Convict gun

[Brad Y]

Thought I would share my main rifle of choice with you guys.

 

Its a pierce actioned 260 improved- 30 degree shoulder and a whisker less taper, but not a true ackley improved- with maddco 1.20" barrel straight for 29 inches. It was 30 but its now on its second chamber after a year and a bits work. The barreled action is held in place by a barrel block which in turn sits on a couple of large pillars and is devcon'ed into place. I can remove the block anytime and the plan is to have future blocks on barrels ready for quick changeover.

 

The whole idea was to relieve any potential stress from the action by hanging a long heavy barrel off it. It paid off with the gun being superbly accurate across all ranges 300-1000yds. It doesnt quite have the ballistics to beat the 7's at long range, but I feel is on par with them for sheer accuracy. Our national state teams championships was held recently and it was the only gun in our state team that shot a possible score. The main benefit from it is that there is no recoil to beat the shooter up from a whole days use. It shoots 140gr VLD's at 2870fps with 43.2gr of H4350 and lapua palma 308 cases necked down, turned and fireformed. No pressure at all in fact its very mild- I can run the mid 2950's with about 45gr H4350 but choose not to for better barrel life as the maddco does seem to be a softer steel barrel. It should go 2000-2500 rounds all up. Next barrel will probably be a benchmark.

 

I have got a 284 shehane barrel for this setup however its not playing the game at all. The barrel is a whisker larger in diameter than the 6.5mm one and I have a funny feeling that the block is pinching on it and upsetting the harmonics badly. I have another stock similar that has a whiddden v block in it and will be trying that out this week to see if there is any difference. I hope there is as that krieger cost me $750AUD plus fitting so 4 ring to 4 ring vertical really isnt acceptable.

 

 

[Ronin]

Lovely rifle.

 

 

Have you considered altering the torque on the barrel block with the 7 mm barrel or having the barrel machined to the correct size ….for the block?

 

 

Lessening the torque may show you its pinching th bore at the current setting.

 

 

Machining would give you a more permanent fix (if it is this causing the problem)

[Brad Y]

Hi mate

 

Yes its been thought about, but the amount of money I have put into this barrel already I dont want to do anymore until it at least shows some positive results. I figured that setting it back up conventionally would show me if it would respond or not.

 

Ive been to the gunsmiths tonight and its been set up to accept a recoil lug and v block setup. I cant get to any range greater than 100m over the next few days so will take it and try to shoot some 100m groups before shooting 400m on sunday at the club.

 

Long term im was a little concerned about the weight that the pierce action can support, but people have hung that size barrel off rem 700's and had it work fine so maybe im worrying a little too much.

[Ronin]

Its surprising how much a barrel can be pinched in a chuck when your setting it up to run concentric in a 4 jaw and spider - you have to be real careful to avoid crush..

 

I suspect the barrel clamp is exerting enough force to constrict the bore and misshape (swage) the bullet as it passes through that section of the barrel - hence the poor accuracy

[Brad Y]

That sounds exactly like what is happening. Its also copper fouling heavily from the start of the chamber forward to the crown so 'swaging' is a great way to describe it.

 

Ive sent an email to pierce asking what they think about hanging a 30 inch 1.25" straight from their action, but if people have done it in the past with rem 700's I should be fine. Next barrel I might not quite go as heavy. Then again if it works on the new setup I may just profile it and try again.

[Brad Y]

I finally got the shehane working today, turns out it wasnt the block after all, but was the 20moa rail that was loctited on back when the 260 was built. On recoil, the rail wouldnt move with the 260, so each time I swapped back to it I thought it was just the barrel. Now the rail is back tight and the screws have been locked with epoxy so they dont come out again.

 

We shot 400 meters and this was my ladder test of 4 different loads in a switchy wind.

 

700 and 900 meters next sunday, will be able to confirm a final load then.

[foxing2night]

fantastic thank you for sharing,

keep us informed as to how you get on,,

 

Darrel

[Ronin]

Pleased its resolved, suggest Losso in the barrel to polish the bore - may help prevent so much fouling.

 

Was using the same targetry at Blair Athol this weekend - lovely to use - instant result and no target pulling….

[Brad Y]

Yes the kongsbergs are fantastic, as long as they are maintained and all the layers restored every 2000-3000 rounds and any debris that falls down into the sound chamber is removed. Just beware that shooting small calibers like 223 with 80 or 90gr bullets or even 6mm 105gr bullets at 1000yds is a little sketchy as well, they dont have the massive echo to consistently read shot location like a 308 or 7mm does.

 

I already use iosso paste as part of my cleaning regime. Not sure why, but this one just copper fouls- hence why I shoot moly coated bullets in it. Easier to clean after a days shooting and with a burnish of moly paste on a patch before shooting, it only takes 1 shot to put them into the group.