Micro-Groove vs Ballard-type cut rifling

danthegunman · Post by **danthegunman** » Tue Jan 15, 2008 1:17 am

What is the difference in Marlins Micro-Grooved BBL's and Ballard-type cut rifling?

A customer called today and asked me if it was OK to shoot lead bullets from his Marlin with a Micro-Grooved BBL. I told him that I had never heard of it but that I would find out for him. What better place to ask.

Post by **Old Savage** » Tue Jan 15, 2008 1:27 am

Microgroove has more land and grooves and they are shallower. They both work fine. Cast bullets should be a couple thousands oversize as usual.

MacEntyre · Post by **MacEntyre** » Tue Jan 15, 2008 7:14 am

A local fellow told me not to shoot lead bullets in a micro groove barrel... I was just about to post the question myself!

I'm glad to know it makes no difference; it makes more sense that way. I'd hate to have different loads for different 30 WCF rifles. Of course, I will clean each rifle well every time I shoot.

danthegunman · Post by **danthegunman** » Tue Jan 15, 2008 8:16 am

I found this on Marlin's web-site as a FAQ.

13. Why has Marlin changed its rifling on Models 1894S, 1894CS and 1895SS from Micro-GrooveÂ® to Ballard-type cut rifling?

To accommodate the use of cast lead bullets. (Jacketed bullets will still function reliably.)

Like I said in my original post I have never heard that someone can't shoot cast lead bullets from any BBL.

What's up with the Micro-Groove BBL?
Did Marlin tell it's customers that your not supposed to shoot cast lead bullets from it's Micro-Groove BBL?

Old Savage said:

"Microgroove has more land and grooves and they are shallower".

Does this mean that a Micro-Groove BBL has tighter lands & grooves?

Charles · Post by **Charles** » Tue Jan 15, 2008 8:30 am

Dan... It has been circulated around the shooting community for years that MG barrels don't do well with cast bullets and it a commonly held belief. You will even find some loading books that say, cast bullets don't do well in MG barrels past about 1.6K fps.

This widly held belief was one of thep principal reasons Marlin switched to the Ballard style rifling in their rifles that might be shot with lead bullets.

Now the truth:

MG barrels "tend" to run larger in the grooves and lands that nominal specs. Most cast bullets designs are designed for barrels of nominal specs and sometime are to small on the nose for optimum performance in MG barrels.

That said, cast bullets that give a proper fit to the MG barrel will do very, very well and accuracy is not degraded.

I have proved all of this several times with Marlin rifles that have both MG and Ballard rifling. I have one 336 (1960 vintage) in 30-30 that runs a full .306 accross the nose and .309 in the grooves. It took a custom mold for me to get good accuracy with cast bullets. But with that custom mold that produces a bullet .307 on the nose, the rifle is a tack driver with cast bullets. I have two other Marlin 30-30s with MG barrels and those run .302 X .309.

danthegunman · Post by **danthegunman** » Tue Jan 15, 2008 8:37 am

Thank Old Savage & Charles.

At least now I can give my client a firm answer to his question.

otteray · Post by **otteray** » Tue Jan 15, 2008 8:58 am

I also have no problem when the correct bullet is used. I water- quench them from the mould, as well, for additional hardness.
Maybe the Marlin microgroove answer from Charles and Old Savage should be in the Stickies.

danthegunman · Post by **danthegunman** » Tue Jan 15, 2008 9:05 am

otteray wrote:I also have no problem when the correct bullet is used. I water- quench them from the mould, as well, for additional hardness.

Maybe the Marlin microgroove answer from Charles and Old Savage should be in the Stickies.

Thats a good idea! How about it moderators?

MacEntyre · Post by **MacEntyre** » Tue Jan 15, 2008 9:48 am

What store-boughten bullets work well with MG?

preventec47 · Post by **preventec47** » Tue Jan 15, 2008 10:10 am

[quote="danthegunman"][quote="otteray"]

Maybe the Marlin microgroove answer from Charles and Old Savage should be in the Stickies.[/quote]
[/quote]

Good God NO. WE HAVE TOO MANY STICKIES as it is !

Git rid of two thirds of em.

Dakota7 · Post by **Dakota7** » Tue Jan 15, 2008 10:37 am

I have used both micro groove and ballard cut. Like any rifle, you just have to find the right bullet, the right size and the right lube. When it all comes together the micro groove will shoot cast as good as any.

J Miller · Post by **J Miller** » Tue Jan 15, 2008 10:49 am

Think about it this way: If lead bullets can't be used in Micro Grove barrels, why are all of Marlins .22 rim fires made with Micro Grove barrels?

Another thought about Marlins comment. They do not acknowledge the use of reloads or hand loads. This is the type of ammo most commonly used with cast bullets. HOWEVER, most cowboy ammo is factory loaded with cast bullets. So through a twisted tongue they are covering their own butts.

Joe

Charles · Post by **Charles** » Tue Jan 15, 2008 10:54 am

A couple of more throught on the Marlin MG in 30-30

1) I don't buy cast bullets and don't have any notion of which ones, if any, would do well in the MG barrels

2) Redding-SAECO makes a mold (No. 306 I think) for the .303 British. It is nothing more than a fatten version of their 30-30 mold. While a lousy bullets for the Brit round, it does very well in the Marlin MG 30-30 because it runs .302 or .303 on the nose. Size it .310 or .311 and all will be well.

3) I have not found a need for any alloy harder than air cooled wheel weight for good accuracy.

However ACWW will roll snake eyes in any rifle when the velocity gets to be about 1.9 - 2 k fps. I have driven the above SAECO bullet at 2.3K fps in my Marlin 336s, with top notch accuracy, but had to go to No. 2 alloy to get er done.

4) In the real world and ACWW bullet trucking along at 1.8 K fps makes a very good deer load.

otteray · Post by **otteray** » Tue Jan 15, 2008 8:34 pm

Charles, you are probably right about WW or with 2% tin added is fine.
I just go a bit farther, maybe unnecessarily. I like gas checks, too.
Mt dad wrote an article about the .41 Mag micro groove Marlin in Handloader 176 ((Aug, Sept '95.)
"My experience with micro-groove barrels has been favorable when the bullet body is long and the driving bands are wide. Even with a very soft alloy, accuracy is good."
He also used factory jacketed hollow points of the appropriate size.

marlinman93 · Post by **marlinman93** » Tue Jan 15, 2008 9:11 pm

MacEntyre wrote:What store-boughten bullets work well with MG?

If you mean store bought cast lead, then I'd recommend the hard cast, or laser cast. I've had great results with Heinrich Hard Cast bullets. They will work great, but remember hard cast lead are not jacketed, so don't try to push them to jacketed velocities!
Pushing cast bullets too fast is what started all the talk about Micro-Groove barrels not shooting well with cast lead. Had folks loaded them to the correct velocites they would have never had a problem.

ohio hunter · Post by **ohio hunter** » Tue Jan 15, 2008 9:11 pm

I have found the non bore rider or full size bullet works best in my MG 30-30. Marlin does not use a throat per se but a "funnel" from the outer case neck size down to groove size. I think this is hard on boolits and the standard bullit shape withstands this better. I also water drop my WW boolits and can use full power(30-30) loadings with these. Most of my hunting is done within 100 yards so I run my hunting loads around 2000fps. With a wide meplat this causes very large wound channels through deer. Jay

Post by **Chuck 100 yd** » Tue Jan 15, 2008 9:15 pm

You mean you can shoot cast bullets in a MG Marlin?

You guys said it ! +1

bobbyjack · Post by **bobbyjack** » Tue Jan 29, 2008 5:47 am

J Miller wrote:Think about it this way: If lead bullets can't be used in Micro Grove barrels, why are all of Marlins .22 rim fires made with Micro Grove barrels?

Another thought about Marlins comment. They do not acknowledge the use of reloads or hand loads. This is the type of ammo most commonly used with cast bullets. HOWEVER, most cowboy ammo is factory loaded with cast bullets. So through a twisted tongue they are covering their own butts.

Joe

early mod 39,39A's aren't MG,My 1948 isn't.

Bob