AI AX Chamber Issues

[LRJammer]

I have a new AI AX in 260 that I got from Mile High. On my first outing with the rifle, I used a load that I have used in my two other 260s. Winchester brass, 42.5 Gr H4350 with a 140 SMK. The bolt was tight to close on rounds and hard to extract. On some, I had to bang on the bolt handle with the palm of my hand to get the case to extract. There are no high pressure signs. This load as been very reliable in both of the other rifles. Both are custom barrels, not factory chambers (one a GAP chambered Bartlein, and one a Criterion.) I thought this chamber might be a little tighter than the others so I adjusted my sizing die (full length Redding Type S bushing die) down to size the case down a bit more. No such luck, the bolt still closes hard. A Wilson case guage shows that the sizing die adjustment took the sizing down to the minimum limit.

I noticed that the brass is showing fairly heavy drag marks on the back half of shiny freshly tumbled brass. All of the evidence suggests that the chamber diameter at the base is a bit too small. Anyone have any experiences like this and/or have any suggestions?

Thanks in advance for any help anyone may be able to offer. This is my first AI and I am extremely impressed with the quality (outside this one issues), workmanship, and accuracy of this rifle.

 

[redneckbmxer24]

Give AINA a call, they should be able to help you.

 

[sib1948]

Give AINA a call, they should be able to help you.

Agree. Call AINA and they should take care of you in short order.

 

[DAVETOOLEY]

Call me I chambered the barrel. 704-864-7525
One question- is this new brass or recycled from your other rifles?

 

[LRJammer]

Call me I chambered the barrel. 704-864-7525
One question- is this new brass or recycled from your other rifles?

Just spoke with Dave. I am going to try loads with virgin brass and see if that takes care of the issue.

 

[HodgdonExtreme]

Just spoke with Dave. I am going to try loads with virgin brass and see if that takes care of the issue.

What you've been experiencing is not at all uncommon when you use brass fired from a larger (diametrically) chamber in a smaller one. This is not at all indicative of any problem with either rifle - simply a small difference in chamber dimensions.

If you've got a lot of fired brass you'd like to keep in service for the new rifle, a small base or Forster "national match" die will allow you to pinch the body down a little extra to "reclaim" the brass for use in the new chamber.

Note: You won't necessarily need to go full throttle with the SB/NM die - You'll only need to run the brass deep enough to size the body enough it fits into the new chamber nicely. Thus, the SB/NM die will only be used as a body die. Your standard FLS die can be used for bumping the shoulder appropriately.

 

[DAVETOOLEY]

What you've been experiencing is not at all uncommon when you use brass fired from a larger (diametrically) chamber in a smaller one. This is not at all indicative of any problem with either rifle - simply a small difference in chamber dimensions.

If you've got a lot of fired brass you'd like to keep in service for the new rifle, a small base or Forster "national match" die will allow you to pinch the body down a little extra to "reclaim" the brass for use in the new chamber.

Note: You won't necessarily need to go full throttle with the SB/NM die - You'll only need to run the brass deep enough to size the body enough it fits into the new chamber nicely. Thus, the SB/NM die will only be used as a body die. Your standard FLS die can be used for bumping the shoulder appropriately.

This works with once fired brass. If it's been shot several times it loses it's elasticity and work hardens at the larger diameter. Sizing will get it back in the chamber but upon firing it goes back to its old size making it difficult to extract. That's why neck sizing isn't used much anymore. Once tight always tight.

 

[LRJammer]

Just an update. I got some new brass and that has taken care of the issue.

 

[sib1948]

Great to hear. Will help me to avoid that issue with my incoming AI AXMC 260 &308.