7mm Calibre in F Class

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7mm Calibre in F Class

#1 Postby Guest » Mon Jun 20, 2005 3:42 pm

Most will know that i have a 284 Win that i am having a lot of luck with now that Sierra have taken the calibre seriously making the 175gr what are others doing in 7mm at this stage. Also on Saturday i did a test with AR2225 or Retumbo in the US i compared it to the load of 54.0gr of AR2213Sc that i have been using with a mv of 2860fps at 800 yards 60.0gr AR2225 (compresed after a long drop tube) shot 1" elevation and 4" higher on the target. i tried AR2217 but it did not show promise in the small amount of testing so i looked through the ADI data and found that in some calibres the AR2225 had the same powder charge as AR2217 with higher velocity and lower pressure. So it is working well at this stage when the rain stops i will chrono the difference but i expect 2900fps.

any one else with 7mm cartriges stick on some info and evryone might benifit i think that 7mm cals will become more popular for the long ranges as people are making dedicated short range rifles.

Cheers Bill

Guest

#2 Postby Guest » Mon Jun 20, 2005 4:32 pm

Iam with U WB long live the 7mm
:idea:
Cheers
RICHARD

Richard

7/284

#3 Postby Richard » Sun Jul 03, 2005 7:11 pm

Hi Guys

As you may have noticed in the ATR I am pushing the 7mm strongly; especially now as the 175MK as slowly coming in. I would like to get my hands on a packet to try.

That being said the latest production 162 A-Max are very good. I have been lucky enough to use some old style A-Max (VLD style) and these new ones are as good.

After a lot of years with the 6.5/284 I am now a convert to the 7/284 case - slightly improved (Shehane reamer). The 7mm shoots in a narrow vertical band at all ranges - something that I can't say about the 6.5 when the vertical flyer keeps in after 1000 odd rounds. The extra weight also helps when the wind starts to get fickle.

For the Australian Team to Bisley in 2009? I would start pushing for them all to use the 7/284 now that the components are available to make it a competitive piece. Having shot in the UK a couple of times and seen Stickledown in a blow, I am of the growing view that it is a competitive choice.

Cheers

Richard
Canberra

Guest

#4 Postby Guest » Sun Jul 03, 2005 7:59 pm

ed
Last edited by Guest on Sun Oct 30, 2005 9:13 pm, edited 1 time in total.

RAVEN
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#5 Postby RAVEN » Sun Jul 03, 2005 11:30 pm

Hi all
I have been shooting 7mm REM MAG for awhile in SA about the only one I know of (bit too much gun I must say) I am having 2X .284W built at present compared to the MAG this will be like shooting .222 recoil wise.

Once there are a couple about I think this will be a better gauge when they can go head to head on the mound with the 6.5 fans.
The long neck 6mm's hybrids seem to be getting good results in the USA
This would be my 2nd choice because of a better barrel life extending the competitiveness usefulness of your equipment.

Barrel changes mostly require new work-up load etc. etc.
Cheers
RICHARD :)

AlanF
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#6 Postby AlanF » Sun Jul 03, 2005 11:51 pm

Richard,

Regarding the .284 Win, how difficult are they to keep down under recoil under F-Class weight limits (and without a muzzle brake)? My 6.5 is okay in that respect, but I calculate that a .284 with 175smk at 2850fps is about 25% more recoil energy.

Matt,

Just a thought about coaching. I'm wondering if there are target rifle coaches who have been to Bisley, who would be interested in adapting to F-Class. If they could adapt, they would be a great asset.

On team selection, its not as simple as choosing the best performed shooters in Queens, OPMs etc. This is coached shooting, so you need the shooters who (a) can shoot very good elevation and (b) will obey the coach's instructions :mrgreen: ! So the most thorough selection method would be a selection trial, coached, with particular attention paid to elevation performance, and the barrels used would need to become "keepers" between the trial and the event. Would it be practical to get everyone together for such a trial?

Alan.

Guest

#7 Postby Guest » Mon Jul 04, 2005 12:41 am

Hi Alan
The 7mm Rem Mag I am using now before it was rebarreled
weight approx 14.5 LBS and Lin Otto has patched my bleeding head up on the line a few times and do have a permanent idiot cut near my right eye to my wife’s discussed this was usually cause by the recoil moving me down the mat and not having shoulder butt contact allowing it to get a run up on me (ouch) :oops:
Anyway since I have had it re-barreled and done a few stock mods I can shoot it free recoil no problem
The weight is now 17lbs
The F-Class weight limit is very generous and I think would tame most cals generally used.
The 284W rifle being built at the moment will weight between 17 and 19 lbs the recoil should be mild well for me anyway :lol:
If the Smith pulls F outa A I should be using it in the SARA queen
But if not I will use the 7mmloudenboomer
Cheers
RB

Richard

Recoil

#8 Postby Richard » Mon Jul 04, 2005 2:41 pm

Good to see this thread developing.

WRT recoil, the straight 284 gives about the same perceived recoil as a 308Win - about a quarter more than the 6.5/284.

There is no "ideal" F-class cartridge - which is one of the reasons I am shooting this discipline. When it comes to National Team selection, however, I think that we can learn a lot from the Yanks and start thinking ahead of time about standardizing on a single cartridge/load for each member. It remains a toss-up between the 6.5 and the 7mm as to bore diameter but challenging perceptions is always healthy.

Matt - as always you are welcome to a stage with the 7mm when you are next at CRC.

R

pjifl
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7mm Calibre in F Class

#9 Postby pjifl » Mon Jul 04, 2005 10:36 pm

I too am watching the 7 mm with interest but remain unconvinced there is any significant advantage.

Does anyone have any real - like trustworthy - data an the relative Ballistic Coefficients of the new Sierra 175 in 7 mm as compared to, for example, the 6.5 mm 139 Lapua Skenar. I cannot see much difference but maybe someone has done some real measurements and has something to add.

Peter Smith.

RAVEN
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#10 Postby RAVEN » Tue Jul 05, 2005 2:41 pm

There are 2 advantages that come to mind
1: better barrel life
2: larger selection of projectiles 162A-Max/168Gr Berger /171Gr Pro Cal 175Gr SMK /180Gr Berger
RB

pjifl
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7mm Calibre in F Class

#11 Postby pjifl » Tue Jul 05, 2005 3:23 pm

Everyone seems to always assume a 6.5 is always the 284 variant using well over 50 g powder. Sure, this will have a much shorter barrel life than a 7mm using about the same weight of powder.

But I believe that everyone simply adopted the 6.5/284 without thinking it through fully. It is overcased and a barrel burner. It was copied from what was used mainly in other disciplines that do not shoot as many shots as we do. I am using 43 g of 2209 in the 6.5 Rogue - you can go up to 45 g and get over 2900. Am expecting over 2000 rounds barrel life which is no worse than what I would expect from a large 7 mm.

So it comes down to bullets. Anyone have reliable BC's for these 6.5 and 7 mm beasts ?

Peter Smith

AlanF
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#12 Postby AlanF » Tue Jul 05, 2005 3:54 pm

Peter,

Sierra seems to have a good reputation with their published BCs :
http://www.sierrabullets.com/index.cfm?section=bullets&page=bc&bullettype=0
Comparing the 6.5 142gr with the 7mm 175gr over the full velocity range used in F-Class (say 3000fps down to 1500fps), you'd have to say the 7mm is clearly superior.

I still think the 6.5 is a good compromise if you have one rifle, and if you could have 2 you might opt for a 6 and a 7.

Alan

pjifl
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Location: Innisfail, Far North QLD.

7mm Calibre in F Class

#13 Postby pjifl » Tue Jul 05, 2005 4:04 pm

I think I trust Sierra more than most to at least compare BCs of their own bullets. But I wonder where the 6.5 Lapua 139 Skenar fits in with Sierras figures. I have this feeling that it may rate a bit better but have to admit that I simply do not know. I just wish there was an easy way to do the measurements.

Peter Smith.

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#14 Postby bjld » Tue Jul 05, 2005 4:20 pm

G'day Peter

I've been following this thread and was thinking the same thing about the BC of the 139gr Scenar. Henry Childs (HBC) posts on Benchrest Central and Long Range Target Shooting and I think he may have tested them. You could search for his posts or send him a PM.

Aside from the BC, the Scenar has a much better finish than the Match King and I use them exclusively.

Regards
Ben

Guest

#15 Postby Guest » Tue Jul 05, 2005 9:24 pm

ed
Last edited by Guest on Sun Oct 30, 2005 9:12 pm, edited 1 time in total.


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