30-06 COAL and CBTO with 178 ELDX

[LambChoppa]

Hey all,

Loading for a factory REM 700

Using Hornady modified case and OAL tool. Using the tool to find my jam point and I am getting a number of 2.802. This is holding the case firm into the chamber via the rod the case mounts on and sliding the bullet until contact, tighten set screw and remove case. Bullet sticks in barrel but a small tap on the side of the stock below action frees bullet.

Using this 2.802 measurement I have my seating die set for a .020 jump and I have my finished cases sit a CBTO of 2.782

This is giving me a OAL of completed rounds that are 3.444. This is nearly .105 longer than the max OAL according to the books. Has anyone ever had something this extreme?? I have shot rounds at this measurement and have chambered and extracted them without sticking a bullet.

This got me thinking as it seems extremely long. The other day with the bolt stripped for the gun and checking the fit of some brass I tried the 30-06 modified case for shits and gigs. The bolt wouldn’t close on the modified case without some good effort. I then compared the modified case to a factory Barnes load and to my sized cases.

The distance form the base to in which the shoulder starts at the top of the body on the modified case seems quite a bit further forward (longer) than on either the factory loaded Barnes or my sized brass. Both the Barnes and the modified case measured 2.044 case base to datum using the Hornady comparator. The Barnes case would however allow my bolt to function relatively free while stripped.

If the shoulder junction on the modified case is keeping it from going as far into my chamber wouldn’t this give me a longer CBTO as the bullet then has more distance to be moved until jam point while using the OAL tool. I was thinking I had a .020 jump but now I’m wondering if I am a lot closer to or even potentially jamming.

Attached are a couple photos. One is a dummy round, loaded Barnes factory load and the modified case. Others are datum measurement of the modified case and Barnes load, OAL and CBTO on the dummy round.

Thanks Alan

 

[spife7980]

So the two cases measure the same on the headspace comparator, thats not the issue. Measure the diameters. Theres got to be a difference somewhere and assigning a number to it will show you where.

Or to skip the modified case middle man: if your sized brass fits the chamber freely then I suggest scrolling down to the video called finding your lands and see what your chamber itself tells you if the distance to touching the lands.

Videos | wheeleraccuracy

www.wheeleraccuracy.com

 

[LambChoppa]

So the two cases measure the same on the headspace comparator, thats not the issue. Measure the diameters. Theres got to be a difference somewhere and assigning a number to it will show you where.

Or to skip the modified case middle man: if your sized brass fits the chamber freely then I suggest scrolling down to the video called finding your lands and see what your chamber itself tells you if the distance to touching the lands.

Videos | wheeleraccuracy

www.wheeleraccuracy.com

I was going to try this at some point. Yes the comparator has the modified case and the Barnes factory case measuring the same. I will check the diameter and see what that measures at various points.

My COAL just seems extremely long. If I chamber my dummy round the CBTO doesn’t change so I must not be jamming to hard in my estimation.

 

[spife7980]

I was going to try this at some point. Yes the comparator has the modified case and the Barnes factory case measuring the same. I will check the diameter and see what that measures at various points.

My COAL just seems extremely long. If I chamber my dummy round the CBTO doesn’t change so I must not be jamming to hard in my estimation.

Compared to a book, sure.
Go off your chamber, not a catch all spec that has to also fit a mid century Serbian death trap designed around short soft point bullets.
Factory rem700s are known for loooong freebores. Means they dont ever have to answer the phone for a round not fitting in the chamber.

 

[LambChoppa]

Thansk for the reply. I will throw a bullet in a case, strip the bolt and see what I get as well. I was thinking maybe I had a ton of freebore.

 

[FLIGHT762]

Factory rem700s are known for loooong freebores. Means they dont ever have to answer the phone for a round not fitting in the chamber.

^^^^This^^^^. I have a few Factory Remington 700's and all have measured very long throats. Can't get near the lands @ max. SAAMI COAL. Nature of the 700 Factory beast.

Do some more measuring, but you may find out it is what it is. You might have to load your ammo @ the 3.340" to get them to fit @ magazine length.

 

[Doom]

If this 30-06 chamber is anything like the 308Win then "… seating die set for a .020 jump" is a bad idea. Note the comment on freebore by @spife7980. Looking at the pictures it looks like the bullet is only about halfway into the neck. I am sure Hornady didn't have the 30-06 in mind when they developed this bullet.

 

[LambChoppa]

If this 30-06 chamber is anything like the 308Win then "… seating die set for a .020 jump" is a bad idea. Note the comment on freebore

What makes you say this??

Did you find the 308Win to like a lot of jump or some other reason? I have shot a load of rounds with the .020 Jump and had no issues. The COAL hasn’t been an issue in my 700. I was shooting a load of A4350 and recently started developing a new load with H4350 and that’s what got me thinking about all this again.

 

[redbullitt]

Seen lots of rifles that take em long! I'd not be too troubled about that as long as you know where lands are in YOUR barrel etc.

Been playing with a 6.5 grendel that will take a 100 eldx out at 2.375 to jam, vs mag length of about 2.255 etc. It shoots well at 2.350 since that's all I can get in the cut mags. 2.320 shot well too fwiw.

 

[Doom]

What makes you say this??

Did you find the 308Win to like a lot of jump or some other reason? I have shot a load of rounds with the .020 Jump and had no issues. The COAL hasn’t been an issue in my 700. I was shooting a load of A4350 and recently started developing a new load with H4350 and that’s what got me thinking about all this again.

Remington 308W chambers have a LOT of freebore. It borders on ridiculous in fact. If I were to load a 168 SMK to touching the lands the only part of the bullet in the case would be the boat tail. 175 SMK isn't much better. As to whether these newer bullets would seat at these jumps I have no personal experience but I would personally not be comfortable with the bullet seated as in the forth picture (look at the neck bulge showing the bullet neck expansion. In my case I don't always load the magazine but I want my rounds to fit

I don't know the reasoning Remingtion chose to go this path with the 308W but I have heard that the 30-06 also had this condition from the few people I have talked/work with. In the 308W the mag length is around +/-2.850" so you can play within that dimension but in most cases going with 2.810 or slightly less works fine with older tangent ogive bullets in the 168-178 range. Only benefit of the longer seating depth is a little case capacity. As for the 30-06 I can't speak for the mag length.

 

[spife7980]

If this 30-06 chamber is anything like the 308Win then "… seating die set for a .020 jump" is a bad idea. Note the comment on freebore by @spife7980. Looking at the pictures it looks like the bullet is only about halfway into the neck. I am sure Hornady didn't have the 30-06 in mind when they developed this bullet.

I didn’t say that, I think seating it for .020 is just fine (provided it doesn’t create function issues like mag feeding etc)

 

[Doom]

I didn’t say that, I think seating it for .020 is just fine (provided it doesn’t create function issues like mag feeding etc)

Was just referring to the freebore comment.

 

[LambChoppa]

Remington 308W chambers have a LOT of freebore. It borders on ridiculous in fact. If I were to load a 168 SMK to touching the lands the only part of the bullet in the case would be the boat tail. 175 SMK isn't much better. As to whether these newer bullets would seat at these jumps I have no personal experience but I would personally not be comfortable with the bullet seated as in the forth picture (look at the neck bulge showing the bullet neck expansion. In my case I don't always load the magazine but I want my rounds to fit

I don't know the reasoning Remingtion chose to go this path with the 308W but I have heard that the 30-06 also had this condition from the few people I have talked/work with. In the 308W the mag length is around +/-2.850" so you can play within that dimension but in most cases going with 2.810 or slightly less works fine with older tangent ogive bullets in the 168-178 range. Only benefit of the longer seating depth is a little case capacity. As for the 30-06 I can't speak for the mag length.

Thanks for the reply. I did notice this and never thought much of it. I always used a minimum of a calibers (in this case .30) diameter in the neck and most times it’s not an issue maintaining this. Im certainly short of this with this load. I hadn’t played with it much or worried about it as my current load is shooting a SD in the 5-7 range.

I have a good load worked up pushing the 178 at about 2800fps with no pressure signs at all. I’m going to work back a little and see if I can’t find a sweet spot while keeping my ES and SD in check.

Thanks