45-70 Smoky cases?

[Moloch]

Yes I know, its a common problem!

I'm using Vihtavuoris N130 load data with 300 grain Sierra soft points, Starline brass and CCI primers. My load is 1.5 grains above the minimum load, so I load 53.7 grain for about 2050-2100 fp/s. The weird thing is despite getting good ignition (no unburned powder grains in the barrel) and AMAZING accuracy (1 MOA with irons! ) the cases do get smoky!

Here is a picture:



Anyone else having this problem with N130?

Used the same load and gave it a good LEE taper crimp but that did not help at all. I'd like to keep this load since it is very accurate and powerful enough for my taste. Should I simply accept that there is some minor blowby? I sure have to clean this rifle a little more thoroughly than any other rifle I own, especially the chamber which I need to scrub a lot with a synthetic brush and solvent.

Oh, forgot to mention I full length-resize with a LEE die.

[Unclenick]

As you say, a common problem. The case is just not sealing the chamber before the bullet gets past the case mouth. You could try a heavy crimp with the Lee Factory Crimp die rather than a taper crimp, but the easier solution is either a heavier bullet or a faster powder.

I note that your velocity numbers match the VV manual numbers. Do you have a chronograph so you can measure them from your own gun with allowance for any difference in barrel length you may have from the 560 mm barrel used by VV for their load development? If your gun also has a 560 mm or a 22" barrel and is getting lower velocity due to a more generous chamber or other factors, then your pressure is lower and you can increase charge weight.

My other suggestion is to try working up to the same velocity with N120. It should be around 1.2 grains less than maximum, from VV's load manual. That will put the pressure closer to maximum and get there faster to help better seal the cases before the bullet has moved as far. You could also start your load workup from the bottom using a magnum primer to assure adequate speed of ignition and it might let you get to your desired velocity with a fraction less powder. You will need a chronograph to tell.

[Moloch]

Thank you for your reply, Unclenick!

Your post mirrors my first thoughts when seeing the cases, the load, even though above VV min load seems to be still on the lower end of pressure.

Funnily I do get considerably higher velocities than VV advertises on their site, at least with the 405 gainers. (up to about 130 fp/s faster, out of my 22'' Sharps) But my cases get sooty still on both 405 and 300 grain loads. I think my Sharps has a relatively tight chamber.

Since I still have two cans of N130 I thought about annealing the case mouth which seems to be notoriously hard and thick on Starline brass (they are considerably heavier than Rem brass). Do you have any experience with the annealing process? I know how its done, I mean do you think it makes enough of a difference to solve this problem or is it a waste of time with this amount of blow-by?

Also what I am going to try is a near max load (taking into account the increase velocity I get with the rifle of course!) to make absolutely sure that it is indeed a pressure related problem.....

[gwpercle]

You're 1.5 grs above minimum and the low pressure creates the "sooty" case.
Try working in 0.5 higher increments, until the soot subsides and see how accuracy is.
Most of my accuracy loads are usually found about halfway between the min. load and the max. load.
Make sure you anneal the case mouths , this helps with low pressure sealing .
After many years of seeing this pattern develop , I now start in the middle and go a few loads higher and a few lower.
Could be a different powder would work better or if the accuracy is good enough...just put up with sooty cases, after all , accuracy rules ... 1 MOA is pretty darn impressive !
Gary

[Jim Watson]

If I were getting MOA from a .45-70 I would not be real excited over sooty cases.

Sure, try stuff like annealing cases or using thinner brass (I forget which is thinner, WW or RP), but don't forget that load.

[Moloch]

I'd like to keep this load because its so accurate thats why I tried good crimping, but that did nothing. I will try some annealing (1st time I'll do this but I watched good videos about how to do it properly). Main problem with the sooty brass is I have to spend more time cleaning the chamber and the action gets a little dirty, and I do not want to disassemble the gun after each range session. Also all the other ammo I reload for my rifles is super clean, so the dirty 45-70 load irks me a little.

My guess is I'm gonna have to do a little bit of everything, annealing, crimping and bumping up the load a little bit. I will try annealing first and see if things improve. Bumping up the load would be last resort since the rifle kicks really good with the 300 at 2000+, it sure wont kick any less at close to 2200 and that will also only hurt accuracy.

Not sure if I want to use magnum primers though, whenever I tried magnum primers in my rifles the barrel got a lot dirtier and accuracy suffered a little.

[Unclenick]

Accuracy can suffer. If they got dirtier, then pressure went down. That can happen with magnum primers if they are unseating the bullet and starting to push it out of the case before the powder pressure becomes adequate.

Annealing may help. Because the case is thick it will conduct heat well, so be sure to protect the head from overheating. If you use a torch to anneal, you can protect it by setting the cases upright in a pan of water about a cm deep. If that is award you can wrap a wet rag around them or you can set them into a wrench socket and use an adapter to spin is slowly with a battery-driven hand drill or screwdriver.

Try not to overheat and oversoften the brass as it will start to split prematurely if you do. Red heat in daylight is too hot.

[NoSecondBest]

Try sizing your cases on the mouth only. Lots of reloaders for this caliber only partially size the case so that is seals better. I have a .357max with the same problem and two different carbide sizing dies for that caliber. One sizes the case .003" more than the other and it soots the case a lot worse. Using the die that leaves the case larger and I get a lot less soot on the case. I only crimp enough to keep the bullet in place. You might want to measure your case to see what it's being sized down to, and you might want to only partial size it. Just some thoughts on the subject....

[Unclenick]

Excellent suggestion! I forget that with my 1895 out of concern for feeding, but with the Sharps that won't be an issue. This brass is not running at pressures that expand it very hard, so it springs back enough for single-loading, for sure. Over time it should gradually get tighter.

Moloch, try that idea. I would size the brass down almost as far as the base of the bullet goes inside, then stop.

[Moloch]

So I got me a propane torch, annealed a case, I heated up the case mouth until it got too hot to hold and dropped it into the water. (no glowing) The discoloration was very minor, but noticeable. I heated up only the first 1/4 of the case.

Loaded it with 54 grains of N130 with the Sierra 300 grain HP, gave it an good crimp. Went to the range and lo and behold, the case was super clean after firing, only very minor soot at the very mouth!
So its true what I read, Starline brass is on the heavy and hard side.





Compare that to the cases I got without annealing! Basically same load!



Wohoo! I fixed something.

[Unclenick]

Heh, heh! Congrats.

[Moloch]

Thanks!

I will also try to do the partial sizing you suggested, my only concern is I will have trouble to use the same amount of sizing every time because I have to unscrew the LEE resizing die a little to do that. I don't think I can do that with good consistency every time I resize the brass.

I think LEE also makes a neck sizer though.

[Unclenick]

Unfortunately, they don't make a neck sizing die for 45-70. Redding does, but it's expensive.

To do it with your Lee die, put a registration mark on the die and on your press to get it back to the same place each time. Another method is to use a block of metal or plastic as a spacer to set up the die or to tell you when your case has gone a certain distance into the die. You will have to decap separately when doing this.

[1100 tac]

I do believe that Starline recommends annealing their new 45-70 cases.

[Moloch]

I think I screwed up, after loading my annealed cases I noticed a step in the brass where the edge of the bullet sits. The bigger problem is it is always on one side, not evenly all around. My theory is that my die or other component is slightly at an angle and this shows when the brass is softer. On hard cases it stays straight. However, on this very die I loaded some very accurate 45-70 loads.

On my non-annealed brass there is only the slightest hint of a bump. I do not think I overheated the brass since it was not glowing by any means, I was holding it in my hands during the annealing process.

The step is very consistent on all cases, its only a little more noticeable on two cartridges. However, when I roll the cases on a flat surface the bullet does not wobble even a tiny bit, my .308 loads wobble more.

Also I do not think I crushed the cases slightly, the bullets went into the cases super smoothly, and I took good care to de-burr the throat. And yes, I full length resized the cases after annealing.

Here is a pic, whats do you think? On the left the annealed case, on the right normal brass. Safe to shoot? Did I ruin the brass?

[Unclenick]

The appearance of the step is normal. It is what is called mirroring of the bullet base. It is less apparent in the harder case because the greater hardness means the case won't bend to such a sharp radius as the soft brass will under the expanding force of the bullet. Don't worry about it being visible.

As to the mirror being on one side, you are correct that this is due to bullet tilt. It can cause a measurable increase in average group size. I used to get that uneven mirroring in all my 45 Auto loads. The solution was (and still is) to use an expander that forms a short step in the case so you can get the bullet set into the case mouth straight and upright before it goes into the seating die. When it starts in straight it tends to stay straight. The Lyman M-die for 45-70. This die will also flare the case mouth for lead bullets if you set it a little deeper, but with jacketed bullets, you only need a mm or so of the step formed. Just enough to let the bullet sit squarely in the case. Your crimp die will remove it.

Below is a comparison of a conventional expander die flare and the Lyman M-die flare with the short step below it. Again, you only need the flare for lead bullets.



NOE Molds also makes inserts for the Lee Universal Expander that form the step.

What Starline's FAQ actually says is that annealing should be unnecessary unless you consistently get the dirty cases. So, you have them. You need it.

[Moloch]

Thanks for your expertise, Unclenick!

I am a bit relieved now, I thought I made the cases too soft with the annealing and ruined an entire batch of rounds. Not sure how I should think about the tilt though, my load that shoots about MOA when I do my part was assembled with the exact same equipment, which I simply could not see due to the harder case, apparently. Maybe its not that much of an issue with a bullet that has this much bearing surface?

I also think it is caused by the sharp edge of the bullet, I load some 405 grains PRVI/PPU soft points and they have a tiny boat tail, just enough to make seating easier and they barely make a step at all. Also I have to make absolutely sure to de-burr the cases before I seat the square 300 grain sierras, I crumpled the neck of three cases because there was a tiny burr. Didn't want to flare the cases because of case longevity, working the neck with crimp and expander and resizing sure takes a toll. Seating has gotten smoother after the annealing though.

I'll definitely look into the Lyman die you mentioned, this sure looks like a good idea. Even if I get good precision with the slightly tilted bullets its still a problem that can be fixed and will benefit accuracy.

Also I never had to do any annealing, I shot bottle necked rifle calibers exclusively until my Sharps rolled along. The only time I ever had major powder blow by was when I loaded a 6.5 swede with a 140 grain bullet seated WAY out, with a large load of very slow powder. The bullet left the case before any kind of pressure built up and the slow powder was diverted back into the action.n That day I got a good idea how Paul Mauser lost his eye with the 96 action.