.308 OAL Question for workup

jwrowland77 · June 28, 2013, 05:52 AM

I was working in my workup for the range this weekend and I came across something I haven't come across yet in the 1 and a half years I've been reloading.

Gun I'm using is a Savage Axis .308. I'm loading Sierra MK 155gr Palma.

I used my Hornady OAL gauge and came up with a ogive measurement of 2.289 which barely put the bullet in the case. From what I read, you should have at least the bullet width in the case, in this case it should be .308. At the measurement to ogive of 2.289, there was not .308 left in the case, once I moved the measurement to ogive back to like 2.250, then there was .310 of the bullet in the case.

After coloring the top of a bullet I finally settled on a OAL of 2.900 with an ogive measurement of 2.241 which as you can see from above, is quite a bit away from the lands. I ran the dummy round I made that had the bullet colored and everything ran through fine, no lands marks on the bullet. Even for the magazine just fine with plenty of room to spare. Plus with an OAL of 2.900, there's just over .308 in the neck.

Well I got to looking in the Sierra manual, and they have a OAL for this bullet of 2.775.

I've never had an OAL this much over a book published OAL.

Should I recheck my measurements even though everything ran through fine, and none of the marker got scratched off from the lands? Can I move it out longer or should I keep at least .308 in the case like I've read?

I'm thinking that this rifle just has a generous throat between where the shoulders catch and where the lands are.

Thoughts?

rduckwor · June 28, 2013, 11:20 AM

Have you bothered yo measure OAL length to the lands in your rifle? That is a logical first step. Then you will know where you stand.

Good luck.

jwrowland77 · June 28, 2013, 11:22 AM

Quote:

Originally Posted by rduckwor

Have you bothered yo measure OAL length to the lands in your rifle? That is a logical first step. Then you will know where you stand.

Good luck.

Well, I know I'm good because the marker did not rub off of the bullet.

Re-read the question. The first thing I do is find the max OAL to the lands.

Rimfire5 · June 30, 2013, 08:09 PM

I have two Savage .308s.
One is an old 10 FP law enforcement model.
It had a really deep chamber like your rifle.
My length to ogive measurement to the rifling was 2.194 with Sierra SMK bullets. That works out to an OAL of 2.896 touching the rifling. While the chamber didn't change much with other bullets, the OAL sure did because the ogive isn't in the same distance from the bullet tip in different bullets.
I got good results with that old rifle with the ogive seated 90 thousands away from the rifling.
I also found similar nodes at 50 thousandths and at 18 thousandths off the rifling, so I generally didn't take chances seating out so far that the neck tension was at risk.
After more than 6000 rounds, the chamber has eroded a lot and the accuracy has started to fall off. It is ready to go back to Savage for another barrel.

My brand new law enforcement model 10 FCP-K has a chamber length to ogive measurement to the rifling of 2.108 with 168 SMKs. That works out to an OAL of 2.813 touching the rifling.
I'm still working on finding the best seating depth for SMKs and the other bullets that I shoot but I am have some initial results at 100 yards.

With factory ammo, it has averaged 0.523 for 4 groups shot with Federal Gold Medal Sierra Match King 168 grain ammo.

The best hand load so far has averaged 0.440 with 168 Sierra Match Kings using 43.1 grains of N140 powder seated at an OAL of 2.790.
Second best hand load averages 0.502 with 168 SMKs using 41.8 grains of N140 powder seated at 2.800 overall length.

rduckwor · July 2, 2013, 05:14 PM

Your wording confused me as I thought you were using a Hornady comparator to get the ogive length of the bullet/case combo. You think you have issues? My Rem 700 is 2.945 from bolt face to leads. I won't be jamming anything with this barrel.

Rimfire5 · July 3, 2013, 08:20 AM

rduckwor,

Now that is a very deep chamber.
The bullet is barely in the neck at that depth.

dahermit · July 3, 2013, 08:46 AM

I had a Ruger "Liberty Model", in .257 Roberts that had way too much free-bore. The only bullets that would stay in the case to just touch the lands were flat-based 120 grain, Sierra. If it tried a 120 boat-tail, and seat them out to the lands, they would not fit inside the case.

I research the problem and found that it was a common malady with Ruger .257 Roberts for that year and the fix was to take the barrel off, turn a few thousandths off the end, re-mount and re-chamber the barrel...I decided to live with it instead inasmuch as I could handload it to get about two inch groups at 100 yards...my least accurate bolt rifle.

It was problematic working up hunting loads for that rifle...it would not show any pressure signs, it would just keep giving round-edged primers and no stickiness to the cases when extracting, until I would get nervous about how much over book the charges had become. With a book max of H380 in the cartridge, the cases would be blackened, indicating case collapse from too little of a slow powder. Finally settled on a book moderate load of H205 and called it, good as I am likely to get.

If I were you, I would do a Cerrosafe cast of the chamber area just to see what it looks like in there.

rduckwor · July 3, 2013, 08:42 PM

" rduckwor,

Now that is a very deep chamber. The bullet is barely in the neck at that depth.".

Yeah, no kidding. I measured it today with the Berger 175 OTM that just arrived. 2.992"!

Holy cow! Remington is really trying to keep us from blowing ourselves up.

jwrowland77 · July 3, 2013, 08:46 PM

Quote:

Originally Posted by rduckwor

" rduckwor,

Now that is a very deep chamber. The bullet is barely in the neck at that depth.".

Yeah, no kidding. I measured it today with the Berger 175 OTM that just arrived. 2.992"!

Holy cow! Remington is really trying to keep us from blowing ourselves up.

Mines a Savage. I thought mine was bad at 2.899

Bart B. · July 4, 2013, 09:10 AM

I've no idea where that old myth (seat bullets into case necks an amount equal to bullet diameter [or something like this]) started. But it's been proved over decades of reloading as well as what commercial and military arsenal loads use, it's not important.

Most extreme example was my .264 Win. Mag. that started out with the Norma 139-gr. FMJBT match bullets seated a bit more than caliber depth (26/100ths inch) past the case mouth. 640 rounds later when it's accuracy went to hell in a hand basket, the bullets were seated about 1/16th inch into the neck. 600-yard accuracy was about 4 inches for the life of the barrel from the start to going bad over just 5 or 6 rounds fired some 640 shots later. I just seated bullets out long enough to be set back by the leade as it eroded away from powder burning and peak pressure.

jwrowland77 · July 4, 2013, 10:31 AM

I'll have to go out a little more then with my bullet at differing distances just to see how it affects my three best groups I had on my workup.

June 28, 2013, 05:52 AM	#1
jwrowland77 Senior Member Join Date: March 23, 2012 Location: Conway, Arkansas Posts: 1,398	.308 OAL Question for workup I was working in my workup for the range this weekend and I came across something I haven't come across yet in the 1 and a half years I've been reloading. Gun I'm using is a Savage Axis .308. I'm loading Sierra MK 155gr Palma. I used my Hornady OAL gauge and came up with a ogive measurement of 2.289 which barely put the bullet in the case. From what I read, you should have at least the bullet width in the case, in this case it should be .308. At the measurement to ogive of 2.289, there was not .308 left in the case, once I moved the measurement to ogive back to like 2.250, then there was .310 of the bullet in the case. After coloring the top of a bullet I finally settled on a OAL of 2.900 with an ogive measurement of 2.241 which as you can see from above, is quite a bit away from the lands. I ran the dummy round I made that had the bullet colored and everything ran through fine, no lands marks on the bullet. Even for the magazine just fine with plenty of room to spare. Plus with an OAL of 2.900, there's just over .308 in the neck. Well I got to looking in the Sierra manual, and they have a OAL for this bullet of 2.775. I've never had an OAL this much over a book published OAL. Should I recheck my measurements even though everything ran through fine, and none of the marker got scratched off from the lands? Can I move it out longer or should I keep at least .308 in the case like I've read? I'm thinking that this rifle just has a generous throat between where the shoulders catch and where the lands are. Thoughts?

July 4, 2013, 10:31 AM	#11
jwrowland77 Senior Member Join Date: March 23, 2012 Location: Conway, Arkansas Posts: 1,398	.308 OAL Question for workup I'll have to go out a little more then with my bullet at differing distances just to see how it affects my three best groups I had on my workup.

June 28, 2013, 11:20 AM	#2
rduckwor Senior Member Join Date: June 26, 2008 Location: L.A. - Lower Alabama Posts: 365	Have you bothered yo measure OAL length to the lands in your rifle? That is a logical first step. Then you will know where you stand. Good luck.

June 30, 2013, 08:09 PM	#4
Rimfire5 Senior Member Join Date: January 2, 2009 Location: Northern Virginia Posts: 982	I have two Savage .308s. One is an old 10 FP law enforcement model. It had a really deep chamber like your rifle. My length to ogive measurement to the rifling was 2.194 with Sierra SMK bullets. That works out to an OAL of 2.896 touching the rifling. While the chamber didn't change much with other bullets, the OAL sure did because the ogive isn't in the same distance from the bullet tip in different bullets. I got good results with that old rifle with the ogive seated 90 thousands away from the rifling. I also found similar nodes at 50 thousandths and at 18 thousandths off the rifling, so I generally didn't take chances seating out so far that the neck tension was at risk. After more than 6000 rounds, the chamber has eroded a lot and the accuracy has started to fall off. It is ready to go back to Savage for another barrel. My brand new law enforcement model 10 FCP-K has a chamber length to ogive measurement to the rifling of 2.108 with 168 SMKs. That works out to an OAL of 2.813 touching the rifling. I'm still working on finding the best seating depth for SMKs and the other bullets that I shoot but I am have some initial results at 100 yards. With factory ammo, it has averaged 0.523 for 4 groups shot with Federal Gold Medal Sierra Match King 168 grain ammo. The best hand load so far has averaged 0.440 with 168 Sierra Match Kings using 43.1 grains of N140 powder seated at an OAL of 2.790. Second best hand load averages 0.502 with 168 SMKs using 41.8 grains of N140 powder seated at 2.800 overall length.

July 2, 2013, 05:14 PM	#5
rduckwor Senior Member Join Date: June 26, 2008 Location: L.A. - Lower Alabama Posts: 365	Your wording confused me as I thought you were using a Hornady comparator to get the ogive length of the bullet/case combo. You think you have issues? My Rem 700 is 2.945 from bolt face to leads. I won't be jamming anything with this barrel.

July 3, 2013, 08:20 AM	#6
Rimfire5 Senior Member Join Date: January 2, 2009 Location: Northern Virginia Posts: 982	rduckwor, Now that is a very deep chamber. The bullet is barely in the neck at that depth.

July 3, 2013, 08:46 AM	#7
dahermit Senior Member Join Date: October 28, 2006 Location: South Central Michigan...near Posts: 6,501	I had a Ruger "Liberty Model", in .257 Roberts that had way too much free-bore. The only bullets that would stay in the case to just touch the lands were flat-based 120 grain, Sierra. If it tried a 120 boat-tail, and seat them out to the lands, they would not fit inside the case. I research the problem and found that it was a common malady with Ruger .257 Roberts for that year and the fix was to take the barrel off, turn a few thousandths off the end, re-mount and re-chamber the barrel...I decided to live with it instead inasmuch as I could handload it to get about two inch groups at 100 yards...my least accurate bolt rifle. It was problematic working up hunting loads for that rifle...it would not show any pressure signs, it would just keep giving round-edged primers and no stickiness to the cases when extracting, until I would get nervous about how much over book the charges had become. With a book max of H380 in the cartridge, the cases would be blackened, indicating case collapse from too little of a slow powder. Finally settled on a book moderate load of H205 and called it, good as I am likely to get. If I were you, I would do a Cerrosafe cast of the chamber area just to see what it looks like in there.

July 3, 2013, 08:42 PM	#8
rduckwor Senior Member Join Date: June 26, 2008 Location: L.A. - Lower Alabama Posts: 365	" rduckwor, Now that is a very deep chamber. The bullet is barely in the neck at that depth.". Yeah, no kidding. I measured it today with the Berger 175 OTM that just arrived. 2.992"! Holy cow! Remington is really trying to keep us from blowing ourselves up.

July 4, 2013, 09:10 AM	#10
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	I've no idea where that old myth (seat bullets into case necks an amount equal to bullet diameter [or something like this]) started. But it's been proved over decades of reloading as well as what commercial and military arsenal loads use, it's not important. Most extreme example was my .264 Win. Mag. that started out with the Norma 139-gr. FMJBT match bullets seated a bit more than caliber depth (26/100ths inch) past the case mouth. 640 rounds later when it's accuracy went to hell in a hand basket, the bullets were seated about 1/16th inch into the neck. 600-yard accuracy was about 4 inches for the life of the barrel from the start to going bad over just 5 or 6 rounds fired some 640 shots later. I just seated bullets out long enough to be set back by the leade as it eroded away from powder burning and peak pressure.