Is it ever OK to have the bolt final seat a bullet?

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bikemutt

bikemutt

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I recently hand loaded 60 rounds of 6.5 Grendel with 120 gr Hornady Amax bullets. Four of those rounds would not let me close the bolt with a normal amount of force. Once extracted, all four bullets showed clear marks from contacting the lands. I am a bit surprised since these rounds COL measure right at 2.260, in theory, they should be 0.003 off the lands, but they are not.

Leaving my flirting with a COL that's on the ragged edge aside, I've had guys tell me to close the bolt more forcefully to account for the rounds that fight back. My concern is I could make a bad situation worse by jamming the action real bad, or worse.

My inclination is to figure out what I did to make these four not seat normally rather than beating them into submission.

Any THR hand loaders come across recalcitrant rounds, and how do you deal with them?
 
For standard chambers you absolutely don't want to be "into the lands", which means, like MEHavey posted, more .003 off of the lands, since that is too tight a tolerance to try to hold.

COL? You want to measure to the ogive, not OAL. And still, you don't want to be less than an average .010 off the lands, and I have never gone more than .020 off the lands when I used to chase the lands in a varmint rifle. I also figured out .040 off the lands shot just as well.

All the Match ammo out there jumps a fair amount to the lands and shoots very, very well.

Jamming bullets into the lands in standard (Even "match")chambers is a great way to run pressures up, and push the cartridge out of alignment with the bore.

Seat them deeper.
 
bikemutt said:
I am a bit surprised since these rounds COL measure right at 2.260, in theory, they should be 0.003 off the lands, but they are not.
Click to expand...

I'm sure you already know this, but the Hornady handbook lists a COL for that bullet in 6.5 Grendel as 2.245". That's only .015" further back than you are now. Have you already tried the suggested COL? If so, how did it shoot?

And closer isn't always better anyway. One discussion of that can be found here: http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
But is it EVER better to jam the bullet into the lands? Well sure, it is not uncommon in the benchrest world. But they are usually using custom rifles with tight chambers and have carefully measured, weighed, trimmed, turned and sorted components and then developed loads for just those conditions.
 
.003" off of your rifling is not a realistic expectation when dealing with mass produced bullets, even if match grade. You can bet that for every one of the 4 that contacted the rifling, just as many were "off" the other direction just as far. Stick with working on a load that fits your rifle and don't worry about a specific distance to the rifling. Imho, I've found form fired brass to be more effective than chasing my lands.
 
bikemutt said:
Is it ever OK to have the bolt final seat a bullet?
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Hey, bike. You're one of the good guys here, so we take the question seriously.

No. It is not OK. There are perhaps a few very specific instances where it is OK, but not you and me.

As Walk and the others mentioned, OAL is not the same as Ogive curve.
You are likely flirting with more danger than you might understand.

There are instances where a world-class or perhaps national-class competitive shooter,
working with barrel manufacturer and match grade gunsmith, develop a specialized rifle
explicitly intended to jamb bullets tightly into the lands, using carefully developed loads
for that specific gun.

But you and I use published data intended for normal applications.
Jamming into the lands so tightly that you need the cam action of the bolt
for final seating of the bullet does NOT NOT NOT work for guns like ours,
nor published load data available to us. It is not OK to use the bolt to final seat a bullet.

If we didn't care about you, we might let you discover this on your own.
But you've been a good contributor here for many years, and we care.

You may have someone later in this thread stating that he does it all the time! It's OK!

But it isn't.

Be careful. Be safe. Be right.
 
Thanks for the feeback Team THR!

I did want to clarify one thing; my intent was not to seat these bullets .003 off the lands, it's just that something, or more likely someone, ahem, didn't fully seat these four rounds. The reason I mentioned the theoretical .003 is because a 120 gr Amax bullet in a Hornady OAL gauge when fully seated has a COL of 2.263", so for a round seated with a COL of 2.260" one would expect it to be back .003 from the lands.

I'll re-seat these four rounds and exercise more care at the seating stage of the press going forward. Also, I'll back down on the seating depth target as well. This rifle is one that so far shoots more accurately with minimum bullet jump. I have tried seating to the COL recommended in the Hornady manual with unremarkable results. Similarly, factory Hornady Match accuracy results are mediocre at best.
 
Being in the lands can increase pressures. But sometimes a rifle is much more accurate with a given bullet seated into the lands. My approach is to carefully work up a load with a COAL during work-up that puts the bullet into the lands the same every time and to keep loads in the moderate range when a bullet is seated into the lands.

But I try and avoid it, if possible. When you need to extract an unfired round, often the bullet stays lodged into the lands and you spill powder in the action. The bullet needs to be pushed out with a cleaning rod. All this is kinda a pain.
 
Is it ever OK to have the bolt final seat a bullet?
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Key word is "ever"...

To that question I say YES.

BUT, not in the way you are doing it. EVER means ever and one reason to use the bullet to do the final seating is, when you are "fire forming" brass where you want to move the shoulder of the case forward.

Of course, a spl. load is used for "this" purpose.

DM
 
Is it ever OK to have the bolt final seat a bullet?
Click to expand...
The only time I have seen this done on a regular basis was several short range bench rest shooters shooting 6mm PPC at 100 and 200 yards. Hand loading on the range they start a bullet and then chamber the round using the rifle's bolt for bullet seating. These are shooters who have carefully worked their loads up. When not using this method intentionally I see chasing the lands with 0.003" clearance as too difficult a tolerance to chase. Sort of unrealistic to try and hold that so no surprise several bullets come to rest on the lands. I would back them up further off the lands. I would look for a sweet spot in the 0.010" to 0.020" range off the lands and see what that gets you.

Ron
 
In an auto loading rifle I look at 10 thou as a safety margin for distance from lands. Just too many things that can go wrong jamming a bullets into the lands at high speed, unlike a bolt where you can gently close the action.
 
Walkalong said:
For standard chambers you absolutely don't want to be "into the lands", which means, like MEHavey posted, more .003 off of the lands, since that is too tight a tolerance to try to hold.

COL? You want to measure to the ogive, not OAL. And still, you don't want to be less than an average .010 off the lands, and I have never gone more than .020 off the lands when I used to chase the lands in a varmint rifle. I also figured out .040 off the lands shot just as well.

All the Match ammo out there jumps a fair amount to the lands and shoots very, very well.

Jamming bullets into the lands in standard (Even "match")chambers is a great way to run pressures up, and push the cartridge out of alignment with the bore.

Seat them deeper.
Click to expand...
I can't add anything useful to that post so I will just say it's very good advice.
 
I was faced with a dilemma recently. For an unknown reason, "human error" did not fully seat the bullet to the preset depth. Instead of tossing the round, I forced the bolt down. The problem was the round would not eject and it would not fire. I then had an unfired live round sitting in my chamber. I carefully, very carefully, had to tap pretty hard on the handle end of a rod inserted at the muzzle end many times until the round dislodged. It was not a comfortable exercise.
 
fotheringill said:
I was faced with a dilemma recently. For an unknown reason, "human error" did not fully seat the bullet to the preset depth. Instead of tossing the round, I forced the bolt down. The problem was the round would not eject and it would not fire. I then had an unfired live round sitting in my chamber. I carefully, very carefully, had to tap pretty hard on the handle end of a rod inserted at the muzzle end many times until the round dislodged. It was not a comfortable exercise.
Click to expand...

Been there done that myself, it's quite unpleasant. The couple times it happened to me it was because the brass was improperly sized, the press operator had not taken the time to read the die instructions, ahem :(
 
The biggest enemy of accuracy is inconsistency. And that what you'd have. Also raises the possibility of the bullet getting stuck in the rifling and being pulled out thusly sending powder everywhere in the action.
Three thou is a very wee, tiny, itty-bitty bit. Probably too close anyway.
 
bikemutt said:
Any THR hand loaders come across recalcitrant rounds, and...
Click to expand...

...YES, and it's still in the spent ammo box along with the empty cases that fired without any trouble. I will disassemble the round and do a complete inspection when I run the box through the wash, but a preliminary inspection reveals a shiny spot on the neck where it was tight in the undersized neck (bolt rifle). This batch of brass has been loaded once already without trouble so I'm guessing that some kind of debris like a brass flake got into the neck during the bullet seating operation, but this is only a guess. I'll know more when I get up off my aching duff and start washing brass. IMO you were smart to not force ammo.
 
This is an interest topic that I have though about a few times. The times when I had a very hard time closing the bolt on the gun. Yes I forced it closed but I never load at max volumes and this was at the ranges so I knew the round would be shot. I guess 1% of the 308 that were load I might had a problem with and I am assuming that it was the case not sized correctly. I always check the OAL of the first 5 308 rounds then about every 5 to 8 round.

On a side note using this gun, after the round has been fired, I still can get the fired case into a case gauge without resizing it.
 
DM~ said:
Key word is "ever"...

To that question I say YES.

BUT, not in the way you are doing it. EVER means ever and one reason to use the bullet to do the final seating is, when you are "fire forming" brass where you want to move the shoulder of the case forward.

Of course, a spl. load is used for "this" purpose.

DM
Click to expand...
Right!

Some claim it's accurate and repeatable for Target shooting.

But know that there's many bad thing that can happen. You WILL eventually try to extract a loaded cartridge and have the bullet stay in the barrel and spill power in the action. It will NOT be safe to shoot with loads you've produced to shoot that have been seated off the lands. It is not applicable for hunting situations or general shooting. ALL loads will have to be worked up and single loaded.
 
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