Develop Load same time as C.O.L. ?

[Supermanofsteel]

I'm new to reloading and am looking for some advice.

This will be my first season developing loads for my guns.

During the developing process should I develop the powder charge based on the factory suggested C.O.L. for the cartridge or should I build up the charge based on what I've determined is the C.O.L for my rifle.

Would it be simpler to develop to my rifle's bullet seating depth and once I find the best groups than tweak the bullet seating depth a few thou either way or will trying to adjust both at once cause more headaches?

 

[Somerset Bar]

COL is cartridge overall length. Maybe I'm missing something, but powder charge is based on projectile weight and type, and the powder type used. COL is just where that projectile needs to sit for optimum placement in the chamber/barrel, no?

Maybe I'm reading the post wrong, could be, but for myself, I use a go-nogo die to check each case I am reloading, and seat my projectile according to the COL. Powder charge is then -somewhat- flexible, as long as you are using the powder manufacturer specs (min max).

For example in my .223 I have a chart of what my powder charge is for 55gr jacketed bullets (all I use), and the various powders I can get. If it's a new powder, I load up 5- 10 round batches of various grain loads and just go shoot. Whatever performs the best I keep that data sheet, tack it up at home and I know what is my preferred load for that powder. The COL is the same in all of them, otherwise you would have problems in the magazines or when loading into the firearm.

For me, the experimentation is huge fun.

 

[grinder08]

The main things with COL is never use less than the minimum it can lead to dangerous over pressure and the more than the maximum can lead to feed problems. They usually give minimum on the loading tables but you should figure out the max as well. Typically I aim for midway between the min and max but individual guns may feed better at different lengths depending on a number of factors. Never go under the min. Dangerous, may go big bad boom.

 

[HeavyTread]

There's another interesting thread about this going on right now here.

My personal opinion is that, for your first couple of batches, stick with the published load data including powder charge and OAL. Then vary charge amount and then vary COAL when you get more experience. Never change two variables at once.

But I'm also new.

 

[HeavyTread]

The main things with COL is never use less than the minimum it can lead to dangerous over pressure and the more than the maximum can lead to feed problems

Longer COAL can also lead to pressure problems.

 

[sunray]

Hi. Fiddling with the OAL is one of the techniques for tweaking the load. It's a time consuming trial and error thing. So work up a load, then you can muck around with the OAL, if you want. Just remember that hunting accuracy doesn't mean one hole groups. Not all rifles are capable of that kind of accuracy and some just won't do it. Consistency is far more important anyway.

 

[Supermanofsteel]

Thanks for the input. I've read the other article and it does touch on what I wanted to know. Basically is it a good idea to start at the recommended COL and adjust powder charge towards max in hopes of finding the best charge for smallest groupings possible or is it better to adjust the round to my rifles best bullet seating depth then work up towards max charge again in hopes of finding the smallest groupings possible.

From what I can gather on this fourm and others since posting this question...

COL as stated in the book means very little as it's based on the rifle the manufacture was using when doing their write up. It is recommended by many reloaders to find the correct bullet seating depth for my specific gun and keeping the bullet a min of .010 off the riffling develop the powder charge up to the max keeping a watchful eye out for signs of excessive pressure.

What I thought would have been two variables at once really becomes one variable once I commit to the bullet seating depth. As that variable becomes fixed and will not change until the best suited powder charge has been found. Once I settle on a powder charge, that variable becomes fixed. If I want to tweak a bit more I can then reduce the powder charge %5 to allow for a variance in pressure as I start adjusting the bullet seating depth from approximately -.060 to a min of -.010 from the riffling.

Once I find the correct bullet seating depth, I inspect the cartridge for signs of pressure and if everything looks ok I can bring the powder charge back up to max charge again.

 

[Supermanofsteel]

Longer COAL can also lead to pressure problems.

My riffle is a .270 reloading hornady 130gr sst and the suggested col in the hornady reloading book = 3.210.

When I used a dummy round to find the actual throat length of my rifle I found the round doesn't engage the rifling until the round is 3.380" long. That's .170" difference.

If I develop a round with a powder charge at the 3.210. I would then have to reduce my powder charge considerably as I started adjusting the bullet closer to the riffling. As your chart shows, if I adjust down to say -.020 to -.010 off the lands (.150 of movement) , I could potentially be increasing the pressure by as much as 6000 psi.

I figure it would be better to just start at -0.020 off the riffling so when I start adjusting bullet depth I minimize pressure variances (keeping in mind I've already backed off by %5) when I try a few rounds at -.030 and a few at -.010.



Please let me know if my thinking is off in this matter. I'm just trying to explain it the way Ive been understanding what I've been reading. If I'm mistaken please let me know as I'm new to this and would greatly appreciate input form more experienced people.

 

[HeavyTread]

Please let me know if my thinking is off in this matter

I wouldn't take that chart as gospel.. it's just intended to show that peak pressure can go up as well as down when seating depth is modified past some 'ideal' low point.

Personally I would stick with one variable. Fix all other variables and carefully modify one at a time. If that's seating depth then of course start well below the maximum listed powder charge and carefully work your way up.

 

[silverfoxdj]

I would take a median COL perhaps similar to what you see manufactured loads set to.. and then work up my loads to find the sweet spot.. COAL is left last for me..

 

[cosmic]

For a hunting rifle, COL is a relatively unimportant tweak, compared to bullet weight and charge weight. Playing too close to the lands is a good way to get into problems for a rookie. Going down to 10 thou is asking for trouble - you wont be able to hold this from round to round. For hunting rifles, I use 30 thou, and I recheck everytime I use a new box of (same spec) bullets.