Home Forums Hunting & Shooting Competitive Shooting 308 chamber variations

308 Win Palma
308 Win M118 LR
308 Win F-TR

What is the difference between them? I suppose the M118LR is throated for the match round with than designation. The Palma I would guess is throated for bullets best for a 1000 yard match. I have no idea what F-TR stands for other than a match of some kind.

F-TR is Midrange/Long Range Prone matches shot with either the .223 Remington or .308 Winchester cartridges using rifles equipped with a bipod and a sandbag in the rear. Originally we used a chamber with .068" freebore, that was pushed out to .170" freebore to accommodate using 185gr/200gr Berger bullets and a cartridges OAL of 3.09"

Which of the three work best with 150 to 180 grain bullets? The M118LR?

Here is the gospel truth!

Do you have a magazine length constraint to consider?

A Remington 700 SA. I have a crapload of the standard ball ammo, hoping to get the best possible out of it. I have one rifle chambered in 7.62 and it makes me happy if that ammo crowds 2 inches in it. It would just be training ammo but want the rifle to handle sleek bullets in the 150 to 180 grain range. A guy bet me his M1A can outshoot any bolt gun. I want to beat that guy also.

I wouldn't want much free bore in that case. I'd probably go with the M118 reamer or a Palma with similar freebore for those bullet weights. I know there are several versions of Palma reamers out there. Let me dig up a pdf if I can find it.

Here are some numbers for comparison purposes:

Chamber data:
Cartridge Name Neck Dia Neck Dia Freebore Lead Lead Max Case Pilot Size NOTES
Junction Mouth Dia Freebore Length Angle Length
308 Obermeyer 0.3460 0.3440 0.3085 0.085 2d 30' 2.025 0.300 JGS #3519
308 Obermeyer Special 0.3330 0.3330 0 3085 0.085 2d 30' 2.018 0.300 PT&G #577

308 Fullbore 2012 0.3435 0.3435 0.3085 0.080 1d 30' 2.025 0.300 PT&G #37960
308 Fullbore 2011 0.3445 0.3445 0.3085 0.050 1d 45' 2.025 0.300 PT&G #15917
308 Palma US Team 95 0.3420 0.3420 0.3083 0.050 1d 45' 2.020 0.2984 JGS #3775 .2985 Bore / .3065 Groove
308 Palma Match 0.3420 0.3420 0.3084 0.086 1d 30' 2.020 0.299 PT&G#7374
308 Palma Bisley 0.3430 0.3400 0.3084 0.080 1d 30' 2.025 0.298 PT&G #8288 Similar to 2012 except for tight mouth

308 Win Match 0.3435 0.3435 0.3085 0.077 1d 30' 2.025 0.300
7.62mm NATO 0.3461 0.3445 0.3166 1d 25'55" 0.300 JGS #3565
308 Win (Tubb) 0.3410 0.3410 0.3085 0.090 1d 45' 2.025 0.300 JGS #3674
308 Win 0.3462 0.3442 0.3100 0.090 1d 45' 2.025 0.300 JGS #3566

I am suspicious that at Rem SA mag lengths many of the newer high performance VLS, Hybrids etc. could end up with the ogive starting inside the case neck and /or be seated so deeply as to use up valuable case capacity. I'd have a talk with your gunsmith on your best option.

You can't push the 185gr fast enough to get the better wind drift values in the shorter freebored chambers. Even if you re-throat the chamber extracting a loaded round out of a short action is a b!tch.

Just jam them and only eject the case. ;-)

Back in the heyday of M1A/M14 Service Rifle, the “.308 Obermeyer” was a popular chamber configuration that also shot extremely well in bolt action rifles. This chambering was optimized around the M852 (168 grain) Lake City load, at a 2.800 OAL for magazine feeding. If I was chambering for a rifle with limited magazine length, I’d look at this configuration.

The “Palma” reamers are set up for 155 grain bullets, and will require you to “deep seat” longer bullets, impacting your powder space.

🤣

Saw that happen at a benchrest match a couple of weekends ago. Fellow was shooting a 30BR at jam, one load had a little too much jam. He couldn't close the bolt so he forced the bolt open leaving the bullet jammed tightly in the barrel. Problem was he dumped a case full of powder into one of those ball bearing triggers. Guess you're not supposed to flush them out with lighter fluid...

IIRC the Palma chamber has a .050" freebore. Not the optimum length for 175gr bullets.

I did leave out the powder part...

I've only played with the Palma 95 and Obermyer chambers. The Omermeyer is great with the 175 Sierras, but the newer sleek 155s don't seat deep in the case at all when near the lands. The new generation 155s do great with the Palma 95 chamber that was designed for the old sierra 155 "copper snails", but still have a longer C.O.A.L. than the mag length the OP requires.

The newer Palma reamer designs have throats closer to the Obermyer and M118 in length.

If I can get a 155 to 3000fps I am happy to 1000.

I think the M118 will work, going with a 12 twist and 26" overall. Thinking light Palma. Boy wish it would cool off some, like to do some shooting without sweating all over my rifle.

Be careful betting against some of the M1A shooters. Got a friend that shoots at Camp Perry most years and he shoots a M1A. Rifle looks terrible, but it's a shooter. His wife has won a competition or two up there with that rifle.


Hope you win the bet.

Well this guy can't be that hard to beat, he doesn't even reload.

Are you sure about that one?

Standard ball ammo, depending on the batch, may not shoot all that great even out of a good rifle. Are you going to compete against him with ball? If so then at least sort it for runout.

You may also want to put a mic on the bullets of that ball ammo. If you look at a lot of prints for "match" reamers the freebore section just ahead of the case mouth is 0.3085" which is generally a good thing. The problem is I've measured some military fmj projectiles at 0.309" on the shank.

No, but you can always check with JGS. I'm sure they would email you the reamer print.

The ball ammo is just there for trigger time, might give him some to shoot! Hah he might go for it. I may pull some of it down and work up another load using the primed cases and powder but a different and better bullet. He wouldn't go for me using my 260 though says it has to be a "military" caliber. This barrel is going to be used just for shooting in general, cast bullets, match bullets, hunting bullets, NATO ball. Knocking down my vast backlog of bullets before I get too old to do it.

I think AJ300Mag's advice along with MikeS' chamber dims are pointing you in a great direction. I'll throw in my two cents as well. In practice, I was looking for good feedback. Ball Ammo never could give me that. If your shooting matters (doesn't matter if it's just practice)...ditch the ball ammo instead of scratching your head wondering "was the me, the rifle, or the ammo?". At the least, do as you've floated; make some Mexican Match out of the ball ie, pull the heads and cap it with something that you know will group good. I've shot good ball ammo, and I've rung steel at 1000 yards with a "good" lot of Pakistani ball out of a 40x. It still doesn't compare to your basic Match Kings.

Story; in the day where the Palma Match host provided ammo to all teams, the host Brits provided what was supposed to be a great shooting lot of RG (Radway Green ball). The team shooters said it was barely passable, and subsequent to that, the US hosted and provided ammo loaded by Bob Jensen on a roomful of Dillon Progressives topped the then new 155gr Sierra. Even though it was progressively with thrown charges, it was head and shoulders better than the RG and was known as the best Palma ammo issued at that point in time. You have the opportunity to do even better by tailoring your load to a single rifle.

Last hint. Set up your wager so that you have to shoot multiple groups and average them. That will tip the scale in your favor. Many an M1A will shoot a good group or two...but they struggle to shoot multiple good groups sequentially. Too many moving parts on that rifle. ..but of course make sure your rifle is up to that task as well.

308 Obermyer

Works for me

He may be in trouble if the other shooter is an XTC shooter and wants to shoot from position.

How come no one's cheering for the M1A?

Go Brandon, er, I mean Garand!

I'd still take that bet. It takes a pretty special M1A to hold 10 shot MOA, and an ever more special XC shooter to hold MOA consistently. I can't even remember when I've been beat by an M1A. Even Nez will tell you he's struggling to match his AR scores with his super M1A.

What you can do and what the OP can do are two different things. I also meant that they would both shoot from position.

lol...I believe you overestimate my abilities. The point was that for out and out accuracy, the M14 has it's challenges (and I'm saying this as one with a soft spot for the old steel and walnut bronco). We can tip the scales every which ways with conditions...hell, I think the OP is Carl B in disguise just messing with everyone. In which case that would probably trump your XC M14 Prone shooter.

The reality is that the OP has left the building. I was waiting for him to ask which smith would warm over his M700, but that question never came, and thoughts of this "what if" are probably long gone from his consciousness.

He spends most of his time up in the Campfire forum, if that tells you anything...