280 AI project revisited

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stagpanther

New member
Taking a break from my faltering Mossberg rescue project--I decided to revisit my 280 AI project. First thing I did was try the LuthAR buttstock--which I hate on AR's but it turns out works very nicely with an MDT chassis. Nice to know that wasn't wasted money after all.

With a long heavy profile barrel the MDT LSS chassis--nice as it is--doesn't balance well unless I get things just right being very short in the fore end, and MDT does not make fore end extensions for their LSS series of chassis, so I decided to make my own. Not very pretty or tacticool, but if it supports without movement I'll be happy.

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Hmmm, I have all the parts except the barreled action (ordered a few months ago) for a 280AI build. XLR Magnesium chassis, TT Diamond Trigger, Hawkins Hybrid rings, XTRII 4-20, Total War Buttstock.
 
Nice specs there CO (too bad they don't do savage LA). My barrel is pretty long, thick and heavy, more of a match style barrel, so the short fore end on my standard LSS chassis makes it hard to prevent the rifle from pivoting. Your fore end looks quite a bit longer. 280 AI is a great cartridge; I like using Redding match bushing dies to load the cartridges, I have to keep an eye on shoulder position and neck tension. There's apparently subtle differences between Nosler's AI brass and others. I couldn't find any brass and was lucky to find a few boxes of exorbitantly priced factory ammo.
 
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stagpanther, I have some new Nosler/Peterson brass for my 280AI's. Both have rounded shoulders till fire formed. Once case is fired formed you get sharp shoulders.
 
I am a proud MDT chassis owner....my advice is get out while you can. Unless you are thrilled with the ergonomics and handling, I would consider bailing to a B&C stock.

I’m considering doing that, but I have to do my due diligence first with the rifle I have....then think next step.

The solution to the LSS is to buy an LSS-XL. The solution to the buttstock issues is their buttstock....or so it seems....not so modular, eh....

Frankly for what I have into mine, the ergos are too poor.

All-in-all, not bad, just not great chassis, IMO. Be forewarned, I get incredibly nit picky when I spend a lot on something. It is a personal failing.

I like your setup. What trigger are you running in it.
 
stagpanther, I have some new Nosler/Peterson brass for my 280AI's. Both have rounded shoulders till fire formed. Once case is fired formed you get sharp shoulders.
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I've already fired all the brass, but I find the brass is "sensitive" to uniformity. Some of the factory stuff will over-expand and needs the shoulder bumped back, after that I use a neck sizer but on occasion a warm load may require the head area be sized.
 
I am a proud MDT chassis owner....my advice is get out while you can. Unless you are thrilled with the ergonomics and handling, I would consider bailing to a B&C stock.

I’m considering doing that, but I have to do my due diligence first with the rifle I have....then think next step.

The solution to the LSS is to buy an LSS-XL. The solution to the buttstock issues is their buttstock....or so it seems....not so modular, eh....

Frankly for what I have into mine, the ergos are too poor.

All-in-all, not bad, just not great chassis, IMO. Be forewarned, I get incredibly nit picky when I spend a lot on something. It is a personal failing.

I like your setup. What trigger are you running in it.
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I did a build with a B&C stock, I'm not overly thrilled with it and IMO they are over-rated for what you get--no accounting for taste I guess. I know about the XL--I have a few--even those could benefit with some extension. Accutrigger is what this one uses. I had no donor receiver at the time I put this together--believe it or not I went out bought a savage axis and used it.:D
 
stagpanther, You post that, subtle differences between Nosler's AI brass and others. How so. Maybe you can answer that? I'm not trying to pick fight and I've mike both so we can compare. Fired might be different as gunsmith use Mason Reamer for my spec 280AI.
 
stagpanther, You post that, subtle differences between Nosler's AI brass and others. How so. Maybe you can answer that? I'm not trying to pick fight and I've mike both so we can compare. Fired might be different as gunsmith use Mason Reamer for my spec 280AI.
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I'll see if I can find it--I googled it myself.

The way I understand it, Nosler is the manufacturer who made it "official" SAAMI spec'd--so there was a slight shoulder difference between their submitted design and the original O.P. AI design. Probably won't make any difference with most stuff of recent manufacture--but there are still some cases (which I assume will fireform no problem) out there made to "original" specs. Might be worth checking to make sure the reamer used to chamber is recent SAAMI spec since there could conceivably be a headspace issue if using a mix of the two specs between chamber and case dimensions. I've found that 280 AI brass is quite "sensitive" to a good chamber fit, it'll let you know immediately if something's off, and why I like using a good set of match bushing dies when loading for it. I've also found that it's easy to keep in check and delivers great consistency in the "sweet spot."
 
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One of the benefits of all AIs is that once fire formed, the brass lasts a long time with minor inputs.

I am hoping to find Peterson brass when mine gets near completion.
 
One of the benefits of all AIs is that once fire formed, the brass lasts a long time with minor inputs.

I am hoping to find Peterson brass when mine gets near completion.
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I agree, I've only had 2 or 3 firings on the factory ammo brass so had to adjust, I've found it pays to get the cases sized to 'ideal" for your particular chamber and then pretty much leave it there with minimal neck sizing if possible.

Good luck finding brass, I haven't been able to, all I could do was buy a few remaining boxes of over-priced factory ammo to harvest brass from. However, Quality Cartridge saved my bacon when it came to 7mm STW brass, and he still lists 280 AI but I haven't checked what dimensions they conform to.

I'mm still working on the foreend extension--I've decided I'm going to have to use the M-Lok slots to attach it to the receiver so I'm waiting on the screws and lock nuts to come in. In the meantime I decided to spruce up the Luthar buttstock so that it looks a bit better.

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I can be patient as I don't even have the barreled action and the pro shop won't make it until they are caught up on production rifles. So I might be waiting a while. :)
 
I am a proud MDT chassis owner....my advice is get out while you can. Unless you are thrilled with the ergonomics and handling, I would consider bailing to a B&C stock.

I’m considering doing that, but I have to do my due diligence first with the rifle I have....then think next step.

The solution to the LSS is to buy an LSS-XL. The solution to the buttstock issues is their buttstock....or so it seems....not so modular, eh....

Frankly for what I have into mine, the ergos are too poor.

All-in-all, not bad, just not great chassis, IMO. Be forewarned, I get incredibly nit picky when I spend a lot on something. It is a personal failing.

I like your setup. What trigger are you running in it.
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Well Nathan--it looks like you fed me a large serving of crow, whether that was your intention or not.;) I recently bought a Howa 1500 barreled receiver in 300 win mag from Brownells and treated the bore with Tubbs final finish lapping bullets. I have a B&C stock that I originally bought, pillared and bedded for a weatherby vanguard in 300 wby mag but it never did shoot very well in it, and so it has sat in the safe for a while. I decided to slap the Howa 300 win mag receiver into it this morning just for grins, to make matters more challenging its blowing over 30 mph into a quartering headwind @ 184 yds where I shot this morning. I honestly was expecting lousy results, but instead got this. Go figure.:rolleyes:

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Barreled Premier Action from Bergara. I am doing the rest.
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I'm sure it will be worth the wait. I have several bergara made barrels and how found them to be fantastic quality for large production commercial grade manufacturing.:)
 
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