Neck Tension

[dromia]

Albert Pierrepoint was supposed to know a lot about neck tension.

[rox]

Couldn't agree more - the 308 has serious limits but that's what attracts us to F/TR - you gotta (try to) read the wind!

I ran a 6.5WSM for a while (i.e 450 rounds and the barrel was shot) - like a laser with 139 Scenars.

Does F/TR limit bullet weight? I was stunned when coaching some MR guys this year who seemed to be using less wind at 1200 than I would have been at 300, with their 220+ bullets. But I guess that at extreme bullet weights you might struggle to keep the elevation sufficiently under control for F class targets? Would barrel weight be an issue too?

Bob.

[The Gun Pimp]

Bob,

No, there is no weight limit for bullets - you can use anything.

We mostly started off with the 155 - and most - including me - still use them. Some prefer a 185 others a 200 or even a 210 grainer.

The general consensus of opinion is that the 155 holds elevation better but in very windy conditions, the heavier bullet can have an edge.

Laurie Holland is doing amazingly well with a 223 shooting 90 gn bullets.

The whole rifle must not weigh more than 18lb 2oz - including scope and bi-pod. My barrel (30 inches tapering from 1.25 to 1 inch at the muzzle) weighs 8lb. Stock 4lb 6oz, scope 1lb, bi-pod 1lb 3oz, action 3lbs (BAT M), odds and sods (trigger, rings screws) 8oz.

Cheers
Vince

[Ovenpaa]

What is your preference for 155's Vince? I hear good things about the later SMK's and Berger offerings however I have stopped with Lapua mostly because I had a few hundred to get through.

I did persevere with the 170 Lockbase for a while and I still think they are worth a further look at some stage.

[The Gun Pimp]

Personally, I shoot the 155 Lapua Scenar. The BC is good & they are readily available for a reasonable price.

If they were more available, I'd shoot the 155.5 Berger - the American F/TR team used this bullet to win the World Championship - but supplies are 'iffy' to say the least and they can be expensive - especially if you have to pay carriage.

The new Sierra 155 is also a very good bullet and some claim it to have better BC than the Scenar - I'm sure it's as good.

The only problem with the Scenar - it's a very long bullet and unless your chamber is 'throated' to suit, you'll find it is pushed back into the case, thus compromising capacity - which you just can't afford to do. You need to be running at maximum.

All good fun!

Vince

[woody_rod]

Personally, I shoot the 155 Lapua Scenar. The BC is good & they are readily available for a reasonable price.

If they were more available, I'd shoot the 155.5 Berger - the American F/TR team used this bullet to win the World Championship - but supplies are 'iffy' to say the least and they can be expensive - especially if you have to pay carriage.

The new Sierra 155 is also a very good bullet and some claim it to have better BC than the Scenar - I'm sure it's as good.

The only problem with the Scenar - it's a very long bullet and unless your chamber is 'throated' to suit, you'll find it is pushed back into the case, thus compromising capacity - which you just can't afford to do. You need to be running at maximum.

All good fun!

Vince

Somestimes the longer the bullet for a given bore size, the further back the ogive where it contacts the rifling, due to the longer nose of the bullet. This also depends on the length of the boat tail. In our local bullet, the Dyer HBC (155 gr 30 cal), it is also quite long, but it has pretty much replaced the SMK 155 (the old one), where although the SMK is shorter OAL, the HBC needs a slightly longer throat because the boat tail is longer, and it is a tangent ogive rather than secant ogive.

I think the new SMK is a bit overrated. Our AU bullet has a higher BC, and is very reliable in length and weight. I really like Scenars, using them in my F Open rifle (139's in 6,5mm).

[sanselm]

Having not seen any of the AUS bullets over here it might be nice to try them, however in terms of the new SMK v the Scenar my only observation is that both myself and another GB F T/R shooter tested them in our rifles and for the same given MV they both used 1 moa less elevation at 1,000 yards which for our rifles were 25/26 moa from 100. For us they worked better than the scenars we swapped from but it may not work for everyone, I do know that they seem a big improvement on the old SMK.

My personal allegiance has swapped though to the Berger 185gr having shot my first possible at 1,000 yds with it at Blair Atholl, it took very little time to get a good load - downside is that they are about as easy to obtain as rocking horse s***

[The Gun Pimp]

Stuart,

Hope you are bringing a sack-full of Bergers back with you!

Cheers
Vince

[lapua338]

An interesting article from accurateshooter.com regarding neck tension.

I simply use an interchangeable, self-centering neck size bushing in my Hornady die to prevent oversizing and overworking the case neck.

Should I be neck turning too? My rifle doesn't have a tight neck chamber so is it really necessary? What difference does it really make to rifle/cartridge performance?

http://www.accurateshooter.com/technica ... hing-size/

[Ovenpaa]

My neighbour has spent a lot of time giving .308 Lap brass the absolute minimum neck turn to to give a uniform neck thickness in the quest for more even neck tension, he also shoots heavier bullets than me in .308 and does seem to be doing rather well at the moment

I tried neck turning on a batch of 10 .308's once and could not see any real difference. I only neck turn when I have no choice such as my 7mm.