How important is bullet seating depth into the case?

N

nmibex

Guest
If I seat the bullet about 0.040 off the lands, the bullet base is about 0.25 into the case beyond the neck. My gunsmith will extend the throat if I want but I'm not sure it's worth the trouble. There is enough clearance in the magazine to accommodate the increased OAL. Do you think extending the throat would improve accuracy enough to warrant the effort?

The rifle is a 280 Improved, Nosler brass with Hornady 154 Interbond bullets. The rifle is for hunting.

Thanks,
Dick
 
What you are asking is, does the depth of the bullet in the case, regardless of jam/jump to the bore, have an effect on accuracy? That is, if the bullet goes in deeper in the case than the neck, is accuracy adversely affected?

While I doubt anyone knows for sure, for every possible situation, the Wolf Pup concept has been used in a number of chamberings, and with that .085 neck, the bullet *always* extends backwards, into the case. Given their success, I'd say no.

See

http://bulletin.accurateshooter.com...al-short-necked-wolfpup-for-hunter-benchrest/

Al Nyhus & I had a long exchange on this general notion, see:

http://benchrest.com/showthread.php?71958-Wolf-Pup-Al-Nyhus&highlight=Wolf
 
Issues I have experienced when having bullet bearing-surfaces seated deeper then the neck are: early pressure, low velocity, and high ES.
In the cartridges that I have "deep seated" bullets -verses- having bullets optimally seated with in the case neck, I can honestly say I feel accuracy is improved, velocity capability is gained, ES are lower, and pressure is less, when the bullet is seated optimally with in the case neck.

Not to discredit the 30-WolfPup and/or the seating of bullets to clip lengths. In those situations, one has to do the best they can.
Can't help but think the powder choices used in those circumstances, could greatly influence over all performance to accuracy, velocity, and pressure.
Maybe all wet here, but large granular types I would think would work better then ball or flake powders to those scenario's.

Happy Shooting
Donovan Moran
 
I really think that a bullet extending into an Improve cartridge is not good. Heck any cartridge.

Anytime I have a rifle built I include the brass I am going to use, along with the bullets I am going to try.

I will seat the bullets in the brass at the best possible length.

I like to establish the same length to the ogive with different bullets of different weight and brands.

Yes, I have shot a .280 Imp for many years. I started out on Partitions, but now really like the Accubonds. 140 grain bullets are perfect for the .280 Imp. 3150 fps out of a 24 inch barrel is good stuff. I feel the 154 gr bullet are a little heavy and not necessary for the .280 Imp. I go from the 140's to 160's; however with the 160's I am shooting a 7 Mag with a 26 inch Hart.

I also recommend a 4.5X14 Leupold scope on a .280 Imp. hunting rifle. Even at 400 yards the crosshairs need to be in the brown.
 
with custom varmint rifles, AI chamberings where groups in the low 2's were the normal, bullets were always seated down in the case. The most accurate barrel I have ever owned was a 6 BRX, would shoot groups in the low 1's and zero's, bullets were seated below the shoulder neck junction.

You can not be asleep when you are seating bullets deep, if/when brass flows and creates a doughnut, just be prepared to take care of the doughnut...this ain't rocket science.

My 6PPC and 6 BR custom live varmint rigs shoot very, very tiny groups, all with bullets seated down below the shoulder neck junction.

If you are trying to set world records, set up your chamber to where the bullet does not go below the shoulder neck junction, that way you will have nothing to blame.

My reamers on the 223, 223 AI, 22/250 AI, 243 AI, and 244 AI all have zero freebore and all of them shoot very tiny groups, and when they start shooting 1/2" groups, it is time to set the chamber back.

The problem is that inexperienced shooters do not know how to diagnose the problem with the doughnut, if/when they become a problem. Seating the bullet deeper in the case will give you more barrel life since you can only jump the bullet so far without loosing accuracy. In some cases, you have to take into consideration the powder capacity. It's your party....
 
@John S., I shoot the 154s for down range energy. I tried Accubond 160s but the gun didn't like them and the 140s were OK but I still want the down range energy for hunting. I'll probably give the 140s another chance because I don't have another large animal hunt until 2013 and have a coues and barbary hunt this winter.

Thanks for the input,
Dick
 
IMHO, it's not worth the trouble to take the barrel back off, and extend the throat because you may well end up causing more problems than you're trying to fix. If the new throat is not concentric with both the bore and chamber, that will be a problem. Is there really even a problem to begin with? Doesn't the rifle shoot well enough for the game you are hunting?
 
Have seen some really good shooting rifles with the bullets way back in the case, I have one of them! If it shoots, leave it alone.
l
Joe Salt
 
Question for those reporting good accuracy with bullet well below neck shoulder junction:
Were/are the bullets that you use/used BTs or FBs? It would seem to me that a FB would tend to be upset to a larger diameter before is passed into the neck, and that a BT might not, and that this could account for the difference in reported effects.
 
Boyd: I'm shooting Berger210 VLDs and They go past the doughnut and does not make a difference! Tried them out further, but they shot better back, can't argue with rifle.

Joe salt
 
Joe,

Is the full diameter (shank) of the bullet below the neck shoulder junction, or just the BT?

Charles,
I thought that the Wolf pup was generally throated pretty bullet specific, so that the bullet was not far into the case. Are there any Wolf Pup shooters out there with information on this?

Boyd
 
Boyd Allen said:
Charles,
I thought that the Wolf pup was generally throated pretty bullet specific, so that the bullet was not far into the case. Are there any Wolf Pup shooters out there with information on this?
Click to expand...
Well, Al Nyhus would be the guy to ask. But on the 6mmBR interview, he said

We set the throat to position the base of the bullet well below the neck-shoulder junction.
Click to expand...

Here is the link:

http://bulletin.accurateshooter.com/2007/04/radical-wolf-pup-case-for-hunter-br/

And I've asked Al this specific question in the past, but you know the search in V-bulletin -- I can't find the posts. My memory is that they always had the base in the case past the neck/shoulder, & never had any problems. Al & I had a long discussion on this when I was thinking of "pupping" a 7.5x55 Swiss case for long range -- and I may still do this.
 
The wolfpup also has an extremely short neck. So it could be that it's bullet grip, even being neck/shoulder junction grip(higher), is about typical, or needed for the successful load.
IMO, little applies for a 280i.

I do know that with coaxial chamber necks(non tapered), tension from neck/shoulder is erratic w/resp to normal neck lengths.
I would not seat bearing through this region. I would have the throat extended to avoid it.
 
nmibex said:
If I seat the bullet about 0.040 off the lands, the bullet base is about 0.25 into the case beyond the neck. My gunsmith will extend the throat if I want but I'm not sure it's worth the trouble. There is enough clearance in the magazine to accommodate the increased OAL. Do you think extending the throat would improve accuracy enough to warrant the effort?

The rifle is a 280 Improved, Nosler brass with Hornady 154 Interbond bullets. The rifle is for hunting.

Thanks,
Dick
Click to expand...

No. I'm partly responsible for this thread getting off topic, by suggesting that even with pure accuracy rounds such as the wolf pup, deep seating a bullet is OK.

Here's the deal: If you have enough neck tension so the bullets in the magazine don't move under recoil, you're good to go. If they do, try a taper crimp, I know it's one more step. (I'm assuming those bullets don't have a cannelure.)

People get all hot & sweaty over even neck tension. Here's another story: Phil Bower set a new IBS 10-shot heavy gun record (since supplanted) a few years back. Some of the cases he used to fire the record group had split necks. I guarantee you neck tension was not even -- since some didn't have split necks.

Yes, for benchrest, where we're striving for .050 improvement in group size, even neck tension may help. You'll find 50 guys who'll swear it will. I guess you'll find at least one who'll say, "naw, other things matter a lot more..." And I don't sweat it myself. But ask those 50 guys "How much improvement will I get" and all of a sudden, you're going to get a lot of "well, "it kinda depends..."

Now if, like me, you already have your own throating reamer, and a delrin guide for the action already made up, and a long T-handle with a stop, you could throat it out without pulling the barrel from the action, at zero cost, and a half-hour's effort. We've done it this way on pure competition rifles, and it works just fine.

I might do that if I wasn't satisfied with the accuracy I was getting, since you say the new OAL will still work through your magazine. But to pay money for the work if the bullets don't currently move in the case during recoil? No. (I'm assuming you're not unhappy with the current level of accuracy. And if you;re not, I doubt this would make that big a change.) And if the bullets do move, I'd first try a taper crimp.
 
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@Charles E., I don't have a reamer the knowledge or skill but my friend that built the rifle said he would throat it out for me if I wanted. I think I will plug away a little longer with load development before I make any changes. I'm happy with the way it shoots but I believe the rifle can do better but probably with someone else driving. The gunsmith used to shoot benchrest and did well so I'll get him to put a few rounds on paper.

Thanks all for your comments. This board is insightful, educational and entertaining.

Dick
 
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