Author Topic: 30-06 Long Throat (Read 2149 times)

lgm270 · « **on:** December 24, 2006, 07:32:09 AM »

Shooters have endeavored to increase the powder capacity of rounds by seating the long, heavy for caliber bullets with the bullet's base flush with the case neck. This usually results in a cartridge OAL that is longer than normal. It means that the barrel's throat has to be modified to accept such a loaded round and, in the case of a bolt action repeater, it means that the magazine has to be long enough unless you're going to be limited to singly loaded rounds.

Elmer Keith did this with the .338 Win Mag, using a full length magnum length (.375 H&H) and using the 275 grain Speer bullet.

Many years ago a gun writer named Steve Timm wrote a piece in Guns & Ammo about his experiences with a long throated 30-06 in a Remington 700 with a 22" barrel. The Remington 700, HOwa 1500 and the post 64 Win M-70 rifles all had the full length .375 H&H length magazines and it was possible to have a 30-06 ctg loaded to a 3.5" OAL.

In a 22" M-700 with no modifcations other than "long throating", Timm reported the following ballistics:

150 Grain Bullet 3,150 fps
165 grain Bullet 2,970 fps
180 Gr. Nosler Part 2,850
200 Grain Nosler Part 2,780

He reported that this rifle seemed to kill as well as a 300 win mag as well as being handier (22'" barrel) and having less blast recoil.

Years ago I worked up loads for a 300 win mag and the best I was able to get with a 150 grain bullet was 3,150, the same as the 30-06 LT. With the 180 and 200 grain Nosler Partitions, I was only able to beat the 30-06 LT's ballistics by about a hundred feet per second.

Has anyone else experimented with "long throating" the 30-06 or any other round? Would love to hear your experiences, opinions, comments, etc.

nomosendero · « **Reply #1 on:** December 24, 2006, 07:50:42 AM »

I read that article years ago, I wish I still had it, good article.

The 700 I have has a long throat from the factory & I have used it to it's full advantage.

Of course Mr. Barsness wrote not long ago telling us it helps very little seating your bullets out to take advantage of the powder
capacity. I figure this was to make the Short Mags look better.

I would say though that your 300 was a very slow 300. I have a 26" tube Sendero & with the bullets seated out in it I get 3,180
with 180's & 3,025 with 200 gr.

beemanbeme · « **Reply #2 on:** December 24, 2006, 11:48:28 AM »

So on bottom line, the long throat gained @150fps. If one could just seat the bullet out without any magazine changes nor feeding problems, I'd say it was a worthy gain. If not, then I'd deem it too much trouble. To be honest, I'd only consider it for the gains you would get with the heavier --200gr-- bullet. I've never fired any bullet lighter than 200grs thru my .300. And I was able to get @2900fps which I think is an excellent balance between weight of bullet and velocity.

nomosendero · « **Reply #3 on:** December 24, 2006, 12:18:53 PM »

That is the nice thing about the model 700 action, all long actions are 375 length, with some as the model 70, they have a block and
you would have to get the long follower, etc. Feeding is not a problem at all.

lgm270 · « **Reply #4 on:** December 24, 2006, 03:21:35 PM »

The modifications did not involve anything except having a gunsmith throat it out, a simple no brainer for a few bucks. This enabled bullets to be seated to a greater cartridge OAL. No changes in the magazine, feeding or anything else. Moroever, he reported that factory ammo was as accurate as before.

nomosendero · « **Reply #5 on:** December 24, 2006, 03:28:58 PM »

That's right, at least in the Model 700. I am looking at doing this in my Model 70 30-06AI. The throat has eroded a bit anyway & that's a way to solve that problem. As I said before, you have to make some mag. mods in the 70, but since I am going to do some work on it anyway, it will be no biggie. And the long throat plus the AI will be very neat indeed.

lgm270 · « **Reply #6 on:** December 24, 2006, 07:49:02 PM »

Quote from: nomosendero on December 24, 2006, 03:28:58 PM

That's right, at least in the Model 700. I am looking at doing this in my Model 70 30-06AI. The throat has eroded a bit anyway & that's a way to solve that problem. As I said before, you have to make some mag. mods in the 70, but since I am going to do some work on it anyway, it will be no biggie. And the long throat plus the AI will be very neat indeed.

If you'res is a post 64 M-70, removing the magazine block and modifying or replacing the bolt stop to accomodate the longer bolt throw will be, as you say, no biggie. I would be very interested in hearing about the results of this combination. Waht is the barrel length on your 30-06 AI? What kind of ballistics do you get with it now? Have you modified your magazine rails for feeding the AI rounds?

I think I read about this exact 30-06 AI long throat project in one of the Wolfe publications. I believe it was in their volume of collected articles about wildcat cartridges. I recall that the guy got pretty good velocities and that the concept seemed to work very well. Nothing especially exotic about it actually. Just rechambering to AI and long throating.

I considered the 30-06 AI, but the Long Throat seemed like a more practical way to go. I acquired a 30-06 Howa 1500 because it has a magnum length action and magazine just like the Remington. I never followed through with the throating job, even though I did "long throat" and lengthen the bolt throw of a .338 Win Mag in post -64 M-70 guise so that I could seat 250 grain Nosler partitions and 275 grain Swift A-Frames as long as possible for increased powder capacity. I got 2,800 fps with the 250 grain bullets and 2700 fps with the Swift 275's in my long throated .338. By comparison, factory .375 H&H ammo with 270 grain bullets are rated at 2660 fps. Of course the .338 does not have the diameter and frontal area of the .375 caliber bullet, but it's an interesting comparison nonetheless.

Best of luck on your 30-06 project.

nomosendero · « **Reply #7 on:** December 25, 2006, 12:28:40 AM »

Yes, it is a post 70.
It is a Featherwt. with a 22" tube. I bought it from a friend, it was one of those once in a lifetime deals. He is one of those guys who
would do a project such as this rifle, then move on to another. He said he would sell it to me only if I agreed not to sell it unless I
sold it back to him. It has a glass bedded Brown precision stock & was magnaported. I probably would not have bought an '06 &
done the AI treatment, in that round you look to gain about 100fps, not quite as much as my 25-06AI gained & not near as much as a 30-30AI will gain as in my Contender. So the Featherwt. had the stock(a great one), magnaport, glass bedded, AI chamber, Leopold Mounts & a good deal of fire formed brass & he sold it to me for $250.00!!! I don't think I will ever beat that deal.

Concerning velocities, I get velocities with my most accurate 30-06 loads around 2,925-2,950fps. Hornady claims vel. of around 2,900
with 30-06 Lt. Mag ammo, I believe with 24" tube. My 30-06's have not reached that, more like 2,875 & that is only one load & I
have not found a 30-06reload to match the Hor. lt. mag. So again, it looks like about 100fps gain. I don't feel I will get the additional
gain that the Timm article showed by long throating because the seating depth is pretty good now & with it being an AI, I believe
the gain will be more like 50fps. Like I said before, I want to do a little work to it anyway & if the gain is a little less, it won't bother me. After all is done I will have less in this rifle than if I had just went to the gun shop & bought a M70 Featherwt. off the rack.
So, I am looking at nudging 3,000fps with the 180, in other words 300WSM perf. with a 30-06 case, or at least within 50fps of the WSM. It would not match a WSM with the 150, but the 180 drops into the WSM case to accomadate short actions. But the 180 is what I prefer & any info you look at with the 30-06AI will show you the 180 is the perfect match. A 300WM with a 24" barrel will get 3,100FPS with careful loads & my 26" Sendero will get 3,180 with my best loads.
Merry Christmas

Don Fischer · « **Reply #8 on:** December 25, 2006, 03:10:52 AM »

This is intresting. Back in the early 70's I had a 7mm rem mag long throated. In those days, I knew no one that had a cronograph so have no idea what velocity gains I made. The rifle was a L61R Sako with a 25" barrel. The reason for doing it was to be able to seat out a 160gr bullet to the same seat depth of 140gr bullets. That worked and I noticed an increase in powder of four grains, if I remember correctly. 160gr Speer w/ 69grs N205 as opossed to 65grs prior. Any velocity gain, if any, would be anybody's guess but the accuracy level went way up. The rifle went from a 1 1/4" rifle to a 5/8" inch rifle. Those days I used a wood ruler and outside to outside measure.

Back then not having access to cronographs, we concerned ourselves with shooting well and velocities equal to "I'm damn sure"!

Today I have my 6.5x06 that was built with a throat that allowed seating out a 140gr bullet so the base of the bullet is even with the base of the neck. I have no idea what standard throating might have been, but I have cronographed loads out of it at 3140fps. Those were hot loads and I backed it down to just under 3000fps.

beemanbeme · « **Reply #9 on:** December 25, 2006, 05:51:18 AM »

Considering that any standard 30-06 is throated to accept a store bought cartridge with a 220gr bullet, just how much more throating would need to be done??? I would assume a 200gr spitzer could be seated out quite a ways before contacting the lands.

nomosendero · « **Reply #10 on:** December 25, 2006, 01:15:45 PM »

If I remember the article correctly, & I mention the article only to reference the mentioned velocities,
the 700 was throated long enoug that the base of a 200Nos. Part. was flush with the bottom of the neck, a good distance indeed. If I do mine at all, that is about what I would shoot for, as it still
gives plenty of grip for the 180's & with a considerable powder gain.

The 220 factory load is seated quite deep to be useable in a shorter mag like the 7400/7600.

Lou270 · « **Reply #11 on:** December 25, 2006, 03:41:46 PM »

Long throat or short throat, if you are getting higher velocities than the manuals list by adding more powder, you are doing so at a higher pressure. Nothing is for free or magical about it.

-Lou

nomosendero · « **Reply #12 on:** December 25, 2006, 04:15:21 PM »

If you are adding more powder to the available capacity, that would be true, but that is not whatr we are talking about.

If you are INCREASING CASE CAPACITY by Improving or by long throating or both then you can add more powder and stay at the same pressures. If this is not true, then you can't move up to a bigger case & be able to increase powder over the smaller case.

Lou270 · « **Reply #13 on:** December 25, 2006, 06:02:00 PM »

I guess I'm just skeptical. If you increase capacity, generally it takes more powder to reach the same velocity. If you are seeing a signifant gain in velocity as implied by velocities in the original post by adding a little bit more powder from long seating a bullet in a cartridge, then I would argue you are just increasing pressure. For example, according to IMR load data, it takes 10 grains more of IMR-4350 to reach the same velocity in a .300 Win Mag as it does in a .30-06 with 180 grain bullets. So, along the same lines, it should take a little more powder to reach the same velocity in a "long seated" vs. "short seated" bullet. I post on another forum that Steve Timm visits now and then. I will PM him and see what his thoughts are now. If somebody tells me they can get 30 fps or something along those lines out of a long seated 06, I might buy it, but 100 fps+ makes me skeptical. Of course, I don't have the original article and am not sure how much velocity Steve indicated he was getting by long seating bullets.

-Lou

Lou270 · « **Reply #14 on:** December 25, 2006, 06:26:08 PM »

Did the article state how much velocity one could expect given 22" barrel and "normal" throating with the same bullets?

-Lou

nasem · « **Reply #15 on:** December 25, 2006, 06:33:27 PM »

long throats, Im supposing, is a nice way to "over clock" your rifle or, caliber in this sence.

Honestly, I wouldn't choose to do it, If I wanted 300 win mag performance, I'd just keep the 30-06 the way it is and buy a 300 win mag, that way I have 2 rifles

The one way I can see the "long" throating bussiness be kinda of nice is if you have, say, a 45-70, maybe you can load it to push 400 grainers at close to 2000-2100 fps (close to lighter 458 win mag levels), but then again, you can just buy a rifle in a 458 win mag.

I do however thing this is a pretty interesting topic, but I highly doubt I'll ever do it

nomosendero · « **Reply #16 on:** December 25, 2006, 06:34:22 PM »

Lou, if I remember right, it was a before and after type article. Steve is big with the Varmithunters
& I am going to try to get the article.

nomosendero · « **Reply #17 on:** December 25, 2006, 06:39:22 PM »

nasem, like many things of this nature it is not for everyone. I already have a 300 & a regular '06, it
is something to do & it would give me a compact gun with considerable power, great stuff.

lgm270 · « **Reply #18 on:** December 26, 2006, 07:07:26 AM »

There is nothing mysterious about seating long, heavy for caliber bullets with the base of the bullet flush with the case neck so that the bullet does not protrude down into the casing and occupy space that could be used for more powder. "Long throating" enables you to increase case capacity. NOthing more mysterious or exotic than that. The point is to maximize performance in the original 30-06 guise with minimal modifications (i.e. lengthening the throat a bit) and loading ammo to different OAL. I believe his OAL was 3.5". The idea is to maximize 30-06 performace without magnum weight, without a 24" barrel length, and without magnum muzzle blast and recoil.

He achieved 3,150 fps even with the light 150 grain bullet. This is as much as I was able to get with my old 300 Win Mag handloads and any factory ammo I used. 2,880 fps was as much as I could get from the 200 grain Nosler Part. I know because I used a chronograph.

Timm reported 2,780 fps with the 200 grain Nosler Partition bullet in his 30-06 LT with a shorter, 22" barrel. What could he have done with a 24" barrel? It would be interesting to see.

lgm270 · « **Reply #19 on:** December 26, 2006, 07:12:56 AM »

[delete]

jro45 · « **Reply #20 on:** December 27, 2006, 04:21:32 AM »

My 30/06 and my 300 Win Mag both have a long throat. I have to use flat base bullets. Boat tails go all over the place. I use normal loads don't want high pressure. At least no more than normal

lgm270 · « **Reply #21 on:** December 27, 2006, 03:13:59 PM »

A good buddy had a 300 win mag Howa 1500 and it has an H&H length magazine and a long throat. He got great ballistics and loved the rifle.

Larry Gibson · « **Reply #22 on:** December 29, 2006, 02:19:35 AM »

Some years back, after reading Timm's article, I came by a well worn (on the outside) Remington M721 for a very reasonable price in '06 that was excellent on the inside as it was carried a lot but fired little. It had a 24" barrel and a long magazine that would take a '06 cartridge with the Speer 200 gr bullet loaded with the base of the bullet flush with the base of the case neck and still have magazine room left. I throted it for that bullet case combination. Back then with RL22 we got just over 2800 fps with the 200 gr Speer. Last I talked to the guy I sold it to (mistake) he was using the Hornady 190 SPBT over H4831SC and getting over 2850 fps with it. I am getting 2740 fps with the 190 SPBT over H4831SC out of a Husky M98 '06 with a 24" barrel. He is using 4 gr more powder than I. If I had an '06 with the magazine length I would do it again but everything I've killed with the standard '06 has died pretty well anyways. So I'll not rush out and buy a rifle to just to throat it. It does work as Timm described it though.

Larry Gibson

Lou270 · « **Reply #23 on:** December 29, 2006, 10:34:17 AM »

For kicks, I went and measured a 200 gr Nosler and got 1.33". I also looked up to see length of .30-06 case length to base of neck, which was 2.1086. If I add 1.33 to 2.1086, I get a OAL of 3.43", or .09" longer than SAAMI max OAL of 3.34. Also is a link to some pressure tested .30-06 ammo with OAL of 3.327 using 200 Nosler and RL-22. I am using this data as it is loaded to 62500 psi vs. typical 06 data which tops out at 60000 PSI. What I am at a loss is to see how seating out a bullet an extra .1-.2, such as in the case of the 200 Nosler in the .30-06 gets 100 fps+ when adjusted for 22" vs 24" barrels without raising pressure. Link to 06 pressure data:

http://bookmarq.com/.30_06Springfield200GrnNoslerPartitionAlliantReloader22LoadsEXDaniel15_March_2006.pdf

-Lou

nomosendero · « **Reply #24 on:** December 29, 2006, 03:13:58 PM »

If you seat out the bullet further, but the throat is the same, well yea. But again, that is not what we are talking about at all. And also again, most magazines won't allow for this in factory form, Rem. is one of the few. Let's say that with your SAAMI length you are
worried about you would have .030" before you engage the lands. If we long throat the chamber & can seat a 200 Nos. Part. where
the base of the bullet is flush with the bottom of the neck & still have .030" clearance, we have increased case capacity, simple as that.

lgm270 · « **Reply #25 on:** December 30, 2006, 02:19:54 PM »

I read a review of the Kimber 8400 long bolt action rifle by Layne Simpson. The magazine box on the full lenght (30-06 etc.) chamberings is slighly more than 3.6" long, which will accomodate 375 H&H OAL cartridges. The Kimber 8400 in 30-06 would therefore be a great candidate for "long throating."

Lou270 · « **Reply #26 on:** December 30, 2006, 04:18:51 PM »

Quote from: nomosendero on December 29, 2006, 03:13:58 PM

If you seat out the bullet further, but the throat is the same, well yea. But again, that is not what we are talking about at all. And also again, most magazines won't allow for this in factory form, Rem. is one of the few. Let's say that with your SAAMI length you are
worried about you would have .030" before you engage the lands. If we long throat the chamber & can seat a 200 Nos. Part. where
the base of the bullet is flush with the bottom of the neck & still have .030" clearance, we have increased case capacity, simple as that.

Shouldn't any factory magazine be long enough to fit a SAAMI max of 3.34" for an 06 length cartridge? I will have to go check, at least the Remingtons, Win, & Rugers LA I have on hand. Anyway, per my original post, seating a 200 gr Nosler to the base of the neck results in a 3.43 OAL. The pressure tested load data I showed has an OAL of 3.33" and is 62500 PSI at 2700 fps in a 24" barrel. I do not know how much jump there is before engaging the rifling in the pressure barrel, but if the fundamentals of "long-throating" are correct, I should re-chamber to be able to move the bullet out .1" (i.e. from 3.33 to 3.43 to seat 200 gr. Nosler flush with the base of neck) and keep the same relationship to the lands, reduce the barrel length to 22", and add enough powder to gain 70-100 fps without being at higher pressure? While I have no doubt there are a few fps to gain, it looks exagerrated to me. Factoring the 2" less barrel length, you are effectively gaining 150-200 fps by long seating .1". Did the original article have pressure tested data or did the author rely on traditional pressure signs?

-Lou

nomosendero · « **Reply #27 on:** December 30, 2006, 06:27:26 PM »

I am sorry, but you don't know what we mean & SAAMI has NOTHING to do with it. The Rem magazines are MUCH longer than a
Ruger & a Win. has a block in '06 length rounds, I know, I have one in front of me & that is mentioned in the article. These rounds
are much longer than SAAMI rounds, that is what we have been talking about all along. Instead of this useless back & forth stuff, if
I get ahold of the article, I will make sure that you get a copy. We are not on the same page at all.

Lou270 · « **Reply #28 on:** December 31, 2006, 05:28:21 AM »

Thanks! I would appreciate seeing it. I'm not really trying to be difficult, just using my (possibly wrong) logic, the gains look inflated. Heck, I have several long throated 700s that I can seat the bullets way out there, so am trying to benfit from the discussion.

-Lou

lgm270 · « **Reply #29 on:** December 31, 2006, 05:40:48 AM »

Quote from: Lou270 on December 31, 2006, 05:28:21 AM

Thanks! I would appreciate seeing it. I'm not really trying to be difficult, just using my (possibly wrong) logic, the gains look inflated. Heck, I have several long throated 700s that I can seat the bullets way out there, so am trying to benfit from the discussion.

-Lou

Hi Lou. Cool handle you have there.

I'm in the process of digging the Steve Timm 30-06 LT article out of storeage and will send you one if you pm me your mailing address.

On another note, you mentioned that you have several long throated rifles. Which calibers? Which loads? I'm very interested in that kind of thing.

Personally I've long throated an M-70 Classic in .338 win for 250 Grain Nosler bullets and have read stories abou this practice regarding the .338 Win by Bob Hagel and Elmer Keith, as well as about the .350 Remington Mag long throated. Is was in Handloader or Rifle magazine. I don't remember the guy's name, but I still have that article too and he reported 2,600 fps with 250 Grain Noslers in his long throated .350 Remington Mag and a 20" barrel! I think he used a commercial Interarms mauser action that was already set up for magnum sized rounds.

Rifle Magazine had an article by John Wooters about long throating a Remington 700 in 7mm Rem Mag. Wooters, a long time devotee and fan of the 7mm Rem Mag, reported 3,250 with the 150 grain bullet and 3150 with the 160 Grain Nosler. When the 7mm Rem Mag first came out, it was touted as producing 3,250 with the 150 grain bullet. Now they've lowered that claim to 3,050fps, the same as the 130 grain .270 bullet. Very disappointing actually. Personally I regard the 7mm Rem Mag as a glorified .270. Without creative handloading it's just not that much more powerful. Moreover, some of the worst game shooting I've ever seen was by guys with 7mm Mag's. The increased muzzle blast and recoil scares them and they flinch. People don't realize that it takes an increased level of skill to shoot magnums. Alas I digress.

Happy New Year to you.