F/TR legal chamber size for 308??

[memilanuk]

"Do they normally measure fired cases at f-class comp.?"

I know am going to catch some flak for this, but I am going to post anyway.

Answer - No.
In the thirteen years I have been shooting FC and that includes a LOT of matches around the USA and 5 countries, I have never seen it done or even suggested.

Actually... it was done on a 'voluntary' basis @ Lodi this year, Larry.

Darrell Buell approached the match officials (the one who is also on the NRA HP Committee, FWIW) about it, and they didn't want 'to make the rule book 3 feet thick'. All that was asked, and all that was done, was to drop the competitor's fired case into a commercially available SAAMI spec case gauge (this one was from LE Wilson, if anyone cares). The goal was to make sure it passed freely into and out of the gauge. Word was put out (to the F/TR crowd, which is maybe why you missed it) that anyone interested, and especially anyone interested in the US F/TR team in the future, would be encouraged to bring a piece of their fired brass to Darrell Buell or Mike Miller (Captain and Vice-captain of the F/TR side of the US F-Class team, for those unfamiliar with their names) sometime during the week. To the best of my knowledge, everybody passed.

Would it be possible to palm off a 'legit' case while having an out-of-spec chamber? Probably, but at this point I don't think any one did. After a lot of discussion, probably the simplest way to handle any 'questions' would be for them to be brought to the match officials, and have them pick a fired case or two from the competitor in question... *after* they have completed their string. The reason I add that last is because of certain... allegations of interference by match officials while a competitor is in mid string that I have heard from other 'related' disciplines. No need for that kind of added stress when it can be handled easily as they remove their gear from the line.

As for the 3050+fps... I'm one of the few people running 'sane' loads i.e. old-fashioned Palma loads down in the 2950-3000fps range that I know of. Seems like most people are gunning for the 3050-3100 range, and some pushing 3150+. At least one person on the 2009 FCWC team had to 'detune' their ammo to fall *below* the HME restrictions in place for Bisley - a .308 155 @ 3150 just squeaks over it. At what point the case starts becoming a 'consumable' like the bullet is a whole 'nother topic...

 

[Keith Glasscock]

Got me curious about what could be done to a SAAMI "legal" chamber, so I pulled down the print and went to town redesigning a chamber reamer for my Win brass (bigger capacity than most others).

The capacity increased, but much less than expected. The volume of the chamber, sans neck, was up from 97.48 grains/H2O to 97.83. If we assume that 57.48 is the case capacity before, the after would be 57.83 (0.35 grain gain)

Maybe someone can QL the change in case capacity from 57.5 to 57.8 and give me an idea about the change in velocity, but I'd bet it isn't much.

I'm sticking with Monte - I'll keep it safe and sane. I'll win when I do the best job of preparing for the match and reading the conditions. In the end, it is the shooter, not the ballistics that wins (e.g. Weil winning with 155's on the wild condition day at FCNC).

 

[Keith Glasscock]

Monte,

HME restrictions at Bisley? Doesn't a 7 WSM / RSAUM/ 284 Shehane exceed the limits (180 gr @ 2950+)? Is there a special limitation for F/TR?

 

[1KBR]

Bussdriver. No special limits for f/tr, but if you run very heavy loads in a 308 with 210gn projectiles and heavy doses of high energy powders, the muzzle energy will be around the limits for ranges in U.K without special sight in rules.

 

[Rustystud]

F-Class FTR rules follow the SAAMI, Small Arms and Ammunition Institute (USA) or the CIP (European) case/chamber specs. If your match director want to check all he or she needs to do is get SAAMI GO and No Go Gauge th check the rifle. Ona Get a SAAMI Case Gauge and check a fired case. Just like "OJ" if it fits is OK.

The only way to cheat in FTR would be to shoot a Wildcat (longer) body and shorter neck 308 case and this would be easily detected with steel SAAMI gauges. The other way would be to shoot 7mm bullets in a necked down 308 case. This too would be detectable by inspection.

The best policy is to be honest. If someone is caught cheating in the club I belong to they are asked to leave and told not to come back. The word gets out and it is called forced retirement.
Nat Lambeth

 

[rcw3]

Why anyone would break the rules to gain an extra grain or two of case capacity is way beyond me. It seems to me there are so many things that must come together shoot a top score in any match that it would be total foolishness to think you would get a real advantage in the match just because you might squeeze a wee more FPS from an illegal chamber. It makes no sense.

Robert

 

[rcw3]

F-Class FTR rules follow the SAAMI, Small Arms and Ammunition Institute (USA) or the CIP (European) case/chamber specs. If your match director want to check all he or she needs to do is get SAAMI GO and No Go Gauge th check the rifle. Ona Get a SAAMI Case Gauge and check a fired case. Just like "OJ" if it fits is OK.
. . .

When you look at the drawing the min head space is 1.630" and the max is 1.640", although "no go" is typically 1.634", so should you use a "no go" or a "field" gage for the max length allowed?

Robert

 

[Laurie]

HME restrictions at Bisley? Doesn't a 7 WSM / RSAUM/ 284 Shehane exceed the limits (180 gr @ 2950+)? Is there a special limitation for F/TR? [BusDriver]

After a couple of incidents of 'escaping bullets' a few years ago, the British Ministry of Defence (MoD) tightened up range safety rules. The main provisions affecting civilian users were that all civilian shooters had to be trained to a certain safety standard and issued with a safety certification card showing the classes of firearm they are certified competent with to be signed by their rifle club chairman before they can use an MoD owned range. Special arrangements apply to foreign visitors shooting in major competitions at Bisley to exempt them.

The other major change was about muzzle energy / use of very long-range capable cartridges. Firstly, .338 Lapua Magnum (widely used by UK military snipers) is now restricted to a small number of very large range complexes and is in effect banned from ordinary MoD rifle ranges. (At least one of the aforementioned incidents involved military use of this cartridge.)

Then an HME (High Muzzle Energy) limit was brought in that was initially set at that of standard 7.62mm milspec ball ammo in military rifle length barrels, ie c 2,800 fps with a 155gn bullet. After a lot of discussions with the UK NRA it was agreed to allow any calibre / ME up to 4,500 Joules ME without restriction. 1J = 0.73756 ft/lbs so this equates to 3,268 ft/lbs. There is however, another separate and longstanding limit on MVs that has survived and affects smaller calibres, of 3,275 fps MV maximum. In practice, this means that most .20 calibre rifles and warm/hot .22s and sixes are not allowed on MoD ranges irrespective of bullet weight employed and ME produced.

The MVs that produce 4,500J are as follows for the key bullet weights:

140gn - 3,268 fps
155gn - 3,106 fps
175gn - 2,923 fps
180gn - 2,882 fps

So, it's perfectly feasible to exceed the limit with a .308 Win F/TR rifle and handloads, albeit it with light bullets - it's actually harder to get there with 200gn + weights as ME is more influenced by velocity than mass, the former being squared in the calculations.

6.5mm exceeding the limit with 140s is just feasible, but in practice this calibre won't be affected - go more than 7 fps above the HME limit and it's an 'illegal' cartridge on the basis of exceeding the 3,275 fps MV limit.

Anything below 6.5 is going to be OK as it's either not feasible to exceed 4,500J or in the case of machined titanium monometal bullets above a seriously large case, the 3,275 fps MV limit is exceeded. (After some alleged problems with machined monometal bullets not being contained by the sand backstops a few years back, all such bullets including Barnes X and TSX etc type hunting bullets are banned at Bisley too!)

7mm in F Class with all but the mildest loads used in the .284 and short magnums is by definition over the limit.

Exceeding 4,500J doesn't ban use of the cartridge in that loading, but there is a mandatory short-range sighting in session required before each event (whole event, not single match) that uses a special target with an aiming mark at the bottom and an area above that the bullet strike must fall within. Any F/TR shooter who exceeds the ME limit should undertake this check alongside the majority of F Class competitors, but I've never heard of anybody doing so. 'HME' cartridge users must also be 'passed out' as competent in use of HME firearms on their range safety certification.

This doesn't affect non Mod owned ranges such as Diggle and Blair Atholl, the other two 1,000yd venues used in GB F Class League competition. As Bisley is part of the Pirbright military range complex, it does apply there.

 

[memilanuk]

HME restrictions at Bisley? Doesn't a 7 WSM / RSAUM/ 284 Shehane exceed the limits (180 gr @ 2950+)? Is there a special limitation for F/TR?

Remember, at the last FCWC the US F/Open team was still fielding 6.5-284 rifles. It's really hard to exceed the HME restrictions with that caliber and commonly used loads. The 7mm thumpers did have to go thru the HME certification nonsense, although if I recall they relaxed things a bit and allowed competitors to be checked out once per event, rather than once each day (or whatever the normal bureaucratic silliness was/is).

 

[Keith Glasscock]

Thanks Monte and Laurie!

My home range requires proof of 300 yard zero before shooting 600 yards regardless of caliber (because someone did something less than intelligent). At least there is a way around the restrictions in Bisley. I'm going to keep thumping the bullets out of the 308 at sane velocities and see if I can't learn to read the wind well enough to win.

 

[XTR]

Why anyone would break the rules to gain an extra grain or two of case capacity is way beyond me. It seems to me there are so many things that must come together shoot a top score in any match that it would be total foolishness to think you would get a real advantage in the match just because you might squeeze a wee more FPS from an illegal chamber. It makes no sense.

Robert

Dude, in competition, I don't care if you are racing fiddler crabs for beers someone will try to game the system. I recently saw a 308AI reamer for sale somewhere, not saying it was used for an F-TR barrel, but it could have been.

I'm fine with seeing chambers/brass checked at the line after a relay.

 

[Keith Glasscock]

Have to agree with XTR, some people will cheat regardless of how little there is to gain.

I don't care if you measure my brass - have at it! Just so long as the standards are communicated before hand so I can check for myself.