Help with 45-70 Load Development

[SingleSeven]

I bought some .459" oversized Cast Performance 405gn GC bullets for my Marlin 1895 in 45-70, but the load data that came with the bullets is garbage. It lists powder type, charge weight, and predicted velocity, but doesn't mention case brand, primer brand/type, OAL, bullet diameter, or anything else useful. Would some of you more experienced hand-loaders either point me to a reputable manual or otherwise suggest a load range for that bullet using IMR 4198, starline brass, and WLR primers? The AA manual lists the Cast Performance GC bullet in the nominal 0.458" diameter, but it doesn't list IMR powders. I'm told the Lyman manual lists IMR 4198 loads for a cast .458" 405gn bullet without GC, but I'm hoping for something better tailored to the actual bullet, unless that isn't necessary. The Cast Performance bullet sits high in the case too if that's of any consequence. Seated to the top of the bullet's crimp grove results in cartridge overall length of 2.565" which is the very max for still being able to cycle through my Marlin 1895. Any help is appreciated. Thanks.

[Scharfschuetze]

What is your goal velocity wise with your Marlin and the 405 grain boolits? That'll have some impact on your powder and charge choices. Your choice of 4198 is a good one for the 45/70.

I use both pistol and fast to medium IMR rifle powders in the 45/70 depending on what my velocity and use goals are.

I size my 405 grain boolits to either .459" and .460" depending on what the mould and alloy throws and I really see no difference in long range accuracy between the two sizes in my Marlin or H&R 45/70 rifles.

Don't get too wound up about case brand or LR primer choices to begin with, just start with the starting load listed and see where you go from there. To be honest, you probably won't see more than a plus or minus 50 fps average velocity between different cases and primers. Be careful with max loads though and work up to them even with known or test data components.

Consider any datum in any manual a strong suggestion and realize that your rifle will probably handle the load a bit differently than the test rifle the authors used in the manual. I rarely every completely duplicate the components shown in the manuals and thus just work up from the starting load and end up where I want to be with trial loads.

I recommend getting either the Lyman Cast Bullet Handbook number 3 or number 4 for your future reference.

[Wayne Smith]

Lyman 49th or 50th reloading manual and the Lyman Cast Boolit manual are what you are looking for. For condom data I like the Sierria manual.

[pmer]

I bought some .459" oversized Cast Performance 405gn GC bullets for my Marlin 1895 in 45-70, but the load data that came with the bullets is garbage. It lists powder type, charge weight, and predicted velocity, but doesn't mention case brand, primer brand/type, OAL, bullet diameter, or anything else useful. Would some of you more experienced hand-loaders either point me to a reputable manual or otherwise suggest a load range for that bullet using IMR 4198, starline brass, and WLR primers?.

I think you'll be fine with the size of .459 Cast Performance bullet diameter. I don't have their data to look at but you should be crimping the case mouth in the bullets crimp grove. Many times I don't record my OALs if I am working with bullets that have crimp groves. Most all of my boolits have precise crimp groves and OAL is dictated by the grove. You will want these crimped in the bullets crimp grove anyways especially with full power loads.

As far as brass and primer goes.. I have Star Line brass and WLRs and would start with minimum loads BUT give Cast Performance a call, I bet they would help with questions. If they are for a Marlin you should be good to go.

[Bird]

I use 34 grains of imr4198 under 3 different 405 grain bullets, and in remington, winchester, and starline brass. Winchester standard primers in all cases. No gas checks, and no leading. Accurate and light recoiling load. Start at 32 grain load, and look for accuracy, and watch for any leadng.

[SingleSeven]

Thanks all, the Lyman manuals it is. I'm looking for approximately 1600 fps +/- 50 fps out of an 18.5" Marlin barrel. Not sure what "condom data" refers to though (which is probably why I have so many kids)?

[JSnover]

Thanks all, the Lyman manuals it is. I'm looking for approximately 1600 fps +/- 50 fps out of an 18.5" Marlin barrel. Not sure what "condom data" refers to though (which is probably why I have so many kids)?

LOL!
Condom would be CastBoolit slang for jacketed bullets.
Having a crimp groove pretty well solves your OAL problem and unless you're shooting for money or trophies you won't have to worry about the missing data that came with your bullets. The only brass I had a problem with was LeveRevolution being short but it was more of an inconvenience.

[SingleSeven]

That makes sense now - I'm surprised the ammo makers don't advertise them that way (e.g., extra protection double wrapped soft points for sale! My concern with OAL is how it might affect pressure and burn rates. Wouldn't a cartridge with a bullet seated deeper generate more force (pressure) because of the smaller initial combustion chamber area (kinda like using shorter brass)? I dunno, it just seemed like it might be an important parameter to specify. Thanks.

[Scharfschuetze]

My concern with OAL is how it might affect pressure and burn rates.

Your suspicions are spot on, but in the end, that's why we start low and work up. If your chosen boolit was designed for the 45/70, then the crimp groove should give you the proper OAL for a repeater such as your Marlin. If it doesn't, then you could consider a purposely designed mould for the round. Some jacketed bullets of .458" calibre will have two separate crimping grooves. One for the 458 Winchester and like rounds and one (the top groove) for the 45/70.

For single shot 45/70 rifles, many loaders will not crimp, but will seat the boolit out to touch the rifling. OAL is not a concern in this case.

[tdoyka]

i use h4198 and 35gr in a 405gr fbfn. it goes roughly about 1400fps. you can use either h4198 or imr4198, but stay low on the powder(31.5gr of h4198) and work it up.

since i am a non-gas check kinda guy, i'm wondering why you use a gc? mine goes plenty fast enuff for deer and black bear.
(this is just a question, not an arguement)

[Tackleberry41]

Dont get hung up on cases, primers, etc. I have found book data to be a guide more than anything else. Its rare to get book data to produce the same results in real life. I was using some 308 data today, but hard to go off the FPS listed as the testing was done in a 24in barrel. And data varies by who tested it, how they tested, etc.

You were not specific on the barrel in the Marlin, some came with microgroove, some didn't. Cant drive cast as hard in a microgroove barrel. I have 3 molds in 458. Only 2 I really use. The Lee 500gr needs to be leemented some more to stabilize as its casts 2 of the driving bands undersized. Other is a NOE 425gr FN/390gr HP, gas checked. May not need it for slow to medium, but I wanted something that could be driven hard since the other 2 molds are plain based.

I do PC some of my bullets, and did with the 390gr. Out of my H&R using 51gr R7, yes max load, a bit hard on the shoulder. That got me 2186fps. I need to mess with it some more, come up with a more reasonable load.

[SingleSeven]

My decision to use a gas check bullet was primarily fear of the unknown (and the fact that the two bullets types I purchased had really good reviews). I've read differing perspectives on obturation, leading, and accuracy and figured a gas check was my safest bet for driving the bullet hard given my beginners level of experience reloading the 45-70. Both of the bullets had positive reviews from folks using them in 45-70 and the Marlin lever guns in particular. I was surprised that the Oregon Trail bullet seated in the crimp grove at 2.520" OAL but the Cast Performance round topped out at 5.565" in the crimp grove. The Cast Performance has a very wide meplat and long front section . I've cycled a few rounds manually and they seem to feed an eject ok. My Marlin is the 1895 SBL stainless guide gun (18 1/2") and the barrel is supposed to be Ballard rifled according to the sales literature.Thanks all.

[Scharfschuetze]

i'm wondering why you use a gc? mine goes plenty fast enuff for deer and black bear.

I've never used a gas check with the 45/70 and have launched 405s pretty fast out of a Browning 1885 rifle without any leading issues. Boolit fit, rifling type, lube and alloy will all have an impact on how fast you can push it without a gas check without leading.

I'd suggest duplicating the old infantry load of 1,300 fps with the 405 slug to start with in your Marlin. The Marlin is a pretty light rifle, and in my Marlin 1895 it's just fine way out to several hundred yards on steel and targets of opportunity. It's a pretty good load and will allow you to shoot most of the day without fatigue. Once you get that load sorted out, it'll be easy to up it to higher velocities and the experience will give you a useful standard to judge your next loads by.

[aspangler]

Try my pet load. 25 grains of 2400 under the 405 flat nose boolit. 1450 fps average of 10 shot group with max deviation at 15 fps +/-. shoots really well for me and is pleanty hard hitting for deer or bear. YMMV

[SingleSeven]

What are you shooting that out of aspangler? And how long is the barrel? I've got some 2400 that's maybe 25 years old, still looks and smells fine, so maybe I'll give that a try next time.

[Norske]

According to my first reloading manual (Lyman 1967) a factory equivalent load for a 400gr bullet is 38.5gr IMR3031. It groups right with factory Remington Core Lokt 405's. My usually preferred powders are Reloader 7 and Ramshot Exterminator. They can provide anything from factory equivalent to "ouch" recoil levels.