Hardness 'required' for 40S&W

[ChrisCbr]

I'm curious as the the 'required' hardness of alloy for 40S&W and similar high pressure loads and what the potential downside/effects are of using too soft an alloy. Will a soft bullet 'strip' going through the rifling and tumble once it leaves the barrel having not been spun up assuming 1:16 standard twist? What are the problems one might encounter with a soft alloy assuming good projectile fit to the barrel?

I ask because I cast with what I have access to - pure lead with pewter added to ~2% to aid fill out. Using the Lyman 175gr mold #401638 (powder coated) I have had no problems with powders in the AP50,WST,N320 speed range and 170 PF. The projectile to barrel fit is spot on and I see no leading out my my AET barrel with final twist 1:24. When might one run into trouble using a soft alloy? I notice a range of opinions on this matter.

[6bg6ga]

You will certainly get a number of different opinions on hardness on this forum. Several things to consider from the get go and those are proper fit and lubrication. I always run bullets larger than the bore size. I never run over 1000fps in 45acp. In 45 acp I can run hardness right at straight lead per my hardness tester.

In 9mm in the past I have run them extremely fast and this resulted in some leading. I backed the speed down to 1000fps and no more leading. In my 40 I used some commercially made bullets and leaded the snot out of the barrel which took and hour to clean. I went back to plated for the 40.

MY 45LC and my 44 mag.... no leading problems and again I stay around 1100-1200 fps with 11 for hardness.

[marlin39a]

I use plain base gas checks on my Lee 401-175-TC bullets when I run them through my lube sizer. Eliminates any lead.

[6bg6ga]

I use plain base gas checks on my Lee 401-175-TC bullets when I run them through my lube sizer. Eliminates any lead.

Very good advice.

[GhostHawk]

Lots of variables. If you are pushing for speed plated or jacketed may be the better choice.

Lube does make a difference, as does the powder and the load.

Fit is king, get that right first.

My only .40sw is a Hipoint Carbine and I started out with moderate loads. They came back very sooty so I went up half a grain. That left me with mid level loads, clean brass, no leading.

But every journey is unique.

[JonB_in_Glencoe]

There is no "real" answer to your question as to what is required.
Casters are a crafty bunch, You may be able to get your soft alloy to shoot successfully in your 40...I suspect others have.
With that said, The group at LASC have put together a lot of respectable info on alloys.
http://www.lasc.us/CastBulletNotes.htm
In that link, about halfway down the page, you will see a chart that is titled "Approximate "Maximum" Chamber Pressure For Lead Alloys (PSI)" That may help you decide if you want to attempt using a soft alloy for 40S&W.

My opinion:
I use 94-3-3 for my 9mm, 40S&W, and other high pressure pistol loads. I've not had success with softer alloys in those situations.

[dragon813gt]

I've used 96-3-1 and 96-2-2 in my 10mm. And they're full house loads. Bullet fit and lube are key just like w/ every other cartridge. I've found it no more difficult to load then 38 Special.

[chutesnreloads]

You may get away with a little softer with the powder coat.Only way to know for sure is to try them in YOUR gun

[ChrisCbr]

Thanks for the replies. I expect the powder coating being very tough will help or largely eliminate leading issues (seems to be the case in my pistol).

JonB, when you say you’ve not had success with softer alloys, what were the failures that arose?

[ChrisCbr]

Oh, I should add that my alloy measures 10 BHN (lee hardness kit). Also, the SVI 40 barrels run a slightly undersized major bore diameter according to Brandon, I don’t have the exact number to hand but it does make shooting lead boolits a breeze as fit is never an issue with a 0.401” sized projectile.

[JonB_in_Glencoe]

JonB, when you say you’ve not had success with softer alloys, what were the failures that arose?

Lead fouling and keyholing, I assume it was caused by Skidding.

[ChrisCbr]

Lead fouling and keyholing, I assume it was caused by Skidding.

Right, so the alloy being deformed by the rifling and ‘free boring’ or skidding over the rifling rather than engraving to the rifling and spinning up correctly.

I assume this is with a conventional lube of some sort.

In theory a gain twist barrel will help with this however I don’t see leading in a conventional 1:16 barrel either however I have see keyholing when using fast powders. I suspect the projectile is skidding even though I don’t experience leading.

[JonB_in_Glencoe]

Yes, I had TL boolit styles and used 45-45-10, as well as traditional Lube groove boolit styles with various wax based Lubes. I use a soap-grease lube now (SL-68B).

I'm not a fan of PC. I've never PC'd a boolit, but I have been given samples...and I had failures with those.

[ChrisCbr]

I guess it depends on the shooting you do. I shoot a lot of competition (IPSC) and the polymer type coatings made the sport possible for me (here jacketed/plated projectiles are expensive).

I’ve had PC coatings fail too due to undersized projectiles and/or case swaged projectiles.

One handy thing I do with PC is spray a bit of CRC teflon dry glide onto them before sizing. Makes them nice and slick

[dale2242]

My generic Lyman #2 works for all my handguns....dale

[Lloyd Smale]

your doing something wrong or don't have pure lead. Pure lead with 2 percent tin isn't going to run 10bhn. more like 7-8. In the last few years I feel blessed if my ww turns out 10bhn. In a semi auto gun I don't fool with alloys softer then air cooled ww unless I'm loading hp's and am looking for expansion. Softer then 10 and you can have feeding problems for he bullet hitting the feed ramp and you just don't get the accuracy out of the softer alloys that you do our of harder ones. Idealy I cast low velocity bullets at between 12-15bhn unless there going to be shot in competition. those start at 15 and go up to straight lineotype depending on the sweet spot for accuracy.

Oh, I should add that my alloy measures 10 BHN (lee hardness kit). Also, the SVI 40 barrels run a slightly undersized major bore diameter according to Brandon, I don’t have the exact number to hand but it does make shooting lead boolits a breeze as fit is never an issue with a 0.401” sized projectile.

[ioon44]

I have good results with 12 to 15 BHN bullets in 9 mm & .40 S&W and using Hi-Tek coating. I shot thousands of these last year in IDPA & USPSA matches with out any leading out of several different guns.
Again fit is king .002" over bore diameter works great for me and make sure the reloading dies are not swagging the loaded bullets.

[6bg6ga]

I like the .002 over bore size

[camp]

I use straight ww powdercoated, .401 in multiple guns both pistol and carbine no issues

[ChrisCbr]

your doing something wrong or don't have pure lead. Pure lead with 2 percent tin isn't going to run 10bhn. more like 7-8. In the last few years I feel blessed if my ww turns out 10bhn. In a semi auto gun I don't fool with alloys softer then air cooled ww unless I'm loading hp's and am looking for expansion. Softer then 10 and you can have feeding problems for he bullet hitting the feed ramp and you just don't get the accuracy out of the softer alloys that you do our of harder ones. Idealy I cast low velocity bullets at between 12-15bhn unless there going to be shot in competition. those start at 15 and go up to straight lineotype depending on the sweet spot for accuracy.

Yes I expect my ‘pure’ lead is not quite pure. The lee hardness kit is straight forward to use so I doubt thats it.

I’m forever looking for ways to harden up the alloy but around here one can’t simply obtain wheel weights. I may have to go to an expensive foundry to obtain pb/sb alloy or similar for hardening purposes...