Gunsmithing 5.10 Whisper /12.7X48 build

[bwfredette]

I'm looking for advice on building a .510 cal suppressed rifle. my criteria are that it will be able to stabilize up to 950 grain cast bullets (thus I've read that an 8 to 1 twist will not be adequate). What are my barrel options? would I be better off forgetting about the 950gr. rounds?

Secondly I want to have an affordable action. a remington 700 LA clone of some sort or an affordable doner rifle. I can't find anything reasonably priced which is a shame... Also my knowledge is not enough to identify the odball action that could be made to work with minimal shop time...

Another option I have read about but not seen any hard evidence of is to have a semi auto that can be forced to operate as a single shot/bolt action for added quietness when desired. I would think that this would be easy enough with an adjustable gas block? Has any one seen this done?

Lastly I like the De lisle Carbine and would like to have a large integral suppressor (please no legal warnings I know the method to legaly follow).

this also leads me to wondering what the minimal barrel length usable for the .510 is and what porting profile the barrel would benefit most from. I'd put up with a hulking 3.5 inch diameter suppressor if it made the report super quiet,

All on topic advice is welcome.

 

[bohem]

Re: 5.10 Whisper /12.7X48 build

The 12.7x48 is built on a 0.590 bolt head; the 338LM bolt face.

You can do this with an Ultra-Mag action Rem 700 and opening up the bolt face. The 950gr cast that I have are shorter than the 750 Amax, shorter nose, no boat tail and a large increase in weight; they have shown stable from 15tw 50's at subsonic speeds with a buddy of mine.

Regarding the suppressor, you don't need a full size 50cal suppressor to quiet a 50 Whisper or 500 Thumper sized case. You're going to end up with something appx. the size of a 300WM suppressor with a big hole through it.

Once they're suppressed, they are extremely quiet and with that much mass involved there is a lot of muzzle energy available.

 

[300sniper]

Re: 5.10 Whisper /12.7X48 build

out of curiosity, how loud is something like that without a suppressor?

 

[dunes450r]

Re: 5.10 Whisper /12.7X48 build

i'm curious of unsuppressed noise as well. i can't see them being too loud....

 

[desertfox01]

Re: 5.10 Whisper /12.7X48 build

as long as the loads are kept subsonic, think about a 45acp from a short carbine sound level. I have been thinking about something along these lines using 300WSM brass. taking a step further,with a intricated suppressor that can be taken apart from the front end so it maintains a 16" OAL so you only have 1 tax stamp.

 

[excaliber]

Re: 5.10 Whisper /12.7X48 build

We just built a 510 cal on a 300 WSM case. We was hoping to just cut the case to 1.625 and seat bullet, but we found out that we had to inside neck ream. Just to time consuming. Next time I am going different route by using 338 Lapua case or 416 Rigby.

 

[mcfred]

Re: 5.10 Whisper /12.7X48 build

I haven't had any issues with my 510 WSM. Federal brass was thin on the necks but Winchester was just fine with a little neck-sizing. I ended up using 7mm wsm brass and opened up the last .025" of the neck to get a case length of 1.700"

AA1680 got 647gr M8 APIs to 1700fps

Never tried subsonics since I've got no can.

 

[762frmafr]

Re: 5.10 Whisper /12.7X48 build

I used an action I had laying around and had the bolt face opened up to the LM size. I run and 8 twist Brux barrel and have never had a problem with anything from surplus bullets to 750 A-Maxes to 975 grain lead cast stabilizing. HERE is a video of what it sounds like suppressed.

 

[bwfredette]

Re: 5.10 Whisper /12.7X48 build

JD from SSK said there was no semi auto that would work; But that would have to be prefaced with "yet". I'm certain it can be done. Would the saiga 30-06 be a good candidate for modification? The 30-06 round is the stame length as the .510x48 and the bolt face is just a little under size? I'm asking because I have never worked with a saiga and do not know its limits.

certainly the Noreen Bad News .338 Lapua ULR could be rebarreled. but it is 5k!

 

[bwfredette]

Re: 5.10 Whisper /12.7X48 build

I seam to be one of the few interested in this topic. Would not a semi auto that delivers subsonic .510's be nice??? The Whisper is the same overall length as the 30-06, I would think many bolt faces could be modified to accept the cartridge. The BAR would seam like a good candidate.

 

[762frmafr]

Re: 5.10 Whisper /12.7X48 build

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Billy Badass</div><div class="ubbcode-body">I seam to be one of the few interested in this topic. Would not a semi auto that delivers subsonic .510's be nice??? The Whisper is the same overall length as the 30-06, I would think many bolt faces could be modified to accept the cartridge. The BAR would seam like a good candidate. </div></div>

I don't know of any semi autos that can handle a Lapua Mag bolt face also, the mags hile they will handle the length, they will not handle the diameter of the cartridge.

 

[AKA-Spook]

Re: 5.10 Whisper /12.7X48 build

shortened 458 socom through an ar-10.... the brass gains in thickness so you'll need to take that into consideration for the reamer design.... or turn a shoulder onto it ala .510.

 

[coose1973]

Re: 5.10 Whisper /12.7X48 build

could i use 338 rem ultra mag brass instead of the lapua
i wouldnt have to change the boltface just the barrel and rock on its a rem 700 and help or info would be much appreciated

 

[biffj]

Re: 5.10 Whisper /12.7X48 build

There is a semi auto version of the AR which was built for .338 Lapua. It would work for a 510W semi. Now the question is why? For the cost in time and cash to make up cases and load ammo its a bit much. The rifle is not a cheap one either and more work and cash to convert to the 510 as well. There are a number of possible choices in bolt guns. I've used 98 Mauser actions, CZ550 Safari Mags and the Desert Tactical SRS. The mausers are painful as a lot of work is required on bolt faces, followers and the receiver to make things work. The CZ and SRS are simple because they are made for .338 Lapua or 416 Rigby to start with. The CZ feeds 4 rounds loaded with US 650gr API or other GI bullets with no problems. Shorter bullets like the 450 or 300gr Barnes softpoints need some work on the follower to make them feed. The SRS requires mods to the magazine as the longer BMG or AMAX bullets will hit the mag due to its shoulder retention feature. The short hunting bullets feed fine.
Its a great round with a wide range of projos available from solids to more active types like the API and tracers from the BMG round.

As others have noted you are looking at the .585" dia rim so the standard magnum bolt faces won't work. You can open some of them up but many will have a very thin remaining ring on the bolt face. Some of the makers of blueprinted Remington actions make a special action for the .338 Lapua sized round.

I've been using a 9 inch twist with all the guns and it works great with the 800gr AMAX types. I've not tried any cast stuff of 900+gr so I can't tell you whether it will work or not. 8" twist would most certainly work with the heavier or the lighter bullets.


Frank

 

[RTH1800]

Just curious, why?

 

[tansinator]

You do realize this post is 6 years old.

 

[softcock]

he Did dig-up an OLD POST... LOL .. but, I always wanted to do-up a .510 Whisper 'boltaction ' .
back in the day, QuarterBoreCom forum was the shit for that design of thought . But Sadly they and that Site been in Defunct Mode for quit some time now .
.

 

[Hoser]

I miss the quarterbore site. Lots of great info there on shooting subs.

Spook from the quarter bore forum built me this 510 Whisper.

 

[Strykervet]

First off, the suppressor shouldn't weigh 3.5lbs. My BMG can weighs 4lbs. and it's a LOT heavier built than you need for Beowulf or Whisper cartridges. I forget who, but some companies make suppressors just for .50Beowulf and that's probably where you wanna start, see if they can ream it out if need be.

If shooting suppressed, and if the .510 Whisper is anything like .300BLK loads in that it has an absurdly small quantity of powder for the given round, relatively low chamber pressures, and sufficient case capacity to totally burn all the powder, then I'd imagine you could use fairly short barrels, perhaps 10" or 12". I'd call whoever is considered to be the guru on this round and ask them the appropriate barrel length for stabilization into a suppressor. And your appropriate twist. You don't want keyholing or unstable bullets exiting the muzzle, and some twists/barrel length/cartridge combos don't stabilize until a few feet from the barrel, so that's why I say ask a guru who's knowledgeable about that round.

Yes, there are gas blocks that will turn off the gas. Most adjust the gas, but some turn it off as I recall but you'll have to look. If I couldn't find what I was looking for, what I'd do is take apart a two position gas block (make sure you can take it apart first) and then weld the second hole shut, smooth it off and reinstall it. Viola, an on/off gas block. If you can't find one that is. You could see if Noveske could make you a switchblock with an on/off.

Good luck with it! I think an integral build with the entire barrel jacketed with the suppressor for maximum expansion and extending a foot or so past the muzzle would be sweet. Start the suppressor at the gas block, that way you'll still be able to switch it off, then with the suppressor over the barrel you get more room for expansion. Then the suppressor could extend a foot or more past the muzzle, up to you really. I have an integral .22 that has a 16" "barrel" that's really 4" with 12" of suppressor, but you can't tell by looking at it. Amazing suppression. I'd try to mimic that in .510 were I you.

Or you could buy the thread on type.