Switched brass and now some rounds won't chamber

[Ryder Bohannon]

Decided to give the Lapua 6.5 creedmoor brass a try and today when I was at the range I ran into some chambering issues. Previously I have been using Hornady brass and have had no issues with chambering at all with any of my reloads. About 1 or 2 out of every 5 rounds of the lapua brass won't chamber in my gun. The Lapua brass straight out of the box will chamber just fine it's only after I've seated the bullet that it won't chamber. I measured all of the deminsions of the loaded rounds and everything comes out to spec. I thought it could possibly be that my bullet is hitting the lands so I kept seating the bullet deeper until it was past factory bullet depth (same bullet as factory load) and some of them still won't chamber. The bullets loaded in the Hornady brass with the same seating depth chamber just fine. The only difference here is that the Lapua brass is small rifle primer and the Hornady brass is large rifle primer.

I ran the lapua brass through .293 mandrel to expand the necks which probably was too big.

UPDATE - Neck OD seemed to be the problem, ran the cases through a bushing die and then seated the bullets and they chamber fine now.

 

[MikeMcCasland]

It's unlikely, but have you measured the loaded neck diameter of the Lapua? Is it larger than the loaded neck diameter of the Hornady?

It would also be uncommon, but not unheard of if the Lapua brass needed to have the shoulder pushed back some. How does it measure relative to a case fired out of your gun?

 

[Codiekfx400]

I would say neck diameter is the culprit if the Lapua unloaded brass chambers just fine. When you insert the bullet the neck diameter is going to grow.

 

[Ryder Bohannon]

It's unlikely, but have you measured the loaded neck diameter of the Lapua? Is it larger than the loaded neck diameter of the Hornady?

It would also be uncommon, but not unheard of if the Lapua brass needed to have the shoulder pushed back some. How does it measure relative to a case fired out of your gun?

The loaded lapua rounds are ~ 0.003" larger Neck OD than the Hornady

 

[Ryder Bohannon]

I would say neck diameter is the culprit if the Lapua unloaded brass chambers just fine. When you insert the bullet the neck diameter is going to grow.

Yeah I measured them and the neck OD on the lapua rounds grew about 0.003" after bullet seating

 

[MikeMcCasland]

The loaded lapua rounds are ~ 0.003" larger Neck OD than the Hornady

Is this a factory gun, or did you have something built and supply a reamer? It'd be strange for a SAAMI spec 6.5CM chamber to not be pretty generous in the necks.

I'm going to guess you don't have a neck turner, but if you do, you could turn .001 off a case that won't chamber to see if that does it. Either way, you'd typically want more chamber neck clearance than .001 in a 6.5CM.

What is the actual reading off the loaded Lapua neck?

 

[918v]

Compare your fired brass dimensions to your sized brass dimensions.

 

[Ryder Bohannon]

Is this a factory gun, or did you have something built and supply a reamer? It'd be strange for a SAAMI spec 6.5CM chamber to not be pretty generous in the necks.

I'm going to guess you don't have a neck turner, but if you do, you could turn .001 off a case that won't chamber to see if that does it. Either way, you'd typically want more chamber neck clearance than .001 in a 6.5CM.

What is the actual reading off the loaded Lapua neck?

Yep this is a factory rifle. Neck OD indeed seemed to be the problem, I ran them through a bushing die and they chamber fine now. Thank you.

 

[MikeMcCasland]

Yep this is a factory rifle. Neck OD indeed seemed to be the problem, I ran them through a bushing die and they chamber fine now. Thank you.

Glad it's working, but now I'm confused.

You were previously unable to chamber loaded rounds, so you ran them (loaded rounds) through a bushing die?

 

[Ryder Bohannon]

Glad it's working, but now I'm confused.

You were previously unable to chamber loaded rounds, so you ran them (loaded rounds) through a bushing die?

No, I apologize the loaded rounds still won't fit unless I really push the bolt in there still. Forgot to mention I ran the brass through die with a mandrel to expand the neck to .293 before loading the rounds. So I took the brass I put through the mandrel but haven't loaded yet and I ran them through a bushing die and then seated the bullets and chambered them and they fit fine now.

 

[MikeMcCasland]

That's still really odd; running cases through a bushing die shouldn't fix a neck thickness/clearance issue. The only way to fix a neck thickness problem is to neck turn.

You can measure loaded rounds that chamber vs. those that don't at the neck.

If that die is a FL bushing die, I'm betting you had some shoulders that were a little proud.

Either way, glad you found a fix.

 

[Ryder Bohannon]

That's still really odd; running cases through a bushing die shouldn't fix a neck thickness/clearance issue. The only way to fix a neck thickness problem is to neck turn.

You can measure loaded rounds that chamber vs. those that don't at the neck.

If that die is a FL bushing die, I'm betting you had some shoulders that were a little proud.

Either way, glad you found a fix.

Yes it was a Redding Type S Full Length Sizing Bushing Die

 

[kissmyrebelass]

.293 mandrel? Or 263 mandrel?

 

[Ryder Bohannon]

.293 mandrel? Or 263 mandrel?

.263 my apologies

 

[kissmyrebelass]

If a 263 mandrel causes the cartridge to not chamber, why wouldn't a 264 bullet cause the same problem? I don't think the mandrel is your problem.

 

[Ryder Bohannon]

If a 263 mandrel causes the cartridge to not chamber, why wouldn't a 264 bullet cause the same problem? I don't think the mandrel is your problem.

Probably because the mandrel only sizes the inside of the neck. My neck ODs were coming out at.293-295 and my gun seems to only chamber if its 291 or below

 

[supercorndogs]

Probably because the mandrel only sizes the inside of the neck. My neck ODs were coming out at.293-295 and my gun seems to only chamber if its 291 or below

If the case will hold a bullet, what size expander you use is not going to effect chambering because the final OD of your neck is going to be determined by how much the bullet expands it {I.E how much neck tension you have.} Your case grew .003 when you seated a bullet because you have .003 neck tension. That is a pretty normal range. Unless you made a false shoulder on the neck by over expanding the neck then sizing it back down part way until you get a slight crush fit on the false shoulder, like you would fire forming some cases. I think you have something else going on.

 

[MikeMcCasland]

The maximum neck thickness supported by a SAAMI min chamber 6.5 Creedmoor is .295....meaning yours should chamber in even the tightest of factory chambers. I would expect most factory guns to be around .297-.299...i.e. there SHOULD be lots of room.

What is the neck diameter of a fired piece of brass? That will effectively tell you the diameter of your neck. If that measurement is greater than .295 you'll know definitively it's not the neck holding you back.

I'm still betting this ends up with the shoulders being a little proud, because what you were saying earlier didn't make sense....about 'running new brass into a bushing die and it chambers now'.