2650fps fossible with a 175gr in 18" .308?

[broylz]

with handloading and different, maybe just more, powder is it possible to get the same velocity from a 24" gun in an 18" gun? if that's a bit tough, is it easier to do in a 20?

shooting buddy has a REPR with an 18" barrel and im debating rebarreling my 30-06 into an 18" .308. I like the option of sibsonic loads but mostly want to go as short as I can without sacrificing anything in velocity. to get there I know I need to load my own...

 

[CK_32]

Should be possible. It will take more powder. I know my 20" can easily achieve about 2550 FPS with a moderate load I'm sure I could get around 2600 to 2700 pushing the pressures in that same rifle. 18" should be able to make it to 2650 if not close but you will be pushing the limits by upping the powder to get there and decrease brass life depending on how much pressure it takes to get there.


Also another huge factory depends on how tight your chamber is. Match chambers usually gains pressure faster than factory chambers. Again work your way up and hit a chrono and see where your at.

If your looking to gain 2650 for a accuracy stand point nodes are more important than speed.


Also the saying of lost FPS between a 20" and a 18" inch is about 60 FPS with the same load. Obviously this is just a example because velocity will change depending on powders and consonants used and conditions along with rifle quality. The 20 to 18" MV difference is not as drastic as the 18" to 16". Supposed to be pretty slim Los of velocity reason why many run 18" on gas guns. Gets good velocity and utilizes a smaller more portable OAL

 

[gpz750]

try some imr 4064. work your way up, but it is doable

 

[5RWill]

Tag.

Getting around 2700 with my 24" 5R wondering what kind of drop i'll be looking at cutting it to 18.5" or 19"

 

[redirt78]

I get 2510 out of my factory barreled 1:12 twist 700 varmint that I had cut down to 18" from 26" with Southwest Ammo 175 SMK and 175 FGMM. I have no idea how much hotter they could be loaded.

 

[Tx_Flyboy]

broylz,

You cannot cheat physics...short barrels suck if you are looking for velocity and range. I know its all tacticool to make a rifle as compact as a pistol, but as long as you understand that you are sacrificing range to look cool, then it's ok.

That aside, the answer to your question is "it depends".

If you are a re-loader it's doable with the right powder and charge weight.

The two powders that come to mind are CFE-223 and 2000MR. Both of these powders are temperature sensitive, so while you may achieve 2650 (at the ragged edge of pressure) in the summer, you will loose velocity in the winter and need to re-dope your load.

You could also potentially achieve 2,650ft/s w VV-540/140, but i've never played w those powders. The same caution about temperature sensitivity also applies.

Lastly, why on earth would you want to re-barrel you 30-06 to a 308? a 30-06 loaded to modern pressure levels will give you factory 300WM velocities & w the right bullets supersonic to 1500yards+.

I know the 06 isnt sexy, isnt tacticool, but it is a tremendous cartridge & offers those in the know incredible flexibility in loads at moderate recoil levels.

 

[Lowlight]

My 18" gets 2605fps out of some loads, and 2575fps out of the most common ones.

I have a tight bore Bartlien on it... my 20" AI with a Bartlein is 2645fps with the same factory loads.

 

[ericthebeard]

I can confirm as well... A 20" Bartlein on my AIAW gets 2640 fps with FGMM. About 100 fps less with SWA and Black Hills 308.

 

[CK_32]

I get 2510 out of my factory barreled 1:12 twist 700 varmint that I had cut down to 18" from 26" with Southwest Ammo 175 SMK and 175 FGMM. I have no idea how much hotter they could be loaded.

Much hotter...

FGMM uses 41.7 grains of powder that has a book max of 45.5c. It's a factory load it's loaded to have safe pressures in all rifles.

 

[RobertB]

I'm getting 2650ish from my 20" bartlien. That's FGMM and SW 175 match. I guess SW clones their ammo. Last batch of each I had shot within 1/4 MOA out to 1K. Zero at 100 and dope to 1k

 

[BoilerUP]

I don't know much about 308...but it seems like one would have to lean on their loads pretty hard to achieve the desired velocity.

Seems like a safer bet would be 2" more barrel...or switching bullets to something like a 168gr Hybrid or even Classic Hunter.

 

[Fatelvis]

Try using PP2000MR powder.

 

[buffybuster]

with handloading and different, maybe just more, powder is it possible to get the same velocity from a 24" gun in an 18" gun? if that's a bit tough, is it easier to do in a 20?

shooting buddy has a REPR with an 18" barrel and im debating rebarreling my 30-06 into an 18" .308. I like the option of sibsonic loads but mostly want to go as short as I can without sacrificing anything in velocity. to get there I know I need to load my own...

The way to get 24" velocity is to shoot a 24" barrel........

While it might be possible to get 2650fps with 175's from a 18" barrel, you'll be leaning on it pretty hard and you're brass won't last too long. Shoot that same warm load in a 24" barrel and you will get even more velocity...... you get the point.

I have a load that gives me 2670fps from a 24" barrel and 2550fps from a 20" barrel. I can live with that.

 

[deadly0311]

I'm shooting 175s out of an 18" Obymeyer barrel with a charge of 44.7 grains of Varget and it's running right at 2640

 

[308Gunner]

Like deadly I have a 20" Broughton that I get 2675 with 44.6 grains of Varget

 

[Bracamonte]

Surprised no one has yet mentioned twist as a factor in MV.

If you keep it a 1:12 twist, I think you could definitely achieve 2650 with a 20". I shoot 185 Bergers out of a 22" 1:12 and get 2645.

 

[RobG]

48 grains of 2000mr/175smk/Fed 210m/Win brass got me to 2650 out of a factory 20" 700 LTR. 47.7 is "book max", 48 showed no pressure signs at all at 95 degrees outside. My guess is an 18" barrel should be able to get there or darn close.

 

[5RWill]

Might be moving to 2000mr then. As I'm shooting a factory barrel as well. Though if my current load will achieve 2500 I'd be happy.


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[JGorski]

I'm betting against anyone getting 2650 in a 18" tube, yes, your best bet would be 47+ grains of 2000MR, I'm shooting 47.3grs of it and getting 2723 in a 24" barrel, same load will net about 2585 in a 18". That is a pretty respectable velocity in my book.
Here's my load, bullets are 178HPBTs, and no pressure signs.

 

[newguy2k3v2]

I get 2640-2680@10ft dependent on temp from my 16" DTA with a 178bthp and 48.4gr of 2000mr. Also running a can so there may be a slight boost there.

It's very warm but even with fc brass I get decent life and .5moa or so with me behind it.

 

[JGorski]

I get 2640-2680@10ft dependent on temp from my 16" DTA with a 178bthp and 48.4gr of 2000mr. Also running a can so there may be a slight boost there.

It's very warm but even with fc brass I get decent life and .5moa or so with me behind it.

Love to see your primers after you shoot. Sticky bolt? My rifle would be shooting your load 2833 give or take. OUCH!

 

[newguy2k3v2]

Never had a sticky bolt on this load, primers have some cratering but everything has in this gun. I can get some pics tonight.

 

[Papa Zero Three]

I've gotten 2700 and 2750 out of both my 20" barrels shooting factory M118. One is a Bartlein 1:10twist 5R and the other is a AAC-SD stock barrel, 1:10 twist. I know both are high MVs for that load and barrel length and was surprised myself honestly but my dope was on out to 850m using that MV. I even had someone else check it and it didn't change,I'm still scratching my head but not complaining. I have my suspicions as to why but nothing more than that. For all I know, the next lot of ammo will bring me back down to the 2600-2650 range. So I am guessing you may be able to get your handloads up there MV wise but it might be on the ragged edge and or inconsistent. But you're kind of screwed in that you said you wanted to go shorter without sacrificing velocity and unfortunately, thats a hard one to beat.

 

[JGorski]

Never had a sticky bolt on this load, primers have some cratering but everything has in this gun. I can get some pics tonight.

I guess I'd lose a bet with you then, haha. My load shoots very well, also, got this at 200yds.(It's just a deer rifle, btw)

 

[newguy2k3v2]

For what it's worth I have read that the 178 Bthps have a shorter bearing surface than 175 smks and 178 amax which may be why I can run a pretty stout charge. I haven't done a side by side work up to verify though.

Eta:about 6 mils to 750 on 100yd 0

 

[GhostFace]

broylz,


Lastly, why on earth would you want to re-barrel you 30-06 to a 308? a 30-06 loaded to modern pressure levels will give you factory 300WM velocities & w the right bullets supersonic to 1500yards+.

I know the 06 isnt sexy, isnt tacticool, but it is a tremendous cartridge & offers those in the know incredible flexibility in loads at moderate recoil levels.

I second this, why not just chop your '06 to 19 inches or so? You'll be able to achieve your desired velocity and then some...

 

[CK_32]

Or just sell his rifle and get a 300 WM all together..

 

[Rprecision]

I understand wanting the highest MV given any set up. The thing I dont understand is why chasing MV is more important then accuracy.

It's a .308 anyways, meaning the differance in shooting 2550 and 2750 still means adjusting the holdovers, only .5 mil less inside 500 and no more then less 2 mil at 1K.

If you get good accuracy at the higher FPS great, but it seems accuracy need be the factor

FWIW, I get right at 2525 out of a Bartlen 5r 1/10 18" gun with 43.3 grains of varget and a 175 SMK. 45.0 is also a accurate load but is just shy of 2600 and has to be used with larger capacity win brass. THe load still puts out 2600 ish

FGMM 175 spits out at 2500-2525 and is stone cold accurate. Its a true 1/4 moa load

 

[SWThomas]

My GAP-10 with 18" barrel, 45.3g of 4064, CCI #34 primers, and 175 SMK got these MVs in 3 shot groups:

2699
2715
2704

With 45.6 it got these:

2721
2726
2726

No pressure signs. 45.6 is the book max for the 175 SMK. I've gone up to 46.0 with no pressure signs. YMMV.

 

[Macmathews]

I understand wanting the highest MV given any set up. The thing I dont understand is why chasing MV is more important then accuracy.

It's a .308 anyways, meaning the differance in shooting 2550 and 2750 still means adjusting the holdovers, only .5 mil less inside 500 and no more then less 2 mil at 1K.

If you get good accuracy at the higher FPS great, but it seems accuracy need be the factor

FWIW, I get right at 2525 out of a Bartlen 5r 1/10 18" gun with 43.3 grains of varget and a 175 SMK. 45.0 is also a accurate load but is just shy of 2600 and has to be used with larger capacity win brass. THe load still puts out 2600 ish

FGMM 175 spits out at 2500-2525 and is stone cold accurate. Its a true 1/4 moa load

Possibly because 2500 may not get you to 1000 without going subsonic,.,

Kyle

 

[Macmathews]

I understand wanting the highest MV given any set up. The thing I dont understand is why chasing MV is more important then accuracy.

It's a .308 anyways, meaning the differance in shooting 2550 and 2750 still means adjusting the holdovers, only .5 mil less inside 500 and no more then less 2 mil at 1K.

If you get good accuracy at the higher FPS great, but it seems accuracy need be the factor

FWIW, I get right at 2525 out of a Bartlen 5r 1/10 18" gun with 43.3 grains of varget and a 175 SMK. 45.0 is also a accurate load but is just shy of 2600 and has to be used with larger capacity win brass. THe load still puts out 2600 ish

FGMM 175 spits out at 2500-2525 and is stone cold accurate. Its a true 1/4 moa load

Possibly because 2500 may not get you to 1000 without going subsonic,.,

Kyle

 

[5RWill]

But it usually is enough, in most cases 2500-2550 will get to 1000 alright.


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[verdugo60]

Why not just rebarrel to 30/06 or cut the barrel down? With Trailboss you could probably make safe '06 subs, and the case capacity of the '06 would get you more horespower with shorter barrel.

 

[broylz]

I am leaning towards going with a heavier 30-06 barrel but the discussion came up with a friend about going 308 because of the subsonic use. I also believe accuracy is most important. I was just curious if it could be done.

I have recently found more info on 30-06 subsonic loads so that kind of takes that argument away.

thanks for the input.

 

[Macmathews]

Well

But it usually is enough, in most cases 2500-2550 will get to 1000 alright.


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In my 700 5r. 308
Anything less than 43 grains of varget with either 178 amax or 175smk.
My rifle would not make 1000

But with 155 scenars and 43 grains of xbr8208. I went 2 for 7. at 1000 at 10" balloons

Kyle

 

[Shoottothrill]

My GAP-10 with 18" barrel, 45.3g of 4064, CCI #34 primers, and 175 SMK got these MVs in 3 shot groups:

2699
2715
2704

With 45.6 it got these:

2721
2726
2726

No pressure signs. 45.6 is the book max for the 175 SMK. I've gone up to 46.0 with no pressure signs. YMMV.

Impressive velocity's. I have a 20" Gap 10 and was wondering what kind of MV you get with 175gr. FGMM? Thanks

 

[SWThomas]

Impressive velocity's. I have a 20" Gap 10 and was wondering what kind of MV you get with 175gr. FGMM? Thanks

I didn't record them but it was somewhere in the high 2500s.

 

[Ishallbie O'Cullkillin]

If I were trying to accomplish this, and going to an 18" barrel meant that much to me, then I would; A - Get an adjustable gas block. B - Use 2000mr powder. C - Have different buffers and springs on hand to smooth out cycling when accommodating higher pressures. I walk around and get in & out of vehicles with an Armalite AR10 carbine, single point slung on my right side. The weight and length are just this side of annoying when compared to an AR15, especially when kneeling to change targets or pick up brass. I've come to accept that it is more prudent to pick the right tool, than to create a tool that does everything ok, but does nothing well.