new 6AI

[1000yardstare]

Just got my new 30 inch, 8 twist, lead lapped stainless MacLennon barrel installed on a 722 action. Closing the bolt on a new 6mm Rem case indicates a very nice crush fit so won`t have to worry about headspace. Using Win brass and primers, Redding Type S Match neck die set. The 722 formerly wore a 6/250 barrel in a walnut Fajen prone stock with Anshutz rail and butt plate, Timney trigger for 300 metre ISU matches. MacLennon trued up the recoil lug, locking lugs and bolt face for me to refresh 25 years of hard usage. He also replaced the original clip extractor with a Sako type - very nice job. The 722 was originally a .308 hunting rifle, serial 117XXX, that I found used in a small gun shop way out in the boonies in the mid 1980`s. Wonder if a Remington expert can tell me what year the original rifle was manufactured? First step is to inlet the new larger barrel into the Fajen stock and rebed the action in JB Weld.

Will fireform cases with 105 AMax, 107 MKing and 108 Berger over a max load of RX22. Sighting in the 6-18X Bushnell at my local 300 metre benchrest range Friday and then Sunday 500 and 900 yard F Class ORA/DCRA practise on a Canadian Army base. After getting a batch of fireformed cases, will work up target loads and chrono with same. Ain`t retirement great!!!!!!!

 

[1000yardstare]

Looks like I have to answer my own question here as to the date of manufacture of 722 serial # 117XXX. Apparently Remington`s rifle records do not go back that far!!?? So much for a company`s pride in their history. Guess storing paper costs too much these days. The 'Blue Book' says 1956-62 for the .308 so the action was at least 25 years old before I made up the 6/250 on it.

Took my new 6AI barrel out to the 300 metre range today. Barrelsmith MacLennon lived up to his rep. Fireforming with max loads of RX22 produced the following five shot groups. Didn`t bother with the chrono:

100 metres
85 Sierra bthp 7/16
105 AMax 1/2

200 metres
87 VMax 7/8
105 AMax 7/8

300 metres
85 Sierra bthp 13/16,thirteen sixteenths)!!!!!
105 AMax 3
107 Sierra MKing 1 9/16 !!
108 Berger 2 1/4

MacLennon says you don`t have to break in his barrels. After the first five shots, I brushed with Shooters Choice for carbon and then swabbed with Sweets. There was no blue or green. Beautiful!
Now on to developing loads for the fireformed cases keeping in mind the barrel life of the 6AI. Don`t want to shoot it out on the bench. Find a good load and then save it for F Class.

 

[1000yardstare]

I have had several e-mails from forum members thinking of building 6AIs to keep updating my progress with my new rifle so happy to oblige.

Got enough fireformed cases to start loading full house. Using Win brass and have not lost a case after 100 fireforms. By checking several sources and my experience with RX25 in a .243 F Class rifle I settled on 52.0 gr RX25 with the 107 class of bullet to start. These loads were safe in my rifle but chambers and seating depths vary greatly from rifle to rifle so I accept no responsibility for the use of these loads.

I had MacLennon throat the 6AI chamber for the 107 class of bullet hence the following COALs. The Fajen stock has no magazine cutout for added stiffness so if a single-loaded cartridge has to be extracted unfired, it will simply be pulled out with the bolt.

105 AMax 3.000
107 MKing 3.065
108 Berger 3.020

Five shot groups at 300 metres in a gusty headwind with no wind flags and no mirage averaged 2 3/8 off a bench for all three bullets. The loads chronod around 3270 at 16C,61F). The cases extracted easily but I would guess by looking at the primers that they are close to max pressure. I will back off to 51.0 gr for the next series of loads which should give me 3200 fps.

The F Class Canadian Championships,DCRA Prize Meet) will be shot on the International target this year with its 1/2 minute X-ring so loads must shoot at this level to be competitive.

 

[1000yardstare]

Was getting a lot of carbon with RX25,too slow I guess) so switched to RX22. Got the following results off a bench at 300 metres,330 yds) using a bipod and rear sand bag. No wind flags, visible mirage. Shot on the boil. My particular 6AI barrel has a long throat so I accept no responsibilty for use of these loads in another rifle. The F Class X-ring scales to 1 9/16 at 300 metres.

3 shot chrono average:

87 VMax 52 gr RX22 3458 fps 5 in 1 3/4 in.
105 AMax 50 gr RX22 3281 5 in 3 1/16,disappointing)
107 MKing 52 gr RX25 3264 5 in 1 7/16 !!!!!,RX22 next)
108 Berger 50 gr RX22 3263 5 in 1 13/16

Target shows 107 MKing 1 7/16 group. Tailwind coming in from the left. Wanted to see effect on target. Moved group 1/2 minute left, 1/4 minute down. Target printed out of a Draw package on my computer. Yellow seems to be the best colour to spot bullet holes at 300 metres. Inner lite-line is F Class X-ring. Inner dark-line is F Class 10 ring/DCRA V-ring. Outer lite-line is ISU 10 ring. Outer dark-line is DCRA 5 ring.

 

[1000yardstare]

Changed to 49.0 gr RX22 with the 107 MKing. Chronod at 3240 fps at 28C,82F). Turned the necks 50% to cut off the high spot. Got the following 1 11/16 group today at 300 metres, bipod, rear sandbag, light wind, no mirage, no wind flags. Slight quartering headwind. Shot by movement of vegetation on backstop just above the target board. On the two low 10s there was a puff of wind on my face just as I shot which may have driven the bullets down a bit. Scores 50-3x on the International F Class target. All shots will have to be in the X-ring in August at the DCRA Prize Meet. I am slowly getting there. The 1 7/16 group on the previous target was with unturned necks. Am making up my mind if turning is worth the hassle.