Load Development questions 45/70

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#49

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Hello all,

I recently decided to start reloading cast bullets for my Marlin Guide Gun since the cost of Hornady pre-made is around 60$ a box. Straight wall cases and Cast bullets are new to me but Im starting to get it, just have some questions around velocity.
Here are my specs.

-Hand picked Remington made Marlin purchased new 2016, 45/70 Guide gun with the 18.5" barrel.
-I am using some once fired Starline brass trimmed to 2.105"
-IMR 4198 powder
-Federal 210 LR primers
-And Bullet Barn 405gr RNFP TLG cast bulllets
- C.O.A.L 2.535 with what I would say a moderate crimp in the crimp grove.
-For the load data I am using the Lyman Reloading Handbook 48th Edition.

I only have half a dozen Starline brass at this moment due to the Hornady brass being uselessly short. Min/Max shows 36.5gr-40.5gr so I loaded up 2 @36.5gr, 2@38gr, and 2 @40.5gr. I also shot 2 factory Hornady FTX as a control.
The data is as follows through my Chrony F-1.

36.5gr = 1580, 1550fps
38gr = 1660, 1688fps
40.5gr = 1730,1790fps
Hornady Factory(2050fps) = 2020fps

Now my question is why is there a 60fps spread at 40.5gr? and is that acceptable? I have a couple theories as to why but I would like to hear some feedback as well.
Also if anyone has some Pre-lawyer load data for these thumpers Id appreciate it.

Thanks,

Cole
 
It could be alot of things, one might be that your gun doesn't like the 40.5gr load, or more crimp than other load an inaccurate throw of powder, bit chances are just is just cranky with that charge, it happens
 
I did a lot of load development with this caliber, pm me your email address and I’ll give you a place to start. After years of playing with that caliber the two best powders I found were H322 and RL7
 
Inconsistent crimp was on my list of suspects too. I think a new case trimmer is on the shopping list also, this one either cuts lots or doesn’t cut at all there is no in between. My scale is leveled and checked with a known weight so I know my powder is accurate. I should have my order of brass in tomorrow so I’ll be extra careful trimming and see what happens this time.
 
How do the bullets fit? Undersize cast bullets can gas cut and be less accurate with larger velocity spreads. Bullet should be at least. 001" larger than groove diameter. Usually that means you want at least .459" bullet but depends on your bore. Gas check bullets might work better at higher velocity you're making.
 
jethunter said:
How do the bullets fit? Undersize cast bullets can gas cut and be less accurate with larger velocity spreads. Bullet should be at least. 001" larger than groove diameter. Usually that means you want at least .459" bullet but depends on your bore. Gas check bullets might work better at higher velocity you're making.
Click to expand...

Jethunter,

These bullets are 0.459" and I forgot to ask if they were gas checked or not when I placed the order, I figured with such a hard bullet they would be alright at 1700fps. I am loading these as "Bear Busters" and opted for the hardest bullet I could get my hands on. If they wont work at least it wont be as bad having to tossing out a box of Barnes.
Thanks,
Cole
 
If they are gas checked they will have an obvious copper cap installed on the base. If your barrel isn't leading then you're probably OK although you might need to shoot a larger quantity to really see what's going on.

In some rifles 1700-1800 fps might be too fast for a plain based bullet and could be OK in others. Basically you need to shoot to find out. If it's a new rifle or barrel it is usually beneficial to shoot some jacketed bullets first to break in the barrel. Shoot maybe 20 or 40 jacketed rounds then give it a good scrub and start on the cast bullets. It can save a lot of work scrubbing lead out of barrels.

Lyman 46th edition shows max load of 41.5gr IMR4198 with a 420gr cast bullet at 1740 fps. It gives me 1850 fps in my 26" bbl M1886 with a 425gr .460" gas checked bullet.
 
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These are plain based bullet, and the barrel has had 2 boxes of Hornady Leverevolution through it. I could not see any streaks indicating lead fouling and afterwards the barrel cleaned up easily and on par with jacketed bullets. I will be doing some more testing soon.
 
Measuring spread on two shots is meaningless. At least five is, and you might then find that the 40.5 gr load has the least spread, and even if it didn't, 60 fps is nothing to be concerned about. In fact I have often seen loads with the smallest spread being the least accurate of what I tried.

As for Load Data, IMR4198 and H4198 is all I use in the 45-70 and 45-90 - right from "Powder Puff" to "Full House". If you go to the Hodgdon Reloading Site for "45-70 Lever Guns", you'll see a Max Load of 46.0 grs (for the rifle, usually with Jacketed Bullets). I wouldn't go that high with a Plain-Based Cast Bullet, but it might be ok.

http://www.hodgdonreloading.com/data/rifle
 
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Andy said:
Measuring spread on two shots is meaningless. At least five is, and you might then find that the 40.5 gr load has the least spread, and even if it didn't, 60 fps is nothing to be concerned about. In fact I have often seen loads with the smallest spread being the least accurate of what I tried.

As for Load Data, IMR4198 and H4198 is all I use in the 45-70 and 45-90 - right from "Powder Puff" to "Full House". If you go to the Hodgdon Reloading Site for "45-70 Lever Guns", you'll see a Max Load of 46.0 grs (for the rifle, usually with Jacketed Bullets). I wouldn't go that high with a Plain-Based Cast Bullet, but it might be ok.

http://www.hodgdonreloading.com/data/rifle
Click to expand...

Andy,

In all honesty this was more so a test to get my Chrony figured out, I tried it several years ago on 7mm rem mag aswell as a 243 Winchester. For the life of me I couldn’t get it to read anything other than my pellet gun so I gave up on it and only recently gave it another go. As for that Hodgdon website I think there is more to it than just bullet weight, I not fond of the thought of having a marlin bolt poke me in the head... I’ll order that Lyman cast bullet load manual today since the only manual I have that has cast data is only giving me loads for trapdoor, and that’s no fun.

Thanks,
Cole
 
#49 said:
Andy,

In all honesty this was more so a test to get my Chrony figured out, I tried it several years ago on 7mm rem mag aswell as a 243 Winchester. For the life of me I couldn’t get it to read anything other than my pellet gun so I gave up on it and only recently gave it another go. As for that Hodgdon website I think there is more to it than just bullet weight, I not fond of the thought of having a marlin bolt poke me in the head... I’ll order that Lyman cast bullet load manual today since the only manual I have that has cast data is only giving me loads for trapdoor, and that’s no fun.

Thanks,
Cole
Click to expand...

45-70 is one of those cartridges that you can generally use jacketed bullet data for cast bullets. Everything else being equal, cast lead bullets generate less pressure than a jacketed counterpart, because there is less friction in a lead bullet entering or travelling through the rifling. If you've ever tried to pound a jacketed bullet out of a rifle bore you will understand.
 
Brass arrived this afternoon, I just loaded up batch from 38gr to 40.5grs in half grain increments and 5 shot groups. I’ll try again tomorrow and see. I’ll order some gas checked bullets too and try jacketed data. Any recommendations for hard casts with gas checks? I see the Bullet Barn doesn’t offer a gas check styled bullet heavy Enough..

Thanks,

-Cole
 
I've loaded lots of 45-70 with 405's from 600fps to 1700fps and have never required a gas check... And after shooting a few critters with a 405 loaded to 1300fps I put aside the notion one needs to really get em moving to penetrate bone and muscle as I've never recovered a bullet... Lots of mass moving there and they don't really expand... Stick to trap door data and you shouldent see any leading but check often of course as every rifle is different...

Try between 13 and 15 grains of trail boss with a 405 bullet barn cast for a plinking load to 100 yards (one of my under 100 yard hunting loads actually)

You'll also find accuracy and velocity with 4198 and 4895 powders, if running below 50% free case volume I always suggest 1/2 a square of single ply toilet paper as a filler and it's a necessity with a powder such as 3031 unless you like pounding bullets out of your barrel...

As for your chrony data... I have trust issues with Chrony brand chronograph's, Shoot a string of 10 rounds at 100 yards when you find a good load and correlate the velocity with the actual hits to determine if your chrony is telling you lies... I run a magneto speed now and still double check just out of habbit...
 
a few thoughts,
- Your'e pushing the 45-70 quite hard at those speeds, especially for a plain base lead bullet. You don't actually need that much speed to be effective with that cartridge, and it may lead the barrel if you shoot more plain base bullets without gas checks.
- my Chrony is sensitive to muzzle blast, it will erratically measure the escaping gases if it is placed too close to the muzzle. 10-12 ft or so is better than 6' away. two shots doesn't tell you much worth making decisions on, 5 shots minimum if you want to learn something. Use diffusers on a bright sunny day with no clouds.
- you can use the short Hornady brass for your cast bullet loads, but because of less case volume pressures will be higher with full power loads. Don't mix Hornady with other regular brass loads, use moderate powder charges and even then work up from below and you'll be OK with the Hornady brass.
 
#49 said:
Hello all,

I recently decided to start reloading cast bullets for my Marlin Guide Gun since the cost of Hornady pre-made is around 60$ a box. Straight wall cases and Cast bullets are new to me but Im starting to get it, just have some questions around velocity.
Here are my specs.

-Hand picked Remington made Marlin purchased new 2016, 45/70 Guide gun with the 18.5" barrel.
-I am using some once fired Starline brass trimmed to 2.105"
-IMR 4198 powder
-Federal 210 LR primers
-And Bullet Barn 405gr RNFP TLG cast bulllets
- C.O.A.L 2.535 with what I would say a moderate crimp in the crimp grove.
-For the load data I am using the Lyman Reloading Handbook 48th Edition.

I only have half a dozen Starline brass at this moment due to the Hornady brass being uselessly short. Min/Max shows 36.5gr-40.5gr so I loaded up 2 @36.5gr, 2@38gr, and 2 @40.5gr. I also shot 2 factory Hornady FTX as a control.
The data is as follows through my Chrony F-1.

36.5gr = 1580, 1550fps
38gr = 1660, 1688fps
40.5gr = 1730,1790fps
Hornady Factory(2050fps) = 2020fps

Now my question is why is there a 60fps spread at 40.5gr? and is that acceptable? I have a couple theories as to why but I would like to hear some feedback as well.
Also if anyone has some Pre-lawyer load data for these thumpers Id appreciate it.

Thanks,

Cole
Click to expand...

I've ordered from Bullet Barn in the past, 350gr plain base @ a actual measured diameter of .457 to .458, not close to the advertised diameter. When I weighted each bullet from my batch of 200 rds, the weight variation was high. I had handfuls of bullets weighting 341gr up 349gr, I even had 3 rds that weight in at 354gr, so my batch was not consistent. I bagged each group weight, 6 zip lock bags, separately and use one bag up at a time. I also weighted each powder charge, IMR 4198, twice, once on a balance beam and the second time on a digital scale from 30gr up to 45gr. After all my efforts the SD and ES was low but my groups with these bullets were not hunting round worthy.

I also make sure the rifle muzzle to chrony distance is always the same for each round fired.

I have a new source for my hard cast with GC and switched to 3031 and I'm very happy with my results but my 2017 black bear was not...
 
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Thank you all for responding, my Chrony was approximately 10 feet (10 literal foot steps). I think my actual velocities are much lower than what it is telling me but i trust the velocity spread more than I trust the velocity reading itself, if that makes any sense.
This preticular unit has the manufacturing date of 1993, and I’m sure there has been quite the jump in chronographic technology since then. I’m going to borrow a friends Caldwell unit to compare to mine.

As far as velocities are concerned I’m just trying to make a “flat” 150-200yd shooter. I am not putting a scope on it nor will it be a paper only princess, just a dependable bush cannon.

-Cole
 
Biggest issue with the Chronys from that era was lighting. When the light was right they worked well, but too bright or not bright enough and the reliabil;ity went to heck. You can make them more dependable by making better diffuser than what came with the unit.

At 10ft you could still be getting blast. Try a bit further. I usually put it out minimum 5 paces or 15 ft and for some rifles I go closer to 20 ft.
 
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