Bullet seating changing when chambered!? (3006)

[tkd4life]

Sierra is probably just putting disclaimers in there for liability reasons since shorter COL, in most cases means higher pressures. I know, having them touch the lands also results in higher pressure.

That's why, unless I am shooting lead bullets, I stay somewhere in between.

John

Agreed, it is definitely important to remember that these manuals are written as much by lawyers as they are by reloading specialists.

 

[outrider58]

The directions posted by Uncle Duke do work. If you happen to have a Lee collet neck die, in lieu of denting the case mouth as described in the Nosler directions, you can very lightly size the neck until you have the needed amount of grip that still allows the bullet to slide in the neck.


In the context of AR15/M16 stuff, NO. It's highly unlikely you're going to get a bullet to contact the rifling when loaded to mag length whether it be a 5.56 or 223 chambering. Interestingly enough, if you reduce OAL on a rifle, it's quite possible you actually see lower pressures, and then possibly higher pressures as you go even shorter. Less initial resistance results in lower peak pressures. If you seat deeper, you have a larger jump to the lands thus possibly reducing pressure. 5.56 chamberings usually have a longer leade. My theory is that many AR manufacturers have more of a 5.56 chamber even if they call it 223 Remington. There are gauges to measure the leade and determine whether your gun falls more on the 223 Remington side or the 5.56x45 NATO side.

Some interesting stuff in this thread.
https://www.ar15.com/archive/topic.html?b=6&f=42&t=428271

I stand corrected. The longer leade in 5.56 barrels is to reduce chamber pressures(not sure why that is needed. Maybe someone could explain the why).

In the OP's case, why does it seem his bore(30-06) was reamed short? Warn reamer or was it intentional?

 

[StickShaker]

I stand corrected. The longer leade in 5.56 barrels is to reduce chamber pressures(not sure why that is needed. Maybe someone could explain the why).

In the OP's case, why does it seem his bore(30-06) was reamed short? Warn reamer or was it intentional?

My guess on the 5.56 longer lead is mainly for reliability reasons. Less chance of dirt/gunk, damaged or long bullets causing feeding problems.

 

[chad2]

So first I started dialing my bullet in .005 and chambered it each time checking for seating depth change. I did this until I saw no change in seating depth this happened at 3.253, so I set my furthest seating depth at 3.250. at this point I was still seeing a scuff ring around the bullet, so in each group I had a 3.250, 3.245 and a 3.238. I started my loads at 50.5 working up by 1 grain in each group.

Group #1 50.5gr imr4350
Seating-3.238= 2525 fps
Seating-3.245= 2539 fps
Seating-3.250= 2492 fps
Group#2 51.5gr imr4350
Seat-.238= 2534 fps
Seat-.245= 2554 fps
Seat-.250= 2544 fps
Group#3 52.5gr
Seat-.238= 2619 fps
Seat-.245= 2594 fps
Seat-.250= 2609 fps
Group #4 53.5gr
.238 = 2732 fps
.245 = 2693 fps
.250 = 2688 fps
Group #5 54.5gr
.238 = 2732 fps
.245 = 2754 fps
.250 = 2726 fps

These loads are very close to the load data velocities. Also there are no significant changes in velocities. my next work up is going to be 53.5, 54.5 and 55.5, to see which one yields best accuracy then I will mess with seating depths and accuracy.

Should I do this differently?

 

[chad2]

Any other suggestions of how I should go about tailoring my load?

 

[Praeger]

Using fiocchi brass and 175 gr smk bullets, I am neck sizing the case twice with a half turn inbetween the 1st and 2nd, then I set my seating depth to 3.290 and on three different cases and three different bullets. After chambering and extracting the seating depth changed to 3.254, 3.258.and 3.260, this is .036 to .030 diff.

So then I tested the new fiocchi 180 gr smk that we have before and after and the biggest change in saw after chambering 10 rounds was .002. Why are my bullets getting pushed in from chambering? This worries me because of spikes in pressure.

Fiocchi has no visible crimp. do i have to crimp the cases? I have heard this can ruin accuracy. My smk's do not have a cannelure.

I cleaned and prepend all the cases before and no case lube was used due to only neck sizing.

Please let me know what I am doing wrong!

If the bullet is contacting the throat or leade as it is chambered, and it is enough to leave a mark on the bullet and/or push it back into the case - it may be unreliable to measure the COL (or CBTO if you are using a comparator). Reason being, if the bullet is bottomed out against the throat/leade enough to push the bullet in the case, it may also pull the bullet from the case when extracted. It may not do this every time, but it can lead to inconsistent readings.

As an alternative - as soon as you realize the bullet is jamming, first give the chamber a good look to see if the rifle has developed a carbon ring which is causing the contact. If you see one, easy solution, scrub it off.

If the chamber is clean, then move to finding the seating depth where the bullet no longer jams in the throat/leade. I prefer to smudge a dummy round using a candle, load and check for contact.

Here's a photo of a .223 round (seated long to demonstrate) and you can clearly see the bright copper ring where the contact removed the smudge. Start long, and increase the seating depth until no smudge. Re-smudge the bullet each time so it is easy to see where contact occurs. Once you find a seating depth where no contact occurs, you can adjust for how much bullet jump you want.

 

[alucard0822]

Lee collet dies often have this problem, any little bit of carbon in the neck, or dirt on the die will reduce neck tension, even then, there isn't much to begin with. For it to work you need to scrub the inside of the neck, and check the diameter of the pin, found one I bought had a little bit of a rough surface and was a hair big, had the same problem you are describing. Thing is full length dies will neck size, just back them out a little, have had much better luck sizing with a standard full length die backed out a couple turns than the Lee collet, sizing fireformed brass only as much as you need also can work in semi-autos, or finicky rifles that can jam up on collet sized brass.

 

[Pinecone]

The meplat (tip) of 175 SMKs are not even. Overall length can vary quite a bit, best is to check using a comparator.

 

[Doco Overboard]

I resize in one fell swoop reduce neck tension by cutting 3 slots behind the case mouth in a freshly chambered 3006, smoke like Praeger and back up ten-15 thou after proving with another smoked dummy round with full neck tension. Check for obvious signs of pressure from minimum starting advertised load for safety. Thats just how I was taught but I cant shoot well enough to tell a .005 difference any more. I think RCBS makes a case mike but I'm a cheapo. Thanks for the good reading, enjoying the info being discussed.

 

[John from MD]

I have been since I was 14 that makes it 50 years or so. Cutting slots in the neck and smoking the bullet IMHO is still the best way to adjust bullet COAL for THAT RIFLE with THAT BULLET.

I know that RCBS, Hornady and God knows who else, make fancy micrometers for measuring cartridges. My basement full of awards says you don't need them. You just have to be patient and work up loads for the rifle you are using.

When I say work up loads, it includes observing changes from powder, primers, cases, case neck tension, bullet shape as well as how long the cartridge is. Also, don't hesitate to try different length bullets. Unless you have had a custom barrel made, you may not have the exact twist that you think you have.

BTW, don't just check bullets close to the lands, check them out .020 back as well. Some guns actually shoot better with a bullet jump, others like to kiss the lands. It takes patience, lots of patience if you want to win.

 

[billymx48]

Get a hornady c.o.l. gauge and find out what depth you can do in your rifle.

 

[Doco Overboard]

I have been since I was 14 that makes it 50 years or so. Cutting slots in the neck and smoking the bullet IMHO is still the best way to adjust bullet COAL for THAT RIFLE with THAT BULLET.
Isn't that what he's trying to do?

 

[John from MD]

I have been since I was 14 that makes it 50 years or so. Cutting slots in the neck and smoking the bullet IMHO is still the best way to adjust bullet COAL for THAT RIFLE with THAT BULLET.
Isn't that what he's trying to do?

I was just supporting your post as I have found that you don't need a mic or ogive measuring wiggits, just use the guns own chamber and lead to make an accurate load.

Good shooters have been doing it probably as long as centerfire reloading has been around.

John

 

[Doco Overboard]

10/4 Thanks John, with a little age comes wisdom and I bet you certainly have more experience than me reloading. I just thought that what has been discussed is relatively common knowledge for getting your kit right without buying into a lot of marketing hype or overthinking something and then losing out on something else which is part of the same task. Although I'm sure the RCBS case mike is a great tool but those dollars can equate into more important components in today's economy.
Brian

 

[John from MD]

Most people can't shoot as well as their gun can. Unless you are a serious benchrest or over the course shooter, you won't notice the small differences you get from thinks like measuring the ogive distance to 4 decimal points or cleaning primer pockets or weighing your brass. I have always trained my students in the discipline and level that they wanted to be. If a guy told me he wanted to learn to shoot rifle at 100 yards, I didn't teach him how to adjust for a 12 inch bullet drop.

Many shooters would be better off spending their money on ammunition or components so they can shoot more often than on gadgets that may or not help them.

 

[Doco Overboard]

Like a good sling and a glove!