Barrel twist

[VSS]

Can someone explain to me a bit about twist rates please?
When I recently went to local gunshop to get .243 ammo, I wanted to buy a couple of different makes / weights etc to try. The chap said he didn't want to make any specific recomendations, or send me off with something unsuitable, so he needed to know the twist rate of my rifle in order to advise me re: ammo.
So, I trotted off home, fetched rifle and went back to the shop, where it was checked out. (It's a 1 in 10, by the way. I know that now).

So, what difference does it make?

 

[jcampbellsmith]

VSS.

A very good question. http://www.riflebarrels.com/products/caliber_twist_rates.htm sheds some light on this. Scroll right to the bottom for more info. It's really down to what you want to do with your rifle. When I had a Sako 75 in 243 another Forum member was most amused to see me send 105gr A-Max sideways through his target. I was using the 1:10 twist that the rifle came with. I later put a 1:8 twist barrel on the rifle and the 105gr A-Max shot very nicely after that.

There's lots of 243 ammo out there, buy a box of as many types as you can and try it out. That's what I did when I got my 243 Ackley.

Regards

​JCS

 

[VSS]

Thanks for the link, JCS.
I was planning to do just as you said - buy a box of as many types as poss (over time - can't afford them all at once), and see what worked best. I was just wondering about why the chap in the shop was reluctant to let me do that without knowing what barrel I was putting them through?

 

[jcampbellsmith]

Thanks. http://www.riflebarrels.com/faq_lilja_rifle_barrels.htm#twist%20rates is also interesting. Regards JCS

 

[223]

tim a 1 in 10 barrel in 243 cal, aim for around 87 grain bullet weight, i reload 87 grain for my 1 in 10 243 and they are deadly accurate mate

 

[VSS]

tim a 1 in 10 barrel in 243 cal, aim for around 87 grain bullet weight, i reload 87 grain for my 1 in 10 243 and they are deadly accurate mate

Thanks mate. I am currently working may way through a couple of boxes of 95 grain Hornaday. Before that I had some 55 grain Winchester Silvertips, but the 95 grainers seem to be much more stable in flight. I'll see what I can find in the way of 87 grain, and try that.
I'm planning to learn about reloading, so all info is good!
Now I just need to find something a bit more exciting than a cardboard box to shoot at. Even the foxes are keeping a low profile around here!

 

[timbeech]

A longer bullet (hence heavier) will require more spin to stabilise it so require a higher twist rate. I'm looking at a high twist rate .223 so I can use 55gn bullets for Fox and also go upto 70grn bullets for the odd mess about on long range targets. A standard 1 in 12 twist will not stabilise the heavier bullets.

 

[VSS]

So, presumably 1 in 10 is higher than 1 in 12, so that would explain why I had better results with 95 grain than with 55 grain? Or have I got that all wrong?
The chap in the gunshop seemed to be of the opinion that 1 in 10 was pretty versatile, and gave me quite a few ammo options.

 

[long_range_rob]

tim a 1 in 10 barrel in 243 cal, aim for around 87 grain bullet weight, i reload 87 grain for my 1 in 10 243 and they are deadly accurate mate

Ditto on that. 95 grainers shoot an inch plus, 87 grainers cloverleaf.

 

[j0e_bl0ggs]

1:10 will stabilise a 100gn bullet, best ask all the old uns how they have managed with the 'wrong twist' for decades....

 

[bogtrotter]

Some find their 1 in 10 barrels won't stabilise 100 gr bullets, but there is no hard and fast rule as many will.

 

[j0e_bl0ggs]

One thing that can be acknowledged to exacerbate things is the fad for shorter barrels and the lack of chrono testing factory ammo and or reloads - especially the unwillingness of some 'reloaders' to 'work up' a load.
This would contribute, to a large extent, the problems people have with stabilisation issues - it is easy to blame the 'wrong twist' rather than admit any other 'cause'.

 

[Snagman]

Another thing that folks forget is that bullet construction plays a part in stabilisation, especially the length of the bearing surface. I've had experience with some guys (couple of younger shooters) reloading heavy VLD bullets and then complaining that they're not stabilising even though their usual load is nearly the same weight. Most of the time it's guys shooting .243 100 grain norma ammo and then trying to stretch their range for target practice by using bergers or A-maxs, I just had to pull a bullet from the norma ammo so that they could see the difference in the bearing surface.

 

[Brithunter]

In the old days t'was Greenhills Formula that they used to determine rifling twist but of course that was before VLD's and other skinny pointed solid copper bullets came onto the scene.

Winchester found that 1 in 10" was fine for 100 grain bullets in most rifles chambered in .243. The problems are probably down to variations in rifling form and dimensions. This is one reason I stayed clear of the 6mm and .243 for so many years.

 

[blunderbust]

When I first got my .243 I had real problems and could only get the Lapau 100 gr bullets to perform in mine. Being a greedy bugger I did not fancy paying £30 plus for them so tried the Geco 105 gr rounds and immediately found the grouping was great sub 1" all the time at 100 yds and very accurate out to 400yds (that is as far as I have tried them) and at £18 for 20 they were just the job. The performance on all Deer was once again great. I now reload and I am working on the Hornady 80 gr GMX and the Barnes 85gr TSX both lead free and I am getting some favourable results so far.

 

[JMS906]

Can someone explain to me a bit about twist rates please?
When I recently went to local gunshop to get .243 ammo, I wanted to buy a couple of different makes / weights etc to try. The chap said he didn't want to make any specific recomendations, or send me off with something unsuitable, so he needed to know the twist rate of my rifle in order to advise me re: ammo.
So, I trotted off home, fetched rifle and went back to the shop, where it was checked out. (It's a 1 in 10, by the way. I know that now).

1:10" twist is the standard for a .243 Win. It will stabilize traditional bullets up to 100g. It won't stabilize Very Low Drag bullets of 95g or upwards as these are longer than traditional bullets and they must be spun at higher RPM, and that requires a faster twist. If you stick with flat based soft point bullets you will be fine. If you start tinkering with boat tailed hollow point bullets, then they will be longer than the equivalent flat based soft point bullet, and they may or may not be stable from your rifle. Bullets with 'ballistic tips' are in fact hollow point bullets with a small plastic tip, so the same caveat applies.

-JMS