Seating Problems

gkleven

gkleven

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Measuring the COAL to lands in my Savage Model 10TR 308 Winchester with 175 SMK's using many methods I find the length less than the Minimum OAL from loading handbook. If I seat to Min OAL length from Handbook it jams the bullet into the rifling. So with the Hornady gauge I get 2.694 to lands while the book says Min OAL is 2.80. I'm worried if I give it even 10 thou jump I may get high pressures.
Any advice or thoughts would be appreciated,having hard time contacting Savage.
 
savage barrel nuts virtually guarentee SAAMI min spec headspacing. Mine is exactly min spec from factory.

A little jam and jump won't likely cause problems unless you are already running max loads. If at max, back down 1 gr and you should have plenty of room for .002 jam or jump.

Regarding the oal of 2.80, that is if you want to use this ammo in more than one rifle that will have chambers cut somewhere between saami min and max spec.

If you are loading ammo seating depth to one rifle don't worry about it. Just work your loads from 10% below max value and work your way up to keep pressure in check.
 
ultimate_monkey said:
work up.from min powder load looking for.pressure signs. Also book OAL is from base to tip , the hornady OAL is from base to ogive
Click to expand...

Good point ultimate_monkey about OAL and ogive measurements. SAAMI throat lengths are "guide lines" and not written in stone.

The throat length in my Savage .223 is longer than the throat lengths in my AR15 rifles. Meaning todays chambers must have room for the cartridge and the company lawyer.

Bottom line, many times when fire forming cases I jam the bullets into the lands to hold the case against the bolt face.

And all reloading manuals tell you to start low and work up with all new loads.
 
Thx for the advice. Think I'll give 5 thou jump and bring powder load back to start and work back up again. What would cause more pressure increase deeper seating or bullet jammed into rifling I worked out lengths both using base to tip and base to ogive
 
gkleven said:
What would cause more pressure increase deeper seating or bullet jammed into rifling
Click to expand...

Both, seating deeper raises pressure because it decreases case capacity. And seating closer to the lands will raise the pressure.

Both seating methods are compensated for by starting low and working up to avoid higher pressures.

Start .020 off the lands and get your best group, then play with your seating depth.

Long range load development at 100 yards.
http://forum.accurateshooter.com/threads/long-range-load-development-at-100-yards.3814361/

"Some of you have asked for more detailed instructions on how I do this. Here they are:
1. Find Jam by seating a bullet long on a dummy piece of brass (no primer nor powder) and apply die wax to the bullet ogive and record it's base to ogive length.
2. Chamber the round and close the bolt.
3. Snap the bolt open and measure the base to ogive measurement. If it is shorter than previous measurement, this is your jam. Do it a few times with different cases to make sure.
4. Load a known powder/primer/bullet combination. I load 4 of each powder charge in 0.5 gr. increments and seat bullets at jam - .020". I use one shot of each to get barrel fouled up and also keep an eye for max pressure at the same time. You can also use these rounds to break in a barrel if you are inclined to. If I encounter pressure on the hotter rounds, I will not shoot groups with the other loaded rounds and will pull bullets when I get back home. Do not shoot in round robin style because position and natural point of aim will be compromised.
5. Shoot 3 shot groups starting from lowest to highest. All groups are shot over a chronograph.
6. Examine target and find the place where consecutive groups line up vertically and ES is the lowest and speed increases the least from one group to the next.
7. Load to the middle of the powder node and do a seating depth test.
8. Load 3 shot groups starting from Jam - 0.005" all the way out to Jam - .040" in .003" increments.
9. When you find the seating depth test that shoots the best, load towards the longest side of the node to allow more room for throat erosion.
10. Final step is to load the new seating depth and load 5 shot groups in 0.1 gr. increments 0.5 gr. on each side of node (if pressure limits are not reached). This will cover an entire grain of powder and you will be able to pinpoint where the powder node starts and ends. In the summer, load towards the low end of the node, and do the opposite in the winter.

HAPPY SHOOTING!"
 
I should record this response. I seem to make it about once a week, at least.

The OAL in the book is just a mention of what THEY used in THEIR rifle. It means NOTHING about what you seat your bullet to (unless they borrowed your rifle for their testing).

The OAL for your rifle is determined by your mag length and the chamber throat in YOUR rifle. Each rifle is different. And the throat erodes as you shoot it, so each year you might find you have to seat your bullets longer.

Go back to the bench and load a round. Now turn the seater a quarter rev deeper, and seat the bullet some more. Does this chamber ok? Probably not.

Load another round and seat the bullet another quarter rev deeper and try that. Keep doing this until a round chambers without rifling marks. Each quarter rev seats the bullet about 12 thou deeper.

Then load one more round, seated another quarter rev deeper and measure it. That is the max OAL for that exact bullet in YOUR rifle.

Make a note of that OAL in your log book. It is about 20 thou off the rifling. Now take all the "long" rounds and seat them to the new setting.

I do this with live ammo if I have a rifle I trust. I live on a farm and have a "safe' wall to aim at while chambering live ammo. You might prefer to do this with a case with no powder in it.
 
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