to 300 yards and to me the whole point of the caliber is the lighter bullets, hence why they come in the twist rates they do. You don't need to go heavier than 55 grain unless you are shooting targets and personally it's not a target caliber.

You need to try one then by all means get a rifle built but do it on an informed choice rather than just reading off the net where you get lots of theory to help you spend money. It's a loud and brash caliber and I doubt you get many on here who find theirs lacking.

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based on the rest of the info you've given, you're not really that fussed with 75's so in that case I'd go a 9 like the factory Savages and call it a day. That will sit you well with the 69 gr match king or the 60 gr v-max, both if which have pretty good BC's for the range you're talking. If you want to crank things up a bit you could drop down to 50's still and ignore the drop figures. I'd still plan for a slower powder with that long of a barrel, but dropping to 60's means a bit more room for powder anyway.

 

rick

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With some things, gaining experience of them will take a lifetime or more and consequently it pays to rely on someone else's previously gained knowledge. A recognised formula for determining twist rate (TR) is: TR = 3.5 (a constant) times the square root of the velocity times the bullet diameter squared all divided by the bullet length (all in inches). You'll note, there's no mention of weight.

 

As ever, this is theoretical which may well differ in practice to a greater or lesser degree but what it certainly will do is put you in the ballpark allowing for you to make any small adjustments should any be necessary.

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All very good points, thanks. I've used a couple of calculator things but its not very easy to find bullet lengths, without buying and measuring.

 

Thing is, I've bought a second hand rifle that probably needs a new barrel and its been sent straight to border barrels - so, I'm a bit past buying a rifle and using it but nothing's set in stone yet with regard to what they're going to do for me. In effect, I'm going to have to have a new barrel - but I'm a bit stuck on the twist rate.

 

Ok, if I were to say I'm happy to use the 50gr and 55gr bullets but would like to have that little bit of leeway to experiment with some of the slightly heavier bullets (dunno which) if I want to at some point, do any of the middle twists (12,10 or 11 at a guess) really shine in this respect?

Edited by fieldwanderer
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personally if it was me I would actually have a long barrel and 1:9 and forget the target bullets and start off with 50 or 55grn vmax or blitzkings.

 

The reason for barrel length is to keep the speed up, there is no point at all in having a 22-250 and running it slowly that isn't what they are about. The other thing is you are also comitting yourself to reloading as well as starting on centerfires which together adds a lot more complications. Fine if you have someone to help who already reloads but otherwise its just making everything complicated. You also won't find much choice of vermin bullets in heavy weights simply because they are an odd choice and there is good reason for that.

 

Blitzkings are a good choice with regard to muntjac if you are going to use them on them.

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in theory it will but its not the 22-250's forte if you want barrel life you wanted a .222 or .223 however that said you are looking at the difference between using 35grn bullets and say 55grn then you will get a longer life and not be running them as fast. 55's will do everything you need to do to 300 yards and well beyond, its not a caliber you will want to take masses of shots in rapid succession so though it is in theory a barrel burner its a lot of foxes. With bullets for quarry you will find most manufacturers only make it to 60 grains in 22-250 and that you will find it hard to get hold of.

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Fieldwanderer,

I assume you have spoken to Lee at Border Barrels with regards to your re-barrel-twist rates,barrel length,bullet choice and your purpose for the choices.

From past experience with Lee he will give the best advice you could get.

 

My oppinion is stick to a 1-12 twist if you want to shoot heavier,you have the choice from 50 to 60 grain bullets all will shoot well if you do your bit, Dont get into the game of chasing rainbows :no: the bog standard 22.250 WILL out shoot you at 300 yds+.

 

If you want to shoot heavier then the 22.250 is not the tool, it just wasnt designed for that.

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When I re-barrel my 1..9 .223 it will be with a 1..8 or 1..7 twist.

 

A 22-250 is a do it all tool, don't under estimate it and don't limit it.

 

IME Whilst the 1..9 shoots 40 to 60grn very well, the bullet weight limits the maximum range, the trajectory drops off quickly after 400yds, and 600yds is about the limit, also the wind has a greater effect on a lighter bullet at any range.

 

It is far better to be looking at it than for it, the 1..8 will do everything you want and a lot more.

It's your money, spend it wisely.

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Fieldwanderer,

I assume you have spoken to Lee at Border Barrels with regards to your re-barrel-twist rates,barrel length,bullet choice and your purpose for the choices.

From past experience with Lee he will give the best advice you could get.

 

My oppinion is stick to a 1-12 twist if you want to shoot heavier,you have the choice from 50 to 60 grain bullets all will shoot well if you do your bit, Dont get into the game of chasing rainbows :no: the bog standard 22.250 WILL out shoot you at 300 yds+.

 

If you want to shoot heavier then the 22.250 is not the tool, it just wasnt designed for that.

 

 

No, I've only had the opportunity to speak to Geoff.

 

I know the .22-250's got a reputation for burning barrels, I suppose what I'm trying to do is make it a little bit more versatile / wind resistant without making it even worse (or at least, not noticeably). Like you say though; maybe that's chasing rainbows :/

 

Given all of the above, I'm starting to think maybe the 1:11 would fit the bill nicely - I guess it's all down to compromises. Lilja's website has a list of weights vs twist, according to them a 12 will go up to 60gr and a 10 will get up to the high 60s (68/69gr) so I guess a long 11, with it's slightly higher velocity, should get somewhere near that too (if I wanted to) but should also put less resistance on the bullet than a 10 or a 9 would - therefore won't slow the lighter bullets much ???

 

When I re-barrel my 1..9 .223 it will be with a 1..8 or 1..7 twist.

 

A 22-250 is a do it all tool, don't under estimate it and don't limit it.

 

IME Whilst the 1..9 shoots 40 to 60grn very well, the bullet weight limits the maximum range, the trajectory drops off quickly after 400yds, and 600yds is about the limit, also the wind has a greater effect on a lighter bullet at any range.

 

It is far better to be looking at it than for it, the 1..8 will do everything you want and a lot more.

It's your money, spend it wisely.

 

From what I've read, the .22-250's higher velocity will give a higher rpm for a given twist (compared to the .223) so a 1:9 in a .22-250 will do what a 1:8 in a .223 will. BUT because of the extra resistance, bullet weight and pressure - it's not good at all for the barrel life, and at £630 a pop - I could do without it being an annual purchase :crazy:

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