I have a 260 Ackley that shoots best with the bullets seated 0.050-0.080" off the lands, dependent on the bullet. At these depths, a few of the bullets now have the ogive down inside the neck. My question is "If I stretch the throat (i.e. move the lands forward) 0.050" will this affect the accuracy even though I'm still at the same distance off?"

By stretching the throat, it gets the bullets ogive out of the neck, gives me a bit more case capacity and still lets the cartridge fit down into the magazine.

As anybody done this? Pros/Cons?

It is quite common to have a (custom) chamber throated for a particular bullet seating depth. Often this involves a longer throat to be able to seat heavier bullets further out. I don't think anybody can give you a guarantee, that your gun will still shoot if you change the throat though. It is one of those "suck it and see" endeavours.

- mike

I have deep throats on many of my rifles even in excess of what you're suggesting.Good accuracy is had by all. roger

Every rifle is diff. The old school of thought that bullets shoot best 0.01" off thalnads just doesn't apply w/ every cartridge or bullet. I also have a 260AI. It's throated for the 142grSMK seated 0.01" off the lands. Even w/ the 1-8 twist, it shoots 85gr SIerras into the low 0.3" & they are quite a bit off the lands. Barnes X series seem to like even more "free bore", so you just have to play around & see what you get.

What are you using the rifle for and what bullet are you wanting to use and what sort of accuracy are you getting now?

I'm shooting a Rem 700 SA with a Rock Creek 8.5" twist barrel. I get the best accuracy from Hornady 129g SST and Barnes 130g TSX. Both are staying close to 7/8", but a few times it does get to 0.5" groups, sometimes 1-1/4". It doesn't like the Accubonds and I've only had one box of Berger bullets to play with. They may do well. It does like both H4350 and RL17 powders. Slower powders overfill the case.

I've always wanted to have a gun that shoots consistently at 1/2" or better, so I ventured in on this one. The main goal is long range targets to 800 yards. At the current group size, the best I can believe in is 400 yards.

So, back to a modified question: Is is advisable to stretch the throat? My concern is that it may ruin the accuracy and change back to a "touch the lands" rifle. In that case, the bullets would no longer fit the magazine.

Bartsche: How far off do you consider deep throats?

I think mho is right, it may be a "suck it and see" endeavor but I'm hoping it falls into bartsche's line - good accuracy is had by all.

Are you looking for .5" groups with hunting bullets, or are target bullets an option?? In reality, the accuracy you are currently getting is more than sufficient for hunting - even at long range.

Anyway, why don't you try a couple of dedicated target bullets, e.g. Lapua or Sierra. You should also consider the Berger bullets. A lot of people have started shooting these for long range hunting, it seems.

http://www.bergerbullets.com/P...nting%20Bullets.html

Another option is to start looking at your reloading process. What process do you use to prepare your brass?? Does your sizing and seating create runout?? If yes, consider changing the setup of your dies, or even getting new dies (e.g. Foster - great quality at lowish cost). Do you have the option to sort brass for neck wall thickness, or even to clean it up by (skim) turning it??

- mike

As much as a quarter inch in7mm., and perhaps a half inch in a .375. In the 7.62 X 41s with a .308 neck length, a 180 grain psp bullet can be seated so the bullet does not infringe on the powder room and still does not touch the rifling.
With the right loadings these rifles are close to or better than MOA.They are not ,however , bench rest accurate.
A 250-3000 throated to handle the longest coventional 120 gr. bullets is Moa with 90gr.Sierra HPs and the bullet is a far piece from the rifling when the bullet is seated with its base near the neck shoulder junction.
It probably is a crap shoot but statisticly It seems to me to be in your favor. roger

quote:

majestrate98

What's the possibility that the need for the 'jump' is due to some condition of the leade? Fire-lapping (or some other procedure) might correct that condition.