Does this sound right?

[DarrellA]

First, I'm a total newbie at hand loading. I'm struggling with bullet seating depth determination. I have had success with my first 20 rounds. I seated the bullets to match the factory ammo I had on hand that have the same 140 grain Berger VLDs. I used the Hornady Bullet Comparator to take measurements. The first batch of 20 rounds shot just fine.

I'm having no luck with the home brew methods of determining when the rifle lands hit the ogive - smoke, sharpie, floppy bolt with the firing pin removed. I just can't get a decent read. So I tried something else. In a sized, dummy round I seated the bullet way long (shallow). The bolt didn't want to close and sometimes the round stuck in the chamber. (Pushed out with cleaning rod) I seated deeper and deeper until the bolt closing feels right and the rounds don't jam. And now I have a new measurement.

But here's where I get nervous. When I duplicated the factory ammo the measurement is 2.156". They shot fine. Playing with the dummy round I am coming up with 2.2725" when the round doesn't jam and the bolt feels like I'm not forcing it. That's a big delta - 0.119" longer (shallower) than the factory ammo. That sounds like a lot to me. I know I should seat a few thousandths deeper for my production run, but I don't know if I'm kidding myself and I'm still jamming the bullet in the rifling and going to create an overpressure problem.

Am I over thinking this? Am I about to blow my face off?

Some other info - Weatherby Sporter in 7mm-08. Factory ammo is HSM, with 140 grain Berger VLDs.


Thanks

 

[Cstanm70]

many factory rifles leave huge amounts of jump between seating and lans. My rem 700 .308 lans are 2.998 with 168 amaxs, factory COAL is 2.8. lans that are close to cartridges are reserved for custom rifles.

 

[vinsonr]

I have had 3 Rem 700 .308's that shot lights out with bullets loaded to 2.21 base to ogive. Don't be too concerned with the diff from factory ammo. Certainly pick your seating depth and re-work your load up from a safe starting point. Your other load with the bullet jammed into the lands could cause an unsafe spike in pressure.

 

[Rem7targetactical]

HOLY S%IT!!!! I was actually just going to write a post about the same thing! I'm using a Sinclair tool (the one that looks like a big nut) and the Hornady OAL modified case gauge and am also coming up with big numbers that I thought were a concern. My rifle was rebarreled with a Shilen pre-thread in 308 and I'm using 175 Matchkings. My base to ogive for the chamber to lands measurement is coming in at 2.230 and when I set OAL to 2.81, it's 2.148 that's a .082 jump!?!?!?! I've heard of quite a few people using .010-.020 from the lands. I'm guessing I shouldn't try to seat the bullet that far out right? I've shot 1/2 moa at 200 yards using 2.81 OAL but am trying to get that more consistently. My average now is 1.2-1.3" at 200 yards off a bench using a bag and bipod.

 

[Thumper580]

Use the Sinclair tool to find out where the bullet ogive touches the rifling. Measure the ogive distance. My 308 typically loves about 10 thousands off.

 

[woostri]

I developed my own simple tool. Take a dremel and cut lengthwise down the neck and into the shoulder of a piece of brass. Polish off all the burrs. Adjust the tension on the bullet by the width and/or number of cuts. Usually one slice is enough. The chamber that brass with your bullet of choice stuck in it. Once it contacts the lands, it will get pushed back. Carefully extract the round and measure either OAL or preferably to an ogive point. I've been able to get consistant seating depths within .001 with this method. Which is more than accurate enough considering I usually jump by about 0.010"

AIM SMALL MISS SMALL

 

[Rattler56]

I developed my own simple tool. Take a dremel and cut lengthwise down the neck and into the shoulder of a piece of brass. Polish off all the burrs. Adjust the tension on the bullet by the width and/or number of cuts. Usually one slice is enough. The chamber that brass with your bullet of choice stuck in it. Once it contacts the lands, it will get pushed back. Carefully extract the round and measure either OAL or preferably to an ogive point. I've been able to get consistant seating depths within .001 with this method. Which is more than accurate enough considering I usually jump by about 0.010"

AIM SMALL MISS SMALL

I do the same with a pice of brass as above and compare it to
My Hornady OAL gauge cause sometimes I like my face, also I
Load a dummy round to run in the action to check with a light coat
Of paint or what ever to make sure that it's not jammed in the lands.

VLD's I find shoot the best in my .243, however if you are not using a
VLD seater you will get a verity of OAL's, my go to OAL for this Rem 700
is 2.884 and that's kissing the lands.

 

[woostri]

Yep, I also make a dummy round with full neck tension with each fav bullet that touches the lands once I've done the measurements and check it in the chamber. That way I always have a reference length for that bullet in that gun. Saves a lot of time, as long as measurements are rechecked everytime. Cause yeah, I like my face too.

AIM SMALL MISS SMALL

 

[DarrellA]

Smoke Test Update

Thanks for the ideas. I'm trying the smoke test again. The problem is, I just don't know what I'm looking at. In the attached photos, have I pointed out (red arrow) where the lands are just hitting the bullet? Or, is the arrow pointing to where the lands just start to hit the bullet and as it was pushed deeper into the barrel the area to the left of the arrow, that's wiped clean, is showing me how deep the bullet is into the barrel?

 

[Paddywagon]

I have had excellent luck with the RCBS precision micrometer for the specific cal you are loading. Used them for years and swear by them. Advantage is that you can measure the case neck and the bullet depth.

 

[DarrellA]

There's a good bit of contact on the lands. How does it feel when the bolt is closed?

What's your goal? Determining distance to lands as a reference to seat off lands or are wanting to seat into the lands? It makes a difference.

Right now I'm trying to establish a datum point of where the lands are. After that I'll start trying to find the sweet spot either off the lands or into them. I don't know which direction I should be going yet, but I would like to know where I'm starting from.

So, is it safe to assume that the area to the left of my arrows that has been swiped clean is actually resting inside the rifling?

 

[DarrellA]

There's a good bit of contact on the lands. How does it feel when the bolt is closed?

What's your goal? Determining distance to lands as a reference to seat off lands or are wanting to seat into the lands? It makes a difference.

The bolt feels "normal". I've found that even with the firing pin removed and an empty, once fired case in the chamber I still have to push the bolt handle down to lock. With very light effort. But it will not free fall closed unless the chamber is empty.

Right now I'm trying to establish a datum point of where the lands are. After that I'll start trying to find the sweet spot either off the lands or into them. I don't know which direction I should be going yet, but I would like to know where I'm starting from.

So, is it safe to assume that the area to the left of my arrows that has been swiped clean is actually resting inside the rifling?

 

[smschulz]

Pretty easy with a bullet comparator and the Hornady or Sinclair OAL gauge.
My Rem 5R is very long as are most Rem's.
My gas guns are much shorter.
I load very long for the bolt gun and much closer to factory specifications on the gassers.

 

[DarrellA]

The area left of the arrow looks like it was rubbed during extraction. The little marks are from the lands. Removing the firing pin isn't doing anything for you, removing the ejector would (that's what pushes on the case head when closing).

DOH! Yeah, that makes sense.

Take a measurement off the test cartridge and call it close enough for seating off the lands. Pick where you want to start your load and roll with it. I would probably pick 0.010 less than your test cartridge. Work up the load and see what charges look good, then revisit the seating depth.

OK, I'll consider the red arrows my datum back off .010" as a starting point. Sound reasonable?

 

[DarrellA]

Pretty easy with a bullet comparator and the Hornady or Sinclair OAL gauge.

I have the Hornady/Sinclair OAL gauge, but have been waiting on a modified cartridge for 2 months and it's still on back-order. I tried fabricating my own, but in drilling and tapping the case I manage to mangle it just enough that I can't get it to seat in the chamber properly. I may try the method of measuring with a cleaning rod and 2 rod stops also. But I may still have to remove the extractor because that seems to be what's preventing me from "feeling" when the bullet contacts the lands.

 

[smschulz]

many factory rifles leave huge amounts of jump between seating and lans. My rem 700 .308 lans are 2.998 with 168 amaxs, factory COAL is 2.8. lans that are close to cartridges are reserved for custom rifles.

My coal is 2.942 (OG 2.316) 178gn Amax and similar uber-long dimensions with other bullets.
I have a batch ready for testing at 2.249/2.874.... .068 jump.
They fit in my Alpha and AICS mags so we'll see.

 

[vinsonr]

I've found that 178 amax's don't mind a jump at all. When I moved to 178hpbt's I seated them the same at first and had terrible results. Seating them out closer to the lands fixed it but forced me to get an aftermarket chassis for my R700 PSS. I've now had 3 R700 PSS barreled actions that love 178hpbt's seated to 2.21 to the ogive.

 

[Cstanm70]

Yea I forgot to mention its a sub half moa rifle evidentaly loves jump.

 

[Rattler56]

The area left of the arrow looks like it was rubbed during extraction. The little marks are from the lands. Removing the firing pin isn't doing anything for you, removing the ejector would (that's what pushes on the case head when closing).

Take a measurement off the test cartridge and call it close enough for seating off the lands. Pick where you want to start your load and roll with it. I would probably pick 0.010 less than your test cartridge. Work up the load and see what charges look good, then revisit the seating depth.

Once again this man knows what he is talking about and remember to start at a low end load with what ever powder and work up, I load in increments of .5 say
34, 34.5, 35, 35.5 etc.
I load 5 each then refine by results, once I have found the sweet spot, then I start adjusting the OAL and on the VLD's I use a Redding VLD seating die, they work great.

 

[BobinNC]

For proper seating depth I refer to what I call the Goldilocks Theory.

Some bullets can be seated too long...
Some bullets can be seated too short...
But some bullets can and are seated just right...

How do you know if a bullet is seated too Long??

Well if you have a repeater (any rifle with a magazine fixed or detachable is a repeater) and you actually want to use it as such (like in feeding from the magazine) then your overall COAL cannot be longer than your magazine. At this point it is irrelevant how long your throat actually is, because if it is longer than your magazine, and you seat your bullets that way, your rifle will not repeat.

Even if you know, for example, your mag box is 2.880" long (like in a standard SA AICS magazine) you really cannot actually load your ammo to 2.880" long. You need to allow some space, like 0.10" to account for uneven bullet tips.

Sierra SMK's are notorious for this, even though they shoot really well, the OAL of the bullets tend to vary by up to 0.15" in some cases. Meaning to have to seat your bullets to a max of 2.865" in your 2.880" magazine, for reliable feeding.

Bullets with polymer tips, like Hornady's A-Max, and many of Nosler's bullets also feature these type tips, and they tend to be very uniform in OAL, allowing maximum use of your magazines interior space.

Magazine issues aside, a bullet can also be seated too long if your rifle throat extracts the bullet from a live case. Folks forget that one of the best bullet pullers ever made is your rifles own throat. Knowing where your lands start is a good practice.

A bullet can also be seated too short. By too short what I mean is that part of the bullets ojive is below the top of the case neck. For example: Many folks try stuff Hornady's 75 Grain A-Max in a .223/5.55mm case and then feed them through an AR's 2.260" max length magazine. Well in doing that they are seating the ojive below the case neck.

Some can get away with that practice, but it is usually frowned upon.


So what is the optimum seating depth???? Well somewhere between too short and too long....and that's one of the reasons we reload is, to find out...

 

[DarrellA]

My Possum Hollow cleaning rod stops arrived today. I took 10 measurements, threw out the high & low and calculated the average of the remaining 8. The results are telling me the lands are .0265" closer to the bolt face than what I was getting with the smoke test. Can't say one method gave me a more accurate answer than the other. But since I was able to get 10 very consistent measurements with the rod stop method, I'm feeling a lot better about what I'm working with as my datum point. Off to the range on Sunday!

 

[DarrellA]

Well, how 'bout that?!

I followed Eric Stecker's procedure on "Getting the Best Precision and Accuracy from Berger VLD bullets in Your Rifle" And, sure enough, one group stood out. The group that's .090" off the lands. Now it's time for the fine tuning. Although, I'm not sure that it's going to get much better than these results. But, who knows?

 

[MtnCreek]

Looking good!