308 F-TR chamber

[venatic]

I am getting a .308 built to shoot F-TR with either 185-200gr Berger's. I have searched around for neck and free bore recommendations which I have seen on here but cannot seem to find again.
I have 800 pieces of Lapua brass (not Palma) so was thinking .341-.342 neck as I don' want to turn brass does that sound correct?

 

[Kakumba]

0.341 is plenty for unturned Lapua brass, IMO. My chamber is 0.341, and havent had any issues. My loaded rounds are ~0.338, so plenty of clearance, just dont let any crap into your chamber, and keep your brass clean and burr free. Of course, you should be doing that anyway, so ought to be no problems

 

[venatic]

Thanks

 

[swadiver]

My Criterion/Savage pre fit .308 barrel has a .090" free bore, i believe. i have been loading Berger 185 Juggernauts .015" off the lands and 43.7 to 44.0 grs of Varget in ADI (Australian Defense Industries) brass with no issues. ADI brass has about the same capacity as Lapua I believe. shoots quarter to half moa.

my understanding is that the 185 Juggs ideally should have a bit more free bore than .090"

 

[Ned Ludd]

Dave Kiff at PTG sells a reamer optimized for the 185 Juggernauts that has .168" freebore. I had the following reamer cut for 185 Hybrids, which are just a bit longer in the bearing surface. However, I have talked with friends shooting the 200 Hybrids using similar freebore (.180"), so it should work for those as well. Pertinent specs are: .342 nk (no turn), 1deg30, .180 fb.

 

[venatic]

That's exactly what I needed
Thanks guys

 

[280man]

In my opinion the 2013 US F T/R is reamer is about perfect for either the 185 LRBT or the 200 Hybrid.

 

[Jefferson]

In my opinion the 2013 US F T/R is reamer is about perfect for either the 185 LRBT or the 200 Hybrid.

Do you have a copy of the print and what is the free bore

Jeff

 

[Scott Harris]

Dave Kiff at PTG sells a reamer optimized for the 185 Juggernauts that has .168" freebore. I had the following reamer cut for 185 Hybrids, which are just a bit longer in the bearing surface. However, I have talked with friends shooting the 200 Hybrids using similar freebore (.180"), so it should work for those as well. Pertinent specs are: .342 nk (no turn), 1deg30, .180 fb.

This is exactly what I would recommend for no-turn Lapua brass with 185 LRBT. Don't get hung up on the endless number of "special" 308 WIN reamers...2013 FTR, '95 Palma, etc. there are only 2 dimensions to worry about: freebore and neck size. .170" FB is perfect for the 185 LRBT and a .343 neck is perfect for Lapua brass which runs around .015" thick. You want .004-.006 clearance between chamber neck and loaded round neck. Beyond those two dimensions, just ask for SAAMI-minimum specs everywhere else.

PS. SAAMI minimum chamber neck is .344

 

[swadiver]

My Criterion/Savage pre fit .308 barrel has a .090" free bore, i believe. i have been loading Berger 185 Juggernauts .015" off the lands and 43.7 to 44.0 grs of Varget in ADI (Australian Defense Industries) brass with no issues. ADI brass has about the same capacity as Lapua I believe. shoots quarter to half moa.

my understanding is that the 185 Juggs ideally should have a bit more free bore than .090"

I should add that my Criterion Barrel's .090 free bore was when new. with 2200 rds through it, it is grown a bit. i did not start shooting the 185's until late in the barrel's life. maybe that is why they are shooting so well with the "short" free bore

 

[Ned Ludd]

I should add that my Criterion Barrel's .090 free bore was when new. with 2200 rds through it, it is grown a bit. i did not start shooting the 185's until late in the barrel's life. maybe that is why they are shooting so well with the "short" free bore

Before having a couple barrels chambered with the .180" fb reamer posted above, I have shot the 185 Jugs for several years in a different rifle that has an identical chamber except that it has only .085" fb. When seated at ~.015 off the lands, the boattail/bearing surface junction is still above the neck/shoulder junction...just barely, but still above. The primary issues you run into running the 185s with such a short freebore are increased pressure and slightly decreased velocity. In that rifle with standard Lapua brass, I'm getting ~2720 fps out of a 30" barrel with Varget, ~2750 fps with H4895. In the nearly identical rifle with .180" fb using Lapua Palma brass, I'm getting 2780 fps with H4895 (haven't tred Varget with that one yet). All of the loads are running predicted pressures (QL) in the 60-61K psi range. Precision with both rifles is excellent.

So you can definitely run the 185s with less than .168" fb. However, you'll hit max pressure faster and get slightly less velocity loaded to equivalent pressure with the shorter throat. As a result, brass life, particularly with standard brass, will be slightly less than with the more generous freebore. I've gotten 6 reloads so far out of the current lot of standard brass with the shorter throat rifle and I expect at least one or two more, so it's really not too bad.

 

[swadiver]

Before having a couple barrels chambered with the .180" fb reamer posted above, I have shot the 185 Jugs for several years in a different rifle that has an identical chamber except that it has only .085" fb. When seated at ~.015 off the lands, the boattail/bearing surface junction is still above the neck/shoulder junction...just barely, but still above. The primary issues you run into running the 185s with such a short freebore are increased pressure and slightly decreased velocity. In that rifle with standard Lapua brass, I'm getting ~2720 fps out of a 30" barrel with Varget, ~2750 fps with H4895. In the nearly identical rifle with .180" fb using Lapua Palma brass, I'm getting 2780 fps with H4895 (haven't tred Varget with that one yet). All of the loads are running predicted pressures (QL) in the 60-61K psi range. Precision with both rifles is excellent.

So you can definitely run the 185s with less than .168" fb. However, you'll hit max pressure faster and get slightly less velocity loaded to equivalent pressure with the shorter throat. As a result, brass life, particularly with standard brass, will be slightly less than with the more generous freebore. I've gotten 6 reloads so far out of the current lot of standard brass with the shorter throat rifle and I expect at least one or two more, so it's really not too bad.

thanks for the info. as of now my F/TR competitions are at 600 yds max, so the 2685 or so fps i am getting with Varget seems to be fine. shooting to a 1000 yds may be a different story. do you mind sharing your H4895 load? i know i would have to reduce down from it due to my shorter seating depth. might give me a good starting point.

 

[Ned Ludd]

H4895 will generally give you about 20-30 fps greater velocity at the OBT node (sweet spot) than does Varget. With the shorter freebore, you just have to be a little more careful with H4895 as the pressure can get up there pretty quickly, especially if your lot of H4895 has a faster burn rate than my current lot. In my setup, 41.9 to 42.1 gr H4895 is the optimal charge weight window at ambient temps in the 70s and a COAL of ~2.896", which puts the 185 Juggernauts about .015" off the lands. I have been using 42.0 gr in the middle of the window. MVs are running from the low 2740's to 2750 fps with that load. If I knew I would be shooting in 85+ degree temps, I'd probably back that off to 41.9 or 41.8 gr to keep the velocity in the same range. You might want to start at least half a grain to a grain lower and work up to find out where you need to be.

 

[swadiver]

H4895 will generally give you about 20-30 fps greater velocity at the OBT node (sweet spot) than does Varget. With the shorter freebore, you just have to be a little more careful with H4895 as the pressure can get up there pretty quickly, especially if your lot of H4895 has a faster burn rate than my current lot. In my setup, 41.9 to 42.1 gr H4895 is the optimal charge weight window at ambient temps in the 70s and a COAL of ~2.896", which puts the 185 Juggernauts about .015" off the lands. I have been using 42.0 gr in the middle of the window. MVs are running from the low 2740's to 2750 fps with that load. If I knew I would be shooting in 85+ degree temps, I'd probably back that off to 41.9 or 41.8 gr to keep the velocity in the same range. You might want to start at least half a grain to a grain lower and work up to find out where you need to be.

thanks much. shooting down here in Florida with the temps in the low to mid 90's, so i will start at least a full grain lower.

 

[280man]

I will post a print picture when I get a second