Advice on accuracy with a Browning 1886 SRC

[surfanarchist]

Hi all,
I have a Browning 1886 SRC, 45-70, and I'm having a devil of a time hitting anything with it. Rifle is one of the commerative U.S. Forest Service models. It has the original sights which frankly I don't see that well. I slugged the bore and came up with about a .457 slug. I have not done the chamber. I've cast bullets from .458 to just shy of .460. Pushed each from new star line brass, federal LR primers and using 32 gr 5744 behind the 405 gr boolits and 38 gr 5744 behind 300 gr boolits. Boolits cut a clean hole so I don't suspect key holing. I'm measuring my MOA at 50 yards in feet. Now I know it's a big red flag when I say I have a hard time with the sights but it's not like I can't see them. They're a bit fuzzy but it's just 50 yards. I've thought about putting a peep on it but then I would need to drill and tap this thing and I'm not ready yet to do that.

So any ideas what might be making this thing less than a straight shooter? What am I not doing right here? Thanks,

Wayne

[fouronesix]

Should shoot better for certain. First try some factory Rem 405 jbullet loads- they are loaded to trapdoor pressures. If it won't shoot those reasonably well then something else is going on. If OK, clean all the jacket fouling out and try either the RCBS 45-300-FN or 45-405-FN. Use an alloy of about BHN 10-12 and fairly soft lube and sized to .458 or 9. [Just make sure the loaded round fits into the chamber before getting carried away with oversized bullets, in other words I'd try the .458 size first--- after all it is a new gun with new specs and no reason the .458 GC won't shoot well]. The RCBS bullets mentioned are both gas checked. Reduce the 5744 charge a little and start somewhere around 25 gr and top with fluffy dacron filler (filling the space between powder and bullet base). Lightly crimp with Lee FCD or carefully roll crimp. See what happens on paper from a rest.

About the sights. The sights are more or less standard types which means they are going to be a little iffy for any target/accuracy load work. Plus, the sight radius on carbines is short by definition. You might try a receiver or tang mounted (if possible?) aperture sight and a medium width blade front sight (the height depending of course on the minimum setting of the rear sight).

[surfanarchist]

4on6,
Thanks. I'm going to try the jacketed Remington's, lower the charge and use filler as you suggest, and I,m going to sand bag the rifle better and start from there. I have a buckhorn sight that I can install without altering the rifle and that will be next. I'm using Seaco molds for 300 gr and 405 gr rnfp sized to .458 with a Star sizer and lathsmiths .458. Neither are gas checks. So my question is how much better are gas checks for accuracy with this round?

[fouronesix]

I've always had better luck with gas checks with smokeless. I've found at the moderate pressures and velocities, the softer alloy gas-checked bullet seems to be a very good combination.

[KirkD]

I have owned several different 45-70's and currently own two, one of which is a Browning SRC 45-70. I've experimented with a lot of different loads. Looking at your 405 grain load, if you are using a plain base bullet, 32 grains of 5744 might be too much. My load is 26 grains of 5744 under a 405 grain plain base bullet for 1,301 fps at 68 degrees F. and 1,370 fps at 82 degrees F. (I've noticed that 5744 is temperature sensitive, but it is my favourite powder because it is less position sensitive than others in its burn rate.) The most 5744 I've tried is 30 grains under a 405 grain PB bullet, which gave me 1,424 fps (10 shot average). Your 32 grains must be up around 1,500 fps or higher depending upon how warm it is when you are shooting. I have found that soft cast, plain base bullet accuracy starts going South as I approach 1,500 fps. Hard cast might be a bit different, I don't use hard cast bullets (except in my 30-30) so I've not much experience with them in a 45-70. I don't know if your bullet is skidding at that velocity, or you are getting gas cutting, or both. Since your holes are round, I suspect the bullet is spinning at the correct angular velocity, but if you've got a channel cut up the side of the bullet, as it emerges out the muzzle, there will be a blast of gas out that side of the muzzle which will change the direction of the bullet. Because it is spinning, its angular momentum will still give round holes, but it will be headed off to one side or the other. You will also get leading of epic proportions in your bore that you will need a tuft of steel wool and some good scrubbing to get out.

Do you see any leading in your bore, especially just forward of the chamber?

If your groove diameter slugs at .457, size your bullets to either .457 or .458, but do not go larger than .458 with a soft cast bullet. By 'soft cast' I mean pure clip on wheel weights, air cooled.

The original black powder ballistics for the 45-70 was around 1,320 fps with a bullet that was 1 part tin, 16 parts lead. That velocity is what I recommend when shooting the 405 grain bullet out of the 45-70. There simply is no need for more velocity for North American game, and you are good for at least 200 yards with your iron sights.

You can use a gas check bullet if you like, but I have found that it does not make a difference in accuracy if you stay down around 1,320 fps. If you want to put it out the bore at closer to 1,500 fps, then I would definitely recommend a gas check bullet. If you stay down around 1,300 fps, I have found that a sheet of single ply toilet paper, loosely folded, rolled, then folded again and inserted butt ends up, does give improved burning consistency and tighter groups. Drop the load from 26 grains to 25.5 grains if you use toilet paper.

My load of 26 grains of 5744 under a 405 grain plain base, soft cast bullet, leaving the bore of my Browning SRC at around 1,320 fps depending upon the temperature that day, gives me 5-shot groups at 100 yards of 2" wide by 3 & 1/2" tall. That is with the original leaf sight with a notch a half mile wide and 58 year-old eyes where everything is a blur. I have ordered a beautiful tang sight from Montana Vintage Arms. My friends tell me that I don't need to drill my receiver, as the one tang bolt holds the sight on rock solid. I shall see. If not, I've no problem drilling the front hole if necessary. For me, the ability to shoot accurately is a desirable thing.

[surfanarchist]

Great answers! The idea that I'm pushing the round to fast makes a lot of sense. I started at 32 gr 5744 because it's the starting load in my Lyman Cast Bullet Handbook but I'll definitely go lower, utilize filler, and see how that does. I have plenty of 5744, 2400, and about a pound of 4759 so I’ll probably load 10 of each IAW the suggestions above and see how it does (I'll bounce these loads against my loading manuals just to be safe and see where they are in relation to published data).
I've not noticed any fouling but it's hard to get a good look at the area just forward of the chamber. As best I can tell it looks pretty clean but I probably need to invest in a gadget to give me a better view.
I cast from straight wheel weights and I melt the stick-on weights (stick on weights are probably about 10% of the total) right along with the WW's. I then add enough tin to equal 2% of the total batch weight so while I have no idea of where it lands in the brinnel scale I'm sure they are pretty soft. I shot last Monday and it was probably about 90 degrees at the Isaac Walton League near Quantico. VA. In fact, since I've owned this rifle it's never been shot on a cooler than 90 degree day.
I have no problem drilling a receiver but this darn rifle is one of those commemorative ones. When I bought it I was looking for a blue one and this thing came up for about the same and in some cases less than the blue ones are selling for. I hate to hang a blue peep sight on the side of a nickel receiver but a rifle that won't hit where you want is just a fancy club so if it comes to that I'll do it. It’s just going to take my figuring out everything else before I'm ready to do it.

[fouronesix]

Give it a go and see what happens. 4759 and 5744 are very similar in how they act and the charge per velocity/pessure unit- that's why they are very close to each other in the manuals that show data for both. 2400 is a faster powder, so pay attention when working up. From my experience, for what that's worth!, on a sliding scale, faster to slower-- 2400, Rel 7 and 5744 tend to behave similarly with the best utility for each dependent upon application. In the most general terms--- for smaller case capacity cast loads, I like 2400. For in-between types, I like Rel 7. For larger capacity, I like 5744.

With any of them and within the very low to low velocity/pressure loads, you'll likely see semi-burned "ghost" kernels after firing. Very normal and I quit paying attention to that a long time ago.

[KirkD]

There's no way I'd drill that receiver either. A tang sight is what I prefer. Here is a photo of one I have mounted on my original 1886 ...

http://img.photobucket.com/albums/v497/3855Win/86-tang-sight.jpg

The Browning 86 SRC has on one hole in the tang, but they say that is enough to hold a modern repro tang sight solid.

2400 is pretty position sensitive, so I'd recommend some toilet paper filler loosely folded, rolled and folded.

[double8]

I've just been thru a bunch of 405 gr Badman Bullets [.459] ahead of 11 gr Unique. A fun load and fairly accurate, even with my 72 year old eyes. 1902 1886 xtra lightweight...45/70 of course.

[double8]

There's no way I'd drill that receiver either. A tang sight is what I prefer. Here is a photo of one I have mounted on my original 1886 ...

http://img.photobucket.com/albums/v497/3855Win/86-tang-sight.jpg

The Browning 86 SRC has on one hole in the tang, but they say that is enough to hold a modern repro tang sight solid.

2400 is pretty position sensitive, so I'd recommend some toilet paper filler loosely folded, rolled and folded.

Kirk D,
Is that an original tang sight or repro? I've been entertaining putting one on my xtra lightweight. Might help with the old eyes.

[725]

Try various powders in the trap door neighborhood. I shoot 3031 with a 415 cast boolit and it's stunningly accurate.

[KirkD]

Kirk D,
Is that an original tang sight or repro? I've been entertaining putting one on my xtra lightweight. Might help with the old eyes.

It is an original. However, a fellow can get some modern reproductions. Lyman still makes them for the Model 1886. Montana Vintage Arms makes a very high quality one as well. Marbles might still make them to ..... not sure on that one. They most definitely make things much sharper for older eyes. I'm 59 and without that tang sight the rear sight is a severe blur and the front sight is not sharp either, but with the tang sight, that front sight is very sharp, as well as the target. I've put tang sights on all my old Winchesters now that didn't already have them.

[double8]

I was thinking of a Lyman "Hawk eye" for these 72 year old eyes, but a tang sight just might be the answer.