.308 ftr chamber specs

[nowler]

evening folks

 

against everything that my head tells me is sensible, i've ordered a ftr build.

 

so, for those of you who shoot ftr, could anyone point me in the direction of what is and what isn't allowed with regards to 308 chambers? and what sort of specs is everyone using? neck dimension? throating length? base diameter?

 

any help, and or advice or even just discussion would be much appreciated

 

kind regards

 

derek

[gunnery]

Hi Derek I shoot FTR at Diggle Ranges the action I use is a Stolle Panda F-Class the barrel is a 30" heavy palma freebore with 1-12 twist I believe the barrel was throated for the 185grn Bergers but it also shoots Lapua Scenars 155grn and SMK 155 palma bullets very well hope this helps you.

[Laurie]

Derek,

 

basically anything is allowed as long as it doesn't move in the direction of an 'improved' case. Small primer / flash-hole Lapua 'Palma' brass is OK - strongly recommended for L-R FTR. So far as neck dimensions go, there's nothing explicit saying no super-turned tight-fit necks, but the GB F-Class League talks every now and then about putting competitors' rifles through a 'minimum SAAMI inert cartridge' test and DQ'ing anybody whose chamber won't accept it. The norm is a 'minimum SAAMI' chamber. I think speaking from memory this has a 0.342" neck section diameter. This suits Lapua brass either as no-turn, or with a light 'clean-up' turn. (I turn mine to 0.0144-0.0147" depending on brass lot, but it's debatable whether it's needed.) The Americans who often use thinner Winchester brass because of price and its high capacity often go for smaller dia. chamber necks down at the 0.340" level and below. I doubt if anybody here does.

 

After that, it's what bullet(s) you think you might want to shoot. Many people (me included) use a 1-10" twist rate come what may. Unlike TR, tight-bore barrels are rare, standard 0.300/0.3080" dimensions the norm. Broughton, Benchmark, and Bartlein are very popular. Modern bullets,especially Bergers, don't seem to care about having a theoretically overdone coefficient of stability. Most gunsmiths are using a throating reamer separately now to produce a freebore for the bullet to be used. With a bit of care in this, you can have something that suits 155s seated very shallow and the 210gn Berger LR BT just a tad on the deep side. This is a favoured choice amongst the Altcar 101RC guys in the league and they'll take ammo with both weights to league rounds and choose what they use depending on conditions. 155s are easier to shoot, hold elevation well, but move more in big wind changes; 210s are the opposite.

 

The heavier Hybrids need some serious freebore, so dual-weight chambers are more difficult, likely not on. Steve Donaldson has had some good results with the 230gn Hybrid in a barrel chambered just for it, but most people think it's a bit too much bullet for the 308 Win, they're expensive, and more often than not you can't get them either. Paul Crosbie has had very good results from the 200gn Hybrid, and (I think) on occasions the 215gn version. if you plan on anything at Blair at 1,100 and 1,200 yards, these bullets give an advantage. At 1,000 max distance, the better 155s at 3,050 to 3,150 fps work out as good as anything over a season. The 185gn Berger LR BT Juggernaut at 2,800 fps + is a great in-between bullet (when you can find any), but most league shooters tend to go for 155s or 200s and up. A just long-throated chamber for 155s is often also optimal for this bullet, and you just start to notice the extra recoil on a bi-pod with this bullet weight, but it's easily manageable. Hardly anybody uses VLDs in FTR - too much trouble with so many good tangent ogive bullets around. Bergers are the most widely used especially at 1K, but the 155 Scenar and new model 155gn Sierra Palma MK have their fans too. If you have a barrel throated to suit the Scenar, very long for a 155, seated optimally with the bottom of the shank at the base of the case-neck, the resulting freebore suits the Scenar, the 155.5gn Berger BT Fullbore, and the 185gn Juggernaut optimally, with the 210gn Berger LR BT still usable.

 

The really hard part of getting a successful FTR build is getting the rifle specs you want, a really heavy barrel, stock you like, good scope, and a super-stable bi-pod while keeping within the 8.25kg all-up weight limit and without breaking the bank to save a few ounces. (By that, I refer mostly to March scopes which are the lightest on the market for this discipline but cost a LOT,) It takes a lot of careful choices on the main components.

 

Good luck.

[gunnery]

that's what I said Laurie

[NICK]

Hi

Just out of curiosity what would the difference in case capacity be between a case fired in a minimum saami spec chamber and a maximum spec one? Would it be enough to offer any edge whilst still remaining in the spirit of the rules?

 

Nick.

[Laurie]

Hi

Just out of curiosity what would the difference in case capacity be between a case fired in a minimum saami spec chamber and a maximum spec one? Would it be enough to offer any edge whilst still remaining in the spirit of the rules?

 

Nick.

 

 

Not a lot in capacity, and the disdvantages would far outweigh any benfits there. Max tolerance brass has to be dimensioned to fit a minimum tolerance chamber and while fireforming the body would give you a little extra capacity, it puts all sorts of strains on the case at the body / web junction and may not provide a consistent fit in the chamber depending on how every case expands. (This is an issue in .284 match chambers. Lapua, Hornady and Norma 6.5-284 Norma cases are ~0.006" larger diameter in the web / body join area than Winchester .284 Win brass. There seems to have been a beefening up of the case at this key point when Norma took the 6.5-284 Win wildcat and turned it into a high-pressure factory number. So the customer and his gunsmith need to specify the brass used when ordering a 'straight 284' reamer. Many match versions are actually described as '284 Win Match - Lapua' or somesuch.)

 

Thin brass does give a real but small benefit. From my min SAAMI chambers, fireformed Lapua holds 56.1gn water, Winchester cases 57.0gn, and the old 1980s 160gn Norma brass 57.4gn. That's 2.3% greater capacity for the old Norma over Lapua which is probably worth another 20, 30 fps at Max SAAMI chamber pressures. However, the thin case may not be as strong, so probably won't take to 'pushing' pressures a bit as well as the very strong Lapua case. (I believe the Match Rifle brigade who know more about hot 308 loads than most tried this brass some years back, but found that repeated max or over-max pressure loads wasn't a good idea in it!)

[nowler]

thanks for the input lads. i was hoping you'd get involved laurie.

 

by min saami, are we saying that that chamber dimensions at base and neck need to be held tight or loose? my understanding is that even min saami spec chambers are loose in comparison to what i'd normally spec fpr a match chamber reamer

 

i'm planning 155's of some flavour or other. no need to beat myself up with anything bigger. it'll be a kreiger barrel for me, other people are welcome to their fashion fads with newer barrel makers, i'm happy with the guy that taught some of them their trade. all other components are under control, making weight wont be an issue.

 

so, just to be clear, is it a gb league thing that is saying what does or doesn't constitute a 308 chamber or is it an icfra led situation? and do you know where i could get absolute clarity on what is acceptable?

 

cheers

 

derek

[Stuart Anselm]

Hi Derek,

 

I have recently been through all of this and the Official line is that for an F T/R rifle to comply with ICFRA rules it must be chambered to CIP with the exception that there is no limit to throat length. The national league follows the ICFRA rules in so far as it ensures that all GB competitors are compliant with the rules when they compete at the World Championships. The main issue with regards to chambers is the neck dimensions, tight necks are not allowed. Technically you require a minumum .344' neck - Birmingham Proof House have some new gauges and if the neck is not .344" then it wont get stamped as 308 Win. There is quite a bit more background to this that would take me forever to type so if you wanted a bit more info give me a call.

 

Cheers

 

Stuart

[Ronin]

D

 

I have a min SAAMI spec 308 Match reamer, throated for 155's (reading your spec, this sounds what your looking for)

 

Im sure Callum has similar, but if you want to use this, just say so - if you need longer free bore for heavier bullets just use throating reamer..

 

Its a .342" nk so wouldn't comply with the new CIP requirements at Proof - it would be stamped 308Win 342" nk at proof I understand.

 

 

If you need to see the print, I have it somewhere.

 

If it were my build, I would be considering using heavier than 155's though……….

 

 

If you need use of the reamer to speed up the build, let me know - reamer has cut 7 chambers so still very fresh..

[nowler]

cheers stuart and andy.

 

i'll speak to the boss next week. he has something like 20 odd 308 reamers so i'm sure we'll find something to suit.

 

i must admit that the heavier bullets appeal from a ballistics point of view, but recoil is what kills people's accuracy, despite what they think they can handle. it's a sub conscious thing.....

 

i'll continue with the research before finalising. i'll give you a phone in the week at some point stuart.

 

cheers again

 

d

[Laurie]

i must admit that the heavier bullets appeal from a ballistics point of view, but recoil is what kills people's accuracy, despite what they think they can handle. it's a sub conscious thing.....

 

 

 

Personally, I think you're wise. Having worked my way up and down the bullet weight scale, I went back to the lighter bullets and I find I shoot a lot better as a result. You know you're working harder to keep everything consistent even with 185s. My two bullets these days for L-R matches are the 155.5 Berger BT and 168gn Hybrid. I have a good lot of 155 Hybrids too, but have found them much more finicky than the 155.5gn which I consider has to be one of the outstanding .30 calibre bullet designs of its age, like the original Sierra 155 Palma was 25 or 30 years ago. It would be nice to be able to use the new Palma too given its large price discount over the Bergers, but I've had little luck with it to date. It may need a much shorter throated barrel than I use.

 

Even 168 produces a bit more subjective thump and movement subjectively. That's not to knock using heavies - many get them to work very well indeed.

 

If you intend to stick to 155s, you may not need the fluted telegraph pole profile barrel that the guys who shoot 210s invariably choose now. A 1-12" Heavy Palma profile suits (and still lets you load the 185 Berger Juggernaut if that later takes your fancy), and even at 32-inches saves you a pound or so in weight.

[NICK]

Laurie.

Thank you for the explanation.

 

Nick.

[Ronin]

No problem Derek, I'm sure Callum has something to suit what your after - the offer stands if my reamers the "missing link"

[nowler]

bonjour

 

well, it seems the definitive rules for ftr chambers are as clear as mud.

 

so the long and the short of it is i'm going with a saami min spec chamber throated slightly long for the 155's with a .342 neck.

 

i'm not fussed if that's legal or not, i'm only gonna shoot for giggles and to annoy other people...

 

cheers for all the advice guys

 

d

[taylor]

I use the USA team ftr reamer .3145 nk min non neck turn

.169 free bore can use for most bullets out their apart from the ultra heavy with out throating out

I thought you weren't coming back derek I was hoping you come shoot f-open

[Laurie]

I use the USA team ftr reamer .3145 nk min non neck turn

 

 

 

.345", Grant?

[1967spud]

 

 

.345", Grant?

its a .284-308 laurie lol

[taylor]

Sorry my fingers can't type

.3415nk

[Laurie]

Interesting. So ... somewhere around 3 1/2 to 4 thou overall clearance with out of the box Lapua, but six to seven thou' with Winchester brass. (I'm not sure what they're using these days, but it was Winchester back in 2011 when the US FTR team came to Tullamore then Blair Atholl.)

[taylor]

I would think it be lapua brass 3-4 thou clearance is perfect that's what I use on a my open neck turned gun

[nowler]

I use the USA team ftr reamer .3145 nk min non neck turn

.169 free bore can use for most bullets out their apart from the ultra heavy with out throating out

I thought you weren't coming back derek I was hoping you come shoot f-open

It's just something for a bit of fun grant. I really enjoyed the Celtic ftr international and I'd rather use my own setup than Paul's leftie guns if I do it again. In addition, my local club has a few ftr shooters and competitions so it'll allow me to shoot there too.

 

I don't have the motivation to go back to shooting f-open to be honest. I was really bored with it towards the end once I'd proved to myself all that I wanted to.

 

4 thou neck clearance is pretty loose bud, but if it's working then what do I know.

 

See you soon hopefully

 

D

[OSOK]

You know what happened the last time you butted heads with Authority , It nearly ended up with you sending a wsm case loaded with 69g Nescafe and the bullet in the wrong way to be examined !

 

you getting back into this is the best news i've heard in a long time

[nowler]

It was bisto. Far more temperature stable a powder :-)

[OSOK]

Your going to have to get your reloading kit up to date , you know standard stuff pestle & mortar , 3' drop tube !

[nowler]

no need mate, gonna use Red Dot behind a 230 hybrid. don't even need to throat it out at all there's so much empty case capacity..... people just need to learn to think outside the box Greg!

 

(note to all muppets: the above is a joke. do not use pistol

powders in a rifle cartridge unless you want to turn your action into a grenade.....)