Accuracy III

420 Views
Last Post 23 August 2018
Topic Is Solved

CBA Member

Ross Smith posted this 19 August 2018

I just finished slugging my remington 700 in 30-06. It has a .300 bore and .308 groove. +- a couple .0001. I did this at the muzzle and breach to see if there was any difference. There wasn't. I have been thinking about those narrow lands and cast bullets. I f we were to design a cast bullet 30-06 barrel how about equal width lands and grooves with the grooves being .005 instead of .004?????????????????????? What about twist?

barrels

Attached Files

16 Comments

Order By: Standard | Newest | Votes

CBA Member

Scearcy posted this 19 August 2018

Like all of us I suspect, I have a handful of 3006s that don't get much use. We are playing with them in the groundhog shoot of course but there has to be more. Now that we have some well designed 165-170 gr bullet molds available. I think it might be very interesting to revisit the old girl.

Personally I wish I had a 12" twist barrel on a 12# rifle to give these bullets a go.

Go for it, Ross.

Jim

Attached Files

Liked by

CBA Member

R. Dupraz posted this 19 August 2018

Both the RCBS 30-165-SIL and 30-180-SP with a dose of IMR 4227 in a 12-13" twist have worked well for me.

Attached Files

Liked by

CBA Member

Ross Smith posted this 19 August 2018

Would SLIGHTLY deeper grooves and wider riflings help prevent stripping? Or is stripping not happening?

Attached Files

CBA Member

Larry Gibson posted this 19 August 2018

I've a 3 groove Broughton barrel on my 30x60 XCB (basically a short chambered '06) and it is excellent. I use cast bullets under 1" in length in it because it's a 16" twist. A Broughton barrel 26 - 31" long with a Palma contour having a 14" twist chambered in '06 would be excellent with cast bullets as long as a 311299. Velocities with excellent accuracy in the 2400 - 2700 fps range will surprise you.

Concealment is not cover.........

Attached Files

CBA Member

Ed Harris posted this 19 August 2018

Deeper grooves and wider lands will simply deform the bullet more. If the bullet fits and the alloy is appropriate for the load stripping isn't a factor.

Most accurate .30-'06 with cast I have is a 14" twist Douglas fitted onto a Sako A2 single-shot action. With full-charge loads around 2200 fps with #311299 it is scary.

Also had a 16" twist Obermeyer 4-groove, government form, tight-bore .298x.308 Palma barrel on a Remington 788 action in .308 which was scary accurate with 160-grain bullets at about 2400 fps, again full charge loads. Shot the barrel out. After initial trials shooting a few hundred NATO Ball and Sierra 150 MKs I never put another jacketed bullet through it, but high velocity cast in full charge loads took the gilt edge off after about 5000 rounds.

Cut up the barrel to make my first Bunny Gun in .32 S&W Long, which I still have.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

Attached Files

CBA Member

Ross Smith posted this 19 August 2018

I've had my best luck in factory rem. barrel with bullets in the 190-205 gr area and I would like to continue there. I'm heavily invested in molds for that size bullet.

Attached Files

CBA Member

Ross Smith posted this 19 August 2018

So is good old 6 groove the way to go?

Attached Files

CBA Member

Ed Harris posted this 19 August 2018

The conventional 6-groove works well and is well proven. The older rifling forms with fewer lands and grooves were primarily manufacturing expedients from back in the day grooves were cut one at a time on a Pratt & Whitney 1/2B machine and indexed after each stroke of the hook cutter. Once they started button rifling and hammer forging you could do them all at once.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

Attached Files

CBA Member

Ross Smith posted this 22 August 2018

Good,bad or indifferent, I just ordered a Douglas xx, 30-06, 14 twist barrel and a timney trigger for my Rem 700. The original had some very mild pitting from storage so it's getting retired. We'll see.

Attached Files

CBA Member

pat i posted this 22 August 2018

Veral Smith said in his book and in conversation that he thought microgroove rifling would be the ticket for cast bullets if you could get it in a good barrel. He might be a little out of fashion now with CNC and 3 week turn around times but I do believe the man knows his stuff.

Attached Files

Liked by

CBA Board

John Alexander posted this 22 August 2018

Sakos in the sixties and I think before had if memory is right had 12 groves and generally shot better than the competition both jacket and cast.

John

Attached Files

Liked by

CBA Member

Bud Hyett posted this 22 August 2018

Frank Marshall referred to Marlin Micro-Groove as Micro-Pop\e rifling. He referred to Pope winning a bet by rifling a smoothly honed barrel with scratches from steel wool. The scratches did not last long, but the concept of light rifling was proved.Pope did this after a challenge to his shallow rifling and how it won matches.

In the early sixties, a magazine description of the SAKO L-461 Varminter mentioned Marlin was furnishing barrels with their 12-groove rifling. I have a SAKO Varminter in .222 Remington Magnum that has 12-groove rifling and shoots consistent ten-shot groups under one inch.

Farm boy from Illinois, living in the magical Pacific Northwest

Attached Files

CBA Member

joeb33050 posted this 22 August 2018

Bob Bross had several Hammerli Martini 30-06 US Team rifles; one had almost no rifling-no depth at all, almost invisible. He said that it shot as well as the ones with "normal" rifling.

Attached Files

Liked by

CBA Member

Ross Smith posted this 22 August 2018

Pat: and others: I also have the noe 30 xcb. Couldn't get good results in my rem. I will revisit that when I get my rem. back with its new slow twist barrel. I see you also play with pb and slug guns and muzzleloaders. that's where I got my lessons on bullet length and twist as opposed to weight. Took me awhile to figger out my ml schuetzen rifle.

So, is marlin still in the micro groove business? Does anybody still make or use those 12 groove barrels?