6mm ARC for Long Range Benchrest

[pengo]

Having come to the end of the line with my 6PPC barrel, I was looking into re-barrelling it for longer range benchrest competitions - 600 or 1,000 yards, also back to 100 yards if that's possible.

However, given the bolt face on my Sako 75, it's not feasible to get a 6BR or 6BRA, so I was wondering if anyone has had any success with the 6mm ARC?

If you wouldn't mind telling me of your experiences, good, bad or indifferent, I would be very interested to hear.

Also what powder, barrel length etc, would be great.

I was hoping to use Berger 105's if it's possible.

Thanks in advance for your input.

Cheers.

Paul

[The Gun Pimp]

You'd certainly be OK for 600 yd BR (I'm currently shooting a 6BR at 600 and 1000) but you might be giving away a bit of velocity at 1000 yds. Why not just open the boltface a few thou and shoot 6BR or Dasher? Easy job for a 'smith. You'd be wanting a 28 or 30 inch barrel.

[firedoc]

Would endorse what the Gun Pimp has advised, we did a similar exercise on our Panda 6ppc bolts. Had them opened up. and had a 6BR and Dasher done, if you like prepping brass you could go the Dasher route or just go 6BR straight out the box. Currently running 30 inch due to Pandas being a lightweight action.

[Laurie]

I'm in agreement with both Vince and Jim (Gun Pimp & Firedoc) re the superiority of the 6BR in this role, and the relative ease / modest cost of having the bolt-face enlarged. (My first BR started as a 223 rifle with a much larger bolt-face enlargement needed.)

 

I'd be a tad wary of the ARC. I spent some time and effort researching this design after its launch. and It's certainly a very capable design ballistically with remarkable performance for the case size/capacity. It is designed with heavy 6mm bullets in mind with a suitably long chamber throat and one turn in 7.5-inch rifling pitch rate specified as the SAAMI standards. However, like other such recent designs with the 7.62X39 / PPC / Grendel 0.447-inch dia. case-head, its factory target market appears to be primarily the US AR-15 shooter rather than PRS, BR, or prone match disciplines. Chambers and hence reamers are meant for this kind of firearm and use, and although in essence the cartridge is a fast-twist 6PPC 'improved', (or a stolen and slightly modified version of Robert Whitley's successful 6mmAR necked-down Grendel wildcat cartridge), there is much more to creating a BR quality rifle than simply a good case shape. So before committing yourself, look closely at who is making chamber reamers and their dimensions. I've no idea how many custom 6ARC rifles have been built in the UK, but would reckon that at best it'll be a handful. Not many gunsmiths will even hold a reamer as a result. Conversely, the gunsmithing world abounds with BR reamers and small-clearance chamber designs optimised for precision shooting disciplines.

 

The same sort of issue applies to brass specs and its manufacturing quality / consistency. I'd be very surprised indeed if the Hornady brass is up to Lapua, Norma, or the specialist US case makers' 6BR standards, and IME Hornady case-heads are often on the 'soft' side. The Hornady ARC case also has a huge disadvantage too which would simply rule it out for me. The small diameter flash-hole (1.5mm vs the older standard of 2mm) is an integral element of the PPC / BR / 6,5X47mm Lapua precision mix when combined with small primer ignition. Hornady reportedly turns out its ARC cases with the large 2mm flash-hole. Had I followed up with my early interest in the ARC, I'd have bought Lapua 6.5 Grendel cases and reformed them - but Lapua suspended Grendel case production in the Ukraine invasion fall-out, and who knows if it has resumed - or ever will. In the current US supply situation for both factory ammunition and components, the ARC was introduced at a bad time, and as comments about it have dried up pretty well completely over the last year or two, it may be only just hanging onto life.

 

A couple of US gunsmiths worked up long-barrel ARC bolt-actions mostly using the little Howa Mini-action, designed for low recoiling long-range varmint and plate / plinking etc use where they apparently do quite well. It has gone very quiet on that front however, and I'm not sure just how much real interest was generated. 

 

 

[pengo]

Thank you everyone, for your advice. I’m really pleased to hear that I can have the bolt face opened up to use 6BR, as this was always my preferred option, so that’s my way forward now.

I’ll be contacting a couple of gunsmith’s to get this done and then see you on the firing line. 👍

[The Gun Pimp]

On the other hand Pengo - I'm slightly favouring the Gay Tiger for 1000 yard when Lapua bring out the brass in autumn.