Max 180 grain hard cast velocity

[BenTen]

Hi guys,

I used the search function and found some good information, but wanted to specifically ask my question. 

What is the max velocity considered to be safe for hard cast 180 grain bullets? 

I wrote the folks at Rushmore, and was told that 1200 fps was generally the limit they suggest due to barrel leading at velocities above that. 

I know a lot of you have experience with cast bullets at velocities a good bit above 1200 fps, and I would love to hear your thoughts. 

Thanks again!

[The_Shadow]

Well many things come into play...Bullet size as it relates to the actual bore diameter is the most important.  I like at least 0.4015" for my 10mm/40 cal bullets and for a Glock factory BBL 0.4020" is a good fit.   Next is quality bullet lube, I am now using White Label's Carnauba Red and it ha been used in rifle at over 2700 fps but some of those would be gas checked.  I shoot some 9x25Dillon 125 grain cast HP's at 1700 + fps without a gas check.
There are many lubes out there, and with good bullet fit it helps to not blow the lube past the bullet as much.
The PC (powder coated) is another option.

1200 to 1300 isn't out of the question if the fit is good to go!

[sqlbullet]

I have pushed cast bullets pretty fast.  Certainly above 1200 fps.

Good fit is 90% of the battle  A bullet that does not completely seal the bore against the 37,500 PSI of pressure will lead no matter how slow you go.

The right alloy is next.  Modern "hard cast" are way to hard if you are chasing velocity.  Your BHN should be in the 12-16 range IMHO.  This is hard enough to deal with the pressure without permanently deforming, but soft enough the pressure can obturate, or temporarily alter the bullet base for a better seal.  According to the Rushmore website they are using Hardball alloy (92/6/2) which will yield a BHN of 16, right on the very top end of the range above.  That suggest to me that you will need to approach max pressure loads to enter the elastic deformation range for base obturation.

I assume you are using the Rushmore coated bullets, which takes the lube conversation out of the mix since those bullets aren't lubed.  Powder coat bullets seem to run fine in most applications where other rules of cast bullets are followed.

If a good lube is indicated then there are options.  One of the few places that Wade and I don't follow the same rulebook is lube.  He likes a hard lube and carnuba red is a very popular and well recommended lube.  I like a lube that only requires heat to flow in the winter, but in the summer will flow without, maybe medium hard?  I make mine and it is Felix Lube recipe with a couple of hard crayons added for color and to increase the lube melt point just a  bit.  In any event, I can agree that Carnuba Red is a solid choice for an off-the-shelf lube and is probably what I would run if I were buying.

I have run plain base bullets above 2000 fps in rifles.  (Don't do this in a gas operated gun...gas checks are required unless you like scrubbing lead out of the gas system.  Ask me how I know).  I tend to lose about 1-2 MOA of accuracy depending on the rifle when shooting cast bullets at 100 yards.  Still very much game-getter accuracy.

Slug your bore, ensure that the bullets from Rushmore are .0005"-.001" over the groove diameter, and use an appropriate for weight powder such as AA#7, #9, Power Pistol, BE-86 or my favorite Blue Dot.  Also, be aware leading signs may be worse at starting loads and diminish as you increase.  The lower pressure of the starting loads may not obturate the bullet base.  Case in point a starting load of Blue Dot with a 180 grain bullet leads my barrels a bit.  A max load of Unique does not.  Both are 1125 fps loads, but the faster Unique powder peaks pressure very early providing the kick needed to seal the bore.  Blue Dot's starting load has the pressure still climbing when the bullet leaves the barrel.

[CtYankee]

Barrels lead for a number of reason in revolvers that aren't applicable to semi-autos, but obturation is the key to leading in semi-autos. There is a specific formula for  matching bullet hardness to chamber pressure {expected chamber pressure/1400=BHN}, but, unless you cast your own, your stuck with what casters cast. As sqlbullet implied; you can get bullets that are too hard and won't seal the barrel except at hand-numbing velocities. Slightly softer bullets that properly fit the barrel may prove to be less problematic than bullets that are too hard.

I have found that polymer coating bullets provides protection from leading and will guard against leading at higher velocities. Some bullets casters have claimed over 2000 fps with their polymer coated bullets - I can neither confirm nor deny that claim. SNS Casting has a statement on the home page warning that the fastest powders have caused leading because they are scorching their bullets and burning off the coating. I haven't seen that problem using Titegroup, but did change to Sport Pistol, that they recommended.

[erdyalx]

With our homemade cast and coated. We have gone over 1700 from 16 inch 10mm without issue. With our g20 we regularly get 1250 with 180's.

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[BenTen]

You guys are awesome - always great information here.  I know it takes time to write responses like that, and I sure appreciate it!  I'll also slug the barrel soon to see where it sits. 

Thanks!

[md66948]

Great Thread. I have a NIB CMMG and I was hoping to reload some 10mms for it with coated cast bullets. My LGS makes their own bullets and does sell them with or without a poly coating. I am watching reviews on youtube of the CMMG pistol in 10mm and it the seems the CMMG pistols like their 10mms running at 1200 fps or more.

I have never loaded 10mm or 40 s&w but I am a longtime reloader so I will be looking a lot in here for anything that I should know about 10mm or 40 s&w. I do have an old S&W Shorty Forty that I only shot once and I plan to reload poly coated bullets for it.

[Neal]

With our homemade cast and coated. We have gone over 1700 from 16 inch 10mm without issue. With our g20 we regularly get 1250 with 180's.

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Nice pics!  What bullet mold are these from, and what brand PC is the fuchsia color?