Marlin 30-30 rifles....an interesting observation.

[Eagleye]

To set the scene, I have 2 - Marlin 336 rifles, both chambered in 30-30 Winchester.
One is a regular carbine 30-30, with a 20" barrel. The other is a 336-A, with a 24" tube.

Both are Micro-groove, but the rifling is different from one to the other. The 336 carbine
has finer grooves and lands than the 336A. Both bores are pristine.

I have reloaded for these rifles since day 1 of ownership, and have developed loads they like.
Early on, I noted that the Carbine did not like the 160 grain plastic tipped bullets [FTX], but
the 336A shot them quite well. Best load in the carbine was the 170 Speer FNSP, chased by
a good load of Leverevolution. The 336A is more catholic in it's tastes, shooting many loads well.
It is not unusual to shoot moa with either if these rifles, using loads they like, but they likely
average closer to 1¼ moa with preferred loads. Both rifles wear low powered scopes.

Over the past 5-6 years, I had accumulated about 40+ rounds if various factory ammo, as
follows: 170 Winchester Silvertips, 170 grain Imperial KKSP, 150 grain Imperial Soft point RN,
Winchester 170 grain Power points, Remington 170 grain Cor-Lokt, and 2 rounds of Norma
170 grain SPFN.

I decided to get rid of the factory ammo at the range yesterday, so toted the 2 30-30's
out and all the factory ammo, plus a box of 170 gr. handloads that both rifles shoot well for
comparison purposes.

All the factory ammo shot reasonably well, staying in about 2½ moa, with one exception.
The 336 carbine with the Winchester 170 grain Silvertip [old style] Only 2 of 5 shots hit the paper
at 100M, and both hit sideways, indicating no stabilization. The 336A shot them well.

My control ammo shot great in both rifles, and all the other factory ammo shot good enough to hunt
with inside of 200 M. I'm betting those Silvertips were a bit undersize, and were not engaging the
very fine rifling of my carbine.

Out of curiosity, I took a couple of those 160 grain FTX bullets and measured their diameter - .3070"
The Speer and Hornady 170 SPFN measure .3076" The Norma 170s that I have are .3078"
I think I now know why the 336 carbine did not favor that 160 FTX - too small in diameter.

It is surprising what you learn, even after many years of background. You can imagine a guy buying
this Marlin years ago, plus a couple of boxes of those silvertips, and condemning the rifle because it
would not shoot them well. Sorry for the long story, just wanted to share. Dave.

 

[Tactical Trunk Monkey]

I found the same thing on my 336 BL, shoots the 170 RN on target every time and accurately, the 160 FTX at the same target at a 100m and couldn’t hit paper lol. It had me scratching my head, I’m still collecting my brass from the 30-30 to start reloading one day. Thanks for the insight, it’s amazing on how just the littlest thing can make a difference.

 

[kjohn]

Interesting, indeed. Thanks for posting your findings. I don't have any Marlins, but like the sturdy appearance of the older lever actions. I bought a .32 WS Marlin lever one time at a gun show, took it to my table and within an hour a fellow came along and lit up when he spotted it. I knew he would appreciate it so I sold it.

 

[pacobillie]

My circa 1954 336RC loves the 160 grain FTX.

 

[bc308]

Good work Dave. I have often wondered about this and have avoided buying any Micro groove rifles. I appreciate guys on the EE that can post barrel shots of strong rifling.

To me, shallow rifling is like going out in early November snow with 30% tires.

For new, and even experienced reloaders, this is why investing in good quality measuring tools can save money in the long run. Trust nothing, measure everything.

Beyond the basic dial caliper (no battery), good info comes from a tubing micrometer, a case run-out fixture, a long arm dial indicator (if you are chasing possible case separation/ headspace issues), pin gauges, etc, etc.

Dave this ought to be posted in reloading as well.

 

[MRP]

Never loaded anything but Hornady 150 rn interlocks in any 3030 I owned, they have all been plunkers not hunters. My micrometer is not as fine as yours ( you engineer types always have the good stuff) but by holding 2 bullets in the micrometer at the same time ( pour boy method) thay seamed to be the larger diameter of any 30cal bullets on my shelf.

 

[Brutus]

If micro groove was the best factor money can buy other big gun manufacturers would produce thier variant of it. Along with Krieger, Shaw, etc.

Even Marlin themselves offer a Ballard rifling option now. Myself I think they should have only offered micro groove in the rimfire barrels only. But that's just me.

 

[woodlotowner]

My observation, regarding the Marlins, is the girth of the forestock. The only ones I own (2 in 35 Rem and one in 30-30) are '70s models with the 'slim' forestock, like the Winchester 1894s. I can't abide the 'fat' versions.