308 minimum distance projectile needs to be seated into the

[SunnyCoast 5r]

Developing a promising load for FTR but looks like I cannot seat the projectile far enough out to get close to the lands in my Rem700 with factory barrel (oal now 3.000" but still 25thou off).
So how much of the pill needs to be in contact with the case neck to be safe and useable?
Excuse the novice question but all of my reloading experience to date has been at recommended magazine length.
help please....

[Razer]

I have a load using Berger Hybrids that are only 50thous from the rim to the boattail taper.
These are still 25thous off the lands.
Can't remember OAL but that is irrelevant as all chambers are different.
If your neck tension is firm and you use a Lee Collet seater, are careful how you store and transport them, push them into chamber with finger before closing the bolt you should have no trouble.
Having said that, there are no guarantees.

[Barossa_222]

I would change projectile or have the gun rechambered to suit the projectile of choice. Not enough bearing surface contacting the neck of the case can lead to poor run out and the projectile can become dislodged/loosen from travel. The old rule of thumb used to be at least as much bullet in the case as the calibre ie if you are loading a 308, at least .308 of bullet bearing on the neck. You can operate with much less, you just have to be aware and keep checking as to avoid train wrecks on the range.

[bsouthernau]

....if you are loading a 308, at least .308 of bullet bearing on the neck. You can operate with much less, you just have to be aware and keep checking as to avoid train wrecks on the range.

I load 210 SMKs with .2" of bearing surface in the neck and have no problems with runout etc.

Barry

[williada]

Razer's and Barrossa's comments about dislodging projectiles are real and the general seating based on calibre like Barossa said is right.

But searching for accurate loads is another thing and Barry might be looking closer to a minimum for our style of shooting.

Practically speaking, you need to be able to have the capability of using up to a .025" jam and to be able to hold that projectile in place as the guys have mentioned in the quest for accuracy. This is important when chamber reamers are designed. Usually, the reamer can accommodate a larger jump in free flight if you have to go the other way, (but not one that pushes the projectile body past the junction of the case neck and shoulder. Only the boat tail should be able to pop down there). These calculations should be based on the longest bullet you are going to use based on the position of the ogive.

It would seem you need to re-chamber at this point in time.

Why? The shape of the throat and leed angle wears to the bullet shape with 1500 plus rounds if you have not re-chambered. Or your cleaning method can vary it. Sometimes remedial action means jamming .025" to get results rather than using a traditional .010" off the lands. I prefer to nip up the throat after 700 rounds and shoot on a fresh throat, but most shooters do not have that opportunity. When people give me a jam figure, I take it with a grain of salt because the base for the calculation depends on the wear of the throat at that point in time. Your seating depth should be based on revisiting the seating depth test so things are relevant to a point in time or every 700 to 800 rounds.

The key to accuracy is in the throat. If it is sloppy you are screwed. Particularly diameter, if you have a long run up into the lands with deeper seating. The length of the throat assists in finding the right timing and combustion but because the lead core is malleable and holds a new shape due to any misalignment it may add to in-bore yaw and destroy groups no matter what efficiency you get from load parameters.

Have a look at the link. This an extreme example. This setup works while the throat is fresh. The author mentions it works with a straight throat. I feel he is not revealing all. It works because the throat diameter is held within tight tolerances. Its length largely determines the efficiency of the load. I can't see a reamer not cutting a straight throat. There is not much holding his projectile, so reduced friction may lower extreme spreads. Perhaps the carbon deposits could be a problem. But I think he would use the original reamer to scrape that out every so often depending on what a bore scope revealed rather than trying to polish it out and run the risk of wrecking a a straight throat. Perhaps this is the real context the author meant.

http://bulletin.accurateshooter.com/201 ... benchrest/

Anyway, its all food for thought. David.

[SunnyCoast 5r]

Thanks for all of the advice. I might sneak them out a bit more. I am using the Lee Collet die. Chamber options are out as the rifle will be going back to hunting duty soon and all funds needed for a new rifle.

[Send-it]

in my factory rem barrel, I've gone as far as only having the projectile engaged into the neck by 2mm (80 thou).
this still wasn't touching the lands, but was getting to about 10 though jump.
this was with 155 HBC pills.
i noted that when i tried 168smk, i could seat them a tiny bit deeper into the case but not much at all really.

Remington factory barrels have got way too much distance to the lands, considering factory offerings are expected to fit into their rather short magazine wells.
this all ended up being single load stuff anyway, but was still frustrating just to have to go to those extremes just to get a projectile out near the lands.

[bsouthernau]

Razer's and Barrossa's comments about dislodging projectiles are real and the general seating based on calibre like Barossa said is right.

But searching for accurate loads is another thing and Barry might be looking closer to a minimum for our style of shooting.

That's right David. Shoting the .308 out to 1200 with occasional attempts at 1500 you need all the boiler room you can get. They're only just into the lands so come out without any problem (apart from having to remove the cheekpiece and bolt!) if I'm required to unload. I wouldn't feel comfortable with them much further out.

Barry