I'm considering a S20 in 6.5PRC. I'm trying to figure out if the magazine length is too short to realistically chase the lands with 140+grain bullets. To get optimal accuracy out of a couple Tikkas, I've had to go to extended aftermarket magazines to chase the lands. Anyone have any experience with this? Thanks!
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Sako s20 Question Re Magazine Length vs COAL
- Thread starter Catskills
- Start date
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I can't directly answer your question on this, but I bought one of the S20 from Eurooptic on closeout in 300 win mag. For the price I don't know how you could do better. The rifle is a shooter. The mag is set for longer bullets at 3.6" and I am loading them right at the 3.58" area. I am off the lands a little, but the gun shoots even quick handloads well under MOA and many of them at or near .5 moa.
I am seriously considering buying another one in 7mm or 6.5prc.
Here is 2 of the groups from load development that isn't finished yet.
I am seriously considering buying another one in 7mm or 6.5prc.
Here is 2 of the groups from load development that isn't finished yet.
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Mikecr
Well-Known Member
You should do seating testing to find the best off the lands (OTL), potentially within your magazine length limit.
If best OTL is not within mag limit, modify the action/magazine.
Never chase lands
If best OTL is not within mag limit, modify the action/magazine.
Never chase lands
Lionel Boyd Johnson
Well-Known Member
Mikecr: This may apply for a new rifle, but do you then recommend ignoring the erosion of the lands? Do a fresh OTL as the lands erode? Modify the action/magazine again? What's your approach? Thanks, Ed
Mikecr
Well-Known Member
I recommend NOT relying on a load starting pressure that an in-the-land (ITL) relationship produces, and instead, finding best initial CBTO that is OTL. With this, you can ignore land erosion for the accurate life of the barrel.
That is, through full seating testing (like Berger recommended), find & set best OTL CBTO. Never touch it again for THAT bullet and barrel.
When you seat bullets ITL you're introducing that condition into tune. You'll be a slave to it, and perpetually chase fleeting results.
That works for under-bore competitors preparing for each weekend, but not so much for most hunters, with hunting capacity cartridges.
My approach with actions is to buy as, or modify to, single shot.
I don't need any magazine compromise.
I can pull a single round out of my pocket and kill what I'm prepared for then.
I don't need to eject my brass off into the weeds somewhere either, so I always delete ejection and pick rounds.
That's not so easy with a magazine in the way.
That is, through full seating testing (like Berger recommended), find & set best OTL CBTO. Never touch it again for THAT bullet and barrel.
When you seat bullets ITL you're introducing that condition into tune. You'll be a slave to it, and perpetually chase fleeting results.
That works for under-bore competitors preparing for each weekend, but not so much for most hunters, with hunting capacity cartridges.
My approach with actions is to buy as, or modify to, single shot.
I don't need any magazine compromise.
I can pull a single round out of my pocket and kill what I'm prepared for then.
I don't need to eject my brass off into the weeds somewhere either, so I always delete ejection and pick rounds.
That's not so easy with a magazine in the way.
With the quality barrels Sako (Tikka) uses, I have no doubt a magazine length load can be found that will shoot MOA. The thing is, I'm looking for something significantly better. I've found it far easier to find the accuracy I'm looking for if I can start testing at 0.010 off the lands. Hence the question. My fear is with common 140g bullets, the COAL to sit 0.010 off the lands will be impossible to meet with the factory magazine. This is particularly true if aftermarket magazines are unavailable. while I very rarely need more than 1 shot when hunting, I have no interest in the single shot option.
FYI, the last Tikka I worked up loads for required an after market magazine to shoot to its potential (it required a 2.923 COAL). Factory magazines were limited to <2.80. Groups went from MOA to one hole groups (this was with 140 BT in a 7mm-08).
FYI, the last Tikka I worked up loads for required an after market magazine to shoot to its potential (it required a 2.923 COAL). Factory magazines were limited to <2.80. Groups went from MOA to one hole groups (this was with 140 BT in a 7mm-08).
My Tikka T3X in 300 WM has a mag length of 3.370". I spoke with Steve Davis @ Hammer recommended the 174 Hammer Hunter which is designed for short length mags. It was a simple task to find a load that shoots .5 moa or better (76.5 - H4831). Hammers are as advertised "very forgiving" regarding seating depth.
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This is the first time I have ever posted on anything like this however I have the Sako S20 in 6.5 PRC. It shoots well with Norma 140 grain Golden Target Match ammunition for 100 rounds, sub MOA for sure at 100 yds. The velocity of this ammunition was low 2800 fps measured with my Magnetospeed V3. The box said it should be 2986 fps at the muzzle.
I just started loading for this rifle, been loading for better than 50 years. My rifle is throated long and when I found the lans with the Hornady 140 gun BTHP match bullet it was so long that the bullet would not stay in the case neck.
With H1000 and H4831 with GM210M primers I was over 250 fps below what Hornady's load sheet said from the middle starting point and was that way up to max charge. I suspect the long throat is the culprit.
I have a promising load at about 2950 fps with the H1000 at .045" off the lans. Need to verify and shoot out to 600 yards which is my goal to start.
