The Marlin 30/30, Micro Groove

[Spindrift]

My brother has had this rifle in his safe for quite a while, this is the carabine version, with straight stock. It has seen little use. But his interest in rifle shooting has recently been revived. Time to find som good cast bullet loads for it!

Consulting the Lyman cast bullet book, I find they recommend sizing .308, and keeping velocity under 1600 fps in micro groove barrels

I decided to try .311, with jacket starting loads instead.

I got the Lee «ultimate die set» just in time to throw together a few loads. I*m curious how many cycles I can use the collet neck sizer before chambering is problematic (I’ll find out).

I decided to start with these three bullets

1) NOE 311-127, a relatively light, FP Loverin design. I have a mould dropping both GC/PB. I started with GC, and conventional lube. This bullet will also allow PC, while still having an available crimp option. I tried these with N110, 13-14 grs

2) Lee c309-150- F. With PC, the maximum COL was to short for available crimp/lube grooves. These bullets drop at about .311 (or slightly smaller), the bullets just clean up a little through the .311- sizer. With conventional lube, I could crimp in the front lube groove, with minimal jump. The bullets were a little «sub- standard», I cast a few bullets at the end of a casting session, and reallized I should have cleaned up the mould first; parting lines, whiskers, slightly out-of-round. Decided to try these with N120, 19-20 grs (Jx starting load)

3) NOE 311-166, RD/TL/GC. THis is, I believe, designed with just this rifle in minbd. With PC, the COL was to short for crimping (hydro-dipping PC would possibly solve that). With lube, I could crimp in the front groove, with minimal jump. N140, 25- 26 grs (Jx starting load; claimed V0= 1750 fps)



The little Loverin- bullets with N110 were unimpressive, I think the loads were a tas to hot. Will try to reduce a grain or two.

The sub-standard 309-150 showed promise. At 20 grs, I got 4 hits quite close and one flier. All shots from prone, with support on a bag, target circles are 1 MOA increments. This rifle is very different from what I’m used to. The trigger is heavy, but clean. The stock is to short, even with the slip- on recoil pad. I’ve shot a couple of groups with factory ammo, and with my current skill with this rifle, I consider 2 MOA «good».



The RD- bullet really made me happy. This group reflects, I think, my current ability with this carabine. Will shoot it some more, and try to up the load a little.

 

[Brad]

That 165 RD bullet was literally designed for that rifle. Size to .311 and drive them as hard as you want. They can handle a full jacketed load and still shoot very well.

My Marlin 30-30 does very well with that bullet and 16 gr of 2400. 2400 is pretty close in burn rate to N110 so thst gives you Some idea of a powder charge range.

Good shooting

 

[Spindrift]

Thanks!
I will try to crank up the load gradually. N140 is the slowest powder listed in the vihtavuori data for 30/30, but necks were clean with these starting loads. N110 is certainly a good idea, it is a fantastic powder for reduced loads.

This little rifle is really great fun!

 

[Brad]

N140 is similar in burn rate to RE15 which is what I used when I hunted with my 30-30. Should work quite well for you.

 

[Ian]

Well, there's a lesson in dynamic fit right there. Got a bad flyer with the two-diameter Lee bullet, just like Snakeoil was getting with his 1903 rifle. The little Loverin has no self-aligning properties and narrow/weak driving bands. The RD, like Brad said, was literally designed for Marlin throats.

I have seen two distinct forms to Marlin throats. One has no step down at the end of the chamber, just a sort of extension of the neck diameter for a considerable distance and then an abrupt angle into the rifling. Unless a heeled, 8mm bullet is used there's no way to fill that space to support the bullet so the RD bullet was made to span the gap. The other chamber throat does have an abrupt step at the end of the chamber and only a slight bevel for a throat. Such chamber throats will only accept a bullet like the Lee 150 or a bullet with a very short nose.

Here's a photo illustrating the differences. Left to right: Pound cast of one of my Marlins with the long, cavernous throat, RD bullet seated for field use, RD bullet seated as long as I can jam it in there, AM 31-185G seated to just touch the ball seat, NOE 312-155 seated to engrave hard, powder coated custom bullet I just made for my short-throated Savage (identical to some Marlins), the reamer with short throat, and las an MP 311-140 seated to jam the lands of the short-throated chamber.



Hopefully you can see the difference between the two chambers and why some bullet shapes do better than others.

The deal with the MG rifling is it is shallow and has a large bore diameter, typically .303" or so. Bire-riding designs for standard .30 caliber typically have noses that are far too small to effectively guide the bullet straight and are thus very limited in their accurate velocity range.

Powder-coating that small Loverin to strengthen its bearing surfaces might change its whole attitude.

 

[fiver]

seating it out so it only has like 2 lube grooves in the neck will help it too.
I have a 150gr. Loverign walt melander cut that loves to go fast... sometimes,, and in some rifles.
it doesn't like the short throat in my Winchester 94 so much.
but seat it out for the Savage jack the load up, throw some mag primers in to make sure and it'll run better and better,,, until I pop a primer out of the case.
mmmm. yeah,, ooops. need to check the chrono from time to time, and in the Wyoming desert shooting prairie dogs and jack rabbits isn't the time to be doing that.

anyway Brad got you on track, then Ian explained why.
the only other thing I can recommend is to put some hard in your bullets.
water drop them or heat treat them, whatever, the microgrooves seem to like to be full of lead and one a bit harder as a general rule.

 

[Spindrift]

Thanks, guys, for highly educational feedback! Really, really good posts everyone.

Ian; I think this chamber is of the first type, «cathedral throat».

I have some of those Loverin bullets PC’ed and ready, I was sort of anticipating PC might help. But first, I’ll play a little more with the RD. And another interesting bullet I haven’t tried yet, the MP sledgehammer.

Fiver, the bullets I’ve shot so far, are BHN 15, nuclear med mystery alloy with 1% added tin (the one percent of my alloy I actually know what is). I’ve taken note of your advice concerning alloy. Next opportunity, I’ll cast some from my harder alloy.

But before I can expect to refine accuracy beyond the «sub-2-MOA@100m», I simply need to get a bit more familiar with this rifle. Just shoot it a bit

 

[popper]

You do have to watch seating length to get them to cycle through, long will single load. Harder WDWW works fine. 16gr 2400 is good for the RD, 29gr of 4895, 335 or LeverE is good for top end. I don't use the neck only Lee, use Fl and a proper expander. Crimp only to remove bell - no worry where the crimp groove is. 2 coats of BLL works for me with a GC - without get leading. Mostly I tumble PC after GC, size again and load so there is just a slight jump. Marlin trigger is a funny one - kinda heavy but a lot of slack before the break. I changed mine to a lighter one without the slack. There is a trick for smoothing the trigger without stoning - on the Marlin guns site. This shows where the rifling starts on mine(whitish scuff mark). I also reduced the size of the meplat and rounded the corner. Gets hung on the nose if fast cycling. Which brings me to Ian's 'fit'. Ever drop a rnd into the chamber muzzle down? Doesn't just slide nicely in does it? Kinda like water going down the drain. Kinda picky but that does effect 'fit' for S.A. , lever or running a bolt fast. Bump the nose, bend the neck, chambered off kilter. Yes, the tube and 2 piece stock make a difference for BENCH shooting. Support close to receiver is best but pivot point is close to butt - harder to shoot. With a rear bag you can use off hand to lightly hold down the barrel just in front of the scope.

 

[Spindrift]

Popper, I'm thinking a crimp in a groove is in place, since I use minimal neck tension.... But I may be overthinking this.

Just made an embarrasing discovery... Loose scope rings Now, there's a simple accuracy tweak.

Just checked the max COL of the MP sledgehammer, sized .311. It corresponds perfectly with the crimp groove. Static fit is perfect, the dynamic maybe not perfect... But this might actually work!

 

[popper]

I just found no need to crimp (I do use the FCD to remove flare) - no setback in the tube mag. Don't even 'crimp' for the AR10 or BO - never been a problem. That is a very small rear drive band! And a huge L.G. I did a 145gr for the 308MX that worked great but was poo in my 30/30. IMHO shorter neck made it work.

 

[Spindrift]

Interesting, Popper- thanks for the advice- much appreciated.

Yes, the sledgehammer is a funny little bullet- designed for the .32 magnums, originally. At least, the displaced lead has somewhere to go

 

[Bret4207]

Popper, good observations on running a cartridge into an action vs single loading. Lots of damage can be done without any intention of doing so.

 

[Brad]

I trim my brass a little short to use the crimp groove. The NOE moulds are just enough fatter on the nose to cause me trouble.
Nothing worse than a slightly long round in a lever gun.

 

[Ian]

That Sledgehammer bullet looks to be about as good as it can possibly get for both the static and the dynamic fit as it moves firward into that "Cathedral Throat". (Name officially coined!)

 

[JWFilips]

I always shot my Micro-groove Marlins with .311" cast traditional lube bullets but loaded them long because I only shot them single shot ( target shooting ) When I went to PC coating I went down to .310"
Shot both 30-30 and 35 Rem
Also never crimped because I was shooting them single shot

 

[Spindrift]

Brad; I will keep that in mind, trimming brass short can be useful.

Ian; sounds good! Sadly, no opportunity to shoot for a couple of weeks. I also think the sledgehammer actually looks very promising!
In Norway, we have quite detailed laws concerning energy levels/bullet weights for different groups of game animals. The 30/30 falls just short of the demands of a big game cartridge. The diminutive roe deer (and smaller animals) can be hunted with the 30/30. Which means, it is not necessary to maximize the terminal ballistic output of the 30/30. A 135grs hp/fp bullt would actually work for all practical applications, here.

JW; I’ll keep that in mind, 310 with PC. The idea now, is to shoot with conventional lube/.311 for a bit, then try some PC. For now, I’d like to preserve magazine functionality. But single loading sure opens a new world of bullet choices!

 

[JWFilips]

I actually have shot 195 grain cast spitzer bullets in My 30-30 Marlin however you have to hand feed them into the chamber & you have to shoot them on bolt close otherwise you can not eject the live round! But they are a hoot to shoot and accurate!

 

[Charles Graff]

MG barrels tend run large in both the lands and grooves. .308 cast bullets will be too small. With the proper bullet, sized .311, the proper bullet temper and the right powder charge, 2,000 - 2,200 fps loads will bring good accuracy. Remember that Marlin 30-30 rifles has a 1-10 twist barrels as compared to Winchester 1-12 twist barrels and that will have an effect. Both makes of leverguns tend to have a very short almost non-existent throat. This will require a bullet with works with such barrels. I have found that 165 grain Ranch Dog and 311407 Mod delivers great accuracy in these MG barrels.

 

[Spindrift]

Today, I loaded some MP sledgehammers with viht n120. Will have to wait a week before I can shoot them.....
They look good, I think! Factory crimp in crimp groove, seated just of the lands.

 

[Spindrift]

Shot the Marlin a bit more, today. The sledgehammer/n120- loads were dissapointing. I’m quite sure, though, I could get this bullet to work with a little development.
The NOE311-166 really delivered, with n140, 25-26 grs. I shot two 5-shot groups with each load. 25grs gave two honest 2moa groups, while the 26grs load (for some reason) gave both the best and the worst group today. One group at slightly more than 1MOA, and one 3,5MOA horizontal string.....

I think I’ll just stick with the RD bullet and 25grs of n140. Since this isn’t my rifle, I can’t expect to have access to it at all times. The misson was to find a decent practice load, and I think I will consider the misson complete, for now.

PS in one photo, I’ve used the zoom function on the target screen