Cast bullets in 45/70 problem

[rock-steady]

I loaded ten rounds of 45/70 using the LEE 405gr cast with wheelweight alloy and 15grains of Unique. I fired five rounds from my Marlin 1895 and my nephew fired five rounds in his Handi-Rifle. At 50 yards, all five of my rounds hit the 18" x 18" paper target. All were key holing. My nephew's five rounds grouped under 1 1/2" dead center of point of aim. No signs of key holing and he said the cast rounds grouped better than the Leverlution rounds he hiunts with. My question is why did identically loaded rounds key hole in the Marlin and shoot great out of the Handi?

[Borregos]

Different bore sizes, you need to slug the Marlin bore and size the cast bullets approximately .001" larger.

[kimwcook]

Borregos is probably on to your problem. If the bullets too small you should be mining lead out of your bore. Slugging it will give you a good starting point.

[Old Ranger]

I had a similar problem with my GG when I got it a few years ago. I had used for the past 45 years, an Ideal (now Lyman) 457124, a 385 gr in Lyman #2, or a 405 in a soft mix of 1:30. With my old original Trapdoors and my Sharps, this bullet was my workhorse slug for years. Flash forward to 2009 and the Marlin GG. It would not shoot this bullet no matter what load, diameter sized (and yes, I did slug the bore at .4565") lube changes and everything. It would keyhole like crazy with this bullet. I switched to the Lee 405 Hollow Base and problem solved. Same with the Lee 340 RNFP. Never a keyhole again. In my weapon, I found that it perfers a shorter and lighter bullet. Even 300 gr RNFP's shoot great but a longer bullet....forget it! KEYHOLE!! Could just be as simple as changing the bullet you use to stop the keyhole problem...Shuck, 20 bucks will get you another mould to use and it will at least not cost much to see how a different bullet performs..

Good luck either way,

Wade

[O.S.O.K.]

Yep. A bit undersized for your Marlin's bore.

If you are using a Lee sizing kit, consider that you can chuck a bronze brush into a hand drill and wrap a cleaning patch around it - then apply some lapping compound - and run this through the sizing die to open it .001-.002".

You will want it about .459-.460". A wee bit oversized cast boolits are entirely safe to shoot and will give better accuracy.

[coyote nose]

Does your Marlin have microgroove rifling???

[rock-steady]

[quote][Does your Marlin have microgroove rifling???
/quote]

I'm embarrassed to say, I don't know. I will look when I get home. I do know it is an older model with smooth wood and it has the cross-bolt safety.

[madman4570]

[Does your Marlin have microgroove rifling???
/quote]

I'm embarrassed to say, I don't know. I will look when I get home. I do know it is an older model with smooth wood and it has the cross-bolt safety.

Should be marked as such!
If not with an unloaded gun looking at the rifling there will be more than the deep 6 grooves(such as usually 12 etc.)
They will also be shallower in depth not deep like the 6 groove ballard!

[piller]

If I remember correctly, Marlin did use micro groove rifling in the guide gun until just a few years ago. Mine has the ballard type and still doesn't particularly like some of the cast bullets.

[O.S.O.K.]

Micro groove rifled barrels will shoot cast boolits just fine! They're just more finicky - especially about the diameter. They REALLY want them a tad ovesized...

[piller]

O.S.O.K., I am not saying that the micro groove doesn't work with cast bullets, just that even with the ballard type rifling, mine is still picky about cast bullets. I have an old Glenfield 60 with the micro groove rifling, and it was great until it had about 85,000 or 90,000 rounds through it. I got an ACCR'RZR tool and it is back to being accurate. I probably wore the rifling down with aggressive cleaning. My Guide gun is accurate with the 350 grain lead round nose, but they are not gas checked and I am getting a little blow-by.

[rock-steady]

The rifle in question is a Marlim 1895SS, serial # 12XXXX. It has microgroove rifling. I've been loading the old remington 405 jacketed flat point bullet over H335. I want to work up a reduced load using cast bullets for general plinking and informal target shooting. What should I use to slug the bore?

[Borregos]

I use pure lead "egg" sinkers from the local tackle shop, lightly oil the bore and pound it through (lightly) with short lengths of dowel.

[Tycer]

Short lengths of about 6". If you use long ones and snap one, they get wedged real tight.

[rock-steady]

This is why I love this forum so much. I learn something new all the time. I've been shooting for 42 years, reloading my own ammo for thirty years and casting my own boolits for 1 month...and now I get to slug my first bore!

[O.S.O.K.]

If you go with a .460" lead boolit, it should be sufficiently snug... I'm betting you get .457-.458" bore. This means casting your own - unless somebody here knows of a source of .460" comercially cast boolits? If I may - I also recommend Lee's liquid alox lube.

[Old Ranger]

If my date codeing is correct that would make your rifle a 1988 production.

Microgroove bores are, as the other's said, prone to wanting larger diameter rounds. Case in point; Had a .30-30 with a bore that miked out at a dead on .308". Shot .308" and .309" jacketed stuff all day, but was forced to use a gas checked cast round sized to .312" and then it was on track. In the 45-70 this will be even more pronounced due to the large diameter of the bore/bullet. The radius will be flatter as compared to a 30 cal and such. I agree that even if your bore mikes out to .457" or so, I'd go at least .460" to see if the problem is resolved.

Are you getting leading in the first few inches of the bore with this bullet/load combination? I'm wondering about that as I'm typing this.....

I do hope you get this fixed and you then can enjoy the cast stuff in your rifle!

Wade

[sore shoulder]

IIRC the Lee 45-70 molds throw bullets that are way undersized and I think that's because they are designed to be paper patched. I have always used .459-.460 bullets in my Marlins and have had no accuracy issues.

[Cliff]

No reason for hard lead bullets in the .45-70. Go with dead soft lead, good gooey bullet lube and a slight taper crimp should fix. Most over crimp a 45/70. Up to around 1600 FPS you shouldn't get leading. Lead will fill the rifling properly and you should decent accuracy. Good Luck.

[shooter]

If you go with a .460" lead boolit, it should be sufficiently snug... I'm betting you get .457-.458" bore. This means casting your own - unless somebody here knows of a source of .460" comercially cast boolits? If I may - I also recommend Lee's liquid alox lube.

Montana Bullet Works has commercial cast bullets in .460. I know there are other quality companies that offer them also, but I can't think of them off the top of my head. Just FYI


If you have the ability, as you obviously do since you are already casting, I'd just get a .460 sizing die and a new mold if you don't have one that throws them that big and have at it. Much cheaper that way, but there are some really good commercial cast bullets available if you decide to go that route.

[Lefty Dude]

Get some gas checked bullets, after you slug the bore. They will shoot better in that micro-bore than bare-footed pills.

BTW; You will most likely end up with Gas checks anyway. This you will do when you get tired of mining lead from the bore.

[Tycer]

If you are casting your own and your mold is a bit small, you can lap or Beagle it easily.

[rock-steady]

Tycer, one question about beagling; do you place the silver tape on both halves of the mold?

One good thing about casting is if the bullets aren't acceptable...back in the pot they go!

[Tycer]

Tycer, one question about beagling; do you place the silver tape on both halves of the mold?

One good thing about casting is if the bullets aren't acceptable...back in the pot they go!

Usually just one, but it really depends on how much you need. Both sides will often leave a parting line, but the sizer fixes that.

[rock-steady]

Alright, time to make a new plan. The boolits I cast mike exactly .459". My question is, would a sizer die in .460" size do anything to a .459" boolit? Or do I beagle the mold and then run through the .460 sizer die? Or just look for a .460" mold?

I will slug my barrel this weekend. Thanks for the advice.