30/06 Chambering how tight

[buzzard]

I have been trying to make a highly accuract 30/06spg. the next step I want to take is to have a reamer made to tight specifications to give the bullet a straight start. Has any one seen a 30/06 group under 1/2 MOA. I need help is it possable to make a 30/06spg. more accurate than a win308?

 

[frankgreen]

You could go two different routes with the reamer. A tight no turn neck or just run standard case dimensions. I don't see one over the other shooting any better.

More critical is the throat design. Our reamer has a .3085 throat dia. and for the throat length I set ours up so it will chamber virtually all factory ammo including old Lake City Match ammo. You can pick the throat length you want. I also set ours up with a 1 degree 30 min. lead.

I just rebuilt my 1903 Springfield and made it into a USMC Model 1941 Sniper rifle. New C.M. barrel, in a 4 groove, glass bedded an original type C stock, modified the handguard for the Unertl scope blocks etc....but the rest is all G.I. including the trigger.

With my first handloads with 155 Lapua's it is shooting .370 average at a 100yds. Shot it for the first time a week ago. Will be headed to the range again this week or weekend and will play with it some more. Remember this doesn't have a full floated barrel. Still using the stock handguard etc....

The .30-06 standard chambers throat leaves a lot to be desired. The throat is more critical than the case dimensions.

It will shoot as good as any .308 will. The .308 is more efficient of a round than the .30-06 but also the .30-06 will handle heavier bullets better due to the case capacity.

Later, Frank
Bartlein Barrels

 

[buzzard]

What I had in mind was srinking the base of the case to .467" to give give it less room to deforme off center when fire forming and the neck to .336" at start out to end at .335" Now I know from You that the throat can be .3085" any more info on what You think reaner dimension's should be would be greatly appreciated and do you jump your bullets

 

[butchlambert]

Buzzard, If your reamer is that small at the base you will probably have to have a custom small base die made. I believe that the factory case has .471 base. I don't see any advantage and only problems shrinking the chamber as you state. All barrels and bullets operate differently. Some you jam and some you jump. You just need to shoot it and see what it likes. In a 30-06 I don't think you can do much better than a minimum SAAMI chamber with the throat to match your seated bullet.
Butch

 

[butchlambert]

Mr. Buzzard,
I was measuring a 9.3x62 when I made that comment. I just pulled and old 30G06 Silvertip round out of one of my old boxes and it does measure .467 just in front of the extractor groove.
Butch

 

[frankgreen]

Buzz, I normally start my loads .010 off the lands. Like Butch said earlier. You have to load and check the gun out to see what it likes. I've seen guns that being off the lands is better than jamming the bullets.

One customer and shooting buddies .308 palma rifle after we talked about basically the same thing did some testing off the bench at a 1000yds. He cut his groups in half and his bullets where .020 off the lands. How does 3.5" groups at a 1000 sound. He was jamming the bullets and was only getting around 7" groups.

I would have a reamer made to your sample round of where you want the bullets seated. You can play with the seating depth from there when you do your loading.

Like I said on my normal match rifles I start .010 off the lands. I load for reliablity and accuracy. The only time I consider jamming the bullets would be on a hard core bench type rifle.

Back to you question of a tight chamber? If memory serves me right my loaded rounds measure .335 on the case neck. My reamer is a standard case dimensions and cut the neck at .340. You could bump up the neck dia. to say a .337-.338 size. This would give you a no turn neck with about .003 clearance. Play with brass. Resize different manuf. brass and see what they measure after sizing etc....as Butch said if you tighten up the base of the case you are probably looking at a custom set of dies. As far as the base of the case you could tighten it up also. Are there magic numbers? I don't think so. I don't think tighten up the case dimensions is going to make it shoot a ton better.

My '06 is shooting mid to low .3's with the first load I tried but remember it is a 03 Springfield. The firing pin itself is a 1/3 heavier than a Rem. 700 long action so the lock time is slower.

Good luck! Frank