Bench rest seating by mistake

[HowieG]

I just had an interesting experience yesterday. I have a Remington Mohawk 600 .243 that I have been messing with some 15 years now. I loaded up a ten round ladder using the 85 grain Sierra HPBT Game King in front of a gradually increasing charge of IMR 4064. During the process, I reached into my pile of measurements and grabbed the wrong one, so I seated the bullets longer than I had intended to. When it come time to shoot them, I noted that a bit of effort was involved in the chambering and determined that the bolt was camming the bullets into the rifling. Sort of a bench rest seating process. Since I was there to collect data, I went ahead and tried them out, starting a the low end of the charge range, of course. Things went well with all ten rounds. No pressure signs. The surprising part was what those bullets did on the target end of things. When I wandered down to take a look, nine of them had grouped up into a little cluster 7/8 inches across. That surprised me a bit since this was a data shoot with varying powder charges out of a rifle that normally doesn't put five rounds, or even three, into groups that small except by accident. I have discovered that this little gun likes it's bullets close to the rifling, but jammed into the rifling is something else.

Any of you see that before outside of a some type of competition gun?

 

[jmorris]

I have seen a die that seats a particular bullet crooked have less than ideal results but if I load the bullet long enough chambering them, seats the bullet deeper, then removing and checking the runout, it goes away. I have a .22 Hornet and if I am using 35 grain v Max bullets I have to do this, takes them from 1.25” groups to .380”.

 

[HowieG]

I have seen a die that seats a particular bullet crooked have less than ideal results but if I load the bullet long enough chambering them, seats the bullet deeper, then removing and checking the runout, it goes away. I have a .22 Hornet and if I am using 35 grain v Max bullets I have to do this, takes them from 1.25” groups to .380”.

I can see that. Jam a crooked cartridge into a straight pipe and the cartridge has to give. That's kind of why I use Wilson seaters.

 

[Varminterror]

Jam a crooked cartridge into a straight pipe and the cartridge has to give.

The cartridge doesn’t HAVE to give. In-bore yaw is very commonly a result of the bullet engraving into the leade at an angle, promoted by non-axial or eccentric seating of the bullet.

 

[Varminterror]

For the OP:

1) Data collected for jammed bullets isn’t applicable for jumping bullets, so the data you collected doesn’t mean anything for any other COAL. You’re promoting a very different primary ignition pressure curve.

2) I personally don’t care to jam for any rifle/load I would use afield where I can’t send every round chambered downrange. The bullet can be seated deeper or be pulled longer - or completely from the case, leaving it lodged in the leade - when a jammed bullet is extracted. It’s always an opportunity to fill your action with powder, which simply isn’t great. I prefer not to jam, and will only do so when I am almost certain I can always send that bullet downrange, and where I would NEED to jam a secant ogive match bullet to prevent yaw as it enters the leade for peak precision.

 

[JFrank]

I have non bench rifles that like bullets jammed although you may require plenty of bullet hold if you plan on ejecting a loaded round.
IMO all data means something' I start my BR guns load development at a jam leaving one direction to work.

 

[HowieG]

The cartridge doesn’t HAVE to give. In-bore yaw is very commonly a result of the bullet engraving into the leade at an angle, promoted by non-axial or eccentric seating of the bullet.

Correct when fired with a jump. I don't think so when you are pushing the bullet in slowly by hand.

 

[HowieG]

For the OP:

1) Data collected for jammed bullets isn’t applicable for jumping bullets, so the data you collected doesn’t mean anything for any other COAL. You’re promoting a very different primary ignition pressure curve.

2) I personally don’t care to jam for any rifle/load I would use afield where I can’t send every round chambered downrange. The bullet can be seated deeper or be pulled longer - or completely from the case, leaving it lodged in the leade - when a jammed bullet is extracted. It’s always an opportunity to fill your action with powder, which simply isn’t great. I prefer not to jam, and will only do so when I am almost certain I can always send that bullet downrange, and where I would NEED to jam a secant ogive match bullet to prevent yaw as it enters the leade for peak precision.

Not saying I liked it. It was a screwup. Just found the situation interesting. Certainly don't plan to do it with field loads. I like rounds to slide in and out of the chamber with ease.

 

[HowieG]

I have non bench rifles that like bullets jammed although you may require plenty of bullet hold if you plan on ejecting a loaded round.
IMO all data means something' I start my BR guns load development at a jam leaving one direction to work.

Makes sense to me. I remember reading about the old black powder days when a target shooter would insert a cartridge in the breech and ram a cast bullet in through the muzzle for a nice engraved fit.

 

[HowieG]

I have seen a die that seats a particular bullet crooked have less than ideal results but if I load the bullet long enough chambering them, seats the bullet deeper, then removing and checking the runout, it goes away. I have a .22 Hornet and if I am using 35 grain v Max bullets I have to do this, takes them from 1.25” groups to .380”.

I have a couple of three boxes of those 35's. Stubby little things. I don't really care for them much. I prefer either the 40 Nosler varmageddon FBHP or the Barnes 40 FBHP. I have a 22 K Hornet.

 

[JFrank]

I have one barrel that shoots 103 vapor trail bullets at .030 jam another barrel that likes 108 Berger at .026 jump , each shoots smaller than you could possibly image.

 

[Thomasss]

I personally feel that is the basis for many of the 6.5 mm cartridges that are coming on the market now. Call them what you want, target, etc. But look at how far the bullets are sticking out of the cartridge. That reduces neck tension and maximizes powder efficiency. But it will be interesting how many survive the test of time.

 

[HowieG]

I have one barrel that shoots 103 vapor trail bullets at .030 jam another barrel that likes 108 Berger at .026 jump , each shoots smaller than you could possibly image.

Wow, thirty thousandths! That's like a drive it in with a hammer jam. A spark plug gap jam.

 

[JFrank]

Wow, thirty thousandths! That's like a drive it in with a hammer jam. A spark plug gap jam.

It's not bad, just feels like a firm bolt close, or some call it a crush fit

 

[Walkalong]

108 Berger at .026 jump , each shoots smaller than you could possibly image.

I have a vivid imagination, but I can't imagine anyone getting exactly .026 jump with every round. Too many variables.

 

[Walkalong]

It's not bad, just feels like a firm bolt close, or some call it a crush fit

Agreed, .030 into the lands is not heavy resistance, not even close.

 

[Varminterror]

Correct when fired with a jump. I don't think so when you are pushing the bullet in slowly by hand.

Your bullet is at the mercy of the cartridge case supporting it. If the cartridge case introduces the bullet to the lands off axis, it’s going to be off axis.

 

[JFrank]

I have a vivid imagination, but I can't imagine anyone getting exactly .026 jump with every round. Too many variables.

I have a wilson microadjust seater so no imaging to it.

 

[HowieG]

Your bullet is at the mercy of the cartridge case supporting it. If the cartridge case introduces the bullet to the lands off axis, it’s going to be off axis.

I don't agree. Here's a quote from jmorris above showing a different outcome.

jmorris said: ↑
I have seen a die that seats a particular bullet crooked have less than ideal results but if I load the bullet long enough chambering them, seats the bullet deeper, then removing and checking the runout, it goes away. I have a .22 Hornet and if I am using 35 grain v Max bullets I have to do this, takes them from 1.25” groups to .380”.

 

[HowieG]

I have a wilson microadjust seater so no imaging to it.

I can certainly agree that certain match bullets are real precise and wilson seaters are as good as it gets, but some of the ordinary bullets vary a bit in dimensions and don't always seat exactly so. Call it a bit of a tolerance. Actually everything we make in this life has a tolerance. I use a comparator to take my measurements off of the ogive and I get a touch of variance.

 

[JFrank]

As you point out that nothing is perfect, my friend always says the darn tools vary that much... Lol

 

[HowieG]

As you point out that nothing is perfect, my friend always says the darn tools vary that much... Lol

I found a couple of hollow points in box of match bullets a while back that were so much shorter than the rest, I spotted them visually. I used them for warm up shots. Just slightly out of spec, lol.

 

[JFrank]

Probably got shoveled up off the floor and tossed into the batch.

 

[HowieG]

Probably got shoveled up off the floor and tossed into the batch.

Yeah, either Monday morning hangover bullets or Friday afternoon let's get out of here bullets........or hump day bullets. What you want is Tuesday or Thursday bullets.

 

[Nature Boy]

One thing to consider. Jamming a bullet to the point that you're camming the bolt closed with some force has the potential to gall your lugs.. Make sure they are well greased and the lug recesses are clean

My suggestion would be to take a more controlled approach to finding your optimum seating depth. I'll be willing to bet that there's more than one node that will yield similar results and not be at the extreme limits