Bullet seating depth and COAL? - The HuntingPA.com Outdoor Community
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post #1 of 15 (permalink) Old 11-29-2016, 10:18 AM Thread Starter
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Bullet seating depth and COAL?

I watched a video about bullet seating depth of your rifle on youtube by someone who apparently knew his stuff.
I followed the directions (to the best of my ability) and measuring my 308 Winchester several times came up with 2.998.

The COAL stated in my recipes was anywhere from 2.735 to 2.810 and SAMMI spec was listed by one program as 2.810 while another was listed at 2.800. One YT vid stated that the COAL was merely what will fit in a standard .308 magazine.


Does that sound right? 2.998 BSD vs 2.800 COAL, or did I screw something up?
I would assume, if correct this is for bullets fed one at a time by hand?

I would like to work up a hunting round that would be magazine fed and a target load for long distance and accuracy for fun, which could be loaded singly by hand if necessary.

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post #2 of 15 (permalink) Old 11-29-2016, 10:42 AM
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Get a oal guage and know what free bore space you have in your chamber. Hornady Lock-N-Load Overall Length Ga Bolt Action
In all of my rifles I can seat bullets .005 off the lands and still use the magazine. The only bullets I've done better jamming were VLD Match bullets.
At this point you also want to be measuring from the bullet ojive also. Not the tip.
Hornady Lock-N-Load Bullet Comparator Basic Set 6 Inserts
This will attach to your caliper.

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post #3 of 15 (permalink) Old 11-29-2016, 01:46 PM
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It is extremely common for factory rifles to be throated much longer than what will fit in the mag. A lot of bullets seem to like some jump. Accubonds come to mind which usually seem to shoot best 40 thous or so short of touching the lands. You should be able to find an accurate load that will load from your mag. Find a bullet, powder, charge weight that shoots accurately first. Then fine tune with the COAL. If you want it to mag feed, don't bother with COAL's longer than what your mag will take. If you're happy to single feed, you can experiment right up to the lands. I doubt you'll need to do that. It's the BR guys that only have one way to get a bullet out once a round is chambered. Watch for pressure signs if you're jamming bullets or not giving them any jump.
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post #4 of 15 (permalink) Old 11-30-2016, 10:43 AM Thread Starter
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Thanks...

Quote:
Originally Posted by ROVERT View Post
It is extremely common for factory rifles to be throated much longer than what will fit in the mag. A lot of bullets seem to like some jump. Accubonds come to mind which usually seem to shoot best 40 thous or so short of touching the lands. You should be able to find an accurate load that will load from your mag. Find a bullet, powder, charge weight that shoots accurately first. Then fine tune with the COAL. If you want it to mag feed, don't bother with COAL's longer than what your mag will take. If you're happy to single feed, you can experiment right up to the lands. I doubt you'll need to do that. It's the BR guys that only have one way to get a bullet out once a round is chambered. Watch for pressure signs if you're jamming bullets or not giving them any jump.
I found this on the Barnes website:

3. Where do I seat the Triple-Shock, Tipped TSX and LRX bullets?
Answer. We recommend seating these bullets .050″ off the lands {rifling} of your rifle. This length can be determined by using a “Stoney Point Gauge” or other methods. You do not have to seat the bullet at, or on one of the cannelure rings.


kdvarmint, Thanks! The links didn't work, but I figured it out and put those items on my list to Santa.
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post #5 of 15 (permalink) Old 11-30-2016, 10:58 AM
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You can get recommendations all day long on seat depths, but the bottom line is YOUR rifle and what it does. And you'll only know it by shooting/experimenting with seat depths.

What I do with a rifle when I start load development is find out the distance to the lands. Then I see how that length relates to the magazine. My end goal is to find the longest functional length for the rifle. That will be determined either by touching the lands OR by magazine box length. I've got a mix of rifles as far as which factor limits them....for some it's the throat. For others, it's the magazine. I rarely pay more than passing attention to the "book" or SAAMI spec'ed COL, because I'm pretty confident I will not wind up there till I'm done.

Regardless, my methodology in load development is to isolate the variables. The biggest variables, (assuming you've selected your powder and bullet) are charge weight and seat depth. So...for a given bullet/powder, I'll use the longest functional length and run my powder charge weight spectrum to see what looks best. Then I'll take THAT charge and work seat depth in from the longest functional length, usually in 0.010" increments. Some go 0.005". Whatever works for ya.....but that's my approach.

I watch guys sort of "grope in the dark" by fluctuating powders/bullets/seat depths all willy-nilly and shoot 100 shots and have no better idea what to do with the rifle than before they started. I have had a rifle set up in less than 30 rounds and no more than 100 usually, till I find a suitable load.

The bigger "guesses" are on powder and bullets. I'm somewhat convinced any given bullet CAN be made to shoot well in any given rifle, with the right load development and some flexibility in use of what powders the shooter employs and seat depth work. Of course, some will shoot better than others.

But for seat depth, you will absolutely tear your hair out if you don't establish a baseline from which to work. For me, I go to the longest functional length and work back from there. Start in the middle somewhere and you're gonna be guessing.

That's just my approach.
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post #6 of 15 (permalink) Old 12-02-2016, 11:15 PM
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My experience has been the bullet being the single biggest difference maker. I'm pretty much convinced (not to be argumentative, just my own experience) no amount of load variations will make a bullet that doesn't shoot well in a particular rifle, shoot well. And I've wasted a lot of powder trying to make the bullets "I wanted" to shoot work. These days I read up on which caliber I'm loading for in a comparable length and twist barrel before I even start. I look for what's commonly working as far as primer, powder, and bullet weight. That's where I start. As far as brass, Winchester is typically the most uniform lower cost. Lapua is preferred. I also use Hornady and with a 30-30 that only needs to kill deer not really further than 150yds, once fired Remington brass of different lots gets it done. I like to buy 150 cases all the same lot per rifle. I shoot some competition bench rest even with my factory rifles. 3 groups of 50 keeps me with 50 loaded, some of another group left over from a shoot, and another group of 50 to be working on reloading. I try several different bullets and weights. It takes minimal time to find the bullet your gun likes best. Then I play with powder charge weight and different powders. A good load will have a very comparable point of impact within a small range of powder weights. Once you've worked out your load, then it's time to "fine tune" it with seating depth. I start load development with all bullets .005 off the lands. For me, I typically find the sweetest spot from .010 jump to .010 jam. I only have one rifle that shoots better jammed. And it is a custom barrel in 6br shooting Berger VLD's. The rest usually end up doing well enough with Hornady bullets jumped. Not that Hornady are always the best shooters, but they usually end up close enough in my factory rifles with a price that's hard to beat for a few 10th's of an inch. Most of my rifles are short actions, and I've yet to have one that I couldn't touch the lands and still use the magazine. Maybe I've just been lucky.
Since you mentioned you're shooting a 308, for target I've gotten very good results with Federal 210m primers, Varget powder, and Hornady 168 A-Max bullets. Short jump between .005 and .010. That's also out of a 26" barrel.

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post #7 of 15 (permalink) Old 12-03-2016, 01:19 PM
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The rifle where it is worst for me to reach the lands is my 300H&H. There's just not enough mag room.
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post #8 of 15 (permalink) Old 12-03-2016, 01:43 PM
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First remember that COAL is only good for that particular bullet and you want to back it off the lands a little. Changing bullets will change the COAL.

In most cases the magazine length is the limiting factor. So see if your initial setting will cycle through the mag. If not you have to make it shorter.
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post #9 of 15 (permalink) Old 12-04-2016, 10:27 AM
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I'm just curious, those that run into magazine length issues, are these older rifles most often? In all of my newer factory rifles, less than 10 years old Savages and Thompson Center, the free bore between reloading manual COAL and actually touching the rifling is short. In my Remington chambered in 270win I got new in 1985 has a lot of free bore. On Nosler website it list COAL at 3.320 I'm loading at 3.500 COAL short jump. Even with this long overall length I have a little room left in the magazine.
I'm wondering if all newer rifles have closer tolerances due to higher customer demand in accuracy verses the good ol days.
First pic 270win load. I added a second pic of my 308win load measuring off the bullet ojive for those unfamiliar. Much more consistency in measurement.
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post #10 of 15 (permalink) Old 12-04-2016, 10:42 AM
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Quote:
Originally Posted by PA-Joe View Post
Changing bullets will change the COAL.
Due to differences bullet shapes and point on a particular bullet where bullet ojive contacts the rifling.
For those new to hand loading and wondering the reason for the difference.

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