Could one neck the .338 RCM up to .416, and seat the Hornady 450 grain .416 cal match bullets deep enough to still fit in a standard length rifle?

There is the 416-300wsm many leave it at 2.86+/- a 400gr is around 1.39" so 3" OAL might be the max don't know the length of the 450gr I show the RCM to be a touch shorter than the wsm.

Using a cannelure would alter things a lot.

No cannelure on that bullet. So I can get it under 3.34...

I have no clue as to the length of the 450gr. However if you ASSUME the OAL of the 416 Barrett is 4.6 and the case is 3.26 then that gives 1.34" of bullet exposed. So That would lead me to ASSUME that since the 450 works in the barrett then you could leave 1.34" out of the RCM and have an OAL of 3.34. As to how much is in the case or how much capacity you use I have no clue.

Doesn't need to be that much in the case. Just enough to get it to 1050 FPS.

A 450gr match bullet at 1050 fps

1050 fps
Speed of sound
He wants subsonic loads.

quote:

1050 fps
Speed of sound
He wants subsonic loads.

I figured that out over this morning. Just wondering what you would then use a slow moving match grade ($.94 each) bullet on?

Ok, wiki says the .416 Barrett case is 3.27" long, and the cartridge is 4.58" OAL. That gives 1.31" of bullet exposed.

The .300 RCM case is 2.1"(I'm sure the .338 is close to that), and the case would get a bit shorter when necked up. Say the case is 2.0" once opened up and the neck squared up on the trimmer. 2.0" plus 1.31" of bullet gives me a cartridge 3.31" OAL, just short of the 3.34" maximum that a standard length bolt action would handle.

All you need to do is expand the RCM neck to 416 and stuff the bullet you want into it, then seat to WHATEVER LENGTH you want.

The COAL depends on whatever the magazine length will handle, if you want to feed from a mag...and that depends on the rifle brand...OR DOESN'T MATTER AT ALL if you single load.

I single load 650 gr milspec bullets in my 50 Makatak to 4.5" and single load in my Ruger Tang...and load 525gr cast lead slugs to 3.30" to feed through the mag.

I have several rifles that I single load the first round and the rest are magazine length because of a long throat, I can seat bullets out to touch(close) and get a bit more velo for the first shot....and my Rem 700 will handle 3.65" COAL.

That long boat tail will take up a bit of room in the case, but you only need about 0.200" for seating at the speeds you are talking about. The neck length plus shoulder length on the RCM case is about 0.490" so you have some room to play with.

Looks like the boat tail is near bullet diameter in length so you will have plenty of powder room for your low velo loads.

Really the only way to know for certain WHAT you can accomplish is to know that 450gr's actual length and I can't find that. Once that lengh is known, you can do the rest of the fiddling.

You need to forget comparing one cartridge COAL to another COAL without knowing ALL the various parameters, and to work with actual real numbers for what you want to accomplish.

I see nothing wrong with doing a 416 RCM...or any other cal up to what the case will expand to. I think the RCM and Ruger cases are excellent platforms for wildcatting...and the WSM...and the RUM...and the....

Urodoji; If you can post the .416/450gr Horn Match bullet length(or anyone) I will certainly appreciate it...and run it through my software programs to see what there is to see.

Luck

I don't have dimensions on the Hornady bullet. Check out this one though...Dave at Lehigh says a 1/8 twist will stabilize it at 1050 fps.

http://lehighbullets.com/products.asp?cat=30
http://lehighbullets.com/proddetail.asp?prod=416-110

This one has a cannelure. I'm wondering if Trail Boss would be a good powder for this. I'm mostly interested in feeding from a magazine. Being able to simply rebarrel a heavy barrel .300 Win. Mag. would make this a pretty simple wildcat.

Yes it would be a simple neck up rechamber/rebarrel.

I ran a quick QL for the 450 gr RockyMountain RBTAL G7, 2.050" bullet, 3.3" COAL, 79 gr case volume, 24" bbl and Trail Boss came in at 17 gr, 100% fill, 32KPSI, 1097fs. I haven't worked with Trail Boss powder so a 100% capacity load with only 17 gr in a 79 gr capacity case looks like something is TOTALLY wrong.

But just about any of the slow burning powders like RL50,7828, MAGPRO, Retumbo etc, at about 35-45 gr will give you 1000-1100 fs at similar to much lower pressures. Retumbo at 45 gr came in at 11KPSI and 1100fs...

I might just check out that Hornady bullet for my 416 Taylor...that might be fun...mag fed or single shot. Definitely a sagerat popper at long range.

Luck

That sounds about right for Trail Boss. For .416 Remington, starting charge is 20 grains, max charge is 29, with a 350 grain Speer soft point.

http://www.imrpowder.com/PDF/Trail-Boss-data.pdf

Oooor.....ever think about using a 338 Fed or 338 RCM in a standard length action, shooting the HUGE 338 280-300gr extreme BC type bullets at 1050? Sierra MK, berger VLD, new Accubond, all have BC's in the .700 and up

That's interesting and good to know...I need to do a thorough check-out of Trail Boss, looks like. I don't go below 85% load density in my shooters and stay at the upper end of the velo spectrum so haven't stuck my toe into the subsonic pool...maybe I should...might work well in my 50-90 Sharps.

Thanks for the info.

Luck

I suppressed, it sounds like a poachers dream.

Slightly OT, but in keeping with the velo requirements for a "whisper" type of cartridge and the use of TRAILBOSS in that application.

I tried some TRAILBOSS in my 50-90 - 525gr bullets and 620 HellBoy - 625 to 725 gr bullets, both brass and lead and that powder worked out nicely...

At some future time I will try some of the 50 cal A-max and other VLD bullets in my 50-90 just to see how a 34" bbl, low velo/HI-BC bullet works against the other 525 to 650 gr cast lead bullets in my inventory.

That stuff is one BULKY powder...even in the 200 plus gr H20 3" plastic shotgun case in the HellBoy the fill % was between 80 and 90...pressure below 18KPSI. The velo was relatively low...less than 1400fs with the 725 gr cast lead but that produced almost 3000 ftlbs of energy...plenty good enough for most large N.A. game.

The other plus side was the low charge amount...40 to 60 gr depending on the slug weight which is 2 to 3 times LESS amount for the usual slow burning powders I use...reduces the recoil by a BUNCH.

I just got in some 1040 gr Beartooth .62 cal bullets and will turn off the bases to reduce the weights to ~750 to 900 gr and see what happens. QL gives some promising numbers.

My MM 700gr mold should be here in another month which should provide some interesting possibilities for both the 2.96" Cheddite plastic cases and the 3" brass RMC cases that should be arriving about the same time.

Luck

rough measurement of the 416 hornady 450gr bullet using cailpers. Boattail section .300". Full caliber section .600".Ogive portion.900". Total bullet measures 1.860".

Why stick with a case like this if you truly want a dedicated subsonic round? I don't have quickload to run the numbers, but why not 338 and 416 versions of a 243 WSSM. You are talking case capacities, I think, slightly over 308 volumes, which have been used before for subsonic applications. The cartridge would have a lot of the attributes of modern target rounds, and work through any action made for a magnum bolt face, but would be ideal in one made for one of the compact magnums. With the Hornady 416 seated at 0.5", OAL would be about exactly 3". Case capacity would be closer to what is needed for a subsonic application, and efficiency would be better than the larger cases, giving better consistency, and slightly less recoil.

Thanks RandyB for the bullet info...

Right on ArtS!!!

FWIW

I drew up a 416 WSSM case using the 25WSSM case dimensions as the basis but changed the shoulder angle a bit by lengthening the base to shoulder junction to 1.27"...case capacity came out to ~62gr H20.

Using the .416 cal, 450gr Hornady seated ~.530" to 3.00 COAL the NET case volume ened up at ~44gr H20.

QL gave 38gr Retumbo, 88% fill, ~1068fs/~1137ftlbs at ~11.8KPSI in a 30" bbl.

Not to bad for a 416 "whisper".

Because of the 0.300" BT and the need to optmize the case neck length to ~0.200 - 0.225" to "getagrip", by pushing the dimensions around a bit, you can increase the case volume to ~63.6gr...and by using the WSM case that has thinner walls you could get to a bit over 66.4gr. Not sure is all that mucking about is required as the lessor case volume will fulfill the requirements.

You could then get into the 2000fs plus range by going to a different powder and filling the case to near 100%.

I think it would make an excellent "whisper" cartridge, but basically worthless for any very long range work...WAY TOO SLOW and once you pass the S.O.S fs a larger cal, heavier bullet, speedier cartridge/bullet would work much better...speaking argumentively.

Luck

I don't see the need to Mag feed a long protruding subsonic round but that's just me. Single load for subsonic and mag feed for general purpose.