I've been reloading ammo for a short time now and have always followed the reloading manual with regards to cartridge length. People I've talked with tell me I need to determine the optimal cartridge length to match the chamber of my rifle. Once it was explained I understood the reasoning of having the bullet as close to the lands as possible without touching.

My question to you is, what is the best way to go about making a dummy round that will get chambered so I know how long it is when touching the lands? Some say to do a partial resize, just enough to hold the bullet in the case. Some say to do a full resize then cut a slot in the neck to allow the bullet to slide when chambered.

What is the general consensus around here?

Are you shooting benchrest matches or are you hunting with this rifle?
Factory chamber or custom?
Do you plan to use this ammo in the magazine?

Now the old standard methiod is to remove your bolt, insert a bullet into the chamber and hold it at the point of "just touching" the lands with a rod (eraser end of a pencil works real well for a 30 cal). Now insert a flat tipped rod into the muzzle until it touches the bullet. Mark the rod where it exits the barrel. Remove the bullet and re-insert the bolt. With you rod, advanced to where it's hitting the bolt face, mark it again at the muzzle. Remove the rod and measure the distance between the marks. That distance is the "OAL" for that bullet that will have you touching the lands, back off from there to get the amount of jump that you want.

Note, changing bullets will change the numbers, so you'll need to repeat this with different bullets that you try.

Some people seem to like sticking a dowel down the bore an marking and measureing and subtracting to much work and cant be very precise

I use the neck sized case with one slit useing a dremel wheel, in the neck. Then just measure the round with calipers and or with a bullet comparator attached to your caliper. Seems to hold the bullet firm yet will slide in when it hits the lands. Bullet pulls out with your fingers when done. Works good repeatedly

I still use the "smoke the bullet" method, although I actually use a wide tip sharpee. If I have a case that is fired in the chamber, I simply neck size it, seat long, chamber the dummy, adjust the seater die and repeat until I get the desired length.

Tailgunner's method works as well, but may vary with bullet tip deformation.

I used the Stoney point, but found it to be inaccurate because the only way to get a true OAL is to use the case in the chamber with the bolt closed. Since the Stoney Point doesn't use the bolt face, the readings are only based off the shoulder, not the true case length.

The rifle I'm loading for is a Savage 10FLP in .223 rem with factory barrel and chamber. I do use it for benchrest shooting and some competition. I don't use the internal magazine since I installed a single shot adapter.

I will probably go with the method described by GSP7 as it seems the easiest and effective for my needs. But he mentions using a neck sized case and I only have a full length resizing die. Will this affect the results?

Once I know the length of a dummy cartridge when it's touching the lands, how much should I back off the bullet from the lands when I seat the bullets? I've heard some say .005".

Use your full length die will work fine.

.010 is a good start. Im useing .005 and I have tryed touching lands also.


Bench rest forum
http://www.websitetoolbox.com/tool/mb/6mmbr

GSP
It's as accurate as the operator, and that's all that can be said for any method. There is no subtracting involved, simply lay your caliper blades against the lines.
Like I said, "for that bullet". Set your sizing die (which works off the ogive) to seat the same bullet to the same OAL, and the distance to the lands will be the 0 for the rest of the bullets in that box, set it to .030 shorter and again the rest of the box will be .030 short of the lands (just like with any of the other methods).

A single edge razor blade works well for making the marks, and I personally don't have any problem judging to within .002 as to when my caliper blade is "on the line" (usually I'm closer than that). But than again, I'm used to working to +/-.0001 tolerances

Tailgunner has the most simple method. For hunting rouunds I would start .030 from the lands and adjust for accuracy. For Barnes TSX, start at .050.

quote:

Originally posted by GSP7:
I use the neck sized case with one slit useing a dremel wheel, in the neck. Then just measure the round with calipers and or with a bullet comparator attached to your caliper. Seems to hold the bullet firm yet will slide in when it hits the lands. Bullet pulls out with your fingers when done. Works good repeatedly

DITTO roger

I have used the split neeck and partial sized neck method but now I use a Stoney Point O.A.L Gauge and the Bullet Comparator.

quote:

Originally posted by tuck 2:
I have used the split neeck and partial sized neck method but now I use a Stoney Point O.A.L Gauge and the Bullet Comparator.

+1

If you load for several calibers and several guns the Hornady OAL Gauge with the appropriate modified case will give you consistant and repeatable measurements. It's just a lot easier and you will measure more often and be more accurate.

After having re-read Tailgunner's method a couple more times (I didn't get it at first), that does seem like a rather simple way to determine the length of a round with that bullet touching the lands. Now to just find a dowel small enough to fit a 22 cal barrel and give it a try.

Even using the COL from my reloading manual, I've managed to make some decent rounds capable of .25MOA but am hoping to improve that with my loadings of the 69gr Matchking and 75gr Amax and seating the bullets .05" off the lands.

quote:

Originally posted by jstevens:
Tailgunner has the most simple method. For hunting rouunds I would start .030 from the lands and adjust for accuracy. For Barnes TSX, start at .050.

make the later .065 for me...and go BACK...

the easist way to determine OAL forthat specific bullet is to take a fired case, bend the edge JUST a little, and use a sharpie.... seat the bullet WAY long, and gently close the bolt.. MORE gently open the bolt... measure the case...
do that 10 times... takes all of 2 mins... no "oal case contraption" ...

knock .030 off that and that is the MAX oal for that particular bullet, as nose shape changes OAL

have a ball

jeffe

Tailgunner we must have posted at the same time, because Your post wasnt there when I wrote mine so I wasnt knocking you or your method personally....What ever...

http://www.sinclairintl.com/cgi-bin/category.cgi?category=RESDTCL&type=store

Sinclair sells a chamber length gauge that works well.......r in s.

quote:

Originally posted by Specter65:
After having re-read Tailgunner's method a couple more times (I didn't get it at first), that does seem like a rather simple way to determine the length of a round with that bullet touching the lands. Now to just find a dowel small enough to fit a 22 cal barrel and give it a try. ...

Not only is it simple, it is by far and away the most accurate. You can use a Cleaning Rod with a Flat Tipped Jag and wrap the rod with Tape to mark it.

You need to use the exact same Bullet to set the Seating Die so the Bullet will just Kiss-the-Lands. Once you have that, convert OAL to ODL and you can easily Seat the Bullets at any distance from the Lands you desire.

Best of luck to you.

quote:

Originally posted by GSP7:
Tailgunner we must have posted at the same time, because Your post wasnt there when I wrote mine so I wasnt knocking you or your method personally....What ever...

Looking back at the time stamp, I'd say that yes, we both posted at the same time.
No problem, no harm, no foul.
We're all here to learn and to assist each other in learning.

Using Tailgunner's method I checked my rifle with the 69gr matchking and found that a cartridge touching the lands will be 2.38". I've been loading this bullet according the the manual at 2.26" giving me .12" or about 1/8" for the bullet to jump before reaching the lands. I take it this is a significant distance capable of creating wobble and affecting accuracy.

I've decided to next load this bullet to 2.34" to get me within .05" of the lands. Does this sound like a reasonable choice?

You never know, they may shoot worse. I would start with a Sierra bullet at .030, not .050 from the lands, then make some up shorter and longer and check for accuracy. It is a trial and error thing, no rules apply. It has to do with the vibration of the barrel and the exit time of the bullet.

I use Tailgunners and Larry's methods .

Works for me . Then again contrary to popular opinion I'm not Anal Retentive .


Shoot Straight Know Your Target . ...