Crimp vs Powder Burn

[bigiron]

I just started loading for a Browning 1885 45-70. I'm working on a load for the 350gr Lazer Cast using H4198 and Varget powders. First loads tried all had a moderate crimp and CCI 200 primers. I know a crimp is not necessary as far as the rifle is concerned but would a harder crimp help in getting a more complete burn w/Varget which was very dirty. Going out today with all uncrimpted loads and a magnum primer in the Varget loads only. I'm looking for 1500fps give or take and have it with 39gr of 4198 and 50 gr of Varget.

[35remington]

Lowish velocity loads with lightish bullets, both of which you are doing, burn dirty with powders of those types. The unburned powder will still be there no matter what you do.

If it shoots well, who cares?

[Scharfschuetze]

With the 1885 and no need to limit your overall length, you can seat the bullet so that it is touching the lead or start of the rifling. This will probably give you more initial build up of pressure than crimping.

4198 is on the fast side of rifle powders and is a pretty good powder for the 45/70. I've used it a bit in the 45/70 with 405 grain bullets and haven't had any overly dirty barrels. At 39 grains of 4198, I'll bet you are closer to 1,700 fps than 1,500 fps. Have you chronographed the load?

[Larry Gibson]

All powders require a certain pressure level to "burn clean". Most often a heavier crimp and/or a magnum primer won't raise the pressure enough unless the load is borderline just below the needed pressure. Your 350 gr bullet is also a little light on mass for Varget to burn clean. However, at 50 gr you might be close, only testing will answer that. You might consider slightly faster burning and easier to ignite H4895 or IMR 3031 powders for use with your 350 gr bullet. You also probably will not get the accuracy you desire with a PB'd cast bullet at the velocity levels Varget will generate to "burn clean".

Larry Gibson

[bigiron]

With the 1885 and no need to limit your overall length, you can seat the bullet so that it is touching the lead or start of the rifling. This will probably give you more initial build up of pressure than crimping.

4198 is on the fast side of rifle powders and is a pretty good powder for the 45/70. I've used it a bit in the 45/70 with 405 grain bullets and haven't had any overly dirty barrels. At 39 grains of 4198, I'll bet you are closer to 1,700 fps than 1,500 fps. Have you chronographed the load?

W/ 38gr I was at 1470, 40gr 1675. I did not chrono 39 which I shot today. I noticed when I seated the bullets on my initial loads I was left with a hairline ring of lead at the case mouth which was easily removed with my thumb nail. I have since turned the expander in enough to eliminate that. I think I will back it up a bit because case mouth measures .458/9 before seating bullet. Bullets measure .460 and feel like they are seating pretty firmly. I will certainly try seating a bit longer. 48gr of Varget is giving me 1450fps and nice 3 shot groups of 1" or less with std or mag primer but very dirty. 50 and 52gr opened the groups way up. I'm currently using a 1-4x Leupold and may put a Burris 3-9x on so I can get a better look. all shooting so far is 50yds. Thanks for your reply.

[Scharfschuetze]

Keep us posted Bigiron.

As Larry notes above, I've also had the best results with 405 grain bullets in my 45/70s for both accuracy and ballistic uniformity. 500 grains bullets shoot well too, but you start feeling the recoil with them after a few shots.

It's interesting that you gained 205 fps with an increase of two grains of 4198. The Lyman #4 Cast Bullet Handbook lists 1695 fps with 39.5 grains of 4198 so your results are very close their data on 4198 and a 350 grain bullet. By the way, that is the starting load in their manual for Marlin 1895 and Winchester Model 86 rifles.

At almost 1,700 fps, I'll bet that muzzle jumped a bit when you touched that baby off.