Bullet jump

[bobcat93]

Hello everyone and happy new year.. let me jump right into it..
I have taken about a 4yr break from load development and have just been busy with life.. ive been shooting here and there but just plinking fun
For the life of me I forgot the method of determining best C.A.O.L. .(.bullet set back off rifling lands)..
That is how I determine my case length..
Measure from bolt face to rifling.
With about a .005 - .020 set back and load up 5 cartridges steping off in .005" increments..
Find the best group..and do 5 more cartridge
s in .003" +/- up and down ..find the best group..
Done. That is my official C.O.A.L. for that bullet in that specific rifle..
Is that how you guys determine your most accurate CAOL
What is your technique..is there a way to determine this length with less shots, and less work?..
I know there is published data that will tell me best bullet jump per bullet design, per bullet manufacturers..
I have that book..but I haven't tried it..I just keep using my method..
What is your process..
Just looking for some new ideas to bring my reloading skills to the next level..
I hope I didn't gloss over this to quickly..im trying to keep it short..not always that easy when dealing with the subject of reloading
I'm full of coffee and ready to absorb knowledge..
I hope some of you are willing to share what works best for you..and any voodoo is much appreciated..
Thanks and safe shooting

 

[TheCZKid]

Do a search for Seating Depth here, as there's a lot of asked and answered questions on that here. That would be a good starting point for your questions.

Search results for query: seating depth

 

[Straightshooter1]

Hello everyone and happy new year.. let me jump right into it..
I have taken about a 4yr break from load development and have just been busy with life.. ive been shooting here and there but just plinking fun
For the life of me I forgot the method of determining best C.A.O.L. .(.bullet set back off rifling lands)..
That is how I determine my case length..
Measure from bolt face to rifling.
With about a .005 - .020 set back and load up 5 cartridges steping off in .005" increments..
Find the best group..and do 5 more cartridge
s in .003" +/- up and down ..find the best group..
Done. That is my official C.O.A.L. for that bullet in that specific rifle..
Is that how you guys determine your most accurate CAOL
What is your technique..is there a way to determine this length with less shots, and less work?..
I know there is published data that will tell me best bullet jump per bullet design, per bullet manufacturers..
I have that book..but I haven't tried it..I just keep using my method..
What is your process..
Just looking for some new ideas to bring my reloading skills to the next level..
I hope I didn't gloss over this to quickly..im trying to keep it short..not always that easy when dealing with the subject of reloading
I'm full of coffee and ready to absorb knowledge..
I hope some of you are willing to share what works best for you..and any voodoo is much appreciated..
Thanks and safe shooting

This method works quite well and is a good as any IMHO:

Getting the Best Precision and Accuracy from VLD bullets in Your Rifle

VLD bullets are designed with a secant ogive. This ogive shape allows bullets to be more efficient in flight (retain more velocity = less drop and wind deflection). While this result is desirable for many rifle shooters the secant ogive on the VLD bullets produces another result in many rifle.

bergerbullets.com

Since I've collected a lot of data over the years with my two rifles that I load for, I have a pretty good idea where to start and with the use of QuickLoad, the amount of time it takes to find a good load set up is relatively short, especially when using powders and bullets that I've already used a lot. With that said, I'll just say that I typically use bullets that are hybrids and will start at .010 off the lands the seat 5-8 subsequent seating depths at .003 increments. This .010 off the lands is nothing more than a starting point and for the most part, I'm not concerned with the distance to the lands afterwards (yeah, I don't chase the lands ). I don't like starting closer than .010 as doing so tends to produce pressure spike that doesn't happen when further away, similar to seating touch or jam; not being useful when it does that due to throat erosion. Note too that this often means a cartridge loaded that long will not fit into my mags. So, if needing to loading for the cartridge to fit one's mags, then the starting point is the maximum mag length.

 

[spudgun]

This works for me over the past 6 years.
1. Find the powder charge that gets me the best grouping at 100 yds. I load 5 rounds starting at say 40.0 gr. then 5 more at 40.2, 40.4, 40.6, 40.8 and 50.0 Once I find the nodes of each charge and pick the one that gave me the best group, I will then go on either side of it +/- to see if it improves. Measure the FPS for each group.
2. Now for bullet jump. Find my max OAL (jam) and back off .01" load 5 and back off .02" on the next 5 and go out to .05" Again look for the best groups at 100 yds.
3. After shooting approx 400 rounds I will again check the Jam and see if my rifling has eroded and need to adjust for the jump distance.

Once I reach a point that I cannot seat the bullet out far enough due to throat erosion, I pull the barrel and cut it back and re-chamber and start over again.

I'm sure there will be other suggestions coming..... Just my $.02 worth.

Break out the popcorn.

 

[K22]

I use the Frankfort Arenal method to measure the base to ogive maximum distance to the lands. It is a rather simple method. All that is required is a caliper and a cleaning rod with two spaces that can lock on the cleaning rod. If you are interested, I will PM you the procedure.

I do this for every new bullet and rifle combo I reload for, and I consider it important, not from an accuracy standpoint but from a safety and functionality standpoint. Let me say from the start, my standard for reloads is to produced safe and reliable ammunitions for varmint hunting level accuracy. I am not a benchrest shooter or long range > 300 yards shooter.

My seating depth is control by the following requirements:

1. The overall cartridge length must fit the magazine.
2. I seat no closer that .010" from the lands, usually about .020" off the lands is my normal standard.

Over the years I have not done much testing varying the seating depth. The most influential factor affecting accuracy in my experience is the bullet followed by the powder selected. The small number of tests I have done did not reveal any significant difference, but it might for your shooting discipline. Quite frankly, I have been able to obtain my precision requirements without spending time and money of that aspect of reloading.