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Discussion Starter · #1 ·
About a month ago I had an experience while shooting some of my test loads for my rifle that is making me rethink the way I go about developing that perfect recipe for whatever bullet I intend on sending down range. I have been hand loading for almost 20 years now and for the most part I have been using the same process with fairly decent results. However, there have been very frustrating journeys as well before stumbling across that "magic load"
Below is what I have done over the years.
1. See an advertisement for some miracle bullet.
2. Find and purchase thatmiracle bullet in whatever weight will match the twist and do the job no matter the cost.
3. Look through the manuals and pick a powder.
4. Find the stop and start range for the powder.
5. Prep cases
6. Fill cases with powder in increments of .5 grains (usually 5 rounds of same charge weight)
7. Seat bullets out as far as I can depending on magazine length or lands/grooves.
9. Carefully shoot and mark groups according to charge weight.
10. Review results and pick the best group, then fine adjust powder and repeat until I obtain the smallest group I can.
11. If groups are not satisfactory I will start playing around with seating depth.
12. If I'm still not happy I will buy more bullets and repeat from about step 3 on....and if that
does not work I will skip to whatever step involves a stiff drink and a break from hand loading
for a week or two.

The reason I ask is; about a month ago I had changed a seating depth on a load .0600 without changing the powder charge and it changed my group size at 100 yards approximately 3.5"
Does anyone mess with their seating depth before changing powder charge weights.
Im curious how much my process differs from others...
GI3
 

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1. Find best powder charge
2. Adjust seating depth

Repeat until I get what I want.

With all that being said, I don't bother worrying about seating depth any more with the M1A rifle. I've found that certain weight bullets (i.e. certain bullet lengths) will usually perform best at specific lengths so I just use those lengths and don't worry about experimenting with seating depth unless I can't get the accuracy I'm looking for.

I use the ogive length as my standard but generally speaking my COALs work out to be about 2.82" for my 168 -175 bullets, 2.80" for the 125 - 155 grain bullets, and about 2.70" for my 110 grain bullets.
 

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Discussion Starter · #3 ·
There are not a whole lot of hanloaders at my local club. I'm greatful yourself and others on this forum for your knowledge and your willingness to share it.

Thank you!
Derik
 

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1. Find best powder charge
2. Adjust seating depth

Repeat until I get what I want.

With all that being said, I don't bother worrying about seating depth any more with the M1A rifle. I've found that certain weight bullets (i.e. certain bullet lengths) will usually perform best at specific lengths so I just use those lengths and don't worry about experimenting with seating depth unless I can't get the accuracy I'm looking for.

I use the ogive length as my standard but generally speaking my COALs work out to be about 2.82" for my 168 -175 bullets, 2.80" for the 125 - 155 grain bullets, and about 2.70" for my 110 grain bullets.
What process do you use to determine the ogive length? I've thought about that some and thought it would require an awful lot of work and would have to be developed for every specific bullet.

My thought was that COAL should never exceed magazine length and then find the ogive length based on the average variation of bullet length. But, that assumes that bullet length differences are contained in the ogive to tip lengths but not in the base to ogive length.

Once you've found the ogive seating depth, do you then add or subtract from that value during load development?

For extra credit, how is ogive pronounced: is it oh-jive , oo-jeeve, oh-give? or ???
 

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I never, ever measured cartridge overall length (in over 30 years of reloading) till I got to messing with these .40 S&W and .357 SIG pistols.

I played with seating depth till the bullet was fit the magazine and was just short of touching the lands when chambered.

I've always changed bullets/powder(amount of powder) to see what my rifle shot best.

If your rifle shoots (likes) best with a certain bullet/powder amount/COAL then record what you made and use it.

I could be wrong but I believe when you changed seating depth you changed chamber pressure/velocity and found a vibration level/amount that your barrel/rifle "liked." I'd be careful about doing that if the powder charge was near max.
 

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I like what they refer to as the Davidson Seating Depth Checker. I have both parts shown below and they attach to your caliper. I've tried a couple of different tools for ogive measurement but the Davidson was the most consistent and easiest to use. If you get one I think the base is a must.

http://www.exteriorballistics.com/reloadbasics/seating.cfm
[FONT=Verdana, Arial, Helvetica, sans-serif]A Davidson Seating Depth Checker. Also known as comparators, these devices allow the handloader to check the critical relationship of bullet ogive to rifling for a loaded cartridge. This relationship is actually much more important to accuracy than the OAL figure which is more commonly used.[/FONT]


There is also a base piece that holds the head of the cartridge and helps align the cartridge for more consistent measurement.


You can get both at Sinclair International
http://www.sinclairintl.com/reloading-equipment/index.htm?avs|Manufacturer_1=DAVIDSON

As for finding the actual dimension for where the bullet contacts the lands, I took a case and used my Dremel to cut three slots in the neck and then I seat the bullet of interest in to the neck (I seat it as long as I can). Then (with a stripped bolt) I carefully place the test cartridge (no powder or primer, just the bullet in to the modified case) in to the chamber and close the bolt manually (I don't have the op rod installed, I just close the bolt by hand and cam it over so that it's in battery). Open the bolt (here's the tricky part) and remove the test cartridge. Sometimes the bullet will stick in the barrel and pull the bullet out of the case so be careful, I push a cleaning rod down the bore from the muzzle and help push the bullet loose. I do this several times and record the ogive length, when I start to get a consistent length I record it as the length to the lands.

You'll find that most times the bullet you are using will make the cartridge too long for the magzine if you want it seated to the lands and in some cases you can't even get the bullet to the lands without the bullet falling out of the case (especially the smaller weight bullets like the Hornady 110 grain Vmax). So what I've come to do is develop my loads by measuring the cartridge overall length (I call the COAL) and adjusting that until I find a length that gives me the best groups. While building the loads I record both the COAL and the ogive length (I call the OGL). When I find the load that gives me the smallest groups I simply record the OGL value in my permanent records. I can't really tell you how far off the lands my bullets are because I don't really worry about it since the cartridges will be too long for the magazine.
 
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And for the bonus round, I always pronounced the word as oh-jive.
 

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That Davidson base piece looks to be very useful for a variety of case measurements. I have the Sinclair comparator that I've been using with the Hornady base piece and I find case alignment to be problematic with that combination.

I've used the RCBS Precision Mic to find the lands on my rifles. That comes equipped with a special 'cartridge' with a floating 'bullet' designed to measure the lands. It works well enough to mimic the distance to the lands but the Davidson comparator looks to provide a more consistent measurement.

I tend to be supra-literal when reading technical posts and, as a result, often miss the actual intent. If I understand correctly, your actual target is the ogive to lands distance that results in the best groups for the specific bullet in use. In that way, it matters little if the bullet length varies from tip to ogive or base to ogive; you've got it covered either way.

Thanks so much for your time and expertise.

PS: With this exchange, I just discovered that posts to your forum here are not displayed in the main forum home page. I'll have to keep that in mind.
 

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RAMMAC: "You'll find that most times the bullet you are using will make the cartridge too long for the magzine if you want it seated to the lands and in some cases you can't even get the bullet to the lands without the bullet falling out of the case (especially the smaller weight bullets like the Hornady 110 grain Vmax)."

I finally got my Davidson Depth Checker and set about determining where a Nosler 168 CC will touch the lands on my Rem 700 5R barrel. I was amazed to find that the Nosler 168 touches at 2.327" (average of 5 bullets) with an COAL of 2.963". The bullet to land measurement of all bullets was within +- 0.003".

My measurement scheme with bullets has a has a problem, thought I, so I redid the measurements with the dummy round that comes with the RCBS Precision Mic kit. The dummy round bullet to land measurement came in at an average of 2.321" +- 0.002", so it looks like all my measurements are playing on the same ball park.

The HS Precision mag on my 700 will handle COAL of 2.81" without too much trouble, but if I subtract that 2.81" from the Nosler 2.963" COAL, I've got a jump of 153 thousandths of an inch!. Thinking that my 700 ought to star in the movie 'Deep Throat XXI, I did a little internet searching and discovered that REM 700s are famous for their long throats and mine is not unusual.

As you pointed out in your earlier post, trying to achieve a bullet jump of 10 to 20 thousandths is likely to leave unfired bullets stuck in my throat. (pun intended).

I'll try the same measurements on my M1A after it gets its new barrel in a month or so. The Davidson Depth seating tool is a real treat. It's measurements give actual numbers rather than the relative numbers of my Sinclair comparator. Thanks for the heads-up on the tool.
 
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