Constant powder charge, Decremented OAL. Valid way to "work up" a load?

[Dannix]

When looking for a mild plinking load, a helpful poster on another forum mentioned success with a particular powder charge weight in the lower mid range of manual data, so I just charged up a bunch of cases with that charge, started with a long OAL, and reduced OAL in .02" decrements until I got an accurate load. Is "working up" a load this way, adjusting length and therefore capacity rather than powder charge, unusual or inadvisable? This is my first implementation of this technique of load development.

[onondaga]

It is not unusual to start where you want to end with velocity and adjust cartridge LOA to optimize for accuracy. Your Accuracy peak may be at a different velocity, but you are looking for a mild plinking load, so it makes sense to start with the velocity you want.

An alternate method I use is to start with a cartridge LOA you are certain that the bullet just touches the lands and back off.040". Use the 040" off LOA and try several charges below, at, and above your target velocity. See if one has accuracy that stands out.. Either keep the best grouping load from there or begin changing LOA to see if there is an improvement in accuracy.

Gary

[DragoonDrake]

I usually work up in length not down. Watch for pressure signs with the way you are working down, but same principle. I start with book list max COL or at a crimp groove and then work up with one powder charge. Once I find the most accurate length (yes I know as length increases, capacity increase, pressure decreases, and velocity decreases), I stick with that length and fiddle with the charge to find my most accurate load.

[Doc Highwall]

I usually start with the bullet touching the rifling and start with a low powder 10% below max charge and work up in 1% increments. I will load 20 rounds with the starting charge for setting up the chronograph and getting on target in case something goes wrong. I will load 5 rounds for each 1% increment to max and shoot over a chronograph looking for a flat spot in velocity gain then play with seating depth in .005" increments. Say 50 grains was going to be the maxium charge so 5 grains = 10% and .5 grains =1% which means I would load 20 rounds at 45 grains, 5 rounds at 45.5 grains, 5 rounds at 46.0 grains til I got to the max load. Now this will be only valid as long as the components are from the same lot and the case weight is held to one grain or less. This will take 70 cases to do for eleven 5 shot groups with 15 starting rounds left over if everything goes right. When I do this I measure each 5 shot group for both horizontal and vertical spread and plot this on a chart along with velocity. When you do this you will be amazed at what you learn and will last a life time in your load development. My target board is large enough that I place two targets vertically with extras on each side in case the bullet impact for six targets total but I only shoot at the center two. The ones on the sides are in case of a large group displacement when changing powder charges. If you find that you have to make a scope adjustment make it after a five shot group and you can use some of the starting charges to make sure everything is going OK.

[btroj]

I suppose I should first ask this- what cartridge and what firearm?
I would never do this in a revolver or semi auto pistol. For a bolt gun it might work. I would prefer to work with powder charge variation first. Find a load that seems to be good then alter OAL as the only variable.
For a plinking load I would ignore OAL and go with what feeds well in that gun. For plinking is a 1/4 inch smaller group at 100 going to make enough difference to devote the time and energy to this kind of testing? Plinking ammo to me means good accuracy, not necessarily great, and large volumes of easy to load ammo. Cheap too!

You are speaking of target type accuracy requirements, not plinking. Spend the time casting more bullets.

Brad

[Bret4207]

I prefer my bullets to just kiss the lands in the throat. That kind of rules out your method, but I can see where it could work. The only issue is in the gun that desires the bullet being well into the throat. If you aren't well aligned and into the throat to start, how do you know it's the load or the length that's the issue?

[Wayne Smith]

I suppose I should first ask this- what cartridge and what firearm?

Brad

Guys, Brad is right. Remember we are 16,000 now, not the original 5,500 or so. Lot of people here don't make our assumptions.

Just as fit is king in boolits, context is king in writing. Always give your context, in our case, usually cartridge and firearm, but sometimes more. I can imagine someone with no experience reading this and creating a blowup by trying to follow this advice. It may work, but it is a very specific application in a very narrow subfield of reloading.

[btroj]

I hear you Wayne. It is a very specific application for a very narrow wu field of reloading.

The OP also said he is looking for a mild plinking load. The method he is speaking of has o use in developing a mild plinking load. If he had a bench gun I might say go for it. But for plinking loads this is way too much work.

Brad

[Jim]

One thing I haven't seen mentioned yet is adjusting the charge weight. I don't know that there is a given procedure in what to adjust first, but I look for the best charge weight first. The OP mentioned that he got his charge weight data from someone on another forum. That person may or may not be knowledgeable in this, but I prefer to do my own research in finding a good charge weight to start with.
As has been mentioned several times, A plinking round should not take up a lot of your time. Competition and/or hunting ammo? Absolutely, it should be researched thoroughly for the best accuracy, but a plinking load? I don't spend too much time making that up.

[Doc Highwall]

My context is for rifle cartridges.

[looseprojectile]

I am old and lazy and when I want a middle of the road load for a new gun I do a search for PET LOADS. Choose one that seems to serve my purpose and load a few and see how they perform. Refine from there if needed. Most always works for me.
Overall length pertains to how they feed and fit the chamber. They gotta look good too. I'm so vain!
The reason I come here is to steal, borrow/use what works for others:drinks:.

Life is good

[DragoonDrake]

I should have stated that was one single shot guns. Revolvers always at crimp groove and my one semi where ever I can get it to feed right.

[Dannix]

It is not unusual to start where you want to end with velocity and adjust cartridge LOA to optimize for accuracy. Your Accuracy peak may be at a different velocity, but you are looking for a mild plinking load, so it makes sense to start with the velocity you want.
Thanks Gary. I don't mind not being unusual in the reloading world, not one bit. :)


My context is for rifle cartridges.
Indeed, I understand the different contexts involved as they are usually obvious. Not too many guys load their auto handguns to just off the lands, for example. I'm loading pistol loads in this case, but I appreciate all the comments regardless as I'll be developing a NOE 311-165 .30WCF load in the future.


I usually work up in length not down. Watch for pressure signs with the way you are working down, but same principle.
The reason I'm working length down is because I wanted cautiously reduce case capacity. Your post makes total sense for rifle loading though, and I'll put it in my back pocket.


One thing I haven't seen mentioned yet is adjusting the charge weight.
Well, I did start the thread with "Constant powder charge" in the title. :) The only technique I used before this point was adjusting powder charge and leaving OAL at manual lengths (pistol reloading), so that's why I posted to see if this technique was unusual.


I can imagine someone with no experience reading this and creating a blowup by trying to follow this advice.
Point well taken and is why I'm not mentioning numbers, just talking concept. Honestly, if a newbie reads this thread and conjures up a load without first checking against manual data, then they failed to do their homework.


I am old and lazy and when I want a middle of the road load for a new gun I do a search for PET LOADS. Choose one that seems to serve my purpose and load a few and see how they perform. Refine from there if needed. Most always works for me.
Overall length pertains to how they feed and fit the chamber. They gotta look good too. I'm so vain!
The reason I come here is to steal, borrow/use what works for others:drinks:.

Exactly. There's some crazy recommendations out there, but that's what discernment and evaluation against manual data is for.


I suppose I should first ask this- what cartridge and what firearm?
I'm loading 9x19mm in a Glock using the last few hundred FMJs I have left before switching to boolits. I know a lot of guys here have given up on attempting to wean their 9mms off full length gas checks, but I'm going to try Pat's 35PB GC die with thin Amerimax AL.

The previously referred to gentleman, a member over a the BrianEnos forum, gave me some general WSF and Silhouette powder charges and recommended LOAs for 115grn HPs and RNs, with the goal being accuracy not fps nor gamer power factor optimized. He's ball park info for silhouette was instrumental in I finding a good silhouette load, at least as quickly as I did anyway, that's quite accurate for me when I do my part and is actually a relatively hot load.

The WSF can was originally slated to remain unopened until I transitioned to boolits, but for some reason I had the urge to develop a more mild load, which WSF seems to be known to be good for, to compliment my Silhouette load. So I cracked it open and started playing. Because the gentleman's silhouette ballpark recommendation proved quite helpful, I decided to just try the lowest WSF charge of his recommended range a go, a lower-medium charge according to the manual, start with a longish OAL and carefully reduce the OAL in .02 decrements. I found the OAL range where groups started to tighten up, so I'll now focus on that OAL range and shoot for carefully shoot groups the next time I'm out.


I use the term plinking because I'm reluctant to refer to the loads as accuracy loads due to some of the incredible shooting the bullseye shooters here do. When I first started reloading not too long ago, I got my feet wet with lower mid range Universal loads. That was a safe way to learn the ropes, but I got a serious accuracy bug as a result as those loads were grouping maybe 6" or so.

I'm reluctant to also use the term competition as competition pared with 9x19mm probably conjures up IDPA/IPSC connections where the two power factor tiers naturally influence loads. I don't mind if my WSF load ends up failing to make minor, and my Silhouette load is beyond minor to the point where it could be disadvantageous in competition. But that said, I would like both to be quite sufficiently accurate for IDPA/IPSC. Perhaps I should use the term "precise plinkers." I'd better go out and trademark that.

Personally, I'd love to see the old power factor level reinstated but rather than having two tiers, the points are awarded based on the power factor level itself, but that's neither here nor there.