Slow .500 S&W

[AnthonyRSS]

I have a 8 3/8" bbl Smith and Wesson .500 that I have been loading for. I chronoed a few loads today and they were significantly below book values. Any advice?

Loads were:

Starline Brass
Winchester LRM primer
350gr Sierra JHP
42gr Lil Gun
avg 1534 fps

Starline Brass
Winchester LRM primer
400gr Sierra JSP
36gr Lil Gun
avg 1430 fps

Hornady Brass
Magtech LP primer
350gr Sierra JHP
17.5gr Titegroup
avg 1299fps

FACTORY
500gr Hornady JSP
1254fps

What say ye? My 3 shot groups at 50 yards weren't spectacular either. 4-5" Some of that could have been me though.

 

[56hawk]

Yeah, something seems wrong. I'm getting 1430 fps with a 340 grain bullet out of a 2 3/4" barrel.

 

[627PCFan]

Slow across the board. Whats your gap? And how much residue are you getting? Unburnt kernels?

 

[AnthonyRSS]

Gap is .006". Powder seems to be burning thoroughly. No unburnt powder or excessive residue. Charges are weighed on a calibrated scale. Even the factory load was 150fps slower than listed. The Titegroup load isn't far off book specs though. The Lil Gun loads are slow.

 

[Hondo 60]

Even the factory load was 150fps slower than listed.

That's perfectly normal.
The major mfgs have test barrels that have ZERO gap, so they get 100% of the effectiveness.
On the rare occasion that I buy ammo, I NEVER get the speed listed.

 

[AnthonyRSS]

Updated loads with H110:
All specs the same except for powder.

350gr, 43gr H110 1561fps

400gr, 40gr H110 1522fps


The loads show no signs of excessive pressures. Primers looked fine and cases fell out of the chambers.


Any advice? Should I start stepping it above book value a little at a time?

 

[56hawk]

I've gone as high as 47 grains of H110 with a 340 grain lead bullet. Cases still fell out of the chambers at that pressure level. Check your velocity against Hornady ammo. The load I listed is what I needed to match factory velocity.

 

[Sport45]

How far is your chrono from the muzzle? I don't know anything about .500 S&W, but do read about many problems with the chrono being set up too close to the muzzle giving inaccurate readings.

 

[AnthonyRSS]

About 10 feet I would say. The loads have a low SD. The chrono seemed reasonable with other caliber loads chronoed.

 

[Steve Koski]

Sell it.

 

[AnthonyRSS]

Sell it.

The chronograph? Its owner probably wouldn't appreciate it.

 

[Steve Koski]

No, the crappy gun. Get a faster one.

Life is too short for crappy guns.

 

[sirsloop]

lol... get a single shot... no gap to steal your fps

 

[SEE IT LIKE A NATIVE]

The only thing I can think of is that the crimp is too loose , resulting in the bullet moving before the pressure wave starts to develop . Kevin

 

[bfoosh006]

Speer had an article in one of the years reloading manual about how much velocities for the .357 Mag. varied between makes of handguns and even sequentially serial numbered, same make handguns... long story short... there was about 275 fps difference between all the same barrel length guns, even the sequentially serial numbered ones were different by about 200 fps. ( My bad, the speed difference is even more than I posted !!!, 376 fps )

You may have truly gotten one of the slow ones....

I will try to find the article on line again..

Here it is ! It is a great read...

http://www.leverguns.com/articles/ballisticians.htm

 

[AnthonyRSS]

Thanks Bfoosh! I had heard of "slow" guns before but hadn't seen the proof before now.

 

[AnthonyRSS]

Update:

Loaded some of the new Hornady FTX 300gr pills today. Tried two loads:

Hornady Brass
Large Pistol Primer
19gr Titegroup
1530fps

Cor-Bon brass
LRM primer
51gr H110
1957fps

Cases extracted easily and primers looked okay.

The H110 load shot to book velocity according to : http://www.hornady.com/assets/files/ftx_load_data/500_sw_magnum_ftx.pdf

What I think is interesting is that 51gr of H110 is well over the Hodgdon book values for the lighter 275gr Barnes bullet. 6gr over. I'm going to work up a load with Lil'Gun to try it out. If everything with that goes okay I will push a 400gr JSP over book values by a bit at a time and see how the velocities and pressures look. I have a feeling, as 56hawk suggested, that the book max values are a bit low.

Hope this helps somebody with the same issues.

 

[Lost Sheep]

I would worry about the loose groups before I would worry about low velocities. On another forum there is a thread from a fellow alarmed about his Super Redhawk showing abnormally high velocities. Consistent, factory as well as handloads, across the board.

Since you are getting low SD (Standard Deviation) I would conclude it is the gun itself just naturally throwing low velocities.

Velocity: First I would slug the bore. Then polish the bore with some judicious lapping. Then evaluate again.

Accuracy: How is the lockup? Do each of the chambers line up well with the bore? Read this article:
http://www.alphaprecisioninc.com/revolver/default.htm
Are you measuring from a machine rest or off-hand or just resting on a sandbag? Load up some 1,000 fps rounds and see how the gun and you perform.

Fiddling with loads, velocity and accuracy can be a wonderful pastime. You can pass a lot of time doing that. Kind of like a Rubik's cube with smoke, noise and flame added. Can be satisfying. Can be frustrating.

Good luck. I hope you have fun.

Lost Sheep

 

[Clark]

I can get 200 fps shot to shot variation in velocity from a revolver with LIL'GUN.

 

[AnthonyRSS]

The accuracy really isn't a problem. The gun shoots better than I do. I need to work on my trigger control and sight alignment a bit more.

Even with the LilGun loads my SD was low. I haven't seen any large variations in velocity with that powder.

Interesting to note that my "light" Titegroup loads were significantly faster with the FTX bullet than with the 350gr JHP. More than the change in bullet weight would make it it seems.

The data for the FTX says it is from an 8 3/8" bbl.

 

[Lost Sheep]

Interesting to note that my "light" Titegroup loads were significantly faster with the FTX bullet than with the 350gr JHP. More than the change in bullet weight would make it it seems.

You mean these two?

Post #1

Hornady Brass
Magtech LP primer
350gr Sierra JHP
17.5gr Titegroup
avg 1299fps

Post #17

Hornady Brass
Large Pistol Primer (Magtech also?)
Hornady FTX 300gr
19gr Titegroup (instead of 17.5 gr?)
1530fps

231 fps more velocity. 18% increase in velocity with a 17% reduction in bullet weight and 8% increase in powder charge? In an 8" barrel.

A few more data points would make a more rigorous statistical analysis possible, but it doesn't seem too far off expectations to my mind. But I admit this is more thought than I usually put into analyzing velocity variations. Usually I just look at how linear/proportional the progression is, not how steep. I avoid power levels where the velocity variation is not proportional to charge weight variations.

Lost Sheep