Jump/jam distance

[Ouroborous]

I just picked up a Hornady bullet comparator to sort pulled SS109's by base to ogive.

Now that I can actually measure from the base of the case to the ogive of the bullet, I wanted to ask if anyone has a good overall jump distance for 62gr SS109 bullets (seated to 2.250 +/- .003) loaded for a Colt 6920?

[eightmillimeter]

The jump distance is very long. The only thing you can do to limit it down is load to 2.25/6 and leave it at that. Also, not all SS109 are created equal, and two batches loaded to same overall length may have different jumps to lands based on position of the meplat.

[jstone]

The jump distance is very long. The only thing you can do to limit it down is load to 2.25/6 and leave it at that. Also, not all SS109 are created equal, and two batches loaded to same overall length may have different jumps to lands based on position of the meplat.

The meplat has nothing to do with the jump. The meplat does not make contact with the bore at any point. You might have typed meplat instead of ogive.

Op the jump is going to be different for every chamber even if you have two barrels made at the same time with the same chamber type. Now that you have the comparator pick up one of the OAL gauge. If you don't know what it is Google it. With the OAL gauge you will be able to accurately find the overall length of a round that will put the bullet into the lands. After you know that number you can easily adjust your seating die to seat the bullet at whatever distance you would like to the lands. It is very simple to use you should be able to find a video on YouTube showing its use.

You will get nowhere near the lands at magazine length. When i checked the OAL i would need to get the ss109 into the lands. There was not enough of the bullet in the neck for tension. The minimum amount of bullet that should be in the neck is the diameter of the bullet. For the ss109 just load to magazine length. If you want to shoot bullets like vld's or Amax 75's you can load close to the lands, but will need to load one at a time.

[Ouroborous]

You will get nowhere near the lands at magazine length. When i checked the OAL i would need to get the ss109 into the lands. There was not enough of the bullet in the neck for tension. The minimum amount of bullet that should be in the neck is the diameter of the bullet. For the ss109 just load to magazine length. If you want to shoot bullets like vld's or Amax 75's you can load close to the lands, but will need to load one at a time.

Ok, for a magazine fed gun there really isn't any way to get close to the lands.

Sounds like getting the bullet close to the lands is more for bolt action rifles then?

[eightmillimeter]

The meplat has nothing to do with the jump. The meplat does not make contact with the bore at any point. You might have typed meplat instead of ogive.



Yes that's what I meant. My main two points were that not all SS109 are equal in shape and that can play with your bullet seating dies, especially when I used to shoot pulled down SS109. Seating depth was all over the place because of different bullets. My other point as you stated as well was that there is no way to get close to the lands when dealing with SS109 at mag length...

[eightmillimeter]

Ok, for a magazine fed gun there really isn't any way to get close to the lands.

Sounds like getting the bullet close to the lands is more for bolt action rifles then?

Not necessarily, my slow fire rounds I load for NRA Mid range do not have to be mag length because you load only one at a time, and I want to say when I used so shoot 75gr Hornady AMAX the OAL was 2.38 or something, for the AR that I used at the time. My rapid fire ammo was 75gr Hornady BTHP loaded to 2.26.

[jstone]

You can seat bullets close to the lands. The ss109's i had when loaded ten thousandths from the lands only had roughly .208 of the bullet in the case neck. If i do not have at least .224 of the bullet in the neck they get seated deaper. Like eightmilimeter said pulled ss109's vary a lot. They also are not match bullets. You are not going to get sub moa accuracy from ss109's. If your loading vld's, 75Amax, or 80 grain or larger matchkings it would be worth the time loading them long to single load them.

The people you see online claiming sub moa with ss109 bullets are cherry picking a group. A true moa or sub moa load will do it on demand, not one group out of the 50 shot.

If you want to develop an accurate load buy some matchkings. Does not matter which weight they are just make sure they are under 80 grains. Load them so they can be fired out of a mag. Once you have your load worked up you should have a moa to sub moa round depending on you and the guns capabilities.

If you are only going to shoot to a hundred yards the 52 or 53 will work fine. If you want to get out past 300 load some 69 or 77's. Matchkings handle jump really well.

[markm]

Measuring jump to lands for SS109s is like putting High Octane gas in a Dodge K car.

WHY WASTE THE TIME? Those bullets will NEVER shoot well.

And the AR typically has so much leade that this effort is beyond mag length... There is so much wrong with this effort, Jackson!

[Ouroborous]

Thanks for the info all.

[jstone]

Measuring jump to lands for SS109s is like putting High Octane gas in a Dodge K car.

WHY WASTE THE TIME? Those bullets will NEVER shoot well.

And the AR typically has so much leade that this effort is beyond mag length... There is so much wrong with this effort, Jackson!

This is exactly what i was trying to point out. I have checked the distance it takes to get to the lands with the ss109, but would never take the time to load to the lands. I almost always take the measurement to the lands, just to know how far off my bullets are off the lands. If a bullet is loaded to maximum mag length they are still around .050 off the lands in my 556 chambers.

[Ouroborous]

Despite not being able to load to the lands at mag length, is there a general OAL range (ogive to case head) for the SS109 or does it not matter at that point?

I just did a quick search for info on ogive to case head OAL but didn't find anything. Anyone have a resource for this?

[eightmillimeter]

Even if there was such a general measurement it would not matter because of the huge inconsistencies in this bullet between manufacturers and batches. If you are loading SS109, any experimentation with OAL is futile and fruitless.

[Ouroborous]

Even if there was such a general measurement it would not matter because of the huge inconsistencies in this bullet between manufacturers and batches. If you are loading SS109, any experimentation with OAL is futile and fruitless.

That's what I figured. I'll save the loading to lands stuff for when I get a precision bolt action!