Correct bullet seating depth??

Grunter

Grunter

New member
Guys Help me out here!

I have a question that is bothering me to no end. How do I know when Ive seated a particular bullet to the correct depth?? Im loadin for the 243wssm AR and am using different bullets. They have no crimp ring so Im not sure what is the correct length after seating. I tried the COL number found with the charts im using but it does not look right( looks like it sticks out too far) If I insert them to deeply am I changing the pressure? I just dont get it yet!

For instance Imrs chart for 58 gr v-max says the C.O.L. is 2.220". Is this written in stone and I should maintain this length or is this just a suggestion? It just dont look right.

Please help me out here as im afraid im doing something wrong. Ive searched the threads and my manuals but cant find the answer I seek. The only reloading I did before was for a handgun and the bullets had a crimp ring so I felt confident I was doing it right.

Thanks for your help, Dave
 
hello, get a col guage "ragn cagin" here sells a good one or a stoney point among other brands.then get a bullet comparator to measure off the bullets o-give.the col listed in the manuals is a guide i don"t know on ar's but most bolt guns will accept a longer col than is published..i may use the col only once to attain a max length for my gun then i attach the comparator to my caliper & measure the o-give then i back up 0.20 thousandths & start load develpment when a load shoots well then seat closer to the lands & see if accuracy improves...it takes a while to figure this stuff out "but"becomes easy with time..your handloading for your gun not someone else's. i hope that helps.....
 
I guess my confusion started after reading the charts for 100 grain loads and the C.O.L. listed is 2.30, but the factory winchester 100 grain loads actually mic at 2.143. So is the C.O.L. just the max?

After using the Freebore tool that came with the RCBS precision mic. The length reads 2.244 after inserting several times and rechecking. If I reduce this number by .02 roughly would I not have the prefered COL for this barrel? If so this would be much shorter than the listed COL in the charts..right?

I still dont get it!
 
+1 to what Dave said, but remember they have to fit into an AR mag, so your OAL will be somewhat dictated to you regardless of the length of the rifles throat. If the rifle was built with the constraints of the mag in mind, then your leade(freebore) may not be too long, and you may be able to seat the bullets just off the lands and still work in the magazine.
Good luck,
F1
 
Dave...........You said .20 off the lands. Did you mean .02?? Some guys say .002 from the lands, but my experience has been that most bullets aren't consistant enough to get that close and not change the seating die repeatedly.
I am by no means an expert at reloading so I'm probably missing something here.

Take Care
Charlie
 
hello charlie,do you use a comparator?? after a initial col & seating a dry round=no powder=no primer at my max col i chamber one to make sure the bolt closes with no trouble...from that point forward i use the comparator & use o-give measurements..i am no pro by any means....if i read my caliper correct yes i start at 0.020 from the lands i deterimine this after a o-give measurement at max col..then back up 0.020 then work from there..i may not have said that right in my previous post & am to computer illiterate to figure out how to get back there without starting over LOL...anyway if i maybe??understand what you are doing?? i don't measure from the bullet tip to base of brass anymore bullet lengths are inconsistant..i only measure from the o-give once i know i can chamber a max col round....it's hard to explain in type...i sure hope this makes sense!!
 
Published COL is not written in stone, it is a standard set so that everybody (arms and ammo manufacturers) are on the same page. As a reloader you can change it from the published standard, sometimes significantly.

From an accuracy standpoint the first rule (and second and third) is consistency. As mentioned, measure off the ogive, not base to tip.

Most folks find that the best accuracy is obtained (in most rifles) by seating very close to the lands. Often in a magazine action you can't do that because you have to be able to load the cartridges in the magazine too.

Seating depth will affect pressure so do your load development carefully and in "baby steps".
 
Grunter why don't the 58 gr Vmax look right? you think it is to long?or what?
Load a dummy round no primer no powder (you should do this anyway, is a great way to set seating dies) Anyhow load the dummy and smoke the bullet tip,(Seat it at max) this is what it is called I am an old timer and before all therse new fangled comparitor things were common, we had to do things a bit differant. Any way smoke the bullet tip useing a candle or magic marker Soot from a candle works better) insert the smoked dummy into the chamber with finger pressure then close the bolt and make sure it locks all the way. Eject the dummy round looking carefully at the bullet tip you will see marks from the leade that is the begining of the rifling. If you don't see them then you are probbily godd to go. If you can see the markes then begin setting the bullet deeper in 0.001" increments. There is a lot of contrversy over seating depth and freebore ect. I know some benchresters want the tip touching the lands and others who want anywhere from 0.002 to 0.010 freebore there you have to expreiment and see what the rifle likes best ( rember that barrel erosion is a fact of life so the freebore will change over time.)
Now the preceding was the way we did it with BOLT ACTIONS.
An AR is a wee bit differant, you need a pressure spike until just after the bullet passes the gas block this only takes a milisecond. but the pressure curve is a bit differant in the AR, than the bolt action.
Once you find the COL for a specific bullet you need to check the actual case capasity with that bullet seated to that length, reduce your powder charge accordingly your COL also has to cycle through the mags and has to have enough pressure to cycle the action.I am planning a build like what you have and have been doing a lot of research on it and the handloading aspects of that round and action. I buy factory ammo as a benchmark to set my handloads to my loads always pass up any factory load.
The 243 WSSM shows COL from 2.220with a 58 grn hornady to 2.300 with the 100 gr btsp at the same time the .223 shows COL of 2.280 with a 40 gr to 2.550 in an 80 grn all of those will feed through the AR mag or should. I would go with the published COL but check the amount of freebore in your rifle. but as was said before when working up loads use baby steps
 
grunter, i grabbed a few loads tonight & did some measuring c.o.l. style.example for a 223 hornady says a #2265 col is 2.200 my measurment is 2.210-2.215.sierra says a #1365 c.o.a.l.is 2.250 mine come in at 2.245-2.255.back to hornady a #22261 says 2.250 mine measure at 2.295-2.300. that last figure is quite a bit more than the listed c.o.l.not to beat a dead horse "but"col is a guide...all our rifles are different..if i measure off the o-give on these rounds i will only find a variance of a thousandth or two but col will vary 5-10 thousandths..hope this helps????
 
Since I'm in the process of getting back into reloading, I've been reading this thread with great interest... It's a question that always bugged me before...

FWIW... Flyrod and others mentioned that OAL for AR's was often determined by the magazine rather than the distance to the lands... My Model Sevens, too! In my 7mm-08, Remington's factory 140 grain loads won't always feed properly. I had to go to Winchesters which are about 1/4" shorter. Funny thing is that both shot basically identical groups! /ubbthreads/images/graemlins/shocked.gif Go figure! /ubbthreads/images/graemlins/laugh.gif

me!

337450.jpg
 
OK so far ive determined after many manners of testing that the measurement from the case head to the 0-give point on the bullet is 1.865 making the overall bullet length of a 87 gr V-max about .80 from clearing the mag and the col 2.328 which is indeed longer than the listed 2.29 col. The listed 2.29 col still puts the round long of making the mag. Long story short ill have to seat for the mag clearance and forget about the optimum distance from the 0-give distance. Is what it is I guess!

Thanks for all your replies as they have given me lots of food for thought. Being new to loading for the rifle I still have lots to learn. The col listings have me baffled still as they apperantly dont apply to this particular weapon, al least as far as 80 gr and larger bullets are concerned. The 58's and 75's can be loaded to the suggested col and fit the mag, although there still miles from the 0-give point.

I need a couple Tylenol's now! /ubbthreads/images/graemlins/smiliesmack.gif /ubbthreads/images/graemlins/smile.gif

Dave
 
Here is a way that doesn't take tylenols

The Ogive the point at which your bullet becomes FULL CALIBER DIAMETER. The Nose doesn't count since it is not large enough in dia to make contact with the rifling.

The boltface sits against the casehead, and the rifling is the point at which the bullet can go no further without being forced. SOOOOO, for every individual chamber, there is a maximum distance (OAL) that is the distance from the closed boltface to the rifling. Now, the round is considered "off the lands by .xxx" when the bullets OGIVE is .xxx" from touching the lands. The bullet is considered "at the lands" when it just makes contact. The bullet is considered "into the lands" by the amount longer than the casehead to rifling measurement it is. At this point the bullet will get small rifling scars where it's jacket is actually slightly forced into the rifling.

Now, you are using a magazine fed rifle, which in the end, the length of the magazine will always dictate the OAL due to it's having to feed from the magazine.

in a semi-auto, if I could get it at say .010" off the lands and still have it feed reliably, I would start my load development there.
 
Dave........Thanks for clearing that up for me. You'r like me, /ubbthreads/images/graemlins/smiliesmack.gif
You are correct in that I am just measuring C.O.L., and not to the o-give. I just ordered the Stoney Point from Midway. That should help a great deal because like you say, (the bullets actual length does seem to vary quite a bit).
You guys did a great job explaining it so that even a dullard like me can understand.

Thanks and Take Care
Charlie
 
charlie, i really think you will like that tool..maybe i"m a simpileton "but" when i started-loading rounds based on o-give measurements my life got simpler..i could make sense of that as opposed to all my variations in c.o.l. lengths.i as mentioned don't care what the length is as long as a round can be easily chambered.just make sure the round is flush in the body of comparator & the base of the brass is flush with your caliper.i always hold up to a light to make sure...you"ll see what i mean..good luck.
 
Good Deal, Pistolero!! /ubbthreads/images/graemlins/grinning-smiley-003.gif
I knew there had to be a simple, easy way!! /ubbthreads/images/graemlins/grinning-smiley-003.gif /ubbthreads/images/graemlins/grinning-smiley-003.gif
 
Take a look at the Stoney Point Chamber-All Bullet Comparator with a 243 cal insert. The web site www.sinclairintl.com lists them for $ 13.95 and $ 3.70 . You will also need a calipers to use with the tool. Every rifle I have seems to like a different free bore--bullet jump. If you have more than one centerfire rifle the tool is worth it.
 
Last edited:
If you are speaking of an AR or any rifle that is magazine fed, you are limited to the overall length the magazine will accept. It is rare and almost none existent in my experience that the throat of a rifle won't accept magazine length rounds. Every rifle I have seen will accept rounds with longer than overall magazine length seating depths. This is why you have to single load 80gr match bullets in AR's. This is the problem I have with magazine fed rifles other than bolt action ones. Magazine is the limit of your overall length. The other problem with the WSSM's is that even normal seating depths with high BC bullets cause them to be seated way deep in the case reducing powder cap or raising pressures.
 
The sinclair tool actually uses a fired case from your chamber to find the lands, it is probably the best $20 I have spent on the loading bench. That and a comparator will allow you to switch bullets and load to the same Ogive-to-land distance every time. I didn't like the stoney point tool because the cases are not fired in your chamber unless you send them shells to thread for you, but at increased cost of course. The sinclair tool will give you a perfect boltface to lands fit, every time, and it is repeatable.

The other "free" method is to use split cases. Take a dremmel tool and run a split from the mouth down to the shoulder/body junction after sizing the neck/case. insert a bullet into it by hand and close the bolt, then gently remove the case and the bullet should have been pushed back into the case by the rifling. Now, knock off a couple of .005", and set the die to seat at that length.
 
Quote:
The other "free" method is to use split cases. Take a dremmel tool and run a split from the mouth down to the shoulder/body junction after sizing the neck/case. insert a bullet into it by hand and close the bolt, then gently remove the case and the bullet should have been pushed back into the case by the rifling. Now, knock off a couple of .005", and set the die to seat at that length.



Thanks for the tip. /ubbthreads/images/graemlins/grinning-smiley-003.gif /ubbthreads/images/graemlins/grin.gif
 
Back
Top