Home Forums Hunting & Shooting Custom Rifles & Wildcats Velocity gain 7/08AI - 280 AI

I want a 280 ai but I have a SA to work with that just needs a barrel job. What am I giving up?
Thanks
Steve

MY 280AI-3206fps with 140NAB from a 24 3/4" tube. MY 7mm-08AI-3150ish with 140 XLC from a 26" tube. If you willing to add the extra tube length to the 7-08AI, not a whole lot. But if you want the "campfire usual" short skinny barrel, you lose velocity with a shorter tube. I'll never do a 7-08AI with a barrel shorter than 26". But, I also aint packing the rifle up mountains either. Figure 50 to 100fps loss for every inch of tube you omit. Your call

If you are going to the expense of rebarreling, why rebarrel to something that is less than what you want? Sell the short action and buy a long action. Should be a relatively inexpensive fix.

Build the 7MM-08AI and go kill [bleep] DRT...mine has a 23" barrel and it shoots great and kills DRT. Don't let a few FPS worry ya any. I have never shoot mine over a chrony but it shoots accurate and kills everything DRT. I shoot 120 BT's and a few 140 Partitions.

I use 120TTSXs , 120 GS Customs and get 3150-3200. It has killed ALOT of game. Use R-15 and Varget and go forth and kill stuff. Mine is a 23" ahead of the recoil lug,Shilen select match SS.
Bill

..nothing that any deer will ever notice,....

I've had both of them as well as the standard versions.

7mm WSM or 7 SAUM both equal or exceed the 280AI slightly.

This.

I would imagine you could sell or trade it in the classifieds pretty quickly.

I'd just shoot the standard version. It and the 7x57 will work on pretty much anything as is.

A hundred or so fps won't make a difference in the field. If it makes a difference in your head go with the 284 Win, 7 SAUM or WSM.

PM sent

This is my shcpeal on comparing 7mm cartridges:

I got a deal on 26" Lothar Walther CM barrel blanks in 7mm 1300 taper = ~ 53 ounces finished
I got a deal on Hornady 7MM .284 DIA 162GR BIG GAME POLY CARB TIP 28452 bullets and moly coated them

Comparing cartridge performance with Quickload and Quicktarget at close to optimum powder choice and 65kpsi:
7mmT/CU ........................26.1 gr H335 2330 fps -471 yards
7-30 Waters ........................30 gr W748 2456 fps -395 yards
7mmBR ...........................31.2 gr W748 2510 fps -360 yards
7mm IHMSA .......................40.2 gr Re17 2704 fps -247 yards
7mm-08 .......................40.6 gr IMR4895 2789 fps -198 yards
7mm-08AckleyImproved .........43.6 gr Re15 2833 fps -171 yards
7x57mm ...........................44.6 gr Re15 2843 fps -165 yards
7x57mmAckleyImproved .........46.4 gr Re15 2873 fps -150 yards
284Win .........................50.0 gr IMR4350 2890 fps -172 yards
280Rem ............................53.5 gr H414 2961 fps -152 yards
7mm Rem short action ultra mag 55.5 gr Re17 3015 fps -73 yards
280RemAckleyImproved ........57 gr IMR4350 3019 fps -71 yards
7mmRemMag ......................68.2 gr Re22 3129 fps -15 yards
7mmRem ultra mag ............83.3 gr IMR7828 3130 fps -15 yards
7mmWeathMag ....................71.8 gr Re22 3170 fps +7 yards
7mmSTW .............82.2 gr Ramshot Magnum 3158 fps 0 yards

What does it all mean?

The 7mm-08AI gives 100 yards in terms of velocity to the 280AI.

But that is if all the cartridges run at 65 kpsi.
In reality the Mauser case head when built with a large primer pocket can be handloaded for one rifle at 67 kpsi, the belted magnums at 72 kpsi, and the Mauser case head with small primer pocket at 85 kpsi.

So if one could get some Lapua small primer pocket 308 brass, neck it down to 7mm-08, the brass will last at 85 kpsi [like a 6mmBR], and the 7mm-08AI will then beat the 280AI.

I personally opened the bolt face, relieved the extractor, cut the feed lips, and chambered for 7mmRemMag. I then in 2011 shot an antelope in 10 minutes at 50 yards, and a mule deer at 400 yards in two hours. I could have done that with a lot less rifle.

I just cant get excited about heavy for caliber bullets. I know about all the LR crowds reason for wanting to run heavier bullets. But to me the 280AI and the 7-08AI really shine with 120 and 140 grain pills. And both rifles can run the 140s past 3100 with sane pressures. Granted that means a 26" tube on the 08. If I'm looking to run 160grns and above, I want a larger case (ie 7MM Mashburn or STW).

You could do something like this on a short action

http://www.6mmbr.com/gunweek095.html

I have the 280AI on a long action and I shoot 160gr AB beside deer I'll use it for elk tag.

I don't think I'd build a 280AI to handle light bullets lot of powder to burn when other case work better. You also have to look at what bullets you want to use and if you plan on going out of state to hunt.

Well good luck

50-100fps loss per inch? Wow. My two chopped bbls had 21" Saami factory chambered 700s were getting 2960 w/139-140s, 3050-3100 w/120s, varget, partial sized, 1.0 over book.

I'd have thought about 30-35fps average loss.

Cliff that was just a general guess. Could be closer to 40. I just know there is velocity loss with shorter barrels. There are no free rides. Know I wouldnt do another 708AI without going with a 26" tube. Seen too much firsthand what they will do. And just cant believe going with a 21 or 22" tube isnt gonna cost me much fps. Had 2 loads in my 7-08AI that ran 3100+. And both showed NO signs of high pressure. If my calculations are correct my 26" 7-08AI @ 3150 and your 21" tube at @2960 there is a 190fps velocity difference. And divided by the 4" difference in barrel length shows a 47.5 fps loss per inch of barrel taken off.

Before you get too carried away in speculation, read this:

Barrel Length Experiment

I'll leave it at this, I have seen what the 7-08AI is capable of with a 26" tube and 140s. And you aint gonna get that from a short( 21 or 22" tube) at sane pressures. And yeah I was approaching the velocities my 280AI runs the 140NAB at. Show me a 7-08AI 21 or 22" tube that will run 140s above 3150 and not be loaded WAY hot. Dont think you gonna have much luck there. So tell me what I missed with the "barrel length thread". I don't build AI calibers just to eliminate trimming. I build them for speed. More velocity means flatter trajectory no matter how minute the velocity difference is. And I want all I can get. I also dont climb mountains. I am in shape enough to carry my rifles to my desired hunting destinations easily. And some of them are close to a mile one way. By all means build whatever you want however you want. But the OP asked what he was giving up velocity wise. I just stated what was possible with the 7-08AI. What the OP or anyone else for that matter is willing to "settle for" is their choice. Satisfaction level is subjective. So to each his own

I'd just run a 22" 7SAUM and leave it there.

Then you should get a 280AI.

When it comes to getting a certain velocity level with your chosen bullets,I have generally found it more satisfactory to use a case of larger capacity (this does not mean that you have to go overboard);but I like a case that does it easily.

While mixing an improved case design with a longer barrel undoubtedly boosts velocities somewhat (as others have pointed out),and you run it at maximum pressure levels,I personally don't care for 26" barrels on rifles that might see action in mixed cover and open country as well.I don't care for a barrel longer than 24" for such a rifle....long or short action included.

Reading graphs and formula's for anticipated velocities is fine as a general guide;and it is true that some smaller cases will come close to larger ones for velocity with lighter bullets,but if you ever want to use the heavier slugs,the larger case will easily distance the smaller one's with those same heavy bullets, and do it without breaking much of a sweat.

When we run up against the cold, hard chronograph numbers,a short action cartridge of limited capacity might just leave you wishing for "more",or may not depending on your anticipated use and perspective.

Personally, I am not so much enamored with short actions and cartridges to fit,have no problems with a 30/06 length action,and see no logic in stretching an improved short action case to do the work that a 280AI will easily accomplish. Seems the cartridge is a good ,well balanced fit for a 24" tube,a handy rifle, while giving an easy 3150-3200 fps with a 140 gr bullet.Seems also that it will manage the heavies well enough(though not as well and easily as a larger case.Should say I have never owned one but have had a bunch of 7 Rem Mags and 280's so know what to expect.This stuff ain't that hard.)

We can talk about what pressures we are running by reading about it, but the truth is this is a WAG,and none of us "know" unless and until we can actually measure the loads for pressures in our rifle.

Your instincts are good....get what you want rather than settle for something less.We are talking about too much money for compromises