Best ammo for a model 51 chambered in 380

[Antiquerifleman]

What is the best ammo for my model 51? Something that won't damage the breach block. So far I have tried s&b with mixed results. Bought some Winchester white box because I heard great things but when I got it home I saw the the tips are flat. I need something that will cycle but isn't too powerful but will feed up the steep ramp with ease. Has anyone used the Winchester white box in a 51 ?

[Mainspring]

"Best" can be difficult to answer. The standard ammo is a 95gr RN-FMJ bullet at about 950fps, I would start with ammo in this category. Your M51 was built at a time when hollow point, self defense ammo was not a big item and the pistol design did not allow for consistent feeding. Give the FMJ a try, try several brands and compare each against the other. Reliability and accuracy are the goals. On the reliability issue attempt to make the pistol malfunction, loosen your grip a bit and don't keep your arm rigid. If a brand of ammo seems to not be reliable then move it down in your rankings.

Hollow point or self defense ammo can be more difficult on the reliability issue. This ammo tends to be higher pressure and bullet profiles are different with various weights thrown in the mix. A bullet with a small diameter opening will probably be a better choice to start with, or any bullet that mimics the FMJ profile.

On guns that have seen a lot of use the Action Spring may need to be replaced. This will go a long ways to preventing damage to your M51.

[Antiquerifleman]

I thought about replacing the recoil spring but the slide is already difficult to pull back. The spring does look original. It's made with that flat wire.

[Antiquerifleman]

Update: Winchester white box shot great and with the least recoil of anything I tried. They fed ok with the original mag despite the flat points. The aftermarket mag was so so. Needed a pretty firm grip for pistol to cycle though.