Critique My Rifle Build

[James]

Thanks Yorkie!
My buddy that is a gunsmith had a very similar response, in that, factory ammo is the part of my initial plan that is least likely to work out well.

My plan to balance the gun is make my own stock.  The suppressor will help, but you are right it’s going to be a bunch of messing around.

Your recommended approach to use a light bullet and getting a highest possible muzzle velocity, I can see how that makes sense. I guess what I am surprised about (and maybe this shows my ignorance) is your comment about powders being barrel length agnostic.  I just assumed faster burning powders in shorter barrels and slower in longer.

Because in my initial (and probably foolish) desire to use factory ammo I have also wondered if going the other direction with a heavy bullet and fast twist to increase the chamber pressure a bit and keep that bullet in the little short barrel a hair longer to burn as much powder as possible.  It would lose some MV this way but the rotational energy would be higher and I am assuming that also helps drive bullet expansion. I have wondered if that’s the reason the new 8.6 blackout cartridge seems to take a super fast twist in a SBR to another level.

I appreciate your thoughts, especially the bullet weight and caliber choice. I really hadn’t thought of outsourcing to custom reloaders. I like that idea and if you have any recommendations they would be greatly appreciated.

This is the first interesting topic I've seen here in a while! 

The only issue I see with your plan has nothing to do with the gun itself, just with the factory ammo requirement. In order for your plan to work effectively, you need to think outside the box (literally I suppose). You'd like to use monometal bullets if possible, which is already going to limit your options for factory loads. The problem you'll have next is finding factory loads using the appropriate bullet to accomplish your goal. You'll actually want a bullet in the 130gr range to help keep your velocity up. You're looking to use it at moderate ranges (inside 350), so BC isn't a big deal. What you really need is a lighter bullet at a higher velocity to make sure the bullet performs on impact. Some of the ammo for places like DoubleTap and Copper Creek might have something that would work for you.

Working within the parameters you initially put out here, the only thing you need to do is locate an ammo company that either currently loads lightweight bullets for the 300 WSM, or is willing to custom load the ammo for you. You could check with some of the custom ammo shops about loading ammo using the lightweight bullet from Barnes, Cutting Edge, or Hammer. A 125-130gr copper bullet with a muzzle velocity of around 2500 fps should be possible from a 10" barrel without too much effort.

Here's where I'll completely change your plan and suggest what I'd do to accomplish the same goal. 

Unlike everyone who's telling you to go with a smaller chambering, I'd go bigger and look at something like the 30 Nosler or 300 PRC. The only way to maintain velocity while taking away barrel length is to add powder. If you go too big though you'll have a hard time getting a good case fill when using lightweight bullets with an appropriate powder. It can still work, I just don't like getting down into the 80% case fill range. Powder choice is influenced more by bullet weight than barrel length, so that isn't even a consideration for me.

The barrel length would have a lot to do with how I wanted the gun to balance. The really short barrel is going to make the gun balance in a weird spot. I'd look at a 12" barrel so that it comes in around 18" with your suppressor on there. I just don't like guns with too much weight in the buttstock.

I'm not a suppressor guy, so I can't provide any intelligent or informed information on that aspect. I would assume that it's going to be tough to find a suppressor that's rated for a very short barreled 300 mag (in any form). That's a lot of muzzle pressure to contain and I'm not sure how many suppressors can handle that.

[James]

This is a risk I don’t think I had put too much thought into, but I should.

I am totally unrealistic, my goal isn’t to make this gun “hearing safe”.  I will still use muffs when I am not hunting. 

My goal is to make it less damaging than a regular hunting rifle.  Will a 10ish” magnum rifle be noticeably more quiet then a 16.5” 308 win or an 18” 30-06?  I am assuming so, but don’t actually know and would love to be able to quantify this.

If you have the money and want to do a fun build have at it and enjoy.  We all love fun gun projects.  Yorke has posted alot of such fun short barrel/pistol projects on here over the years and it's fun to follow along.


I guess my issue is with the physics of the plan.   The best suppressors reduce roughly 23-26db (based on actual testing not marketing claims).  Rifles in standard barrel lengths range from 150db-175db depending on chosen cartridge, and will vary from there based on how short you make the barrel.   And unsuppressed 308 with 24" barrel is 156db, and with 20" barrel is 170db.  A 10" barreled 300WSM hasn't been officially measured, but you're likely going to be pushing 180db-200db in that setup.  140db is the pain threshold level for hearing, and what suppressors are designed to get you below.  In your desired setup, you're likely going to be in the 150-170db range with suppressor.   


Plus with 10" barrel a portion of your powder isn't going to burn in a factory ammo cartridge, it's going to blow through the suppressor and out the barrel.   Factory ammo isn't likely to perform like you think it will.  You'd need to hand load and experiment with different powders to optimize velocity and powder burn. 


I would call the suppressor company you're thinking of and asking them about the rating for 300WSM barrel specifically in 10" barrel.  The cans will be in the 5-10" long range depending on company.  So cutting your barrel and adding a can is going to put you back into the 16-20" barrel+suppressor length range.


Yes I realize the suppressor also helps calm recoil....but again you're creating excessive recoil by shooting a 300WSM in a 10" barrel and putting a suppressor on it to end up at the same recoil level (or higher) than you'd be at with a different cartridge choice. 


Again, it sounds like a fun new gun project.  But just make sure you understand the physics of it so you're not disappointed when your suppressed SBR is shooting at 160db ratings.

[James]

Thank you for running those, I appreciate it.

I was initially thinking 150-180 grain for 300WSM, but Yorkie has me thinking 130 grain now.

I had a friend of a friend run 150 grain Barnes TTSX a few years ago though a reloading software program (maybe QL?) and came up with 2855 ft/sec. I can’t remember all the details unfortunately.

2265 ft/sec is obviously not what I am looking for in 300WSM, and even a larger caliber while better was hoping for more MV. I would love to hear if you have any more thoughts or insight  to loadings that could get the MV up a bit higher for 338, 300wsm, etc.

What weight bullet are you thinking about using if you were to go 300 WSM?

FWIW, running a 300WSM with a 10in tube and 200gr bullet through QL it says RL26 will be the best powder for velocity and at max chamber pressure 2265 fps. 

Running the same build spec and bullet but chambered in 308 QL says CFE223 is the best powder and at max pressure 2085 fps.

BUT, to get that extra 180fps with the 300 WSM you'll be using 25.3 grains more powder.

If I were insistent on building such a short barreled setup I think I'd look at doing a .338 maybe something like the 338 Ruger Compact Mag or even necking up the 308 to 338.

QL says a 10in 338 RCM with 200gr bullet will go 2300 using 63gr CFE223 and a 338-308 will go 2210 burning 46.7gr powder.  IMO, either one of those, in such a short build, would be a better choice than the 300 WSM.

[James]

I appreciate your support!

Given your experience with suppressors how much can one expect from a 10ish” barreled magnum rifle and a high quality suppressor? I understand I am in the minority asking this kind of crazy questions.

I have no delusions that it will be quiet, but hoping for substantially more quiet than a regular round 308/30-06/etc. in a 16-20” barrel unsuppressed.

Don't think anyone makes a suppressor rated for a 10" barreled 300 mag.  The shortest are 20" for the 300 mags and up, 10" for the 223/5.56 capacity cartridges.

That’s not true.

https://deadairsilencers.com/products/sandman-k/





https://deadairsilencers.com/products/sandman-s/





BLACK HAMMER ARMS
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GLOCK Certified Armourer

Do it. Have fun. Kill elk.


BLACK HAMMER ARMS
Type 07 Class 2 NFA Dealer
http://www.blackhammerarms.com
https://www.Silencershop.com/blackhammerarms
http://www.facebook.com/blackhammerarms
https://www.instagram.com/blackhammerarms
GLOCK Certified Armourer

[b23]

Thank you for running those, I appreciate it.

I was initially thinking 150-180 grain for 300WSM, but Yorkie has me thinking 130 grain now.

I had a friend of a friend run 150 grain Barnes TTSX a few years ago though a reloading software program (maybe QL?) and came up with 2855 ft/sec. I can’t remember all the details unfortunately.

2265 ft/sec is obviously not what I am looking for in 300WSM, and even a larger caliber while better was hoping for more MV. I would love to hear if you have any more thoughts or insight  to loadings that could get the MV up a bit higher for 338, 300wsm, etc.

If you drop down to something like a 125gr Hornady SST QL says you could launch those from a 10in 300WSM at around 2680 using RL17.

I'd talk to Zak at TBAC, he's a very smart dude and will always take your call or call you back, but on something like this I'd look at using a 338 suppressor or maybe TBAC's new Magnus can.  On a build as extreme as this I would think a bigger volume can would be the way to go but Zak would know for sure.

[dreadi]

I appreciate your support!

Given your experience with suppressors how much can one expect from a 10ish” barreled magnum rifle and a high quality suppressor? I understand I am in the minority asking this kind of crazy questions.

I have no delusions that it will be quiet, but hoping for substantially more quiet than a regular round 308/30-06/etc. in a 16-20” barrel unsuppressed.

Don't think anyone makes a suppressor rated for a 10" barreled 300 mag.  The shortest are 20" for the 300 mags and up, 10" for the 223/5.56 capacity cartridges.

That’s not true.

https://deadairsilencers.com/products/sandman-k/





https://deadairsilencers.com/products/sandman-s/





BLACK HAMMER ARMS
Type 07 Class 2 NFA Dealer
http://www.blackhammerarms.com
https://www.Silencershop.com/blackhammerarms
http://www.facebook.com/blackhammerarms
https://www.instagram.com/blackhammerarms
GLOCK Certified Armourer

Do it. Have fun. Kill elk.


BLACK HAMMER ARMS
Type 07 Class 2 NFA Dealer
http://www.blackhammerarms.com
https://www.Silencershop.com/blackhammerarms
http://www.facebook.com/blackhammerarms
https://www.instagram.com/blackhammerarms
GLOCK Certified Armourer

Much of what has been posted in this thread about the db SPL true. I don't take on measuring sound levels for suppressors but, I will say that my Ruger MkIII with a three inch barrel suppressed, is louder than my Ruger 10/22 with 16" barrel suppressed. I will also say that https://pewscience.com/ performs test on multiple platforms with suppressors and you can expect to get an experience that represents logarithmic nature of sound. One of our members "2tallmike" has a rifle in a similar yet smaller caliber package than you're thinking about building. Perhaps he can chime in or give you some of his experience in a PM.

[fly-by]

I am looking to make a purpose-built short barrel hunting rifle for hunting Roosevelt elk in their thick jungle habitat, but can still ethically harvest across a clear cut when that rare opportunity arises.

Goals:
-Short as possible overall barrel length for maneuvering in the thick jungle of western WA
-Still be able to ethically harvest game to at least 350 yards with copper bullets.
-As corrosion resistant as possible.
-Be very comfortable, ergonomic, and easy to carry while still hunting
-1 MOA accuracy or better, because only accurate rifles are interesting.

What is your goal in terms of energy at 350 yards and are you still set on copper bullets only?

[LDennis24]

Check this out:

https://matchgrademachine.com/velocity-testing-thompson-center-barrels/

I got to thinking of a gun I could imagine with large calibers and short barrels and looked up Thompson Contender barrel velocities and found this.

[kselkhunter]

I think your best bet is to call Thunderbeast and the various suppressor suppliers and tell them of your plan.  Ask them if they have any cans in development that would be rated for a 10" 300WSM and can provide real-world 30-40db reduction.  Maybe they have something out now or in development that could do it. The pewresearch summaries supports what I referenced earlier from other websites in testing of 23-26db best case of those suppressors tested....but technology keeps advancing and maybe the newer suppressors can get you there.  I think the people that can answer the question best are the engineers at the suppressor companies.   They'll have a better idea of how to extrapolate your starting db point with a 10" 300WSM. 


Alternatively you could reduce powder load to reduce db levels.   But that defeats your purpose of going with 300WSM.   
 

Good luck in your project.

[James]

Thank you

Check this out:

https://matchgrademachine.com/velocity-testing-thompson-center-barrels/

I got to thinking of a gun I could imagine with large calibers and short barrels and looked up Thompson Contender barrel velocities and found this.

I am pretty stuck on using copper bullets. I haven’t really worried about energy because if you have enough velocity for a copper bullet out of a hunting cartridge there is plenty of it to take game.

What is your goal in terms of energy at 350 yards and are you still set on copper bullets only?

Great thoughts, thank you.  I think your suggestion lines up in the same place the people that recommend big bore revolvers and lever guns.  Probably the smartest approaches to fix as much of my “problem” as possible without doing a crazy project. aka what a sensible person would do.

I would suggest the following.  Go with a 16 inch barrel just for ease of paperwork and costs.  Use a chassis style stock with a folding butt stock to shrink the package for field carry.  Get online and check out some outdoor suppliers in England.  They routinely use a style of moderator there that is shorter and fatter than what we see here, designed for this very purpose of suppressing flash and bang from short barreled rifles.  Finally look at a smaller optic, trijicon acupoint makes a great little 1-4 variable wide field optic to top a light short rifle with.

[James]

It’s become painfully obvious to me I need to do a lot more reading and thinking about suppressors.

Am I reading that correctly that the Sandman K is 5.4” long and only adds 2.9” in total length so it’s a reflex style?  If so that is way better than the Mantis I was looking at in regards to added length.

Much of what has been posted in this thread about the db SPL true. I don't take on measuring sound levels for suppressors but, I will say that my Ruger MkIII with a three inch barrel suppressed, is louder than my Ruger 10/22 with 16" barrel suppressed. I will also say that https://pewscience.com/ performs test on multiple platforms with suppressors and you can expect to get an experience that represents logarithmic nature of sound. One of our members "2tallmike" has a rifle in a similar yet smaller caliber package than you're thinking about building. Perhaps he can chime in or give you some of his experience in a PM.

I think your best bet is to call Thunderbeast and the various suppressor suppliers and tell them of your plan.  Ask them if they have any cans in development that would be rated for a 10" 300WSM and can provide real-world 30-40db reduction.  Maybe they have something out now or in development that could do it. The pewresearch summaries supports what I referenced earlier from other websites in testing of 23-26db best case of those suppressors tested....but technology keeps advancing and maybe the newer suppressors can get you there.  I think the people that can answer the question best are the engineers at the suppressor companies.   They'll have a better idea of how to extrapolate your starting db point with a 10" 300WSM. 


Alternatively you could reduce powder load to reduce db levels.   But that defeats your purpose of going with 300WSM.   
 

Good luck in your project.

[dreadi]

It’s become painfully obvious to me I need to do a lot more reading and thinking about suppressors.

Am I reading that correctly that the Sandman K is 5.4” long and only adds 2.9” in total length so it’s a reflex style?  If so that is way better than the Mantis I was looking at in regards to added length.

Much of what has been posted in this thread about the db SPL true. I don't take on measuring sound levels for suppressors but, I will say that my Ruger MkIII with a three inch barrel suppressed, is louder than my Ruger 10/22 with 16" barrel suppressed. I will also say that https://pewscience.com/ performs test on multiple platforms with suppressors and you can expect to get an experience that represents logarithmic nature of sound. One of our members "2tallmike" has a rifle in a similar yet smaller caliber package than you're thinking about building. Perhaps he can chime in or give you some of his experience in a PM.

I think your best bet is to call Thunderbeast and the various suppressor suppliers and tell them of your plan.  Ask them if they have any cans in development that would be rated for a 10" 300WSM and can provide real-world 30-40db reduction.  Maybe they have something out now or in development that could do it. The pewresearch summaries supports what I referenced earlier from other websites in testing of 23-26db best case of those suppressors tested....but technology keeps advancing and maybe the newer suppressors can get you there.  I think the people that can answer the question best are the engineers at the suppressor companies.   They'll have a better idea of how to extrapolate your starting db point with a 10" 300WSM. 


Alternatively you could reduce powder load to reduce db levels.   But that defeats your purpose of going with 300WSM.   
 

Good luck in your project.

and it weighs 44% less. Keep in mind, the K versions indicate they are the shorter versions of a longer S version. Shorter can mean less suppression. However, I get it. I went with the shortest 9mm suppressor possible  at that time for a particular firearm, despite there being other options on the market that may have suppressed better.

You could take the aforementioned advice and call Dead Air, and ask them if their Nomad Ti or LTi would work with your ideas....they weigh even less  The Nomad Ti with a Xeno mount weighs 10.3oz.  If you'd like to put your hands on a Sandman K, Sandman S, or Nomad Ti, come see me.

[Wea300mag]

James, build that gun and you will be as cool as this guy.

[Rat44]

I went down a similar road back in the 80's.
Short barreled carbines were all the rage at that time .
Bought a Rem 700 30/06,cut the barrel to 16 1/2" and put it in a Kevlar stock.
Has the ballistics of a long barreled 308 and only weighs 7 lbs with a 2 3/4 shotgun scope on it.
Carries like a dream.
My version of a timber gun that will handle clearcut shots.
But you pay the price in recoil ,noise and finding a load that worked with that short a barrel.
Good luck in you search,

[Caseknife]

Running lots of different calibers/combos through QL, the 300WSM is your best bet with 130TTSX, other cartridges don't get the velocity, but you are only going to get about 2550fps with RL17.  With the 130TTSX at 350 yds you still have about 1750fps which should expand the bullet, how much, don't know, kind of at the limit.

Thing that I would be concerned with, and which I don't have any experience with yet, is the 5-10% of the unburned powder entering the suppressor.  How much heat will that create burning 5-8 grains of powder within the can?  Hunting situations wouldn't be a concern, one to two shots, but load development or just sighting in the rifle may be problematic.