Marlin Microgroove and cast bullets


R.H. Lee
August 25, 2004, 10:46 PM
I've got a Marlin 30-30 Model 336 that I would like to reload for, on the cheap. Can I use cast lead bullets, and if so would they have to be gas checked? Is the bore diameter the same as .308?
Does this combination work, or does it cause excessive leading?

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August 25, 2004, 11:21 PM
The micro groove/cast bullet deal is LARGELY bunk. Micro grooves TEND to work better with longer(heavier) cast bullets. Gas checks certainly keep the bore free of lead at higher velocities as does harder alloys. Unigue powder and a 150 or greater grain bullet works well in 30-30 up to about 1500fps without a gas check. Full power loads I like a 170-190grain gas checked bullet and RL-7 for 2000 fps velocities. Lee molds are cheap and work well, as do many other flat point molds. BTW my experience has been with Marlin .45-70, .35 rem and 30-30 336's.

August 26, 2004, 01:23 AM
Slug your bore and use bullets that are a thousandth over the actual bore size for best results.

August 26, 2004, 06:29 AM
Having tried MANY times to shoot accurate lead bullets out of Marlin micro-groove rifles Their is no doubt in my mind that they are UNSUITED for cast lead bullets. At lower than factory velocity you can get accuracy but why load a .357 magnum at .38 Special velocity? Over the years I have shot hard lead cast bullets with and without gas checks in a Marlin 45/70 (2), 1894 .357 magnum (3) 1894 .44 Magum (3) Ruger Deerslayer .44 Magnum (2) and M1 carbines (3). All but the M1's performed poorly but even the M1's needed "warm" loads to create enough gas to operate the action. The "new" Marlins (45/70 guide gun) work great with cast bullets and their traditional rifling. I always had to go to a '94 Winchester or Browning '92 design for good cast bullet shooting. I still shoot 340-405 grain 45/70 loads for my Guide Gun and a 170 grains GC hard cast bullets out of my Remington 788 (30/30) at ranges of 200 yards with outstanding success AT 1900+ fps (= factory load).

Other rifles I have successfully used cast lead bullets at or above factory velocities are; a repro Sharps carbine, a Martini-Henry, a Ruger #3 45/70 loaded to 85% of the power of a 458 Win Magnum (the recoil was brutal), and a Winchester .375 (great combination!).

August 26, 2004, 02:45 PM
My only experience with centerfire Micro-groove and cast bullets was when I owned an 1894 44 Magnum. Shooting a 240 cast bullet resulted in slingshot-like accuracy. Some of the bullets apparently hitting the target sideways. Shots all over the place.

Since the rifle shot so damn good with the jacketed bullets I just continued to use them in the rifle and used my cast bullet loads for my revolvers. If the Micro-groove barrel is suppose to be so cast bullet friendly I doubt Marlin would have changed to the more conventional Ballard stlye barrel just for the hell of it.

August 26, 2004, 04:46 PM
I have a Marlin 1894 in 44 Mag and did a test with cast bullets. I sized some medium hard (approximatly 19 BHN) cast bullets to 0.430 and another batch to 0.432, both with gas checks. The cast bullets sized to 0.430 were very accurate, the ones sized to 0.432 were just slightly less accurate. Both loads were around 1575 fps. So I am not sure about the "micro-groove curse". I was worried it might not shoot cast bullets well when I bought it since I roll my own for everything I shoot. But I am happy with its accuracy with my loads.

August 26, 2004, 08:30 PM
I have shot a lot of cast bullets out of a Marlin with microgroove rifling. It shot great with them.
Do an internet search on cast bullets. You will find that there are a number of foums dedicated in part to cast bullet shooting. Read and learn. This is a good one to get you started:
This is the same website but this link has some articles taht might be of interest to you: Note that there is a lot of information on the .444 Marlin rifle and cartridge. This is a microgroove barrel. You might read that stuff and realize that the same principles apply to the caliber of your rifle.

One brief comment: Cast bullet shooting is usally not just a matter of loading bullets into cases and firing them. You have to use the correct alloy for the velocity and cartridge you are shooting, you have to choose the right lube (usually commercially cast bullets use the easiest lube to apply, not always the best), the right bullet shape + diameter + configuration + ................................. I would hate for someone to try one bullet, not have success and announce to the world that cast bullets and his brand and type of rifle are incompatable.

August 26, 2004, 09:43 PM
Cast bullet shooting is usually not just a matter of loading bullets into cases and firing them.That's the key--especially with the microgroove rifling you're going to have to match the bullet to the bore. NOT what it SAYS on the side of the rifle or what the factory says, but REALLY measure the bore and buy/make your bullets accordingly.

August 27, 2004, 12:35 AM
One brief comment: Cast bullet shooting is usally not just a matter of loading bullets into cases and firing them.

For all my revolver/45auto shooting this all I ever do and achieve pretty good to excellent results. As for my former Marlin - it was such an outstanding shooter with the jacketed bullets that the fact I had such bad results with my limited cast bullet project did not really bother me.

As to what others have mentioned about their Micro-grove accuracy - I believe you completely. But I am not prepared to measure my bore and start up bullet manufacturing in order to produce the right size slug , alloy combo and lube type. I can see how that may be appealing to some folks but to me it is simply too much of a hassle.

August 27, 2004, 01:23 PM
About my only experience with shooting cast lead in a Marlin with Microgroove was in a 336 in .35 Remington. It was extremely accurate with the old Lyman 358429 SWC cast of old linotype metal. Weight as cast was 172 gr., IIRC.

I only had the one cf rifle at the time, so I had to find a way to use it for everything. I used this bullet and 2400 powder in my .357 too so it made for a logical economy.

Never had the opportunity to chrono the load (this was back when the things cost as much as a used car), but it was likely doing something around 1100 f/s. With my then-young eyes and a Williams FP receiver sight it'd keep five rounds inside of 3/4" at 50 yds. Plenty good enough for everyday chores like coyotes and feral dogs too close to the livestock and small game.

Leading wasn't much of an issue. A couple of swipes with Hoppe's and a brush followed by a couple of patches was all it ever took to keep it looking like new.

August 27, 2004, 01:33 PM
I just picked up an 1894fg (.41 mag) and emailed Cast Performance to ask them about using their 250 gr. WFNGC with my microgroove barrel (this is the bullet Federal uses for their 'castcore' load). Here's the response I got:

Sir, I have one of the 41 Marlins and I am shooting the 41/250wfngc in it.
The 255grn and the 265grn are a little to long for the gun. You can have the
gun modified to feed the longer bullets if you would like. I have a 44mag in
a Marlin that I had worked on to feed the 44/320wlngc. We have used the 41
on buffalo and it worked just fine. The 250 seems to shoot rather well in
the marlins. The micro grooves work just fine with cast bullets. The 45-70
with the micro-groove is very accurate. With the micro-groove barrel you
should shy away from shooting soft lead bullets. The hard cast work just
fine. We have shot the 440grn in the 45-70 at 1900fps with great results and
no leading.

August 27, 2004, 06:19 PM
From the Marlin Firearms web site:
14. Q) Why has Marlin changed its rifling on Models 1894S, 1894CS and 1895SS from Micro-Groove® to Ballard-type cut rifling?
A) To accommodate the use of cast lead bullets.(Jacketed bullets will still function reliably.)

In the mid-1970s, Marlin saw an upswing in shooter interest in old style guns. This was a time when European replicas started to cross the pond to a willing US market. Why not cash in on the fad? Bring the 1895 back in .45/70 and add the then new .444 Marlin? By then, Marlin had their newly designed rifling system called Micro-Groove. Micro-Groove was expected to bring new accuracy to the 100-year-old .45/70. If you are going to use only jacketed bullets, Micro-Groove really is an improved system. But those of us who like the .45/70 know that the only way to get better performance is to handload, and the best bullets are cast bullets. Much to our dismay, cast bullets didn't function too well in the new Micro-Groove barrels. Reloaders brought this to the attention of management at Marlin.
One of the reasons Marlin is so successful is that they listen to the market. Because of the comments by handloaders, the early 1990s saw Marlin going back to the old deep Ballard-type rifling. Several outdoor writers were invited to try the new/old Marlin. Randy Garrett provided his hard cast super bullets. It was soon obvious to the writers who were at the shoot that the teaming of these two new products was a home run.

enough said.:D
Note that there is a lot of information on the .444 Marlin rifle and cartridge. This is a microgroove barrel. No it's not! But it used to be.

Again from the Marlin Website;

Caliber 444 Marlin
Capacity 5-shot tubular magazine
Action Lever action; side ejection; solid top receiver; deeply blued metal surfaces; hammer block safety.
Stock American black walnut pistol grip stock with fluted comb; cut checkering; rubber rifle butt pad; tough Mar-Shield® finish; swivel studs.

Barrel 22" with deep-cut Ballard-type rifling (6 grooves).

Twist Rate 1:20" r.h.
Sights Adjustable semi-buckhorn folding rear, ramp front sight with brass bead and Wide-Scan™ hood. Solid top receiver tapped for scope mount; offset hammer spur (right or left hand) for scope use.
Overall Length 40.5"
Weight 7.5 lbs.

August 27, 2004, 08:01 PM
"Note that there is a lot of information on the .444 Marlin rifle and cartridge. This is a microgroove barrel."

Here is a quote from the link posted (I thought it might help out the guy looking for advice):

"In new production guns both the .444S and .444P now employ a Ballard-style cut-rifled barrel with a 1:20" twist, whereas the older .444's had Micro-Groove barrels with a 1:38" twist. The new style barrels are more forgiving with poorly fit cast bullets, and shoot well with properly fit cast and jacketed bullets as well. However, the older Micro-Groove barreled guns had an undeserved reputation for not shooting cast bullets over 1600 fps. This was and is pure hogwash! The fault lies with the bullet and bullet fit! When these Micro-Groove barrels are properly fit with a well designed. hard, gas checked, with a strong front driving band, cast bullets will rival or even out perform jacketed pills at any velocity range reasonably attained with the .444 Marlin."

So what can you do with this information ?
You might want to call Beartooth and talk to them since they are obviously doing exactly what you ask about. Vernal Smith is another good guy to discuss this with. I believe his company is called Lead Bullet Technologies (LBT). He has a bood called something like "Jacketed performance from cast bullets" or something to that effect (I have two copies but I am at work).
Beartooth sells commercially cast bullets, LBT sells moulds.

R.H. Lee
August 27, 2004, 08:34 PM
I appreciate everyone's response to this thread. It sounds like fitting the cast bullets to my 336's bore is the way to go. If I slug the bore, the correct bullet diameter is .001" over, correct? That would be after sizing, right?

Although I have cast and reloaded many thousands of handgun bullets, my experience with cast rifle bullets is limited to (I don't even remember the mold) some 30 cal. that I gas checked and fired in an old two groove 1903. I used Unique (I think, this is from memory), and I think the velocity was somewhere around 1700 fps (from the reloading book I used at the time).

August 27, 2004, 09:15 PM
the older Micro-Groove barreled guns had an undeserved reputation for not shooting cast bullets over 1600 fps. This was and is pure hogwash! Ask Marlin, they didn't think so and made the decision to change to DEEP CUT ballard rifling, maybe they made a mistake. My Guide Gun shoots casts bullets just fine and I don't have to slug the barrel or use very heavy cast bullets (to keep the velocity low and prevent "stripping"). It will shoot full power 340 grain cast bullets better than ANY factory Marlin with Microgroove rifling. It's a matter of physics, not opinion.

August 27, 2004, 10:34 PM
444 has it right ! the microgroove is more sensitive to bullet diameter and hardness but with the right bullets is is very accurate. Far too many shooters just slap in any bullet without understanding this.

August 28, 2004, 03:42 AM
My Guide Gun shoots casts bullets just fine and I don't have to slug the barrel or use very heavy cast bullets Exactly.It will shoot full power 340 grain cast bullets better than ANY factory Marlin with Microgroove riflingUnlikely. If the bullet is properly fitted to a microgroove bore, there should be no improvement in accuracy going from the microgroove to the ballard style rifling.

The change was done to make it EASIER to get good accuracy, not because good accuracy wasn't possible before. A lot of folks were like Yodavader and were not interested in the hassle of slugging the bore and finding bullets that fit/sizing bullets to fit.

It's too bad that the old Marlin forum isn't working anymore. It seemed like about every other poster on that forum was shooting cast bullets and a good number of them through microgroove bores.

August 28, 2004, 07:30 AM
FULL POWER 340 grain cast bullets better than ANY factory Marlin with Microgroove rifling The key is full power loads, not the OVERWEIGHT bullets that increase the bearing surface yet reduces the velocity. Deep cut Ballard rifling is superior to microgroove rifling for cast bullet shooting.

August 28, 2004, 04:58 PM
Most folks consider 300-400gr to be lightweight bullets in 45/70.

There's commercial ammo available in bullet weights from 300 to 550 grains--most would say anything in the low to mid 400s is midweight. Most of the cast bullet shooters are working in this weight range--I believe you're the only shooter I've ever heard classify them as "OVERWEIGHT."

As for "full power", there's a lot of debate as to what that means. However, something in the 400-420gr bullet weight range @ 1850fps probably qualifies as pushing "full power" in most folks' minds.

Some interesting reading...

This fellow has done a geometric analysis of microgroove vs ballard showing that with a properly fitted bullet, the microgroove rifling actually has more engagement surface contact witht the bullet than ballard/cut rifling.

In this one, John Taffin describes a 405gr 1800fps load for a micro-groove 45-70 that gave excellent accuracy. Sounds like a non-"OVERWEIGHT" 45-70 bullet at full power to me...

A guy claiming MOA accuracy @ 1800fps out of a 45-70 micro-groove bbl.

Ok, am I trying to talk people into buying 45-70 micro-groove guns for cast bullets? NO! (Not that it's much of an issue since Marlin's not making them any more.) But if you already have one, you should be aware that it WILL shoot mid-weight and heavier cast bullets at "full power" with excellent accuracy. IF you fit the bullet to the bore properly.

August 28, 2004, 07:02 PM
A number of these posts talk about slugging your bore: I don't have to do that. I don't want to have to do that ...............................................

What does slugging your bore take, 2-3 minutes, done once the whole time you own the rifle ?
Yeah, spending that precious two minutes is something to avoid at any cost: it is too much of an effort.

August 29, 2004, 01:47 AM
Well 444 I really don't slug the bore of any gun I reload for and will not start just so I can shoot lead bullets in a Micro-Groove barrel. Really does matter much these days since the only Micro-Groove barrel rifle I own now is a Marlin 39 rimfire and it obviously shoots lead bullets pretty well.

I mentioned for the Micro-Groove 44 I owned the jacketed bullets achieved great accuracy with practically any load listed using the H110 and 296 that I used back then. That was good enough for me. And like I mentioned before - if it were such a cinch to get good accuracy with the Micro-Groove system using lead bullets then why did Marlin change to the Ballard style?

August 29, 2004, 08:37 PM
if it were such a cinch to get good accuracy with the Micro-Groove system using lead bullets then why did Marlin change to the Ballard style? Cowboy action shooting.

Lots of non-reloaders/beginning shooters suddenly wanting to shoot factory lead bullet loads out of "traditional style" guns.

Same reason that nearly every major ammo manufacturer has started selling a lead bullet load for the 45-70.

August 29, 2004, 11:32 PM
For what it is worth, I didn't slug the bore of my 444 Marlin. And I didn't cast my own bullets. I went to that link I posted above (Beartooth Bullets), and read their forum. I saw what those guys (the guys that obviously knew what they were talking about) were using in this rifle and ordered them from.................Beartooth. And, it worked fine. I was more than happy with the accuracy.
There were two reasons why I mentioned anything about slugging bores and all that: #1) a couple people mentioned having problems. This tells me they wern't using the right bullet and might benefit from doing a little research into the matter before they made any blanket statements about the subject. #2) The guy that asked the original question might very well have a microgroove barrel. He wasn't asking about buying a new gun, he wanted to make the one he has work. He might want to buy a mould and cast his own bullets. In that case, he needs to order the mould the right size. After he casts the bullets he is going to lube them. Why not use a lube that has been proven to work in a similar set-up ?

I have no idea why Marlin went to Ballard rifling. One reason might be the perception on the internet that microgroove won't shoot lead. Those that have tried it know it works, but many others continue to spread the rumors. As was mentioned, Cowboy shooters buy a lot of lever action rifles and also shoot lead bullets. I am sure they didn't want to lose that market over a rumor. Of course this is nothing but speculation and probably isn't true, but it is a theory.

August 30, 2004, 12:43 AM
I have 3 45-70 "new" model 95 Marlins. The first is a 1973 edition with straight grip and NON MICRO GROOVE Rifling, the second is a 1978 version with pistol grip and micro groove, the last is a stainless guide gun with Ballrd rifling. I shoot a 405 grain wide flat point gas checked bullet (LBT) with RL-7 in all three guns. The sizer/luber (Lyman 450) has a .459 sizer in it. The earlier gun shoots 1" at 50 yards with its Lyman peep, the Micro groove gun shoots 1.5" at 50yds with a 1-3x Weaver scope, and the guide gun shoots 2" groups at 50 yards with it's Ashley mounted 2x Leupold Scout scope. Since these guns will never be pointed at any thing smaller than hogs at any longer than 150 yards- who cares?:p

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