280AI Necked to 338 Neck Length Question

elkaholic said:

You should have no problem getting the velocities that you are looking for. The .338 Sherman would probably hold approx. two more grains than a .300 Sherman which would put it near 79 grains. IMR 4831 would work well as would H4350, RL17 and even up to RL22 with the heavier bullets. You would have to fire form the Sherman by using a false shoulder. If you wanted MAXIMUM velocity gain, the Sherman would do it but if the extra hassle is not worth it to you, the gain would not be that much.......Rich

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Based on capacity gain, it looks like the 338-280AI would be roughly in the middle between the 338-06 and the 338 Sherman. I was running some rough estimates of 338-280AI velocities based on Hodgdon 338-06 data and it looked to me like I would be able to meet or exceed my stated goals fairly easily. The numbers I was getting were fairly close to what I know good handloads for the .338WM will produce. All of that makes me think that there is a fair probability that a .338 Sherman would just slightly outperform the .338WM. I find that possibility intriguing.

As for the false shoulder, would a .35 Whelen neck sizer die do the job? I am conflicted between going the easy route with the wildcat or going all the way and building a Sherman. In the end, MAX performance may be hard to resist. I also see the opportunity to learn a few extra reloading tricks as a net plus.

Hmmmmm...

TOM H said:

If you took 280AI neck it up to 338 that case would hold app 71gr/R-17 to the top of the case mouth and if you filled to the start of the neck it be appr 65.5gr/R-17. The 35 WhelenAI to the top of the case mouth it hold appr 72.gr/R-17 and do same to 30x280AI it hold appr 70.5gr/R-17. A new 280AI case filler to case mouth hold appr 70gr/R-17.

You going to run pretty close to 338-06AI velocity and I would use 338-06 data as start loads.

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When I was quoting case capacity, I forgot to note that I was going by grains of water. Having actual information on the likely case capacity with the powder that I want to use gives me a clearer idea of what I could expect. That is some excellent information! Thank you!

I concur with your thoughts about using 338-06 data as starting loads.

benchracer said:

Based on capacity gain, it looks like the 338-280AI would be roughly in the middle between the 338-06 and the 338 Sherman. I was running some rough estimates of 338-280AI velocities based on Hodgdon 338-06 data and it looked to me like I would be able to meet or exceed my stated goals fairly easily. The numbers I was getting were fairly close to what I know good handloads for the .338WM will produce. All of that makes me think that there is a fair probability that a .338 Sherman would just slightly outperform the .338WM. I find that possibility intriguing.

As for the false shoulder, would a .35 Whelen neck sizer die do the job? I am conflicted between going the easy route with the wildcat or going all the way and building a Sherman. In the end, MAX performance may be hard to resist. I also see the opportunity to learn a few extra reloading tricks as a net plus.

Hmmmmm...

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I don't know that you could exceed the WM but you would be very close behind with less powder and a non-belted case which is a plus. My 300 Sherman is not far behind a 300 WM so that is what I base it on. I forgot to address your question regarding the chamber reaming! I do not have a .338 Sherman reamer so you would either have to use a .338'06 reamer first to get the neck dimension and then clean up with a 300 Sherman reamer or use the Sherman first and use a .338 neck reamer. I've always wanted to increase the "Sherman Family" to include a .338 as I think it would be pretty impressive for the case capacity and would work nicely on a std. actiion. So many options and so little $$$$$......Rich

benchracer said:

When I was quoting case capacity, I forgot to note that I was going by grains of water. Having actual information on the likely case capacity with the powder that I want to use gives me a clearer idea of what I could expect. That is some excellent information! Thank you!

I concur with your thoughts about using 338-06 data as starting loads.

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The Nosler 280AI case length is 2.525 and neck length is .345". After my got her 280AI I had 30-280AI build and after I got few cases fire formed I neck up some to 338.

I've got a set of dies for a 338-270HGT and the body length is 2.090" has 40 degree shoulders and neck length is .370" and case length is 2.490" long. there is article in Wildcat Cartridges Vol II page 461 about this wildcat and it's about the only written information about this case. It's pretty close to a 338x280AI. they have data for a 200gr Speer@ 2900fps plus and 250gr Sierra mid 2600fps.

I used 280 cases to fire form reason for that 270 case to the shoulders is 1.948" and the 280 length to shoulders was 1.999". I have the dies in storage not sure if I have any cases and if your interested you can have reamer made from the dies and I'll send along the loading data and it be a good start on something no one else has. You have to talk to reamer guy might be able to use 280AI reamer any way if your interested PM me and you can have them.

TOM H said:

The Nosler 280AI case length is 2.525 and neck length is .345". After my got her 280AI I had 30-280AI build and after I got few cases fire formed I neck up some to 338.

I've got a set of dies for a 338-270HGT and the body length is 2.090" has 40 degree shoulders and neck length is .370" and case length is 2.490" long. there is article in Wildcat Cartridges Vol II page 461 about this wildcat and it's about the only written information about this case. It's pretty close to a 338x280AI. they have data for a 200gr Speer@ 2900fps plus and 250gr Sierra mid 2600fps.

I used 280 cases to fire form reason for that 270 case to the shoulders is 1.948" and the 280 length to shoulders was 1.999". I have the dies in storage not sure if I have any cases and if your interested you can have reamer made from the dies and I'll send along the loading data and it be a good start on something no one else has. You have to talk to reamer guy might be able to use 280AI reamer any way if your interested PM me and you can have them.

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TOM H, thank you for a very generous offer. I will keep your offer in mind. I am still figuring out what I am going to do. When I have the parts I need for the build, I will talk things over with my smith. The outcome of that conversation will have a large impact on my final decision.


If elkaholic ever decides to go ahead with development of his .338 SHERMAN, I hope to be involved somehow. I may just decide to go simple for now and wait for Rich before I go the whole nine yards...

338 Sherman is near!

Why not make it a 338-06ai? Then you could def neck up in one step and use lapua brass. End result is pretty much the same w/ better brass and less metal being worked, right?

ohiohunter said:

Why not make it a 338-06ai? Then you could def neck up in one step and use lapua brass. End result is pretty much the same w/ better brass and less metal being worked, right?

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338 Sherman has considerably more capacity than the A.I. I can't use Lapua brass to do that but I am going to use RWS which is pretty good.......Rich

elkaholic said:

338 Sherman has considerably more capacity than the A.I. I can't use Lapua brass to do that but I am going to use RWS which is pretty good.......Rich

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I wasn't suggesting the sherman didn't have more capacity. I was suggesting using 30-06 brass instead of 280ai brass due to less sizing and better brass availability.

ohiohunter said:

I wasn't suggesting the sherman didn't have more capacity. I was suggesting using 30-06 brass instead of 280ai brass due to less sizing and better brass availability.

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I understand but the neck would be WAY too short if I used '06 brass. I wish I did have Lapua brass..........Rich

elkaholic said:

338 Sherman has considerably more capacity than the A.I. I can't use Lapua brass to do that but I am going to use RWS which is pretty good.......Rich

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Are you far enough along in the project to know actual, measured, case capacity? Just curious. Based on measurements of Norma 338-06 brass, I am expecting the AI to come out around 75 grains.

I am curious to see if the Sherman case will have enough capacity to utilize RL-26. Not having handled RL-26, I have no idea what the grain size looks like. I also need to buy the QL update disk (the version I have dates to before the release of RL-26), which would probably give me the answers I am looking for.

I have had a 338-06AI in the works for awhile now. No idea when I will see it. I have a rifle with a low round count, Krieger 5r, in 6.5-284 that I was going to sell, but not sure if I would be able to get the price I am looking for (even though I would be selling it at a substantial loss). I am thinking I might keep it and make it a 338 Sherman. Brunos is just down the road from me. I could have a 4-groove Krieger with no wait. Do you need a guinea pig to get started?

elkaholic said:

338 Sherman is near!

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BTW, I have wanted to pick your brain regarding your expectations for the 338 Sherman, but hesitated to hijack someone else's thread to do it.

When I first began to consider the 338-06, I spent considerable time thinking about the 338 WM relative to the other 338's. It seems to me that the WM occupies a sort of no-mans-land in terms of case capacity relative to available powders. Its case capacity is about ideal for RL-19 or H4831. Not enough capacity to make use of powders like Retumbo or H1000, like the RUM and Lapua can. Too much capacity to benefit from powders like RL-17.

I have long heard the 338-06 described as being very close in performance to the 338 WM. From what I can tell, the right bullets and powders should virtually erase the performance gap between the two, especially in the AI version. Based on my research, from a 26" barrel, I expect to be able to push a CE 200 MTH to 3050ish (using RL-17), with accuracy, and be able to feed it from the mag. On the high end, it looks like I may be able to push the 285 AMAX nearly as fast as the various 250's (around 2600 with RL-22/Norma MRP), though I would have to single feed it.

What bullets and powders do you have in mind for your 338 Sherman and what sort of performance are you anticipating? What barrel length and COAL do you have in mind?

I thought this might flush you out of the timber! Good to hear from you.
I am WELL along with the build. I have all the parts and will have a reamer and dies by the end of Dec.
I usually get flack on my predicted velocities, but so far they have been pretty close. I do think that I will be right at the capacity to use RL26, and if that is true, I expect to be EASILY in the 2700's with a 250 Berger and 2800 would not surprise me. I should also be able to break 3100' with a 200 grainer. I know this is WM performance, plus a little, but the Sherman will have a better throat than the WM and better utilize the capacity which will be around 78 grs. with Norma brass. I am also going to try the tough RWS brass even though it usually has slightly less capacity.
The coal will be approx. 3.565" to the lands.
You can pm me for a Phone# if you want to call. I am REALLY excited about this one and I pretty much guarantee the performance will surprise some people........Rich
p.s. RL26 is dense and short grained. I will be able to load around 68 grains behind the 250. BTW, Krieger does not make a 4 groove in the 338 but a 5r. I have a 5r Bart 3b for my build.
Let me know right away if you want dies ordered and I MIGHT be able to add them to my 338 order. If not, it would only be a couple months anyway.

If the 338 Sherman can make use of RL-26, based on some very rough estimates, my best guess is the high accuracy node will come in around 2830 with the Berger 250, from a 26" barrel, which should give it very similar drop and drift numbers to the 215 Berger/300 Win Mag combination.

If that proves out, it would be pretty remarkable from a case in the -06 family.

RL-17 looks like it would still be the powder to beat with the lighter bullets. As you stated, the 200 grain class bullets look like they will run @ 3100 or so.