HELP! fist load test! ocw vs ladder questions

[kingfamous]

Im getting ready for my first load test. .308 175 smk's varget. Max. is 45gr. starting at 6% lower at 42.3 at .3gr incriments until 45gr. 3 at each, total of 30 rounds.

Im confused about the two tests. ocw and the ladder. From what I have read, newberry site says ladder test waste bullets and powder. He does the ocw test at 100yds. 6mmbr likes the ladder at 300yds+ ocw uses seperate targets, ladder same poa on one big target, track the shots for best vertical spacing. Am I right so far? Can't you see the same results from the ladder test, as long as you keep track of the rounds you should be fine right? I just don't know why the ladder is at 300+ and the ocw at 100yds. From your experience, what is the best test to find your powder weight?

 

[arborpro]

Re: HELP! fist load test! ocw vs ladder questions


I think ladder test is better for determining how your loads will perform consistently for longer ranges past 300 yds. Where Optimal Charge Weight(OCW), is fine for initial load development. which is a fancy term for exploring how your rifle will perform at 100yds+/-.
Now all the other variables start to way in. we always want the best group the rifle can produce. but there is much more to consider. will you be shooting all your cartridges from the magazine or will you be single round loading. if loading from the box then cartridge overall length (COAL) must be considered. ease of bolt operation must be considered if you using follow up shots.
When I develop a load for target shooting (rapid fire) I want a load that shoot sub MOA, that feeds easily from the box, Bolt operation is easy. which means i want the COAL as specified in the manual and feeds well out of the box. I also want to full length size my cases and want a load that doesn't show much pressure so the bolt operates smoothly.
If I'm not limited to just a few powders I use the 85% solution for load development. which is I want to use the slowest powder that gives me the velocity I'm looking for that will produce the best groups for the range I'm competing at.
Starting point is a powder charge weight approximately 85% of the cartridges water capacity with the appropriate powder. such a charge will fill the case to the shoulder. This can be determined by weighting a unresized fired case on your powder scale (digital preferd). Fill case to max with water and weigh . jot do down the weight then use your fingers to insert your bullet to the specified seating depth that you determined (Box length COAL) to displace water. Wipe off access water from outside of case and weigh again. The difference in the weight is the cases water capacity. Multiply that weight by 0.85 to get a tentative starting charge weight. Remember that reloading manuals start with the fastest powder at the top of the page and the slower powders are at the bottom. Find a powder that comes close to the velocity you want listed in the manual and work your loads from there(starting from the lowest powder charge listed) increase the load in small increments to see if your group shrinks. Remember when measuring group the vertical spread is where you should be most concerned with as horizontal spread could be caused by the wind.
Now that you have a good load that groups you can you the ladder method to check and modify your groups beyond 300yds.
Arborpro

 

[vman]

Re: HELP! fist load test! ocw vs ladder questions

I will try to say this in as little words as possible.

Ladder test aims to find the accuracy window (a range) at which the projectiles leave the barrel with the most consistant muzzle velocity which is directly in line with bullet drop. For example if your bullets came out at 2750 FPS average with an extreme spread of 5 FPS, you would have a range of about 2745 to 2755 FPS, which translates to pretty much no difference in bullet drop.

If you could shoot at a range with no wind, a load like this would be easy to get going thru the one hole.

The OCW looks for similar results however you have groups of same charge weights.

The reason i dont like OCW is that people get confused by groups that are spread out sideways (horizontal). They might have a group that all shots sit in the same horizontal plane, but wind pushed them around so the group appears bad... but really, wind is not included in this equation. Wind has nothing to do with load development, but rather shooter skill.

Just remember, load development aims to get consistent muzzle velocity.

Some people also believe that seating depth plays a role in stability and therefore appears like wind has had an effect... to counter this out of the equation we aim to get concentric brass with close to zero runout on our handloads, and often we seat on the lands. This pretty much removes that extra element of uncertainty so all you are left to deal with is working out the accuracy window.