45-70 cast boolit questions.

[Blood Trail]

I have a couple Marlin 1895’s (one JM stamped). I heard that the micro groove barrel doesn’t like bullets with lube grooves.

Any experiences with cast boolits and Marlin rifles yall care to share?

Thank you in advance.


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[GregLaROCHE]

I shoot greased boolits and PCed boolits with grease groves in a micro grooved barrel. I find both work well for me.

[Tar Heel]

Cast bullets, in general, do not perform well in micro-grooved barrels or those with polygonal rifling (Glock) due to "slippage". Slippage is when the rifling can't grip the bullet enough to spin it, as in the case of soft lead rather than a hard copper jacket. Lead bullets can be fired in micro-groove barrels or barrels with polygonal rifling if they are cast VERY HARD and pressures are kept slightly lower. Sizing .002" over groove diameter also helps but may prevent chambering.

For me it was not worth the extra effort and I sold the Marlin for a Winchester. The Winchester happily digests all I feed it.

[GregLaROCHE]

Cast bullets, in general, do not perform well in micro-grooved barrels or those with polygonal rifling (Glock) due to "slippage". Slippage is when the rifling can't grip the bullet enough to spin it, as in the case of soft lead rather than a hard copper jacket. Lead bullets can be fired in micro-groove barrels or barrels with polygonal rifling if they are cast VERY HARD and pressures are kept slightly lower. Sizing .002" over groove diameter also helps but may prevent chambering.

For me it was not worth the extra effort and I sold the Marlin for a Winchester. The Winchester happily digests all I feed it.

A lot of people disagree.

https://castboolits.gunloads.com/showthread.php?370675-More-on-Micro-Groove-rifling&highlight=Micro+groove+barrels

[Larry Gibson]

The two above posters are both correct.

There are a lot of variables which determine whether a lube bullet can, and it certainly can, "slip, skid, etc. in a micro-groove barrel. The problem is one of the shallowness of the grooves. Regarding the 45-70, many don't know, forget or don't understand that the .460 sized lubed bullet fired out of a .458 groove barrel does not mean the bullet comes out of the muzzle at .458 diameter. Actually the lubed cast bullet will come out with a smaller diameter than the groove diameter. The reason is the bullet rides on a layer of lube while in the barrel. The lube is basically a liquid as the bullet rides over it. Liquids do not compress (hydraulics) but the alloy will. Thus the lubed bullet is sized down in the bore less than groove diameter.

How much depends on the alloy hardness, the acceleration rate, the lube, etc. Now, if the grooves are only .02 - .003 deep and the bullet is compressed, i.e. swaged down, .002 - .003 then there isn't much bullet hanging onto the rifling and the bullet will skid across the lands losing it's spin rate. Those that have success with lubed cast bullets have found the right sizing, hardness of alloy, lube and acceleration rate to prevent the bullet from swaging down so much the grip on the rifling is lost.

PC'd bullets do not ride on lube but on the harder PC which is solidly adhered to the bullet. The PC'd bullet si swaged down to groove diameter and maintains the grip on the rifling. Ergo they perform well in micro-groove barrels.

[MostlyLeverGuns]

I shoot .460 300 gr cast bullets in a 1980 Marlin 1895 and a recent 1895 Cowboy, 2MOA or less is easily attainable with some load development. I haven't pushed for much more than 2000 FPS with 300 gr RCBS GC flatnose. Mostly shoot 1600-1800 fps for practice and some plain base at 1200 +/-, I have other rifles that recoil less for fun. I have Marlin Microgroove's in 30-30, 35 Rem and 444 that all shoot very accurately with cast boolits, .311 for the 30-30's, .360 for 35 Rem's and .432 for the 444. Bullet fit is the key.

[rintinglen]

^^^^What he said!!! I have found that in 30-30 and 357 Micro groove rifles, boolits need to be larger and harder for best accuracy. I heat treat boolits sized.311 for the 30-30 to get best accuracy, while my 357 needed .359 boolits to perform its best. I regret parting with the .357. The 30-30 was nothing special, but the .357 was pretty good rifle.

[Wally]

I have a Marlin 1895 and 1894C both with MG barrels. Both shoot very well with cast bullets as long as the bullets are sized to be bigger than the groove diameter. As MOSTLYLEVERGUNS has stated, I too size the .45-70 to .460" and get 2~2.5 MOA accuracy with them using the RCBS 325 U cast bullet. RINRINGLEN I almost gave up on my 1894C with cast bullets-- any cast SWC that I tried in it was just no good. Then I tried the Lee 130 & 158 RNF sized to .359"....was able to hit 3" cans at 150 yards with both consistently. Sadly the bullet that I thought was ideal in it failed miserably---the 358429.

[robg]

if boolits are slightly bigger than bore and loaded to sensible levels you should get decent accuracy.

[barkerwc4362]

I have an 1894C with a microgroove barrel. I shoot hard cast .359 180 grain and 158 grain bullets over stout charges of WCC 820 and 2400 with very good accuracy.

Bill

[Bigslug]

I've yet to enter the Microgroove arena with cast on a recently acquired .30-30, but A couple of formula items I'd consider:

1. Do a pound-cast of your chamber and throat to find out what YOUR gun REALLY needs.

2. A bullet sized to fit THAT.

3. Relatively hard alloy - as has already been mentioned.

4. Since soft alloys may be out, go for a large meplat to get your tissue damage - you aren't after a flat, extreme range trajectory with that platform anyway.

5. Take a look at Leverevolution as a possible propellant. In the above .30-30 with copper, load workups provided speeds well in excess of what the old data indicates is possible. Again, with no expansion due to hard alloys, meplats and speed become your friends. . .and .34" meplat .45-70's are just FUN to plink with - at 1600fps, they turn milk jugs into fog banks.:mrgreen:

6. Consider a gas-checked bullet design - particularly one where the gas check forms the back of the rearmost lube groove. The check will act as a scraper and the groove in front of it a reservoir for the scrapings.

[JesterGrin_1]

I have a couple Marlin 1895’s (one JM stamped). I heard that the micro groove barrel doesn’t like bullets with lube grooves.

Any experiences with cast boolits and Marlin rifles yall care to share?

Thank you in advance.


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You did not mention what boolit you plan to use but the Ranch Dog design made by NOE now in 350gr was made just to fit the Marlin 45-70 chamber and is hard to beat. I would look up posts with Ranch Dog Outdoors as he did extensive testing with Marlins and bullet designs. I sure wish I had his load information. But I am sure you will find it on the forum or someone will chime in with the information. At 100 yards I would get 3/4" groups. :)