New bullets - How to develop new load?

[Tawadc95]

This may be a bit okie but it works good for me determening COAL for my semi auto pistols.

 

With the barrel out of the slide I put an avg. trim length, sized and empty case in the chamber and measure from muzzle to case head. 

 

I then seat a bullet till I get the above obtained length (can be tedious when you get close) and seat it .020 deeper.

 

No guessing that way. 

 

It is necessary to have the case taper crimped to a proper case mouth diameter to make sure cartridge is indeed seating in chamber properly.

 

For 9 mm I'm using 4.0gn of  AA2 under a 124gn Badman polymer rn at 1.14O COAL. The AA2 meters well, has no real noticeable muzzle flash with my 3" barrel and shoots to point of aim out to 20 yds and only 2" low by 25 yds. 

Edited March 2, 2018 by Tawadc95

[rooster]

Tried various ways of measuring oal, never got good results.  I got this method from someone on this forum, quick and easy.  Get a dowel or some other rod close to your bullet size.  Put it down your barrel all the way to breach face, make a mark at the end. Be precise as possible.  Take barrel out and drop the bullet that you want the oal for in the chamber and push it firmly until it stops.  Run you rod back down the barrel till it touches the nose of the bullet.  Mark the rod.  The difference between the lengths is your max oal for that bullet shape.  Back off  whatever you want,  I do about .015.  That’s it.  Took longer to explain than to do it.

[Tawadc95]

Sounds easy.

[IDescribe]

The width of the pencil mark is going to be your standard of precision, and relative to the thousandths of an inch we deal with with OAL, the width of a pencil mark is a lot larger than you think.     I've done it.  It works, but it's not recommended if you're after precision.   

 

Edited March 3, 2018 by IDescribe

[rooster]

I use a razor blade to make the marks on the wooden dowel rod.  You could check pretty easy by making a round at the max oal length determined then drop in the barrel.  It should sit flush with the hood and not pass plunk and spin test.  If it’s not perfect just adjust for it.  

[IDescribe]

8 hours ago, rooster said:

I use a razor blade to make the marks on the wooden dowel rod.  You could check pretty easy by making a round at the max oal length determined then drop in the barrel.  It should sit flush with the hood and not pass plunk and spin test.  If it’s not perfect just adjust for it.  

 

 

Excellent.  I thought about using a razor in that fashion. But rather than try to improve that method, I just stuck with what I've been doing forever.

My method:

I just make a dummy cartridge -- size, bell, seat, and crimp -- and I seat it too long, then I seat 2 - 3 thousandths deeper, and deeper, and deeper, and plunk and spin each time until it spins freely and without drag, and that's it.  I end up with a max that's within 0 - 2 thousandths of true max.  It's pretty fool-proof.  

 

From the true max, I'll knock off .005 - .010 (depending on mood, whim, and star alignment) as a starting working OAL, then adjust down to tune for accuracy in load development.  And sometimes with coated lead, I'll go .010 longer than true max and load into the lands.  

Edited March 3, 2018 by IDescribe

[rooster]

We’re the same, I used that method too.  It works great also.

[Hi-Power Jack]

6 hours ago, IDescribe said:

with coated lead, I'll go .010 longer than true max and load into the lands.  

 

I've never heard of that, before.

 

What's the advantage  ?

 

No feeding problems  ?

[IDescribe]

On 3/3/2018 at 1:28 PM, Hi-Power Jack said:

 

I've never heard of that, before.

 

What's the advantage  ?

 

No feeding problems  ?

I'd read a number of times about people casting their own bullets often finding the most accurate loads to be ones where the bullet is loaded long enough to engage the lands when chambered. 

 

I went a long time without trying it myself, then inadvertently loaded a few hundred rounds too long, long enough to engage the lands, and it was a load that I had been loading regularly, but a couple of hundredths shorter.  They chambered fine, so I shot them, and accuracy was better than than the shorter load that was out of the lands.  Since then, when I develop a load with coated lead, I'll load into the lands to see how it likes it.  Sometimes it's a bonus, and sometimes not.

[Hi-Power Jack]

You are talking about semi-automatic handgun ?

 

Not a bolt rifle ?

[IDescribe]

I am talking about what I'm doing being with a semi-automatic handgun.  But, yes, what I had read about bullet casters doing it was typically regarding bolt rifles.   To be clear, I'm not loading long enough to jam the bullet into the rifling, set the bullet back, or hold the action out of battery.

[Hi-Power Jack]

8 hours ago, IDescribe said:

  regarding bolt rifles.   I'm not loading long enough to jam the bullet into the rifling 

 

Oh, sorry, thought you said you were "jamming the bullet into the rifling" with a semi-auto pistol.

 

I'd be afraid to try that, due to possible pressure increases.     

[IDescribe]

23 hours ago, Hi-Power Jack said:

 

Oh, sorry, thought you said you were "jamming the bullet into the rifling" with a semi-auto pistol.

 

I'd be afraid to try that, due to possible pressure increases.     

 

I wouldn't want to use max loads from published data and be loaded into the lands -- that would be a pressure concern I'd want to avoid.  And I for sure wouldn't want to take someone else's load, and swap it into a short-throated pistol like a CZ and have it jammed into the lands.  But I don't worry about it when I'm working up my own for a particular pistol. 

 

Also, because straight-walled pistol cases shrink as you reload them, and because most 9mm cases are shorter than the SAAMI spec of .754 when they're brand new, most of the cases we're reloading are considerably shorter than the .754 the chambers are cut for, meaning they often don't truly headspace on the casemouth the way they're supposed to, more like headspacing on the extractor.  So I have wondered when I've gotten good results with loading just a little long into rifling engagement if that serves to line the bullet up with the bore more consistently.  That said, that light rifling engagement doesn't always produce the best accuracy, so I may well be attributing the better accuracy to the light rifling contact when in fact it's just coincidence.