Help me build a chassis gun on a Ruger American 308 platform

Long Guns
1

I’m a muzzleloader and shotgun guy with a few off the shelf rifles, this component “build it yourself” stuff is a mystery to me.

I’ll be shooting 300 yards often (CJRP - it’s our longest range) but I’d like to be able to reach out further. I already have the Ruger, but I need all the rest, and have just been confusing myself trying to sort through all the options out there. Barrel, chassis, stock, foregrip, trigger …

Of course I’d like to pull off the best for the least and I only have one hard requirement, an adjustable stock, both in LOP and cheek height

The current gun has a stainless tapered barrel, I’d like to swap with a bull barrel. Can I do that after the build, or does it have to be done before to fit the different shaped barrel?

Other than that I don’t even know enough about this to know what questions to ask

2

Put all of your mental and financial energy into the barrel first. Precision rifles are actually precision barrels with shit attached to it.

Make sure u get a barrel that has a twist optimal for the load u will be shooting.

3

Barrel. Stock/chassis. Trigger. Optics.

4

150 gr FMJ BT

5

That’s kinda light for precision shooting. 169gr OTM will be much more accurate, and is most common for those chasing accuracy. If 150gr is what u wanna shoot that’s fine too.

What is the purpose of the build, just bench shooting, maybe some hog hunting, just another range toy perhaps?

6

Exactly why I’m posting this. I’d no idea that 150 would be too light
And yes, all of the above

7

It’s not that 150 is too light, it is just not optimal. Heavier bullets have a higher BC (ballistic coefficient) and can buck wind better.

Milsurp usually comes in 145, 147 and 150 gr FMJ, and is by far the cheapest 308 because it’s the most available. You will probably practice with the lighter rounds and do your precision work with whatever round your barrel likes.

Of the three primary twists for 308 1:12, 1:11, 1:10, Personally, I’d go for the 1:11 twist as it stabilizes 150 to 168 inside the sweet spot. While it’s mostly true there is no such thing as over stabilization (for example - shooting 55gr M193 in a 1:7 barrel, it is wholly unnecessary to have such a fast twist. In fact, if all u r gonna shoot is 55gr and 62gr, all u need is 1:9)

U can go crazy with internal ballistics, trying to build the perfect rifle that shoots everything like a laser just ain’t gonna happen, but at the same time you can still get a good range for stabilization.

It’s not just bullet weight. u gotta consider, length, BC, SD, velocity, all this adds up to the bullets performance and how it will behave from chamber to muzzle.

As far as what will be the most accurate, you will have to buy at least one box of match grade everything and shoot for groups. You can also tighten up groupings with hand loading, which is a whole other ball of wax.

Just something to consider… You will be spending probably over $1,000.00 to build this rifle. If its a project then that’s cool, but if all u want is a precision rifle with adjustable this and that, maybe just get a Ruger Precision Rifle.

8

I have about 2K IMI .309 147 gr BT seeds. Those should be fine at the 300 yard range at my club, right ? I have about a dozen other assorted boxes of Sierra and Nosler .308 seeds in various weights from 100 gr to 190 gr
This is the IMI

IMI 309 dia 148 grain
IMI 309 dia 148 grain988×551 69 KB

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My Brain Hurts
My Brain Hurts509×441 39.3 KB

10

Federal Gold Metal Match uses a 169 gr. Boat Tail Hollow Point bullet. I can put two clean holes through a quarter at 100 yards off the bench in my Remmy 700

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11

Is this a typo? .309 does exist but usually hard cast for lever guns or in 7.62x54mmR for them commie rifles.

Assuming it’s a typo, what u have is M80 Ball freedom seeds. u can expect about 2 to 3 moa from them, and load data is not easily found. Looks like most folks are working up their own LD using modified 150gr recipes. This bullet seems finicky about seating depth too.

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Yup, that was a mistake. They measure out at .311 (ish) - so they will go to my SKS

311
3111920×2184 195 KB

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.312 is mosin nagant food.

Edit: You could resize them but no idea what it would do to the shape.

14

Check this out
I thought this wasn’t right, went back and remeasured using 3 different types of caliper
The Mitoyo is off, they are .308

20241206_120018
20241206_1200181920×2560 248 KB

20241206_120315
20241206_1203151920×2560 566 KB

20241206_120321
20241206_1203211920×2560 665 KB

20241206_120438
20241206_1204381920×2560 166 KB

15

That makes things better, but not exactly simplified. There is still the dearth of 147gr load data to work around.

Have u made any handloads with those boolits yet? Maybe do a run of 20 or 40 and see how they do in the RAR in it’s current form.

16

Found this online:
For lead core 147 FMJ’s the standard for military brass is usually 42.5 grains of IMR-4895. Somewhere between 42.0 and 43.0 grains is usually good with 43.5 grains being considered max and that can be a bit hot in military cases but alright in most commercial cases. I wouldn’t go below 40.5 grains of powder.

42.5 grains of h4895 in a Military case is about the equivalent to M80 ball. Somewhere around there, going up or down a bit, you will find where your rifle groups best.

Mine are non-magnetic, open back lead core seeds
I’m reloading for the Ruger American and my .308 Garand, so I’ll start at 41 of h4895 and see where it goes from there. Its asking a lot, but I’d love to find a round that both guns find acceptable at the 300 yard range (At that distance, with the open sights, the Garand just has to hit a 7" steel gong I already have, I’d like to be accurate with the RAR)

17

the load your RAR likes is unlikely to be loved by the Garand. You have two options, load to factory (sammi) spec for both guns, or custom load for each rifle.

You will get the best accuracy out of the RAR with once fired brass that is not full length resized and maybe this will be unnecessary but you can also lead out the bullet to be closer to the lands. That may not be necessary though as I recall my RAR (original recipe) was a very snug fit in the chamber.

You will get the best results with the RAR if u create a load just for that. But check this, if you manage to create a sub moa load for the RAR as it is now, it may hate that same load after you build a new rifle off that receiver. But still, a good idea to see what the potential for that bullet is.

18

Neck resizing !
I hadn’t thought of doing that for the RAR, but it makes the most sense. Let the chamber size the rest.

Looks like it’s going to be two different loads

Crap, now I need another die.

19

And thanks for being the voice of reason
I would have just wasted a lot of time and components to get to where we are right now.

20

When it comes to getting people squander their money and time, I’m here to help.

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