Chasing the lands/How much meat to leave in the bone?

[TX Badger]

I have a 260 AI and with the longest bullets currently on the market, OAL is 2.933" (Bullet seated at the lands) and my mag is a fraction over 3". I was considering having the throat re-cut bc I am getting very compressed loads without any pressure signs or getting close to where others are loading in this cartridge.

So, I can go .067" longer before I run out of mag space.

?s
My thought was to have the throat cut .05" longer so that I am not immediately at the limit. Is .017" a significant amount of room for chasing the lands?

How much throat erosion has anyone else seen in a comparable cartridge?

Is .05" significant enough to see a difference in performance or should I just go to a faster powder?

Am I missing any other considerations?

 

[Rich Coyle]

What wrong with compressed loads?

I did a 2,000 round test with a.223. There was .021" erosion per1,000 rounds.

 

[Mikecr]

Why so insistent on managing a touching lands condition?
If your seated bullet bearing at touching reaches donut area in necks, I'd get the throat extended to well clear that, do full seating testing, as recommended by Berger, and load develop from there.
Here I'm confident you'll find that touching is not most accurate.
If load density or a magazine get in the way of accuracy, then change powder or convert to single shot port loading.

The priority for a LR hunting gun should always be accuracy.
And if you choose most accurate seating off the lands(OTL) to begin, you won't ever have to chase lands -regardless of erosion. This best seated CBTO will hold no matter what else you do short of barrel replacement.

 

[TX Badger]

I am not afraid to compress loads or load further off the lands. The problem is if I go over 47gr of 4831sc I cannot maintain seating depth, they are so compacted. And many others are listing 48.5gr as their go to load. I would like a little more speed and pressure wise I am still low. Seating deeper/further from the lands would make this even worse.

I'll load to the most accurate depth and powder charge in the end. But I want to be sure I'm not handicapping the cartridge by not having enough throat.

 

[Gord0]

My personal opinion on a 260, or 260ai in your case is they need a long action. If using a short action you're probably going to be stuck single loading to realize the full potential of the cartridge. Single loading really doesn't give up anything on a long range rig.

 

[TX Badger]

I agree on the limitations that I have run into, but it's on a short action and I want to shoot some competitions that require it to be a repeater. So back to the original questions.

Will .05" increase in the throat give me enough additional performance to be worth the hassle?

Would I be better off just switching to H4350 to get some additional speed?

 

[Edd]

An additional .050" will give you room for about 1 more grain of powder.

 

[Gord0]

Now I see why you want it to be repeater. I don't think you'll get the added performance you want with only .05" deeper. Some more knowledgeable minds may chime in though. A powder switch might get you there. R26 at the slowest, H4831sc H4350, not sure where the other reloder powders fall in there, or what you're currently using.

 

[bill123]

The priority for a LR hunting gun should always be accuracy.
And if you choose most accurate seating off the lands(OTL) to begin, you won't ever have to chase lands -regardless of erosion. This best seated CBTO will hold no matter what else you do short of barrel replacement.

Mike,
I always thought that chasing the lands was the way to regain precision with a worn throat, until I observed that chasing the lands did nothing for the precision of my loads. I now chase velocity and have had good success doing so.

So many people talk about chasing lands, I've got to think that there are some cases where it works. Is it necessary w certain bullets like VLDs?

Bill

 

[TX Badger]

An additional .050" will give you room for about 1 more grain of powder.

OK, that helps. 1 more grain, a little space left to chase... Seems like a it's worth it. Especially if it ends up liking them off the lands.

 

[Varmint Hunter]

It may be worth it just to reduce powder compression. I'm not a big fan of compressed loads. IME it causes the CBTO length to vary noticeably more than an un-compressed load and there is always the question of bullet creep which some shooters have spoken about. That may vary depending on neck tension.

I'd be more inclined to try a faster powder before recutting the throat, but that's just me.

 

[WeiserBucks]

Have you tried a drop tube? It helps a ton with compressed loads .

 

[TX Badger]

Have you tried a drop tube? It helps a ton with compressed loads .

Yep, I used a drop tube and an electric toothbrush to get the powder to settle more. Still couldn't maintain seating depth.

 

[Edd]

OK, that helps. 1 more grain, a little space left to chase... Seems like a it's worth it. Especially if it ends up liking them off the lands.

It wouldn't be worth it to me. If I wasn't satisfied with the current combination, I would probably change something other than the freebore. But since I don't know what the current freebore is or what components are being used, I'm just guessing.