Hello everyone!
This is my first post on this forum. I recently purchased a Glock 20 Gen4 as my first Glock and 10mm. I also purchased two boxes of Underwood 135gr hollow points for self defense ammo.
I work at a gun store where we cast our own lead bullets. I picked up a box of 155gr SWC as they were the lightest we cast and I figured I could run the velocity up on those more so than the 175gr SWC or 200gr FP.
I currently tested two loads, one using HP38 and Accurate #5. I had much greater success with Accurate #5 than the HP-38 and from what I've read that is what I should have expected.
Does anyone have any suggestions for a load or where to start that will get me closer to the thump of the Underwood? I'd like to work up a load that simulates the power that I get from shooting that to practice with. I know the Underwood stuff is pretty hot so I don't realistically expect to get super close to it, but anywhere in the realm of nearby would be nice.
I ended with 9.5gr of Accurate #5 but I didn't have a chronograph so I didn't want to keep pushing it.
Thanks for any advice!
I use Blue Dot, Power Pistol and 800X on many of my cast bullets. Bullet fit to the bore is going to be a factor as well as lube. What velocity are you wanting?
Here are some loads I tested the 156 is the same bullet as the 175 but the 156 is a HP cavity.
Lyman Devastator 10mm/40S&W Hollow Point Bullets
10mm
156 grain COAL 1.255"
Power Pistol 9.6 grains 9/10/07 S&W1006 5"
Winchester LP primers
Velocity 1400 fps
10mm
156 grain COAL 1.255"
Blue Dot 11.0 grains 9/10/07 S&W1006 5"
Winchester LP primers
Velocity 1225 fps
10mm
156 grain COAL 1.255" 06/27/09 S&W 1006 5"
Power Pistol 7.2 grains
Winchester LP primers
Velocity 1125 fps
156 grain COAL 1.255" 06/27/09 Glock 29 3.78"
Power Pistol 7.2 grains
Winchester LP primers
Velocity 1030 fps
Smith &Wesson 1006 5" Barrel
Lyman 175 grain TCBB Cast 10.4 grains Blue Dot
1152 fps Low 5.29 Extreme Spread
1157 fps High 3.60 Standard Dev.
1154 Average
I'd like to run the velocity up as high and safely as possible. My understanding (at least on the box of Underwoods) is that the Underwood stuff is 1600 fps.
I'd like to get up pretty high to get a good feel for the same power, etc.
Well it will use slightly less power than what he was using for the jacketed stuff, but he was driving the 155's to 1500, using IMR800X 11.2 grains. this is stout loading...and (not for the public)
Here is the pull down of that round...
http://10mm-firearms.com/factory-10mm-ammo-pull-downs/underwood-155gr-tmj-nfp-not-for-the-public!!-pull-down/ (http://10mm-firearms.com/factory-10mm-ammo-pull-downs/underwood-155gr-tmj-nfp-not-for-the-public!!-pull-down/)
Cast bullets may not hold up well at these pressures and velocities and can cause leading and base erosion depending on the ally and hardness used and lube may be blown past the bullet rendering it ineffective.
You're on your own to work at those levels! ???
I appreciate the response. I do know that Cast bullets will have a tougher time (if at all possible) being pushed at a high velocity safely.
The ones we cast are a 21 on the Brinell hardness scale, so I'm confident that they are pretty tough.
When I start to work up my load, other than looking for flattened primers, deformed cases, etc., what should I be looking for to ensure I'm doing this safely?
Is a chronograph necessary? If so at what velocity do I render this experiment over? Or is that only half the tale?
And on the pull down threads, how are you guys identifying the powder used?
I really, really, really would like to not blow my gun up and would really, really, really, like to keep my appendages intact.
QuoteThe ones we cast are a 21 on the Brinell hardness scale, so I'm confident that they are pretty tough.
Just because the cast bullet is hard doesn't mean it won't lead you barrel. Proper fit is critical and good lube properties go a long way to keeping the barrel pristine!
QuoteIs a chronograph necessary? If so at what velocity do I render this experiment over? Or is that only half the tale?
Without the chronograph you are working blindly, period! Sorry to be so blunt! You will never know where you rounds stand!
QuoteWhen I start to work up my load, other than looking for flattened primers, deformed cases, etc., what should I be looking for to ensure I'm doing this safely?
YES! all of those things are of concern! However you are running the Glock-20 4th gen, many guys experience FTF's FTE's with various high impulse loadings. Some have experienced case blowouts! This has a lot to do with slide timing and lockup! In a factory Glock barrel when you see the bulge or SMILE you are over the safe limits, Period! The factory barrel you will see cases will expand to 0.434" to fill the chamber, then you will see stress marks (real fine lines on the surface of the brass). This may happen and the primers may still show no signs...Why is that you may ask? The same primers are used in other rounds with even more pressures above what the 10mm runs at! Besides what some consider a flat primer, may not be flat to others, and different brands act differently!
Quote1600 fps
If you are wanting to work up your loads to values that are unrealistic and working blindly without a chronograph, you will be stepping off the charted loads. Bullets driven at the speed you originally posted are not going to be in a pressure range to be safe and the brass will likely blow out and damage your gun and injure your hand!Quoteon the pull down threads, how are you guys identifying the powder used?
Well that is a good question! I don't always know! But there are many that I do know and cross reference to known data and a pictorial database of powders I collected from various sources. The performance has to fit the profile of known data.
There are many that have (? ?) question marks with some possibilities listed.
Factory Glock barrels are known for not handling cast stuff well. You can expect leading problems.
Greg
Quote from: Geeman on February 10 2014 05:52:44 PM MST
Factory Glock barrels are known for not handling cast stuff well. You can expect leading problems.
Greg
Geeman is both right and wrong. They are "known" for it. And, if you stuff .401" cast bullets you bought at the local sporting goods store, a Glock barrel will almost certainly lead.
But, it has nothing to do with polygonal rifling or some other mystical quality of Glock barrels. It has to do with the rules of success with cast bullets not being followed.
Rule #1. Bullets must fit the bore of the gun you are shooting. And while a .401" bullet is the correct fit for most 10mm/40S&W guns, it is NOT the correct size for any Glock I have examined, or any Glock someone I trust has examined.
Glocks run oversize in most dimensions, including groove diameter. I need to run .403" bullets in mine. Supermoose, you need to slug your bore, measure the slug and add .001" to the largest reading you get. Then cast and size your bullets accordingly. This holds true for aftermarket barrels as well.
The next challenge you may face is getting a bullet that fat to fit in the mouth of a 10mm case without either expanding the case to where it won't chamber, or swaging your carefully sized bullet back down to .401-.402" (leading will ensue). My G29 works fine, but I think I am lucky.
Another option is to use a softer alloy. Yes, you read that right. If you can't get the bullet fat enough in the chamber, then it has to be soft enough that it will swell and fit the bore. However, you are running a razors edge here when chasing uber velocity. Too hard with an undersize bullet and you will get gas blow by, which will lead the bore. Badly. Too soft and your lead will be subjected to pressures beyond it's elastic range and the base will permanently deform causing erratic accuracy and leading.
You might get there with enough patience and experimentation. There are guys at cast boolits who push lead to amazing pressures and velocities. But, I would bet against a 155 gr cast bullet in a factory 10mm glock barrel making 1500 fps without leading. Too many strikes against it up front.
Gas checks and/or after market barrel will make this a lot easier to achieve.
Oh...And yes, if you are going off book, get a chronograph. Just takes one KaBoom averted to offset the cost of a decent chronograph.