New FO rifle

[Woody_rod]

A quick update on the rifle so far:

It has shown some good groups, but some flyers made them look worse than they would have been. Seems the reason for this is copper fouling near the muzzle, which I have never come across before. Thinking that the velocity (3000fps+) and twist rate has something to do with it.

Now have a switch barrel in 308 for FS, so I can shoot with the usual crowd. Am tempted to do one in 6BR also, for shorter ranges in FO to save the bigger one for the longs.

[Woody_rod]

An update on the 260 INCH chambering:

Well, I have now used the 260 INCH in competition, which is better late than never. Was supposed to be finished for the 2010 WA Queens prize, but you get that.

I started the GSDRA comp this past weekend with a 6BR, which now is seen as an obvious mistake, but this won't be repeated. The 6BR in my rifle was completely untested other than 40 rounds being fired to get some sort of group going, It shoots pretty good, but nowhere near like the 260.

Elevation, despite the terrible conditions on Saturday, was never more than 1MOA, and 90% inside 0.5MOA. Sunday at 700 and 800M showed better conditions and how the rifle could perform. The elevation after sighters was the best I have ever shot, and definitely under 1MOA, most inside the height of the X ring. I lost two points on wind, which was easy enough for someone with relatively limited shooting experience as myself.

The cartridge shoots very flat and takes some getting used to after shooting a few thousand 308 rounds. Come up from 700m to 800m is 3.5 MOA, for a total of around 16MOA from 300m.

The short neck had no detrimental effects that I could see or otherwise notice.

When I get back from holiday, I will develop a load based on the 123 grain Scenar for the shorter ranges, and down loaded to the same MV of the 139 grain. I feel this will be a better choice than swapping barrels to a 6BR.

[Mark Hamersley]

Hi Rod

I had a similar aim and found an accurate load for the 123gn scenars (at 100m, yet to be tried further out) at 3,300 fps. When you plug the numbers into the JBM calculator it suggests it is flatter to 1000 yds than the 139gn going 3,000 fps and with similar wind drift. Just some food for thought if you have problems getting a reduced load working.

I'll be doing my usual testing/refinement during club shoots when the Swanbourne range opens and let you know what I find.


best regards


Mark

[Woody_rod]

Hey Mark,

Shame you could not shoot in Albany, I was looking forward to talking to you.

I have been told something similar by Robert Chombart and Phillipe Gineste (the "C and G" from CG) using the slightly lighter bullets for the 6,5mm. I know Phillipe uses the ligher bullets for 300M ISSF in France for his std 260 Remington chambering. It seems that the 123 Scenar has a higher BC than the 107 6mm SMK anyway. Just watching the bullet flight of the 6BR vs the 260 INCH shows a much flatter trajectory in the latter - much like yours vs 308 Win when I was watching at Wurgabup.

What comparitive load are you using for each bullet weight? For example, if I just use the same powder weight as the 139, might be a good point to start at? I get zero pressure signs at 3060fps now with the 139 Scenar, so 3,300 fps should be easy enough with the 123 grainer. Our 223 Rem rifles show much more pressure than the 260 ever does or did.

Are you able to come to the Wurgabup shoot? I am thinking of getting a new trophy going for a long range aggregate for us guys with FO rifles, such as 800, 900 and 1000 yard agg where the flat shooting calibers start to make a difference.

[Mark Hamersley]

hi Rod

For comparable loads I did a bit of research before trying 53, 53.5 and 54gn AR2213 for the 123gn. I have a working load of 52.5gn AR2213SC for the 139gn. Best group with 123gn was with 54gn AR2213 but I need to do more testing around this during club shoots to confirm.

I'd like to get to Wurgabup to see your INCH in action but I have work commitments that may get in the way. I'll keep in touch.


best regards



Mark

[IanP]

Hey Woody,

Dont get get too wrapped up in velocity being the goal, its accuracy you want! I read somewhere, "velocity is the girl you date but accuracy is the girl you marry". The velocities you are getting with 139gr Scenars are pretty good but accuracy is what you want.

Keep your 260Inch for 300-600m ranges and if you want to be competitive in the longs, when the wind blows, then invest in something that can launch 180gr, 7mm or 210gr, 30cal projectiles.

I have a 22BR that launches 90gr VLDs at 3160fps and 6.5x47L that launches 139gr Scenars at 3000fps and 284Shehane that launches 180gr VLDs at 2940fps. If I shot just one rifle in all comps at all distances it would be the Shehane. Heavy, high BC projectiles are king and its just down to what case you want to put them in.

Cheers,

IanP

[Woody_rod]

Ian,

I have also seen that overall accuracy will win out. My rifle is now very accurate, but the shooter has no experience with it. Just time will make the difference I think. I was losing points by overcorrecting, but not on elevation, and some by not having any zeroes.

Watching the 6BR shoot at the same time as the 260 INCH, I am not going to bother with the 6BR any more. It has the same looping trajectory as a 308 at long ranges. The only thing going for the 6BR I was watching was the 20 years more experience of the shooter. A std 260 Remington has a better long range perfomance overall than the 6BR. Fine weather performance is one thing, wind is another.

We are already looking at a 7mm version of the same INCH idea. We can already see the potential of the 260 INCH and will persue it. The local competitors don't use anything larger than 6,5mm as far as I know, so we really only need to worry about local comps at this point. I have only shot 2 comps with an FO rifle, so will be some time before I have enough experience and skill to go against people elsewhere. I do shoot FS, but don't find it very exciting.

I will be going back to TR this year, so will be diluting my FO experience further.

[bruce moulds]

woody,
how will you chase the rifling with that short neck?
matt p used to use a 6.5x57 improved of some description, which had a lovely long neck (which also protects the throat), allowing progressively longer coal as the throat disappears, and roughly the same case capacity.
his neck length also allowed the bullet to be above any potential donut.
bruce moulds.

[Woody_rod]

Bruce,

Good question about the neck length and chasing the rifling. One answer is I fit barrels every week, so I can throw the barrel into the lathe whenever I need to. The other answer is the bullet is still seated within the case to some degree, so there is plenty of scope for moving the bullet forward.

I don't agree with the long neck thinking about throat wear. No matter how long the neck is (or isn't), the throat is going to wear the same.

On donuts, I neck ream everything now, after our 223's started to show signs of problems with them.

[Matt P]

Bruce,


I don't agree with the long neck thinking about throat wear. No matter how long the neck is (or isn't), the throat is going to wear the same..

You have done the test with several barrels ?????

[Woody_rod]

Onto something about my loads used, and some other general observations with developing a one-off wildcat:

On bullets; I have been using Lapua Scenars like I have discussed above, until this past weekend, where I used Nosler Custom Competition in 140 grain size for the 260. The Lapuas are 54c each, where the NCC's are 44c each, so there is more than one benefit.

Sometimes, with loads, we can be lucky right? For a change, this time I was lucky that the first seating depth was correct - set on zero jump. The second one at 0.020" was nowhere near as good. The load otherwise was the same as the Scenar settings: 48 grains of 2209 with Lapua cases, CCI BR2 primers. Obviously the MV range is within what the barrel prefers.

On the range last Saturday showed that the grouping was superior to the Lapua. I am guessing more due to a bit of luck, and not fine tuning the Scenar quite enough. One of those situations where the barrel just likes one bullet more than the other maybe. The day was typical for the past few months, with pretty ugly front fishtail, tending 10 oclock and gusting to 40-50 km/h. Yuk. Anyway, shooting two 4's for sighters (after guessing the elevation for 600 yards), I shot a 58.5, with elevation inside the X ring, with the two bull eyes just missing the 6 line (on the waterline).

The next closest F Class score (albeit in std) was 98.1, with the 260 ending on 113.9 (58.5 and 55.4). Very pleasing indeed. The top TR guy (AU team member) shot a 96 from 100 - whom has a 99.8 average. The second detail showed a 1MOA group height at least, as I lost one high, and two low.

I still find it difficult to get used to the lack of windage and elevation that these 6,5's shoot. I am aiming within the 6 ring, where the FS people are aiming in the 3/4 ring. It does me no good when I go back to FS or TR.

Some other things about using a one-off chambering:

I need to make my own small base die, as the FLS die I have does not quite do it. This is typical, as my 308 Forster is the same...I have to use a small base die every now and then to tweak the brass. It is mainly due to using brass from Laurie Ingram's rifle (RIP), where his chamber is just slightly different. It is the bit of case about 4-5mm ahead of the bolt face (as always) that is the problem. It just needs tucking back in, which is made more difficult only due to the wildcat chamber.

I am sure that a small base die for the 30-06 will work (as recommended by Robert Chombart), as it has the extra length needed to get over the shoulder of the case, moreso than the 308 die. I made my own neck die to use std size bushings, but no longer need this, as I now have all my cases fire formed. This die is made with the same reamer as the chamber. This die can be bored from the top down to leave just the bottom bit, which will then work to make the bottom of the case smaller. The usual issue of clearance with the case holder for the press will be apparent.

There is simply no pressure signs that I can see. Primers are still the same shape as when fitted, only with the firing pin dent.

One observation that was interesting, was the FLS cases do not seal the chamber as well as fire formed ones do. There was a little more carbon showing on the case neck than my own fire formed brass. I think this is just due to the case size, with fire formed units showing almost no carbon on the necks.

[AlanF]

...I still find it difficult to get used to the lack of windage and elevation that these 6,5's shoot. I am aiming within the 6 ring, where the FS people are aiming in the 3/4 ring. It does me no good when I go back to FS or TR...

Rod,

I think you're perpetuating a myth that the high BC projectiles in F-Open shoot so far inside 308s and 223. If the rifles are zeroed, and you're aiming off just inside the 6 ring, then 308/223 will need to aim well into the 5 ring, in fact closer to the 6 ring than the 5. At normal velocities with common projectiles a 308/223 will drift in the same wind about 1.4 to 1.5 times as much as a 6.5. Even if you took the fastest, slipperiest 6.5 around and shot against the slowest 223/308, this factor wouldn't exceed 2.0.

Alan