280 AI Barrel Length for Suppressor

[Joelweb]

I'm sure there will be different opinions on this, and I'd like to hear them. I've got a Kimber Mountain Ascent in 280 Ackley that I've had for nearly a decade. I love this gun--it is a pile driver and shoots great with handloads. I hate to mess with it, but I'm fed up with the earplug scramble and ordered a Banish Backcountry suppressor. Kimber makes an adapter that will make it fit.

I'm going to get the barrel shortened. It is presently at 24". I'm leery about cutting too much given the standard case size and am leaning toward 22", although I'm also considering 21".

Anyone here have real world experience cutting down a 280AI? How short and what are you seeing for velocity changes? Thanks in advance.

 

[MThuntr]

Knowing those are pretty thin barrels I'm not sure how far you'd have to chop for the right thread diameter but your gunsmith will be able to help you with that. I don't know if you'd notice much of a loss by going to 20 or 21 and adding a suppressor. You could be out 100-150fps but possibly gain back 40-50 with a suppressor (that's a guess based on sample of 1 for adding suppressor to a 20" barreled rifle)

 

[BrBa]

Velocity loss is going to vary based on your powder and bullet weights. If you use faster burning powders it may reduce your delta to some extent. 2 inches less doesn't seem like a lot, but adding the weight of an adaptor and suppressor on the end of a thin barrel is going to change the harmonics. I went thru a similar exercise with another rifle and decided to go with a rebarrel with heavier contour.

 

[HGL]

My .280 Ackley wears a 22" Brux with a Tbac 7.

My velocities with RL-26 are below. Granted, 26 gets some good speeds in the .280 but its almost impossible to find these days, got a couple pound stash for hunting loads.

168 VLD @ 2875
162 ELDx @ 2950
160 AB @ 3000

I'd be fine with any of the above loads running 50 fps slower from a 20" tube. My gun loves H4831sc too, but its a good bit slower in the velocity department, ymmv.

 

[2Stamp]

My 280ai CA Ridgeline with a 22", and a SiCo Omega, gets 3080 with barnes 145 LRX and H4831sc. I didn't push the reloading on this to see how fast it'll go, just book max. I have no idea it that's average or not.

I haven't messed with heavier bullets yet though.

 

[pods8 (Rugged Stitching)]

My 280ai CA Ridgeline with a 22", and a SiCo Omega, gets 3080 with barnes 145 LRX and H4831sc. I didn't push the reloading on this to see how fast it'll go, just book max. I have no idea it that's average or not.

I haven't messed with heavier bullets yet though.

I don't think you have much to push there imho, I'm at 3130fps with the 145LRX using IMR7828SSC in a 24" barrel and its a load that is hard on primer pockets but this is with fire formed Rem brass (set it up before other brands besides nosler were making brass) so better brass might hold longer. What brass are you using and how are your pockets holding up?

For the OP thats showing 25fps/in dropping from 24" to 22" with a similar stout load.

 

[2Stamp]

I don't think you have much to push there imho, I'm at 3130fps with the 145LRX using IMR7828SSC in a 24" barrel and its a load that is hard on primer pockets but this is with fire formed Rem brass (set it up before other brands besides nosler were making brass) so better brass might hold longer. What brass are you using and how are your pockets holding up?

For the OP thats showing 25fps/in dropping from 24" to 22" with a similar stout load.

Good to know. To be fair, I really don't have a need to push it harder.
I'm using a mix of Nosler brass and formed Norma. Pockets have been good, no issues.

 

[passinggas33]

I have a 280AI in both a 24” (custom) and a 22” (kimber Mtn ascent). My gunsmith felt that going much shorter than 22” because of the flutes might start to impact the harmonics of the barrel and potentially lose accuracy. Super happy with that one at 22”. IF I were to do my custom all over again, I would have a 20” barrel on it with a permanent suppressor. The speed difference between MY two hand loads is only about 20 fps so not that big of a deal.

 

[Joelweb]

Appreciate it, everyone.

 

[Unckebob]

I had my 24" barrel cut to 20" because I wanted to use my suppressor.

Using the same box of factor ammo using the 140g Nosler BT. I lost 100fps.

I am glad I went with the 20" barrel.

 

[Unckebob]

I took my 20" 280AI out to test my new Garmin chrono today.

To test how must velocity I was leaving on the table, I shot a few rounds of Hornady Prevision Hunter @62g. The box said the velocity was 2850 in their 24" test barrel. I got 2710.

I was getting just under 3000fps with the 145 LRX that I hand loaded.

 

[bigunit]

Mine has a 22" carbon barrel.
It's favorite loads so far are:
Sierra 165 tgk @2925 h4831
Hornady 162 eldm @2880 w h4831
Hornady 180 eldm @ 2825 w 7828ssc

 

[Krumfola]

This was helpful info. I’m starting my build and I think I’ll go 22” to be run with a TBAC Ultra 7. Planning on 162gr ELDX factory stuff and don’t wanna risk dropping below 2700fps with a 20” barrel.

Having a hard time choosing a stock at the moment.

 

[Ktwebb33]

I had my 24" barrel cut to 20" because I wanted to use my suppressor.

Using the same box of factor ammo using the 140g Nosler BT. I lost 100fps.

I am glad I went with the 20" barrel.

How do you like carrying around the 20” suppressed? Trying to decide if going to 18” would be worth taking another hit in velocity, to gain even more in handiness running suppressed full time in the woods. Best I can tell numbers wise at 18” I would still be plenty good out past my comfortable hunting distances. Above 1800fps out to around 600+ yds give or take some, which is more than enough for me.

 

[Krumfola]

Update…

Kelbly Atlas Tactical, McMillan A3 (edge fill), 22” Carbon 6 barrel, topped with an S&B 6x42. Factory Precision Hunter ammo had my velocities at 2810 with a TBAC Ultra 7.

Using Accurate 4350 I’ve been able to get velocities up to 2880 with great accuracy.

225 yard zero, 2.7 mils at 600 yards with just over 2000fps impact velocity.

9.2lbs loaded with suppressor

 

[Ktwebb33]

Update…

Kelbly Atlas Tactical, McMillan A3 (edge fill), 22” Carbon 6 barrel, topped with an S&B 6x42. Factory Precision Hunter ammo had my velocities at 2810 with a TBAC Ultra 7.

Using Accurate 4350 I’ve been able to get velocities up to 2880 with great accuracy.

225 yard zero, 2.7 mils at 600 yards with just over 2000fps impact velocity.

9.2lbs loaded with suppressor

What’s your thoughts on staying above your 2700fps at 20”, or even 18”? If you’re getting upper 2800’s, I’d figure someone would be above 2700 @ even an 18”.

 

[Krumfola]

I feel like 2700 is easily attainable at 20” and would be very close at 18”. The 162gr ELDX has a good enough BC that even if it were slightly below 2700, it would still be good out to 500 or so.

I was looking for a minimum of 2700 because the only turret available from S&B for my scope was limited to 32cm (3.2mil) and I wanted to get to a max range of 600 yards on game.

 

[Ktwebb33]

I feel like 2700 is easily attainable at 20” and would be very close at 18”. The 162gr ELDX has a good enough BC that even if it were slightly below 2700, it would still be good out to 500 or so.

I was looking for a minimum of 2700 because the only turret available from S&B for my scope was limited to 32cm (3.2mil) and I wanted to get to a max range of 600 yards on game.

That makes sense. 600 yds is what I have in my head also for a current build. I just really want 18” to work out. If I’m not mistaken, as long as the 162 stays above 2600mv, it doesn’t drop below 1800fps until 600+. I could be wrong. No real world experience.

 

[Krumfola]

Yeah, according to 4dof, 2600fps at the muzzle should give you 1800 at 600 yards. 18” would be pretty handy and lighter than mine too.

 

[280rem]

Just getting my setup going. I had a kimber mountain ascent cut from 24 to 20.5”. I never shot the gun before cutting (some things you don’t want to know). My wife has identical gun with original barrel. With the factory Barnes 152 Lrx loads, wife’s gun was getting 3056 fps mine was getting 2933 with the same nomad ti on each. I put my cgs hyperion k on and got 2907 with it. I’m very happy with this setup so far, accuracy was sub moa with several loads. Waiting on a scythe ti that will probably my go to for this. Very happy with this. Ultra ultra lightweight. MA very lightweight and then getting rid of 3.5” of barrel helps offset weight and length. Swaro z5i 3.5-18x44 on it.