Micro groove rifles must stay under 1600fps........

[shredder]

And other myths busted!

I cast up a bunch of Lyman 358315 200 grain 35 cal RN out of water dropped wheelweights. Lubed them up with speed green and sized .358. Harsh winter set in and I have been forced to sit and wait until I can at least poke my nose out there without having jack frost tear it off!

Then I read that boolits cast from that mould do not shoot well in the 336 and are notorious for casting undersized for the microgroove rifling. Then there is the issue of staying under 1600 fps. Presumably someone has experienced this as it is all over the Lyman cast boolit manual. This lead me to believe I may have made a great error of judgement getting set up for that boolit and size without having done enough research. I immediatly purchased a NOE copy of the RCBS 35-200-FN knowing that all the posts about that boolit must have some substance behind them.

Today I finally snow-shoed into the local range (literally) and gave my new .35 Rem Marlin 336 a bit more of a workout. I finally got to shoot some loads with the Lyman boolit and it really shoots well in my rifle. The catch is that the top load was by far the most accurate load. 20 grains of 4759 gave me 1800fps and a 1.5 inch group for 17 shots at 100 yards. I confess to a scope!

I have found that some things are fine in print but I want to question it, so like a fool I just loaded up the most accurate load with a PSI in the very safe zone for the Marlin rifle and let the rifle speak. I was prepared for 20 rounds of "where are my boolits going?" and instead I got a cloverleaf at 50 yards with my first 3 shots sighting in. Got my attention for sure! I shot the rest at 100 yards.

By the way, I ceaned the rifle barrell well when I first unpacked it from the factory box. I shot up 100 rounds of Remington factory ammo in my first couple of outings. I started shooting cast right after that, and I still have not cleaned the barrell again. It is gleaming like a mirror after the speed green treatrment today and shooting like a champ!

[dverna]

It will never work once the temperature goes up. Your results was pure chance and is due to the cold weather making the bullets harder and less likely to strip in the rifling.

You are in for real trouble with that load.......











Just joking!!!!! Old wives tales abound. Nice load and nice shooting

Don Verna

[btroj]

Old news, we have known this for a long time.

I am glad to see that another person has learned, from first hand experience, just how bogus the 1600 fps ceiling is.

Make a bullet that fits the bore and any sane speed is possible with micro groove rifling. My 30-30 does just fine over 2K fps despite the micro groove rifling.

[Char-Gar]

Yep, you are about 15 years behind in myth busting. We have done it over and over again. MG barrels sometimes require a different bullet for correct fit, but one you have a bullet that is the correct fit, 2K plus fps is easy to come by.

[shredder]

The nice thing is that the boolits lightly engrave on the front driving band when seated to the crimp groove. Like a match made in heaven! Nice light lube star at the muzzle, so much to like. I still want to cast up some NOE 35-200-FN and see how they do.

[singleshot]

Maybe whomever came up with that simply fat-fingered the number and MEANT to say: "Micro-groove barrels must stay under 2600 fps." Because....they know that 30-30 and 35 rem were the most common, so it's a cartridge/pressure limit. :-)

[Mr Peabody]

I've taken cast gas checked bullets to 2400fps in a .444 marlin micro-groove to good effect. If they fit right they shoot very well.

[303Guy]

So in reality, what is the real difference between the Marlin micro-groove and another rifle with standard rifling? Is it in the throat or something? What is the groove/bore diameter in micro-groove? I'd have thunk the micro-groove would be superior for cast due to having more driving surface area.

[MtGun44]

4759 is going away after 2014. Buy your lifetime supply this year.

Good results, glad it is working for you.

Bill

[shredder]

I heard that 4759 is going to be withdrawn. For sure time to stock up.

[45 2.1]

Graf & Sons still have SR 4759 in 8 Lb. jugs....... probably. They did have several hundred jugs of it.... not now though.

[imashooter2]

So in reality, what is the real difference between the Marlin micro-groove and another rifle with standard rifling? Is it in the throat or something? What is the groove/bore diameter in micro-groove? I'd have thunk the micro-groove would be superior for cast due to having more driving surface area.

The difference is that microgroove has more shallower grooves. That's it.

[youngda9]

I shoot a RD265 boolit out of a micro grooved Marlin 44mag at 1650fps using ACWW and Recluse lube.

Size and lube is the key!

[singleshot]

The difference is that microgroove has more shallower grooves. That's it.

And more of them.

[44man]

Scares me, this will be the second time 4759 has been discontinued. I am going to bitch at Hodgdon and all of you should.

[Char-Gar]

The difference is that microgroove has more shallower grooves. That's it.

I think there is more than the number of grooves. This comes from my work with four Marlin 336 MG rifles in 30-30 and one 1895 in 44 Magnum. This true the MG barrels have more grooves and shallower grooves, but the bore diameter (diameter across the lands) is most often several thousands larger than the standard .300 in 30 caliber (.308 X .300) and often the groove diameter is also a thousand or two larger as well.

Here is a pic of a loaded round for the carbine, with the custom bullet. The nose tapers from .304 to .307 and then a short .310 band that just fills the throat of the barrel. This bullet was made for the one rifle and performs splendid in that one rifle, but is not for other rifles.

My 30-30 MG barrels run .309 X .303, 310 X 303 and .309 X 305. It is also common for Marlin 30 caliber MG barrels to have little or no chamber throat/leade/freebore, but rather a chamfer on the rear end of the barrel in front of the chamber.

If a cast bullet is used that requires nose support, it won't be supported unless the nose is larger than the nominal .300 or even .301 or .302. A bullet with a body of .310 or .311 will work just fine. Some bullet with a large driving band in front of the case mouth will also often give problem chambering in some of these rifles.

These MG barrels in 30-30 will shot cast very well, but mine require bullet with larger noses and often shorter top driving bands to give first rate results.

[303Guy]

Thanks. So, with shallower grooves there would be less tendency to form tail fins and generally distort the boolit. So give the micro-groove the right boolit it should shoot as well if not better than most. How often do stamp indenting in the bore of Marlin rifles turn up? I've heard of a few instances from this from members posting here.

[Char-Gar]

Jeff...My experience with the 30-30 MG is they will shoot as well as any other 30 caliber barrel of the same twist IF the bullet fits the barrel. My first success came with SAECO 305 which is nothing more than a fat version of their 307 30-30 bullet. In my experience this makes an excellent bullet for the 30-30 MG barrels.

If my understanding is correct, Marlin used a broach to cut the barrel dovetail cuts on the barrels of some of their rifles. The broach was slammed into the metal and it was removed in one machine stroke. A dovetail that is cut with a mill does not stress the metal as much. By looking at the bottom of the dovetail, it is easy to tell if a broach or a mill was used. With a broach cut, all of the tool marks in bottom of the groove will run at a 90 degree angle to the bore, where as the mill will leave the characteristic swirl tool marks.

I am down to two Marlin 336s now, a Texan carbine made in 1960 and a 336A rifle made in 1972. Neither of them have given me any issues barrel constructions under the dovetail cuts. Both shoot cast bullets very well, but I did have a custom bullet mold made by Mountain Molds for the carbine due to the large bore diameter .305 and almost non-existent throat.

This bullet (see pic) tapers from .304 to .307 on the nose before a short .310 band to fill the short throat. The body is .311. This bullet was designed for the particular rifle and gives excellent accuracy in it, but is all but useless for most other rifles.

[leadman]

I had a 357mag Marlin 1894 that shot the Lee 158gr. RFN sized .359", small bevel base, very well at over 1,600 fps with excellent accuracy. The saeco 180gr RFN GC was very accurate also when sized to .359". Velocity was equeal to the lighter boolit also.
Neither leaded. Did have to go to about 15 to 17 BHN to get the higher velocity loads to perform.
My son wanted it so I have not seen it in awhile.

I'm going to call Hodgdon on the 4759 as I use this for most of my rifle loads.

[selmerfan]

Why is Hodgdon discontinuing 4759? I just considered starting to do load development with it, but passed on the 4759 I saw this weekend and bought two pounds of Blue Dot and two pounds of 2400 instead, as I haven't been able to find Alliant powders on the shelf anywhere. What will 4759 do that other powders like 5744 or 2400 won't, other than the bulk that helps prevent double charges?

[MtGun44]

Call Hodgdon and ask. I have the info, but not my place to release it
publicly. See what they say about why - this isn't just some way to
irritate customers.

Bill