Help! Short chamber in 280AI ???????

[JVS]

Had a 280AI built by a reputable shop called Sterling Precision. I went to shoot first batch of hand loads through it yesterday and they would not chamber. I could see rifling marks on the bullets. These are Barnes 140ttsx loaded to 3.33 COAL. The COAL that multiple loading manuals call for. Double and triple check measurements. All on point. I seated one of the bullets to 3.00 and it chambered with ease. I had some .284 162eldx at the house too so I loaded them up at 3.33 and they chambered no problem.
Looking for some incite.
Is this rifles chamber short?
Is this a Barnes bullet deal? I haven’t loaded many copper monolithic bullets in the past. They definitely have less of a taper to them compared to eldx.
Thoughts
Opinions please.

Thanks in advance Jordan

Edit: I called Sterling and they assure me this was chambered to SAMI spec 280ai.

 

[axeforce6]

Barnes listed load data for that bullet is 3.270 OAL. Sounds like you’re jamming the bullet into the lands. You should check what your OAL with a gauge.

 

[BrBa]

I would call Sterling and let them know. It all depends on the reamers they use, which may or may not be saami spec. Did you provide them with a dummy round (no primer or powder) loaded with your bullet at your desired c.o.a.l. when they chambered the barrel?

 

[BrBa]

Sorry, I should try reading. I see you called them already. I've heard some brands of reamers have very little freebore, while some have more. Unfortunately it sounds like you didn't specify a custom throat so they chamberer it standard for their reamer.

Barnes all copper bullets tend to run long for their weight, but I don't think that particular bullet should be touching lands with a c.o.a.l. at 3.33. Just my opinion.

 

[BrBa]

I was looking over my notes on a recent barrel replacement for my 6.5 Swede. I loaded 2 dummy rounds to the same c.b.t.o. length and asked the smith to throat it for 0.050" jump to the lands based on the lengths I provided, since mono bullets tend to like some jump. One round was a Barnes 127 gr LRX with a c.o.a.l. of 3.120". The other round was a 124 gr Hammer Hunter with a c.o.a.l. of 3.141", so there may be some truth here that your 140 gr Barnes just needs to be seated deeper. Your throat still seems short to me, but who knows.

 

[JVS]

I was looking over my notes on a recent barrel replacement for my 6.5 Swede. I loaded 2 dummy rounds to the same c.b.t.o. length and asked the smith to throat it for 0.050" jump to the lands based on the lengths I provided, since mono bullets tend to like some jump. One round was a Barnes 127 gr LRX with a c.o.a.l. of 3.120". The other round was a 124 gr Hammer Hunter with a c.o.a.l. of 3.141", so there may be some truth here that your 140 gr Barnes just needs to be seated deeper. Your throat still seems short to me, but who knows.

Thank you for your knowledgeable responses. I think you are on point. I am gonna run some rounds through it this wk and see how it shoots. Sterling Precision told me to bring it by and the will look it over as well but they are confident all is to spec.
It Just kind of freaks me out when I paid a pretty penny for a rifle and having an issue I never had before

 

[A382DWDZQ]

The COAL that multiple loading manuals call for.

This is not for the 140ttsx. I see that for a Nosler, and as a max COAL for the cartridge, but that is for a lead core bullet with a different profile. As @axeforce6 pointed out, Barnes says 3.27.


Here is an image of the 145LRX, 150TTSX, 162SST, 139SST, and 150 Scirocco with a line on where it meets the 6-27 Hornady comparator. With the SSTs, they are listed as 3.290 and 3.280 respectively. You can see how of the four, the TTSX has it ogive the furthest forward. The LRX is listed at 3.30. The 150TTSX also has a COAL of 3.270, so 140 is probably similar profile, just shorter. This is why measuring CBTO is very useful…and/or why it’s important to look at the COAL for the bullet.

 

[JVS]

This is not for the 140ttsx. I see that for a Nosler, and as a max COAL for the cartridge, but that is for a lead core bullet with a different profile. As @axeforce6 pointed out, Barnes says 3.27.

View attachment 622694
Here is an image of the 145LRX, 150TTSX, 162SST, 139SST, and 150 Scirocco with a line on where it meets the 6-27 Hornady comparator. With the SSTs, they are listed as 3.290 and 3.280 respectively. You can see how of the four, the TTSX has it ogive the furthest forward. The LRX is listed at 3.30. The 150TTSX also has a COAL of 3.270, so 140 is probably similar profile, just shorter. This is why measuring CBTO is very useful…and/or why it’s important to look at the COAL for the bullet.

Thank you! This goes to show there is always something to learn! Copper bullets are a different animal!

 

[A382DWDZQ]

ps, for me what it boils down to is that you can probably load LRXs and get better performance than the 140TTX, and load them a bit longer. I am pretty sure at the same velocity, the 145 outperforms the 140 once it gets out past like 500-600 yards.

 

[BrBa]

Also keep in mind monos should be loaded a bit deeper than a cup & core bullet with an identical ogive to avoid a potential pressure spike if loaded too close to the lands. Barnes recommends a min. 0.05" jump for their monos, so their recommended c.o.a.l. for the TTSX and LRX likely includes that 0.05" jump.

Their recommended c.o.a.l. for the 139 and 145 LRX is 3.30", while the 140 and 150 TTSX is 3.27". Only way to know how much jump those lengths will have to your lands is to measure.

 

[VAHunter01]

You should measure the CBTO first. If you don’t have the tools to do so, use a sharpie for each bullet you’re planning on using.

Very easy/simple to do, then you won’t be guessing.

 

[JVS]

You should measure the CBTO first. If you don’t have the tools to do so, use a sharpie for each bullet you’re planning on using.

Very easy/simple to do, then you won’t be guessing.

What does CBTO stand for?

 

[VAHunter01]

Cartridge Base To Ogive

 

[wind gypsy]

SAAMI 280 AI spec has a short throat.