For the past few months I've been collecting components for a build to fill a gap in the safe.
I wanted something in 6mm for spotlighting and fox shooting and although I have a .243W barrel for my Tikka it's a pain to change barrels and sight in.
While my 6PPC/6BR switch barrel target fun would be almost ideal it's single shot and too heavy for hunting on foot so I started looking for ideas.
The requirements for the cartridge were it needs to be 6mm and capable of .243 like performance with 65-95gr bullets. It needs to be a repeater action and reliably feed from a magazine, something the 6BR case isn't known for.
There's a good number of cartridges that fit the bill, Lapuas 6.5X47 case is commonly necked down to 6mm but I already have one necked up to 7mm and I'd rather not risk the confusion of having two guns running the same brass. Then there's the 6.5mm Creedmore case, again commonly necked down. Then there's .243 and .243AI. Good performance and the factory ammo option but the eventual winner for me was the 6XC case. Norma brass although a little expensive is good quality and availability is ok. The 6XC delivers similar performance to the .243W case but with better barrel life.
I originally ordered a carbon wrapped varmint profile 6mm barrel but when it didn't arrive in the shipment and was scheduled for delivery in another 8 weeks I cancelled the order and went back to looking for a blank locally. When a No3 profile Maddco barrel with a 200 round count appeared really cheap but chambered in 6mm Remmington I hit the books to see if it was usable. Indeed it was, the short fat nature of the XC case meant the reamer would clean up the entire chamber meaning the gunsmith could simply cut off the existing thread and cut a new thread then chamber as normal. While David Tubb developed the 6XC to shoot 115gr bullets normally they use fast twist barrels but mine is a 1:10" twist like most .243's but seeing as I'll be only hunting with mine I'm not interested in shooting bullets over 100gr so it should be fine.
Seddo's Guns had Stiller Tac30 actions in stock so the order was placed and the action sent to my local gun smith. I chose this action because being a clone of a Remmington action it would be easy to get stocks, a trigger and other components for. While not capable of the precision of a single shot benchrest style action the Tac30 will feed from a magazine and ha a bit more clearance built into it so it will still function should you get a bit of dirt or dust in it in the field.
I have a customised factory Remmington trigger I took off my BR rifle to fit a 1.5oz trigger which I hope will fit. It's been worked down to a crisp 6-8 Oz break and should allow excellent trigger control
When it came to a stock for it I initially purchased a silhouette style stock from Hatchers rifle stocks here in Australia but the more I thought about it the more I realised although it would have been fantastic to shoot standing it wasn't the best shape to shoot off a rest or bipod so I held off on doing the final sanding and finishing. I purchased an Atlasworks Aluminium bottom metal thinking I would use AICS magazines but when I saw Magpul P mags were around $40 I changed my mind and started looking at the Magpul polymer bottom metal which comes with a 5 round P mag.
While researching the Magpul mags and DBM I watched a clip on their Hunter 700 synthetic stock. This the ticked a few boxes for me with its full length bedding block that goes down into the pistol grip and the flexibility of their M lock system. As it turned out Magnum sports had both the DBM and the Hunter 700 in stock and the deal was done.
The action comes complete with a Pic rail and given the long range potential of the 6XC cartridge I started looking for options for optics. I really wanted a scope in the 4-16 or 6.5-20 mag range because even if you don't use that much magnification in the field it's nice to have when developing loads on a bench at the range when conditions are ideal.
I watched the second hand market pretty closely and when a Minox ZA5 4-20x50 came up second hand under $500 I grabbed it. Minox use the same SCHOTT AG glass used in the Zeiss Conquest range and have a reputation for reliable mechanicals as well as having 4 power at the lower end rather than 6.5. Though only a 1" main tube they have 80moa of adjustment life time warrantee. Good buying I think and I'm keen to test it out.
So now it's all coming together and the barrel is going to the gunsmith to get chambered. While he's been waiting for a new reamer to arrive I ordered 200 Norma cases before the price goes up. I managed to pick up a five boxes of Berger 69gr High BC flat base varmint bullets. These have a G1 BC of .308 which is pretty impressive compared say a 65gr Vmax which is .280 and the Bergers flat base should stabilise it better at hunting ranges which tend to be under 300m.
I also picked up three boxes of Noslers 80gr ballistic tips. These have a G1 BC of .329 which should make them a good choice for longer ranges, some research shows some American coyote shooters using them successfully out to 800y.
I already had some 65gr Vmax to try and some 85gr Hornsdy Interbonds. These are a bonded core bullet with a tapered jacket and are suited to heavier hall game than the other varmint pills. Their BC is approaching .400 and no doubt ill be Playing with them as an option for goats, pigs and even fallow deer.
I've seated all 4 bullets as dummies and took some measurements. By doing this you can compare different bullet shapes and how their shape changes their seating depth for a given over all length or base to ogive length. Having this information allows you to choose how much Freebore you want (distance from the case mouth to the lands) no point making the Freebore too short and needing to seat heavier bullets really deep in the case but silly to make the Freebore long enough to seat a long bullet right out then having the lighter ones jumping right out of the case before they reach the lands.
I worked off having a minimum of 75% bore diameter of bullet in the neck, so about 4.5mm for a 6mm bore. This is probably enough to keep a bullet straight in the case when it feeds out of a magazine. A lot of people say 1 caliber is about right but remember I'm looking at a bare minimum for a short bullet, a longer one will be more. I seated all 4 bullets with around .160" (4mm) in the neck, this takes a bit of fiddling because of the different shapes and measured them from the base of the case to the ogive with a hornady OAL gauge. Then I looked at the lightest bullet and roll nder it down to give a bit more neck engagement and for a number around .220" Freebore (bullet touching the lands). I calculated that the heaviest bullet seated to the same base to ogive length (and there for the same distance off the lands) would give it an extra .130" or so in the neck. Remembering that's from the start of the boat tail not the base of the bullet.
Now I have my Freebore length my gunsmith can cut the chamber then cut the throat. Of course it's always better to err on the short side with Freebore because it's easy to cut it a bit deeper later on if required, not so easy to put it back
Pick and figures later on, a lot of info here but thanks for reading
Chronos