seating depth and group size

elpac3 · Oct 9, 2015

Been working on new loads for the .222 Remington.

Loading manuals all give a max. cartridge overall length of 2.130. Shooting bullets seated to this depth gave acceptable results but nothing stellar.

Started measuring ogive length for the three bullets I am working with, 40 grain Nosler Ballistic Tip, 50 grain V-max and 52 grain MatchKing.

Seating the 50 & 52 grainers out to an OAL of 2.160 made a considerable improvement in group size. This length happens to be .010 off the lands in my rifle.

Thinking the gun likes .010 off the lands I measured the ogive on the 40 grain ballistic tip and determined an overall length of 2.228 would give me .010 off the lands. Seemed like a huge difference from the max 2.130 recommended in the manuals. Was really hesitant to go that far but the numbers all checked out. .010 off the lands and slightly more than one caliber seated depth.

Loaded up some rounds and off to the range. Absolutely amazing results. Group dropped to .195 (off a rest) - a new personal best.

Can't say enough about the importance of measurements based on your individual rifle / bullet if you are looking to get the most from the cartridge.

txbirdman · Oct 9, 2015

Yep that's one of the things a handloader can do that the factories can't. I usually sacrifice a piece of brass by splitting the neck down to the shoulder with my Dremel tool. I run this brass through my neck sizer and begin to seat whatever bullet I'm working with at the time out long in the modified case. As I chamber the round slowly the rifle does the final seating of the bullet to the maximum OAL. I then carefully extract the brass and bullet to measure and record the max OAL with that bullet. When handloading the actual ammo I reduce the OAL by .005 to .010. I (like you) have noticed a substantial improvement in grouping with some rifles. With other's not so much. Seems each gun is a law unto itself.

novalty · Oct 9, 2015

I started my first reloads for my Remington 700 VLS in 308 with the same method as txbirdman. However, when seating 20 thousands off the lands the rounds are way too long to fit into the magazine well. Kind of a pain, as now I either have to shoot it as a single shot, or sacrifice the length to fit the rounds into he magazine well.

M29since14 · Oct 9, 2015

That's nice shooting with your .222 - and good handloading too.

The seating depth thing can be a frustration in the case of some cartridges and rifles, unless you are willing to always single load. I also have a Rem. 700 in .308 that shoots best with cartridges that are too long for the mag box.

elpac3 · Oct 9, 2015

txbirdman said:
Yep that's one of the things a handloader can do that the factories can't. I usually sacrifice a piece of brass by splitting the neck down to the shoulder with my Dremel tool. I run this brass through my neck sizer and begin to seat whatever bullet I'm working with at the time out long in the modified case. As I chamber the round slowly the rifle does the final seating of the bullet to the maximum OAL. I then carefully extract the brass and bullet to measure and record the max OAL with that bullet. When handloading the actual ammo I reduce the OAL by .005 to .010. I (like you) have noticed a substantial improvement in grouping with some rifles. With other's not so much. Seems each gun is a law unto itself.

Absolutely right - each chamber (gun) is a rule unto itself and simply because it worked for me in one rifle does not necessarily mean it will work in another rifle. Couple that with all the other variables, powder, primer, case, bullet - - - and it can make you hair hurt.

Fortunately I found the sweet spot before all the hair is gone.

Magload · Oct 9, 2015

Elpac3 I am impressed with that group was that @ 100yds? What rifle were you using I want one the bucket list is filling up again.

Yes Magazine in a AR is a limiting factor and I have my 223 Rem 55gr V-Max so they just verily fit. I have a single load adapter on order as I want to test longer loads and some longer bullets. I think the thing was caller a sled and keeps the round lined up so it feeds. How to make a want to be bolt action out is a AR.

SMSgt · Oct 9, 2015

I learned that trick a long time ago in my Rem 788 .223 and 700 .30-06. My buddy couldn't use my -06 rounds because they would not fit his Win 70. Each individual gun would have its own perfect COL.

elpac3 · Oct 9, 2015

100 yards

1957 vintage Remington 722 with Timney trigger and Boyds thumbhole stock, Nikon mildot scope.

mtgianni · Oct 9, 2015

Shortening the oal can raise pressures, lengthening it can only lower them but give incredible results with bullet jump. IMO, the major reason for many OAL minimums is that they fit through most magazines.

Twoboxer · Oct 9, 2015

mtgianni said:
Shortening the oal can raise pressures, lengthening it can only lower them but give incredible results with bullet jump. . . .

IME that is not necessarily true with rifles. At least if muzzle velocity is an indication of pressure.

"Test" rifle was an old 30-06 with a long chamber to handle the wide range of bullets. 167/168gr bullets can not be loaded long enough to hit the lands in this rifle without leaving little more than a sliver of bearing surface in the case.

As COL went from mag length to near the lands, MV decreased for a bit then began to increase with the highest MV being those cartridges seated closest to the lands.

In my mind, this correlates to the oft-stated caution that seating a bullet close to, at, or in the lands increases at least the initial peak pressure, if not also the peak pressure.

fredj338 · Oct 9, 2015

OAL is very gun & bullet specific, so take book data as a ref, not gospel. Most rifles, most bullets, will shoot better with the bullet closer to the lands. Some rifles & some bullets like to have a run at the rifling, so there are no magic numbers.

fredj338 · Oct 9, 2015

mtgianni said:
Shortening the oal can raise pressures, lengthening it can only lower them but give incredible results with bullet jump. IMO, the major reason for many OAL minimums is that they fit through most magazines.

Just not right. The closer the bullet is to the lands, the faster pressure builds. So loading shorter often reduces pressures a little. It's not like handgun loads. Think of the longer throats in the Wby line of rifles.
The fastest rifle powder is still slower than the slowest handgun powder. So unless talking very small rifle cases, like the 221 fireball, Hornet, etc, seating deeper & even compressing powders doesn't have a lot of affect on pressures, it's offset by the bullet jump to rifling. Now get a short throat, compressed load in a small case, yes, pressures are going to go up.

Magload · Oct 9, 2015

elpac3 said:
100 yards

1957 vintage Remington 722 with Timney trigger and Boyds thumbhole stock, Nikon mildot scope.

Dam that is a petty rifle. I love a wood stocks. Don

shovelwrench · Oct 10, 2015

I recently read an article describing a load work up starting with seating the bullet AGAINST the lands......

Then doing load workup from below the minimum charge, to right past the maximum charge (in 1/2gr increments).....

Starting with one bullet from each load and shooting at individual targets for a given load, stopping at the highest load that showed any signs of pressure. (theory being that this is YOUR guns max with the given bullet)

THEN, shooting one round at a time from each load at that loads target until your out of rounds (again, stopping with the one that showed pressure, and not shooting any higher loads)

The whole purpose was to find
A: your rifles MAX
B: barrel harmonics sweet spot.

The sweet spot comes in where you have a string of loads that grouped well....

After deciding which loads to work within, you begin to seat your bullet back, and in theory, begin to lower pressures slightly.

Working through the whole process again with bullet seating only and a load picked in the middle of your couple good grouping loads.

A friend of mine and I tried it with our 7mags, but have only got past the first load step, and neck sized. He decided that was good enough and loaded 30rds, slightly off the lands.

His rifle NOW shoots fantastic.

I haven't got to sit back down to mess with the length, but its coming before deer season!!!!!

Does all that make sense?? LOL

Magload · Oct 10, 2015

I read a similar article where you worked your way through your loads firing one shot at a target the next load at the next target and so on till you started over with the first load at the first target doing this till you had a 3 or 5 shot group at each target. This averages out the differences you get as the barrel heats up and also get fouled. I might even clean the barrel after the second round and fire two fouling shots and continue with the groups. He did not start against the lands but .030 jump i believe. Then picked a group and started moving the bullet forward. Don

noylj · Oct 10, 2015

COL: for the reloader, the COL is determined by the how long a round the magazine will hold or, if single loading, how long the throat is.
SAAMI sets the COL for .223 Remington as 2.125" min and 2.260" max. This is for the industry, for loads to fit any gun, and does not apply to the reloader who is making loads for his/her guns only.
2.130" is NOT a max COL and I have not idea what manual would show that as a max COL.
For accuracy, you can use a "ladder," that involves shooting one round at a given charge weight at 300 yards and determine the range of charge weights that all group together. What this should be telling everyone is that, within that range, all shots will hit to about the same POI and that, just maybe, unless you are shooting well beyond 300 yards, precise charge weights may not be very important.
I have read that, due to the comparatively larger cases for rifles, that pressure actually goes up with longer COL (due to approaching the lede/rifling) and goes down with shorter COL (due to the very small change in internal volume having almost no effect and the longer run-up to the lede dropping pressure). I have no idea.
I just set the round to fit the magazine and load from there. If loaded singly, I would start with the bullet almost touching the lede/rifling. That is all the COL experiments I have needed in 40 years.

Gamecock · Oct 10, 2015

noylj said:
SAAMI sets the COL for .223 Remington as 2.125" min and 2.260" max. This is for the industry, for loads to fit any gun, and does not apply to the reloader who is making loads for his/her guns only.
2.130" is NOT a max COL and I have not idea what manual would show that as a max COL.

Sir, we're talking about .222 Remington, not .223.

seating depth and group size

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