280 AI Initial Load Dev - Help

[sanpedroranch]

I'm not saying that's diminishing returns, but way more work than I'd put into designing a rifle. Weatherby free bore was for velocity and nothing more. The cartridges don't act any different if you put a standard free bore in them. I don't have experience with that but it makes sense.

I'm not saying that's diminishing returns, but way more work than I'd put into designing a rifle. Weatherby free bore was for velocity and nothing more. The cartridges don't act any different if you put a standard free bore in them. I don't have experience with that but it makes sense.

It is diminishing returns to be honest. I get very interested in these things. I chalk it up to being an engineer. I like going down rabbit holes that most of the time have no significant change to the end results when it comes to this stuff.

 

[35WhelenAI]

It’s a but of both a tad of the latter but more of the first. my first load work up I ran the 142 SMK . It did eat into case capacity, but where the loss was more noticeable is where pressure was seen in relation to charge weight. The barrel with the normal weatherby freebore and the first version without the weatherby freebore. Without the freebore I saw over pressure significantly sooner than with the freebore. I’d have to find the original reamer print that I had made to give exact dimensional differences. From memory I recall I was able to gain several hundred fps without pressure indicators with the freebore. There is a direct correlation between higher pressure and higher velocity. Also depending on burn rate some of what I’m saying can be mitigated. That freebore is what made speeds possible and allowed the weatherby cartridge line to handle the higher pressures. Hence why his initial rifles were built off the proven K98 known to handle the highest pressures only second to the arisaka action. It’s also why the mark v from 257wby up has a 9 lug action and if I recall the most contact surface are of the locking lugs of just about any action in production.

What pressures were Weatherby rifles loaded for with Factory ammunition? Did they go above SAAMI specs? Interested if there's industry data for that.

For what it's worth, I have a 300 Win Mag in the safe. It had tremendous free bore from the factory. I am able to load it to a 3.600 overall length. As a result I shortened the bolt stop and put a magnum length follower in the magazine along with taking a sheet metal filler out of the magazine to seat them to the longer length. Based on case head expansion, I was able to gain decent velocity by just the case capacity increase from the free bore and not go over pressure. Free bore is a big part of why the weatherby cartridges did what they did and do what they do

 

[TxhunterPRC]

Better than VV data would be Nosler data with that same powder for that same bullet. You are 100 FPS over a Nosler max load. You start 10% low and work up. When you reach published velocity call it a day. It's that simple. That was a great first post with all of the minutia and information, but none of that is pertinent other than the powder charge and the velocity with the components you are using. Ultimately you wanted to know if you are over pressure or not, and you are.

I knew I was overpressure. I wanted to know why I wasn't seeing the signs like I normally do with other cartridge's. The design of the cartridge makes sense, just never thought of it.

 

[TxhunterPRC]

I have moved away from this load anyways. Could not get the ABLR's to shoot as good as I was hoping. Going to move forward with the 175 elite hunters. Shot them today and they did great. Just need a little tuning.

 

[35WhelenAI]

Each rifle is a mechanical thing, no two are identical. Based on the combination of components and the firearm itself, there is a reason pressure limits were established and it's only prudent to stick within those and go get your animal.

 

[Harvey_NW]

Just need a little tuning.

Please document and post results.

 

[sanpedroranch]

I have moved away from this load anyways. Could not get the ABLR's to shoot as good as I was hoping. Going to move forward with the 175 elite hunters. Shot them today and they did great. Just need a little tuning.

I havent had very much success getting ABLR's to shoot better than 1-1.25 moa FWIW

 

[TxhunterPRC]

Please document and post results.

When I went and shot the seating depth test on the ABLR's yesterday, I had loaded up 6 175's as well just to see how they would shoot. Had 3 with 59.5g and 3 with 60.5g N560. Seated .04'' off the lands. 59.5g avg was 2842 fps and 60.5g avg was 2900 fps. Both groups averaged just over half an inch at .604'' and .569''. Still have some room to move up based on a calibrated GRT ladder, so I will be doing that next. Should be able to get out in the next few days.

 

[wind gypsy]

So you shrunk the freebore to match the distance to the lands you wanted and lost velocity? Or are you saying you shrunk it so much that it pushed the bullet back into the case? The first example doesn't make sense to me, the latter does.

Seating depth aside, less freebore means you're going to have more pressure with the same load. More volume behind bullet when it meets engraving pressure from lands = less pressure.

I've always wondered how the weatherby cartridges would shoot if they had a smaller freebore but didn't adjust the bullet seating depth or even maximized it keeping 10thou off the ogive of the bullet.

They wouldn't achieve the same velocities that has been a basis for marketing and their load data would have to be modified.

 

[Chris in TN]

My main hunting rifle since 2017(?) has been a .280AI. Yes, the AI case 'hides' pressure well due to lack of taper, and for goodness sake there's nothing in North America you can't kill cleanly with book-spec loads or less.

 

[204_ruger]

I am planning on trying N160 N550 and N560. In my Xbolt 280AI 1@8 26-inch barrel. Bullets i am going to try are Berger. 150gr and 168gr Classic Hunter bullets.

 

[cbuck516]

I am planning on trying N160 N550 and N560. In my Xbolt 280AI 1@8 26-inch barrel. Bullets i am going to try are Berger. 150gr and 168gr Classic Hunter bullets.

I wouldn’t skip over N555 if that is an option for you. I have found incredible accuracy with N555 in several -06 type cartridges. It’s not going to give you the fastest MV of the powders you listed, but its accuracy potential and temperature stability is really impressive. One of my hunting loads from last year included N555 in my 25-06AI and it consistently shot under 1/2MOA at 300-400 yards, sometimes under 1/4MOA. I’ve really struggled to get the same level of accuracy and low ES/SD out of N560.

 

[SloppyJ]

I wouldn’t skip over N555 if that is an option for you. I have found incredible accuracy with N555 in several -06 type cartridges. It’s not going to give you the fastest MV of the powders you listed, but its accuracy potential and temperature stability is really impressive. One of my hunting loads from last year included N555 in my 25-06AI and it consistently shot under 1/2MOA at 300-400 yards, sometimes under 1/4MOA. I’ve really struggled to get the same level of accuracy and low ES/SD out of N560.

That's really interesting! Tried it in my 6 creed with 95 NBTs and it got me some extra velocity but nothing worth stocking another powder for so I kept my H4350 loads for that. I didn't even think about it in 06 style cartridges. I picked up some N560 to try for my old model 70 in .270 I just grabbed and have a little N555 left that I can test out too.

 

[UnckleBob]

Each rifle is a mechanical thing, no two are identical. Based on the combination of components and the firearm itself, there is a reason pressure limits were established and it's only prudent to stick within those and go get your animal.

If someone really wants extra velocity that bad, they should (imho) just buy a 7RM or 7 PRC.

To me, the genius of the 280AI is recoil. You get all the performance you actually need without unnecessary recoil.

I can shoot light bullet to make mine perform more like a 270 or heavy bullets to perform the same tasks as a 7RM.

 

[2Stamp]

If someone really wants extra velocity that bad, they should (imho) just buy a 7RM or 7 PRC.

To me, the genius of the 280AI is recoil. You get all the performance you actually need without unnecessary recoil.

I can shoot light bullet to make mine perform more like a 270 or heavy bullets to perform the sane tasks as a 7RM.

^THIS.

The other benefit of the 280ai is the need to trim is greatly reduced. I think when it comes to the 280ai, there are a lot of guys really pushing them, so others see that as the norm "my gun should be getting that much". I do have a couple loads that rival the comparable sized bullet in the factory 7RM. But in when I load for it general it ends up where it ends up.