Why load long?

[Bimmer]

On 9/15/2016 at 6:35 PM, Edge40 said:

I would say the only reason to load longer than SAAMI specs is because the gun will function better.  Better usually meaning accuracy and function.  Some guns such as 2011's tend to like longer ammo for feeding purposes.  That being said a glock may not even be able to fit really long ammo in its magazine...

 

I shoot Glocks, and they like SAAMI-length:  1.135.  I tried going to 1.150, and I had jams jams jams. 

 

I'm shooting powder-puff loads:  155gr SWCs over 4.5gr of Unique. 

[CHLChris]

My Glock mags won't even feed with 40's loaded to 1.160!  Wow those 2011 mags must be deep.  I tend to load mine closer to 1.125 just to make sure I don't cause magazine problems.

[lcs]

 Let's stick to 2011 40s.  

 

If you look at store bought 40 ammunition, it will probably run in every factory 40.    

 

Why would you load long.   When we start using very fast powders that can generate very high pressures, loading long is kind of a safety feature.  If the bullet were to "setback' during the feeding process, you have a slight safety margin.  If you reload correctly, setback is rarely an issue.

 

I can tell you loading long with some barrels causes issues.  Loading long pushes the ogive of the bullet closer to lands of the barrel which can increase pressures.  Loading long also changes the position the bullet hits the feed ramp, in some instances slowing the feeding process.  IMO, loading long in 40 has no real benefit, but if your gun feeds and runs with loaded long bullets press on.   

 

As they say, "if it ain't broke, don't fix it".  I don't recommend starting out loading long.  You may encounter problems that most people would blame on the mags,  and you'd be chasing the wrong problem. 

 

I do like the reasoning.  "It's closer to the target"  

 

[tanks]

I had bunch of factory .40 S&W I wanted to use up. So, I took them to the range. It was like using a single shot pistol it just would not feed properly and rounds would get hung at the lip. Went back to my 1.180OAL rounds and it worked flawlessly.

[BGREID]

I started loading to 10mm length because that is what fit the magazine. Loading issues went away. I am playing with the idea of using the spacers from my 9mm mags to see if that works with factory ammo. I shoot a 2011 EDGE.

[IDescribe]

To clarify a couple of things, you can't feel chamber pressure in the recoil.  Recoil is energy, and it's reciprocal to muzzle energy.  It's a product of bullet mass (and gas mass to a lesser degree) and velocity.  It makes no difference what chamber pressure is.  It's quite easy to make higher pressure loads that recoil less than lower pressure loads with the same bullet and pistol.  The whole point of using faster burning powders is to get lower recoil at the expense of higher pressure.

The reason lengthening OAL lowers peak pressure (which is the pressure that we want to control so the gun doesn't kaboom) is that smokeless powder burns faster the more pressure it's under, and the faster it burns, the faster pressure increases, and the faster pressure increases, the faster it burns, and the faster it burns, the faster pressure increases, and so on, and so on...  It's a positive feedback loop.  SO anything you do at the very beginning of the burn to increase pressure results in a geometrically higher peak pressure.  One thing that increases pressures is decreasing the initial size of the combustion chamber inside the case, which is accomplished by shortening the OAL.   This is why "setback" can blow up a gun.   

That's a general reloading reason why longer might be better than shorter.  The .40 S&W has been known to kaboom with reasonably modest setback, so I'd say it's a reason worth making note of.  And other reasons specific to the 2011 have been provided earlier in this thread.