Up to now, I've always loaded my cartridges to whatever length the reloading manual says. Now I'm about to load some Hornady V Max 60 grain bullets for my Bushmaster Varminter, 24" bbl, 1-9 twist. I know there is a procedure to fine tune cartridge length to a specific rifle.
Something about inserting a long cartridge into the chamber and letting the bullet be pushed back, or looking for rifling marks on the bullet etc etc.

My question is what is the right way to do all this. These cartridges would be fired in this rifle only. I've ordered some Lapua brass but won't see it until at least March. Right now I have some "range cases" prepped and case trimmed to 1.750".

Looking for max accuracy.

Thanks

Steve

Google search "seating to the lands".

Is that rifle an AR platform rifle? If so, you will likely be limited by what will fit in the mag before you get to one that is just off the lands.

I have seen some modified mags that will take a longer OAL, but this was for specialized long range work. Basically, the front of the mag was cut away.

Stoney point makes a tool that sets a rifle up for you. What the tool does is make the measurement repeatable. They sell a modified case that has a larger flash hole in it along with an expanded case neck. A bullet easily slides in the case & the stoney point tool pushes the bullet into the lands.

You can make your own test case or buy one of theirs for 3 or 4 bucks. I recommend using one of their test cases, its set up to do the job correctly for nominal loot.

You can actually use a coat hanger or any other thin rod to set a bullet in the test case. You simply put the test case in the chamber with the bullet you want to use & push the bullet forward with the wire until it hits the lands/won’t go any further. Make sure that the case is all the way in the chamber. Do the test 2 to 3 times marking the wire each time to make sure that the bullet depth is correct. Then make up a test bullet to make sure that it chambers properly & keep that test bullet so you can set your dies for that bullet in the future.

Bullets have different shapes & all of them should be tested for fit this way. You’ll be amazed at the length of the bullet jump in some of the chambers out there. One of the worst I’ve seen was a Tc contender barrel in 223 that I had. I tried setting that barrel up for 55gr fmj’s just off the lands. The throat in the chamber of that barrel was soooooo long the bullet wasn’t long enough to be able to be sit on the lands & be crimped in the case.

Don’t worry about if a bullet will fit in the mag or not, you can always feed them in 1 at a time. That’s what people do at service rifle shoots for offhand & the slow fire prone on the back fence. Stone point also makes a tool that measures the bullet lengths that uses different sized holes for different calibers. Here’s on set up for the .223 that I also measure 22lr match ammo with. The measuring tool helps when you’re reloading; you can check your bullets to make sure that their not too long. An out of battery discharge is not pretty & this tool is cheap insurance to ensure that doesn’t happen.


Good luck, be safe & enjoy

Yes the rifle is an AR.

Here's what I've done so far. Without any special tools or case modifications I made a dummy round (no primer and no powder), made sure it was "too long" and chambered it by hand the first time allowing the lands to push the bullet back. It now measures 2.275" as compared to the 2.250" col from my HORNADY manual. And it clears the magazine though just barely and will chamber from the magazine. Of course I only have one but even so this particular magazine seems to accept it well

So I guess the dummy cartridge is just off the lands when chambered.

What is my next step? Do make up a live round and test fire it at this length or, as some have suggested, do I shorten it by .010-.015" first?

Thanks

Steve

A thing I learned was to take a case and make three equidistant vertical cuts in the neck with a Dremel. Then I seat a bullet in the end and slide it into the chamber and close the bolt. This lets the bullet slide more easily in the neck than just closing the bolt and jamming it into the neck. When I carefully eject the round, then I can tell how long it should be to just touch the lands. I measure from the ogive, not the tip.

Thank you chuckS1, that’s what the stony point tool measures, from the ogive. You get a true reading that way. Measure some loose bullets & you’ll find that they can be as much as 20/1000’s difference in blammo bullets & 10/10000 difference in match bullets.

The place on the ogive where the lands hit it is always the same. It wouldn’t matter with a bolt action, you can feel if the bullets too long when you close the bolt. Just be careful when you’re loading for the ar.

Out of curiosity why aren’t you using a heavier bullet?

Stony point comparator
Stony Point Equipment

[QUOTE=Out of curiosity why aren’t you using a heavier bullet?

[/QUOTE]

This particular bullet was highly recommended for longer range accuracy in a 24" barreled AR. Hope it's true - I'd like to knock off some coyotes from my back porch at 200+ yards. :-) Oh....and I have 400 of them!

300 & in you'll be smoken them. I use any bullets that I can get my hands on for practicing offhand/standing with the ar @200yds.

200 yds is nothing for an AR and a target the size of a yote. Even 55gr FMJ will lay them down at that range with boring regularity.

Shoot them all so they don't migrate east!

Agreed. For your intended usage I would just stick to a 2.255" COAL for optimal feeding and function. The rifle will have no problems delivering if you do your part.

2.255 sounds good - but I've already loaded 15 rounds, 5 each at 2800, 2900, and 3,000 fps with Varget at 2.260".

Now I have to wait for a break in the blizzard to quit so I can try them out and refine the data for the load I really want to use.

And M1gunner - I'll do my best. :-) Hope also to get an electronic call and put it 200 yards behind my back porch and then sit inside and wait. Hunting is sure a tough sport!!!!

If you'd like I can email you some calls as MP3s and you can play em from your computer or portable MP3 player....

What I have is limited but there are some coyote calls.

A little experimenting will find the COL that works best in your rifle. 55 grn Sierra BT spitzers did wonders in my Rem 788. Struck coyotes like lightning.