throating 7mmRemMag for 180 eld-m

[AKSavage]

Since my factory Savage 7RM barrel is toast, I'm looking to rebarrel it for the same cartridge but with a custom savage pre-fit barrel in 1-8 twist, and throated long to be able to load the Hornady ELD-M 180 grainers to full potential. I loaded up some dummy rounds: COAL at 3.670" and 2.810" base-to-ogive, with the bullet seated so the boat tail junction is just above the neck-shoulder junction on the brass. Magazine length issues have been solved and I'm ready to move on to order the barrel.

I have two questions: the first is whether, in your experience, it's worth it to spend extra to have a long-throated reamer made, or whether I should just order a standard chamber and have the throat extended with a throating reamer. (I know of at least one barrel maker that makes Savage pre-fit barrels and says they will throat the chamber to whatever length I want for no extra charge.) So, pay $180 for a semi-custom reamer + $50 extra to have it chambered with my own reamer, or just have the throat reamed long and save over $200?

Second...although I can send a dummy round in and have a reamer cut to match it, does anyone have any experience with this combination, enough to be able to tell me what throat length will need to be? I was thinking in the .095" range but would like to know if I'm in the right ballpark.

Thanks!

 

[MudRunner2005]

Personally, I would never throat a rifle for a specific bullet. What if your barrel doesn't like that specific bullet? Then you're going to be going back to the smith to have your brand new barrel's chamber reset back a couple threads with a standard throat so it will be able to shoot any/every other bullet available.

Not saying it will happen, but it is a possibility. I've had barrels that just simply did NOT like certain bullets. And when that happens, you don't want to have to deal with anything that was setup specifically for that bullet it doesn't like. Instead of moving forward, that's being forced to take 2 steps back, before you can try again with something else.

 

[elkaholic]

If you know that you have a very competent smith I would just have him throat it out but I think it would need to be much longer than .095"? Probably almost double that?

 

[elkaholic]

Personally, I would never throat a rifle for a specific bullet. What if your barrel doesn't like that specific bullet? Then you're going to be going back to the smith to have your brand new barrel's chamber reset back a
couple threads with a standard throat so it will be able to shoot any/every other bullet available.

Not saying it will happen, but it is a possibility. I've had barrels that just
simply did NOT like certain bullets. And

when that happens, you don't want to have to deal with anything that was setup specifically for that bullet it doesn't like. Instead of moving forward, that's being forced to take 2 steps back, before you can try again with something else.

I will have to disagree. Any throat will SHOOT every bullet available but will be a compromise and leave performance on the table. You have to look more at a weight, style, length of the bullet range you will shoot primarily. If his throat doesn't like a 180 ELDM, it will be close to throated correctly for a 180 Berger or similar style. You do of course have to take into account your mag length and if you are willing to single feed, etc.
IMO .....RICH

 

[MudRunner2005]

I will have to disagree. Any throat will SHOOT every bullet available but will be a compromise and leave performance on the table. You have look more at a weight, style, length of the bullet range you will shoot primarily. If his throat doesn't like a 180 ELDM, it will be close to throated correctly for a 180 Berger or similar style.
IMO .....RICH

While having a hybrid ogive, the ELD lines seem to have a noticeably longer bearing surface than the comparable Bergers. I have also noticed they seem to require an extra 1/2 to 1 inch of twist for similarly weighted bullets. That's another big reason I was turned off the ELD lines of bullets. The Berger 180's can stabilize in a 1:9, and the 180 ELD's recommend a 1:8. I know Berger recently changed this, but I have zero issues stabilizing 180 Hybrids in a 9.25" twist in my 7mm STW.

 

[elkaholic]

That's true but it is better than a short throat and will come closer to working. It is better to seat the longest bullet up into the neck a bit than stuff it into the case. Another good reason for longer necks too! You also twist fast enough to cover the most difficult to stabilize which won't hurt a bullet requiring a little less twist.

 

[MudRunner2005]

That's true but it is better than a short throat and will come closer to working. You also twist fast enough to cover the most difficult to stabilize which won't hurt a bullet requiring a little less twist

This is true. You know I'm all about wildcatting and experimenting with cartridges, but when it comes to throat lengths, I just don't mess with that, unless it's removing the freebore from a Weatherby. Because as we all know, by the time you hit lands in one of those, the bullet is no longer in the case neck...And for me, that kind of jump just don't cut it.

 

[AKSavage]

That's true but it is better than a short throat and will come closer to working. It is better to seat the longest bullet up into the neck a bit than stuff it into the case. Another good reason for longer necks too! You also twist fast enough to cover the most difficult to stabilize which won't hurt a bullet requiring a little less twist.

That's pretty much what I had in mind. I have no interest in shooting lighter weight bullets out of this rifle so my thinking was to throat it for a specific bullet that will put me in the right range. I would still have enough neck to seat a shorter bullet (170-175g) another 1/8" out, or to push a bullet back into the case a little without getting too deep into the casing. So it would be more accurate to say I am throating for a certain RANGE of bullets. That said it would not hurt to load up a few more dummy rounds with other bullets and try to find a OAL/throat length that would adequately fit as many of them as possible. Maybe PERFECT for one bullet, but still allowing others.

 

[AKSavage]

If you know that you have a very competent smith I would just have him throat it out but I think it would need to be much longer than .095"? Probably almost double that?

Well, that's the problem right there. I would be asking the barrel manufacturer to throat it out for me. So given that I assume you would prefer to spend the extra for a (semi-)custom reamer? It occurs to me that I could then also specify a (slightly) longer neck to allow my brass to grow a bit before trimming. Hmmm. Thoughts on that?

As far as the throat length, that's where I'd have to study more reamer prints. I got that .095" from another post, but it was a bit vague. I'm good at math but don't know enough about reamers to take my OAL measurement and translate it into a throat length. To complicate matters, I have two different 7mm inserts for measuring base to ogive length, one from Hornady and one from Sinclair, and they give different lengths, so it's hard to know which to trust.

 

[DUSTY NOGGIN]

Well, that's the problem right there. I would be asking the barrel manufacturer to throat it out for me. So given that I assume you would prefer to spend the extra for a (semi-)custom reamer? It occurs to me that I could then also specify a (slightly) longer neck to allow my brass to grow a bit before trimming. Hmmm. Thoughts on that?

you will find that 7mmRM once fired brass is very short as it is , you will end up trimming less than you want just to even them all out , after doing that i dont think you will have to trim for a long time ... i cant see how increasing the length at the neck mouth to free bore shelf/angle could help much

 

[just country]

morning, very good and knowledgeable replies. read
close the replies from the senior members of this
site and ur question will b totally answered. why not shoot
a Barnes or Hammer bullets. there r to many varibles that can
go wrong with throating a chamber. I had a 7mmmag. throated
long ago. the accuracy went away. I had made my 1st
300W Mag. still have the weapon. scary accurate. GBOT TUM

 

[elkaholic]

I would not recommend lengthening the neck as you will be jumping the bullet over a lot of space and also, as mentioned above, the cartridge has plenty of chamber length already.
The potential problem with throating separately from the reamer is concentricity. I guess that is a call you will have to make.

 

[L.Sherm]

Having the freebore for a certain class of bullets is certainly better cut with the correct reamer, but if done correctly with a throater no problem. If you have the barrel maker throat it I would make sure they guarantee the accuracy before and after.
If you order a reamer call JGS and talk with Jason or Grant about what you want or send dummy rounds. Dave at Manson is good to. Measure some loaded rounds on your neck dia. And if you want a no turn neck go min. 003 over .004 is better all brass is not the same thickness just some things to think about when ordering your own reamer.

 

[desertcj]

I don't have an answer for you but I had the exact same thing done by Shilen for my 7mm Rem Mag. I'm sure they used a throating reamer. I haven't shot it yet, so I can't say much but I obviously feel that throating longer is better if you have the mag length to accommodate. Taking ogive measurements off of a few dummy rounds should give you a good average. I wouldn't make it too difficult for your Smith though, find out where you want to be and send a few dummy rounds of all the same bullet set at the OAL you want.