Author Topic: Marlin microgroove rifling question... (Read 3027 times)

IronKnees · « **on:** January 04, 2003, 09:45:40 AM »

Can anyone explain to me what Marlins' microgroove rifling is, how it differs from "normal" rifling, and why they are using it... I have two Marlin lever action rifles. My 1895 in .45-70 and my .30-30... I know for sure that the .30-30 is micro grove, but it was my understanding when I purchased the .45-70 that it was not micro grove... However, I am really not sure, and really don't know how to tell by looking, or how to find out. Now, one thing of interest. I have yet to find any bullet and powder combination that my .45-70 will not shoot well with. However, I can not hit an 8 1/2 x 11 target from 25 yards off hand with the .30-30... I have NEVER found any load that shoots worth two hoots in this gun yet... and am very disappointed with it.

Cheyenne Ranger · « **Reply #1 on:** January 04, 2003, 10:28:36 AM »

My Marlin 1894CS in .357 is also microgrooved. Those who know say that lead bullets don't do well but mine seems to be OK. I know that the ones they are making for Cowboy shooting are not microgrooved because of this.
Have you tried different bullets?

IronKnees · « **Reply #2 on:** January 04, 2003, 10:36:55 AM »

My .45-70 (1895) likes everything, jacketed, different weights, and I also shoot 340 and 500 grain lead... all are accurate. If you are asking have I tried different bullets in the .30-30, you bet i have... just about everything out there..and I can't find anything it likes... not even close.

ButlerFord45 · « **Reply #3 on:** January 04, 2003, 10:43:02 AM »

I have no idea of Marlins customer service, but this 30-30 sounds like a good time to find out. Give'em a call, very little to lose,a buck for a phone call and a few minutes of your time and everything to gain

MFC
100 KENNA DRIVE
NORTH HAVEN, CT 06473
PHONE: 800-544-8892

http://www.marlinfirearms.com/repairs/index.php

Just a thought

Toby from MO · « **Reply #4 on:** January 04, 2003, 12:20:26 PM »

I'll give it a shot. Marlins guns are have either Micro Groove rifling or traditional Ballard style rifling.

Remember, I am shooting from the hip here. When you look at a ballard riflings you notice, I think, 6 wide grooves seperated by the lands. With the Micro, the grooves are much smaller and the lands are closer together. I believe the rate of twist would remain the same, such as different rifling for the same caliber, but the difference is a higher number of lands and grooves.

Toby

w30wcf · « **Reply #5 on:** January 04, 2003, 12:48:48 PM »

IronKnees,

Sorry to hear you are having trouble with the accuracy of your Marlin .30-30. I own a 336A with has a micro groove barrel and it is one of the best shooting guns I own with jacketed or cast bullets. Like your .45-70, it shoots everything well.

The current micro groove .30-30 barrels have 12 lands and grooves.

From the sounds of your problem, one possibility might be that your muzzle crown may be damaged. This is one thing that would cause the problem that you are having.

How old is your rifle?
Did you buy it used or new?
Does it have a scope? If so, there could be a problem with that.
What bullets / loads are you using?

If you bought it used, another possibility could be that the rifle was improperly cleaned from the muzzle, and could have cleaning rod wear inside the barrel close to the muzzle.

A friend of mine had an old Marlin that grouped horribly with some bullets even printing a sideways profile. It turned out that the barrel was somewhat larger about 1" in from the muzzle, no doubt due to cleaning rod wear. We cut 1 1/2" from the end of the barrel and the results were astounding. 5 shots in 1 1/2" @ 50 yards for starters!

w30wcf

Buford · « **Reply #6 on:** January 04, 2003, 02:05:02 PM »

The Beartooth Bullet site has the most information I have seen on this subject. Microgrove rifling has served us well for quite some time without notable complaint - an "expert" or two voiced their opinion and others followed with sheep like devotion. I have Marlins in .22lr, .357, 30-30, .44 Mag, and .45/70 - all with Microgrove rifling and all shoot well with cast and jacketed ammunition. The fellow at Beartooth appears to be knowledgeable and well informed.

Cheyenne Ranger · « **Reply #7 on:** January 04, 2003, 03:26:22 PM »

Here is the URL for the Marlin Lever action forum. Maybe one of them could answer your question:
http://www.marlinfirearms.com/cgi-bin/ubb/forumdisplay.cgi?action=topics&forum=Cowboy+Rifles&number=4&DaysPrune=30&LastLogin=

IronKnees · « **Reply #8 on:** January 05, 2003, 08:42:30 AM »

I bought it brand new, and it has never been cleaned from the front. I ALWAYS take all my guns down and clean from the breach... On the ones that I can't do this, like revolvers and such, I use inserts made from squeeze bottle tops that fit inside the muzzle, thereby protecting the crown... this is something that I am very fussy about...

IronKnees · « **Reply #9 on:** January 06, 2003, 08:06:37 AM »

Thanks a bunch for all the replies... I just put my two Marlin rifles back in my gun case. My 336 has "microgroove barrel" stamped right on it. It's a bit difficult to see inside that .30 cal. bore, but I could see the difference. My 1895SS is NOT microgroove. It's bore is big enough that I could easily see the six lands and groves inside it, and it does not have the microgroove notation stamped on it... Dave

w30wcf · « **Reply #10 on:** January 06, 2003, 02:08:02 PM »

IronKnees,

Since it is a new rifle, have you tried shooting it with open sights if it is scoped? Could be there is a problem with the scope. I have seen that problem often enough during my club's annual sighting in days.

If your rifle is not scoped, is there any "play" in the open sights?

Have you had a chance to try any factory 170's?

There has to be an answer here somewhere. I have shot a number of .30-30 Marlins and they were all accurate rifles.

w30wcf

norville · « **Reply #11 on:** January 07, 2003, 01:22:32 AM »

Have you tried factory stuff? It took me almost a full year and some 50 different loads in my 356er to get it to shoot decent. The factory still out shoots my loads. I was very frustrated with this rifle and ready to dump it 'cause I have had great sucess with reloads in the past. It's just the gun. I'm still trying to find a great load for it.

norville

Advocate · « **Reply #12 on:** January 07, 2003, 01:56:55 AM »

I read a piece by Finn Agaard in the American Rifleman evaluating a 336 30--30 AI by Clifton custom guns. The article said that Marlin's monogram was stamped on the barrel with such force that it altered the concentricity of the bore and that was one of the reasons Clifton re-chambered to the 30-30 AI round. It also had an intersting discussion of how the assembly of the rifle caused the magazine tube to exert pressure on the barrel that impeded accuracy. I know little about lever actions, but there is apparently an art to trouble shooting them, just like every thing else.

The Blade · « **Reply #13 on:** January 07, 2003, 02:25:25 AM »

Ironknees,

I have had a similar experience as you. My Marlin GG in 45/70 shoots cloverleafs at 50 yards with a peep sight, but my microgroove 30-30 shoots well over an inch at 50 yards with a scope and factory ammo. The 30-30 exhibits quite a bit of vertical stringing as well.

I studied the rifling in my 30-30, and it's rough as a cob. The chatter marks in the muzzle are VERY apparent. It's a candidate for fire lapping after I make a few other modifications.

I've been reading McPherson's book "Accurizing the Factory Rifle." He goes into a great amout of detail as to the causes of inaccuracy of some of the Marlin lever action rifles, and the gives fairly simple antidotes for each of the gremilns.

The crown, the way the magazine tube is held, the forend and butt bedding, the extractor claw, and the way the barrell is mated to the receiver can all cause what you're experiencing.

If you are able, try to pick up a copy of the book. Even if you don't do any of the modifications described in the text, it's still interesting reading about the various effects of the way these rifles are put together.

By the way you describe the problem, it sounds like the ammo is not the problem. It's most likely one of the items that McPherson addresses in his book.

Hope that helps...

The Blade