Velocity descrepancies from load manuals?

[ibcguy]

I'm new to reloading, just having made my 3rd batch of reloads (357 sig and .41 mag). My shooting chrony just came in from Midway, so I went out today to measure some of my .41 mag loads.

Here is the starting load that I used, per the Speer #14 manual.

Powder: 20.5 grns of H110 (each load measured w/ electric scale)
Bullet: 210 grn Speer Sportsmaster (jacketed hollow point)
Primer: CCI 350 large pistol magnum
Brass: various

I was a little disappointed in the velocity results I was getting. Average velocity was 1123 fps (Speer publishes 1237 fps with this load). I was shooting these out of a 4" S&W 357PD (titanium/scandium)in approximately 54 degree weather. I know there is going to be some variation in velocity due to barrel length, temp., etc. but I was expecting to be closer to the published velocities.

Also, on one shot the chrony read 1620 fps, which I have a hard time believing as the shot sounded/felt the same, and no obvious signs of overpressure on the case. What do you think would cause that reading?

Anyways, how much variation do you guys see between published load data and actual velocities measured in your guns at the range?

Thanks for the help!

 

[Dean Williams]

You won't often get the same velocities shown in loading manuals. Every gun is unique, and that will affect bullet velocity and pressure. (Your load shows max in my Speer #12. I don't know if it's different in the #14)

If your barrel is shorter than the barrel on the test gun, the velocity you get will probably be less.

If the test barrel was not actually part of a commercial firearm, in other words, they used a test barrel/chamber, the velocity you get will probably be less.

They probably used a different lot of powder than you have.

They were probably shooting at a range with a different ambient temp.

Chronographs can be fooled, and it seems to happen fairly often. The 1620 fps round was probably just the chrony, but it would make me wary of my loading technique if I were a new reloader.

I would sort my brass if I were working close to a max load, if I were you. All brands of brass of a certain caliber do not hold the same volume, and that will certainly change chamber pressures.

In my experience, my handloads that are exactly the same as those in a loading manual are regularly lower than the book shows. Same thing with testing factory loads and comparing the test figures with the factory's claimed velocity.

 

[NCsmitty]

I concur with Dean Williams on everything that was mentioned. It is very important to get a good crimp when using H-110.
One of the important issues is the use of the same brand of brass in working up a load and making sure that they are the same length as that will affect the previously mentioned crimp. Consistency is the key to accuracy.

You'll find that between different manuals, you will often see vast differences in min & max recommended loads. It's wise to err on the side of safety.

NCsmitty

 

[Shoney]

If you will look at each listing of loads, you will note that each probably uses a different weapon (Win, or Rem, Sav, Rugr, Colt. S&W, so on) and different components (primer, case, bullet) in addition to the variation in the powder amount; and they are doing the testing in different parts of the country where elevation can be a big factor in speed. What they usually do not list is where they conducted the tests, but geographic location and weather at time of testing factor in.

Combinations of factors can cause great variances in velocity and pressure. Here are a few factors:

Primer: strength, brisance - is a measure of the rapidity with which an explosive develops its maximum pressure
Barrel: length; tightness of bore; height of the lands; distance of bullet to lands; temperature of barrel;
Bullet: bearing surface of bullet, alloy of bullet; shape of bullet; distance off rifling;
Brass: new/used elasticity; manufacturer, volume; crimp;
Powder: new, aged, old, batch powder was from;
Weather: ambient air temp., barometric pressure, humidity
Elevation: above sea level
Other: I am sure I have not listed all

 

[ibcguy]

Ok, thanks guys, I feel better now. I use the Lee Factory Crimp on my .41 loads, so I guess I'm ok there. I'll slowly start increasing the load...not sure if I'll ever get to the max published load, as the recoil is already pretty brisk.

 

[Dean Williams]

I'll slowly start increasing the load...not sure if I'll ever get to the max published load,

Just because you aren't getting the same velocity as the book doesn't mean that you aren't already at a maximum load.

 

[ArchAngelCD]

You got just over 100 fps less than the published data. I would jump for joy if all my reloads came that close to the published data.

 

[R.W.Dale]

Velocity descrepancies from load manuals?

is the normal state of matters. actually meeting published velocities would be the exception

 

[RidgwayCO]

Looking at my Speer #14, they used a S&W 57 with a 6" barrel for testing. Getting 114 fps less with your 4" barrel is well within the range of normal.

By the way, isn't your "Sportsmaster" bullet made by Sierra? Using the data for a Speer Gold Dot Hollow Point instead of a true JHP can also cause problems, as Speer says to load the GDHP more like lead bullets rather than jacketed.

 

[Steve C]

As RidgwayCO pointed out, you are shooting your loads form a 4" barrel and the manuals use a 6". I've chrono'd 20.3grs of H110 behind a Hornady 210gr XTP JHP out of my 6" S&W 57 and it averaged 1,286 fps.

The other factors are different pistols will produce different velocities as well as component mix. For a 4" barrel you're getting a normal velocity reduction due to barrel length.

 

[mkl]

The maximum published load is based on pressure, not velocity.

Never exceed the max load powder weight in an attempt to attain the published velocity. You may very well exceed the maximum pressure and end up with a blown up gun!

It has been my experience in many years of reloading that in 95% of the cases, the maximum load in grains does not give the velocity published in the reloading manual.

 

[ibcguy]

Thanks for the responses guys.

RidgwayCO is right, the Sportsmaster is a JHC made by Sierra, not Speer. My bad.

I know the published load data is based on pressure, not velocity. One of the reasons I'm interested in this to begin with is my 357pd was purchased as a woods gun. My other choice was a 10mm, but I went for the .41 mag as most people indicated the .41 mag offers a good bit more "power". I'm seeing the Double Tap 10mm 200 grain loads are running hotter than most of what I'm seeing for 210 grain .41 mag loads, so I am a little curious.

I'm learning alot though, and I appreciate the info.

IBCGUY

 

[ArchAngelCD]

ibcguy,
For a woods gun or for that matter any gun, velocity isn't the best way to evaluate the possible performance. Your bullet choice will greatly effect how effective the round is against an attacking animal. Sometimes too much velocity will lessen the effectiveness of the bullet. In both calibers a very hard cast bullet with a large meplat would be the best choice in bullet driven to safe velocities for that bullet.

For example, a 45-70 is a fairly low velocity round by today's standards yet with the proper bullet it will stop any animal in North America. The 300 RUM does 3000+ fps yet at 1850 to 2000 fps the 45-70 Gov't can do just as good a job or better. (at fairly close ranges that is)