I just picked up a restocked but otherwise origional FN sporter in .257 Roberts. I have been doing up a few loads to try this weekend,
and I as of yet have not found the lands.
I just loadeed the 115 GR Nosler balistic tip to 3.146and the bolt closed easy as pie and there are no rifleing markes whatever on the bullets. I have a few 117 gr nosler round nose bullets that might find the lands as they are not so stream lined.
I know the europeans like a deep throat but this is the linda lovelace of rifles. My CZ 550 in 7X57 is similar and it shoots prety well, but this is making me nervous. Would this concern you ? ...tj3006

I've seen (and refused to buy) a couple of older "Bob" rifles that seemed to have been throated to allow Long-seating of117gr Round nose bullets, mabey you have found another one?

So, could it be throated "too deep" for your intended purpose? yes.


AllanD

quote:

Originally posted by Thomas Jones:
I just picked up a restocked but otherwise origional FN sporter in .257 Roberts. I have been doing up a few loads to try this weekend,
and I as of yet have not found the lands.
I just loadeed the 115 GR Nosler balistic tip to 3.146and the bolt closed easy as pie and there are no rifleing markes whatever on the bullets. I have a few 117 gr nosler round nose bullets that might find the lands as they are not so stream lined.
I know the europeans like a deep throat but this is the linda lovelace of rifles. My CZ 550 in 7X57 is similar and it shoots prety well, but this is making me nervous. Would this concern you ? ...tj3006

The throat like the crown, is a critical piece of the pie. The bullet needs to enter the bore straight. If the bullet has to hop, skip and jump to reach the lands, then yes it's way too long and a concern.

A lot of people in this position, opt to have the barrel set back to close the distance to the lands. This can sometimes make all the difference. For a quick check, size a case, stick a flat base bullet nose first into the neck and force the bolt closed. The flat base of the bullet will stop at the lands. Extract the case and you should have a fairly accurate picture of how much actual throat you have. Of course a Stoney Point gauge works a little better. Talk to your gunsmith and see what he suggests.

quote:

The throat like the crown, is a critical piece of the pie. The bullet needs to enter the bore straight. If the bullet has to hop, skip and jump to reach the lands, then yes it's way too long and a concern.

True! A throat can indeed be too deep. The unfortunate part is that it is not possible to state that the throat is too deep until you thoroughly test a number of loads, and fail to find one that shoots well. Even when this happens, it is not always possible to state positively that it is the long throat that is at fault.

For example, I've had several rifles that delivered much better accuracy with bullets seated quite deeply than when the bullets were seated out, closer to the lands. Same bullets, same powder charge, etc......

on a 257, within reason, no the throat can't be too long. But the twist CAN be wrong. Seat the bullets to 2.8+.0275 or so, and start with middle loads... and siff if the group improve.

I have one on a 1903 (flaigg custom) that I can not tough the rifling with a 100gr bullet, or the bullet would fall out of the case. It's a 5/8 gun.

Some benchrest-types engage the lands when they seat the bullet. This is great for super high accuracy... provided that the gun and load provide suitable accuracy, this is not required nor desired in a hunting arm... Remember, a hunting arm is going to be subjected to "dirtier" conditions that a bench rifle.


Recall that the weatherby chamber spec for all their chambered rifles is huge... and if one does not try to touch the rifling, these rifles tend to deliver more than acceptable accuracy for hunting, and if you switch to barnes X, loaded at nominal length, they deliver great accuracy.

In short, for loading a bob, start at a little longer than nominal length, and work your loads and OAL as normal... provided that throat has a lead, it acts as a funnel, and frankly, if the gun would be MOA if touching may or may not deliver nearly the same accuracy.


Should anyone disagree, please jump on a plane and come shoot MY bob

jeffe

I guess that's why all those Weatherby rifles won't shoot worth a damn

Have you shot the rifle yet? It's made it a lot years with the throat right where it is now.

I've owned a few rifles that had deep throats that were real shooters. I'd give it a try before I got too concerned.

Terry

You are talking about a field hunting rifle and not a bench rest one holer. I don't see a problem with the Fn 257 R because it should shoot around 1" as it is chambered. A tight throat on a field rifle has left a bullet stuck in the lands on one of my hunting rifles years ago. Most factory chambers are cut a little extra long on the throat to handle all types of bullets.

I think I ma probably just being a little parinoid. I have high hopes for this rifle. I have assembeld 3 loads 6 rounds each for it with different bullet weights and powders.
I bet one or mor will shoot good !!! tj3006

It would be better if the throat were the right depth, but sometimes one will shoot well with a lot of freebore. Just part of the mystery of rifles...


Okie John

Hmmm, what about a 257 Ackley Improved?