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Old January 25, 2019, 05:21 PM   #1
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45/70 questions

Hey everyone. I am still new at reloading but do have a few calibers under my belt.
I am starting to load 45/70 for use in a ruger #1 & a winchester 1885 high wall. Both are modern single shot.
I am loading 350gr fmj with a crimp grove.
Using H4198 powder
Case length is 2.105
all load data for the c.o.l. Is 2.545 or 2.550.
This gives me two issues.
1. When I seat the bullet to 2.545 it does not even come close to the crimp grove.
2. Trying to chamber a round at this length doesn’t come close either. An empty case at 2.105 will seat fine. With bullet will only chamber at c.o.l. 2.465. Witch is at the proper location of crimp grove.
So my question is how will this change in seating depth affect the pressures.
Any advice would be helpful. Thanks.
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Old January 25, 2019, 05:47 PM   #2
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Jacsd1, first of all, you're talking about two different guns. They won't be the same as far as chamber spec's simply because the Win 1885 is made to exact SAAMI specs and the Ruger gives you a bit more throat to work with. I know this because I own a Win (Miroku) 1885, and I've owned a number of other 45-70 single shots. Since you're shooting single shots, crimping/cannelures are not really overly significant. Just seat the bullet so that it's a couple of thou off the lands if you like, or use the cannelure regardless of the coal. It's not a problem if it's a bit longer/shorter than the book calls out as long as it chambers in the gun without having to use the lever to "cam" it in to close. FWIW, this is the least fussy cartridge I've ever loaded for. My Win 1885 will shoot several different loads sub 1moa at 100 yards. I have NEVER gotten the lighter bullets (350g or less) to shoot as well as the ones 400g and up. They shoot well, but just not as good. I have pages of data on file for different bullets and powders/powder charges I've tried at the bench to support this. Most all long range competitors use bullets close to, or over 500 grains. They just shoot better. IMR4198 or H4198 are two excellent powders, and one of the best in my gun (a call to Hodgdson will confirm you can interchange data between these two. I called). You will find that the Win 1885 may have a problem chambering the longer/heavier bullets. This is common. I took my gun to Turnbull and had them run a reamer in it to their specs and it will now chamber even the heaviest, longest bullets. You can always seat the bullet deeper to get it to fit as long as you're shooting Trapdoor loads where pressure is low. I shoot them all the time anyway. They are super accurate and I have yet to recover even one from a deer I've shot. Even the Trapdoor loads just breeze right through the biggest whitetail. If you have any specific questions or would like further info, send me a PM and I'll let you know what I've learned about this cartridge. I've owned 1885s, 1886s, Sharps, and a TC in this caliber. It's probably my favorite to shoot.
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Old January 25, 2019, 07:43 PM   #3
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All that^^^^

I've been loading for the .45-70 for about 20 years, and I'm fixing to start loading for a Pedersoli 1885, now, too. Every rifle is different, for sure, and I would tailor each cartridge for that rifle alone. NSB is correct... cannelure and crimp is not necessary on a single-shot rifle.

IMR4198 is a good .45-70 powder to start with. When I first started loading the big .45, I used slower powders... big mistake. The slowest powder I use now is IMR3031, and normally it's IMR4198, AA5744, or the like.

Don't discount cast bullets, either.

"I have this pistol pointed at your heart!"
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Old January 25, 2019, 08:28 PM   #4
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I’ve been loading the .45-70 for over 45 years in a bunch of different firearms. All shot very well with bullets from 300-450 grains, jacked or cast, with the right load. The powders I use the most today are IMR4198, IMR4227 and Trailboss. Both the OP’s rifles are strong, but frankly I have stopped using the Ruger-level loads (after I shot a brownie with one) for the Trapdoor-level loads. Easier to shoot, just as accurate and plenty powerful for most any use.

The OP should give us enough information to help him. Exactly what bullet is he using? What overall length does the bullet maker recommend (Speer lists 2.71”)? How much powder? What primer? What will he be using his rifles for?

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Old January 26, 2019, 12:22 AM   #5
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So my question is how will this change in seating depth affect the pressures.
The answer is that deeper seating the bullet reduces the space available for powder and that increases pressures.

But, there is a second part of the answer, which begins with the question "Does that matter?" and the answer to that is, in some cartridges yes, and in others, "not so much".

The .45-70 is a large capacity case, and its a low pressure round a small change in the bullet seating depth doesn't have nearly the effect it has in a small capacity high pressure case like 9mm Luger or .40 S&W.

Plus, you are shooting from single shot rifles, strong ones, at that, so crimp is irrelevant. you don't need to crimp for single shots. If you were running a lever gun, or a bolt, crimp would matter. In a single shot, it doesn't.

What matters is the length of the throat of the barrel. And the profile of the bullet being used. Max overall loaded length (with bullet) for the .45-70 is 2.550". With the usual profile bullet, rounds loaded to that length ought to chamber in all firearms in that caliber. Ought to, isn't "will" some guns aren't able to take all bullets at that length, and need something a little shorter. SHORTER hurts NOTHING, in this case.

The max loaded length number is a number you should not try to exceed, not a number you need to meet. Load your bullets to a length that chambers in your gun(s) and don't worry if its a little bit below listed max length. If you are loading to levels at the max working pressure of the gun, you do need to be carefully working up your loads and a tiny change might move you from Very hot, to "too hot" but if you aren't, maxing things out, small differences in seating depth (resulting in shorter overall length) aren't going change the pressure enough to matter.

I've been loading .45-70 since '83 and my guns have been Ruger No.3, Marlin 1895, Siamese Mauser (rebarreled) and a T/C Contender. Its a great round, amazingly accurate in many guns but does drop fast, so long range shooting is an art not easily mastered, but it can be done, with enough "work".

the straight case, and (relatively) low pressure of the .45-70 means slow "magnum" powders simply don't work worth a damn. "Medium" burn rate rifle powders are the slowest burning thing you should use in the .45-70. "Fast" rifle powders like IMR 4198, 4227, and 3031 work pretty well.
Faster powders (considered slow pistol powders) can also be used, but take great care to ensure you get one, and only one charge of powder in the case. A double charge of something like Unique or 2400 WILL blow up your gun (even a Ruger).
All else being equal (and it almost never is) bigger bullets tend to work better.
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Old January 26, 2019, 04:22 AM   #6
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Thank you very much gentleman. Being new to loading That first pull of the trigger on a new load gives me a little rush safety wise. Lol. You all answered my questions perfectly and is much appreciated.
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Old January 26, 2019, 01:50 PM   #7
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OP, no need to get deep into theory, you weren’t asking for a doctoral thesis. You need to realize that any pressure change caused by deeper seating depends on the starting pressure. If you are loading to Trapdoor pressure levels, then a few tenths of an inch seating depth won’t matter a bit. If loading to maximum Ruger-level loads it will. It’s that simple.
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