260 Rem case problems

[ballison]

Jim,
Which insert are you using on your bump gauge? I use the one in the video with the .400" insert, and get 1.625" on my 260 fired brass, and resize to 1.623". If you're using the same insert, and getting 1.566", that's a pretty big difference. SAAMI specs are 1.630" - 1.640". As for your charge, I am WAY above 39gr with a 130gr bullet and am fine with pressure. I don't think that's your issue. To get a case separation, it's almost always from over bumping the shoulder, but having a hard time nailing it down. I would hate to think it's specific to the Lapua brass.

 

[Jim Tisdale]

The body and insert are from Sinclair. Same as video. Insert marked 26A pkg 09-10260.
I'm not even touching the shoulder...I'm not FL sizing. I load a virgin round and end up with a case that is way longer and has a clear groove near the base.
It's almost like the chamber near the rear is too big coupled with the fact (possibility) the Lapua is too brittle.
Ive only tossed out the bad brass that isn't safe to shoot.
I'm also going to work a little more with the Federal.

 

[ballison]

It looks like you have the wrong insert for a 260, but that still doesn't explain the issue. The one you want for a 260 is the "308 family", #0910200. In my experience, the headspace on virgin Lapua brass is short, but it usually grows to fit the chamber in a firing or two, and I have never had separations. Maybe if your case isn't being supported at the base, the diameter is expanding too much and weakening the brass. Glock had this issue with some of their older .40 cals. Maybe someone here can shed some light on that variable.

Just for shitz & grins, measure the headspace of 5 fired cases, then measure the headspace of the same 5 cases AFTER resizing them. Even though you're only neck sizing, I'm curious if the headspace is changing.

 

[jlow]

It looks like you have the wrong insert for a 260, but that still doesn't explain the issue. The one you want for a 260 is the "308 family", #0910200. In my experience, the headspace on virgin Lapua brass is short, but it usually grows to fit the chamber in a firing or two, and I have never had separations. Maybe if your case isn't being supported at the base, the diameter is expanding too much and weakening the brass. Glock had this issue with some of their older .40 cals. Maybe someone here can shed some light on that variable.

Just for shitz & grins, measure the headspace of 5 fired cases, then measure the headspace of the same 5 cases AFTER resizing them. Even though you're only neck sizing, I'm curious if the headspace is changing.

I don’t think we (and the OP...) are talking about the same thing. First, charge weight means nothing without bullet information.... Second headspace with Hornady tool in my AI AT with a .260Rem barrel is also 1.624” so the OP must be using the wrong tool, it’s no wonder the bumps are way off and the heads are coming off....

 

[Milo 2.0]

The body and insert are from Sinclair. Same as video. Insert marked 26A pkg 09-10260.
I'm not even touching the shoulder...I'm not FL sizing. I load a virgin round and end up with a case that is way longer and has a clear groove near the base.
It's almost like the chamber near the rear is too big coupled with the fact (possibility) the Lapua is too brittle.
Ive only tossed out the bad brass that isn't safe to shoot.
I'm also going to work a little more with the Federal.

Take your caliper to the base area of case, if over .470", your chamber wallowed out.

 

[Scott Harris]

I've been using it to see how much the brass grows.
I wish I could post a pic. It would be SO much easier to show my problem.
The Lapua grows from 1.553 (virgin) to 1.566 after one (1) firing of 39 gr of H4350 and the base gets a very pronounced crack in it. Velocity is about 2760.
Same charge, bullet, seating; everything..the Federal grew from 1.159 to 1.562 with no visible problem on the base.
I understand 39 is too much for the Lapua. I'll start over with a lower charge.

what is the measurement after resizing???

 

[Scott Harris]

The body and insert are from Sinclair. Same as video. Insert marked 26A pkg 09-10260.
I'm not even touching the shoulder...I'm not FL sizing. I load a virgin round and end up with a case that is way longer and has a clear groove near the base.
It's almost like the chamber near the rear is too big coupled with the fact (possibility) the Lapua is too brittle.
Ive only tossed out the bad brass that isn't safe to shoot.
I'm also going to work a little more with the Federal.

26A is the wrong insert, you should be using 20A....20 degree shoulder.

749-011-477WS
Sinclair Bump Gage Insert, 308 Family, 20°
Mfr Part: 0910200

 

[Jim Tisdale]

Ok. I was using the wrong insert. I have the 20A and I'll re check them tomorrow as well as the area near the base. I'm pretty sure the fired cases measure more than that though.

 

[Scott Harris]

Ok. I was using the wrong insert. I have the 20A and I'll re check them tomorrow as well as the area near the base. I'm pretty sure the fired cases measure more than that though.

It's always possible that the Savage lathe was not in adjustment and created an overly large base. But, I'm just trying to figure out how much you have been bumping the shoulders during resizing. To figure this out, we need an accurate measurement on fired and resized cases with the bump gage.

 

[Jim Tisdale]

Jim,
Which insert are you using on your bump gauge? I use the one in the video with the .400" insert, and get 1.625" on my 260 fired brass, and resize to 1.623". If you're using the same insert, and getting 1.566", that's a pretty big difference. SAAMI specs are 1.630" - 1.640". As for your charge, I am WAY above 39gr with a 130gr bullet and am fine with pressure. I don't think that's your issue. To get a case separation, it's almost always from over bumping the shoulder, but having a hard time nailing it down. I would hate to think it's specific to the Lapua brass.

I've used the wrong terminology. I'm measuring from the base to the shoulder, NOT a datum point.
I'm using the Sinclair body and (now) the correct 20A insert with the same results.

 

[Zero333]

We just want to know the measurement of the brass with the D .400 (Hornady) / 20a (Sinclair) insert after it's been fired, and after it's been sized.

With the correct insert the fired brass should measure anywhere between 1.619" to 1.624"...

My 243/260/308 go-gauge measures 1.619" with the headspace comparator. It used to measure 1.620" when the insert was still new, but after using it thousands of times it must of worn down one thou or so.

 

[Jim Tisdale]

Using the correct (this time) Sinclair 20A insert (this, according to what I read, will provide a different measurement than the Hornady .400) I think I would benefit from the .400 over the 20A.
New 1.1552
1 fired 1.561
Neck sized 1.561
Area near base .470-.471

 

[jlow]

I think there is still something terribly wrong with either your tool or method. I just went and measured five of my new unfired Lapua .260 Rem brass with my Hornady headspace gauge - all between 1.6190 and 1.6200 - average 1.6195". Exactly the same as Zero333. Your number 1.1552" is 0.46" different i.e. 1/2 inch.... The Sinclair could sit slightly different on the brass's shoulder but no possible way 1/2" different. I would suggest going back and checking the user manuals. Are you sure you are using .260Rem brass? It sounds silly to ask but you are so far off....

The other thing I can point out is 0.406" between your new and once fired - is that a typo? Even if your new is 1.552, it's still 68 thousands short...

 

[6MMsteve]

is this a new gun , have you looked at your chamber with a flashlight to see anything odd looking

 

[Shaggy357]

I've been using it to see how much the brass grows.
I wish I could post a pic. It would be SO much easier to show my problem.
The Lapua grows from 1.553 (virgin) to 1.566 after one (1) firing of 39 gr of H4350 and the base gets a very pronounced crack in it. Velocity is about 2760.
Same charge, bullet, seating; everything..the Federal grew from 1.159 to 1.562 with no visible problem on the base.
I understand 39 is too much for the Lapua. I'll start over with a lower charge.

I will assume the 1.159 should be 1.559. Federal is .006" longer to begin with. Federal grows .003" on firing. Lapua grows .013 on firing. That .010" difference in growth can easily be remedied with a false shoulder or bullet seating depth. Lapua growing .004" more than the Federal tells me it is already softer. 39.0gr of H4350 is not a hot load. It is well below my load with a 142 cup and core home grown that is similar to the 142 Match Kings. If it were me, I would buy a new batch of Lapua brass, open the necks with .284 expander, then slowly adjust my sizing die down until that new case fits my chamber just enough to allow the bolt to close. I would load up my 39.0 gr of H4350 and go shoot the load. I would set the sizing die for the next few reloads to just touch the shoulder. Why move the shoulder at all if the bolt closes?

The smith who gave you the good to go by checking your head space, did he happen to try a .308 "Field" gage in the chamber? Even if your chamber is oversize, if you size your brass to fit your gun, you should have no worries.

My advice from the old goats home.

Steve

 

[Scott Harris]

Using the correct (this time) Sinclair 20A insert (this, according to what I read, will provide a different measurement than the Hornady .400) I think I would benefit from the .400 over the 20A.
New 1.1552
1 fired 1.561
Neck sized 1.561
Area near base .470-.471

Those numbers are perfectly normal. Your fired case is growing .009 from new, same as I've always seen with Lapua brass. .470-.471 at base is also normal.

Neck sized??? You can't bump the shoulder with a neck sizer, are you using a full-length die?

 

['Freak]

I think there is still something terribly wrong with either your tool or method. I just went and measured five of my new unfired Lapua .260 Rem brass with my Hornady headspace gauge - all between 1.6190 and 1.6200 - average 1.6195". Exactly the same as Zero333. Your number 1.1552" is 0.46" different i.e. 1/2 inch.... The Sinclair could sit slightly different on the brass's shoulder but no possible way 1/2" different. I would suggest going back and checking the user manuals. Are you sure you are using .260Rem brass? It sounds silly to ask but you are so far off....

The other thing I can point out is 0.406" between your new and once fired - is that a typo? Even if your new is 1.552, it's still 68 thousands short...

Sinclair’s insert is cut with a taper same as the chamber shoulder at a particular shoulder angle, not like Hornady’s insert that’s an orifice bored the same ID as the diameter at the shoulder datum line.

 

[jlow]

Sinclair’s insert is cut with a taper same as the chamber shoulder at a particular shoulder angle, not like Hornady’s insert that’s an orifice bored the same ID as the diameter at the shoulder datum line.

OK, thanks! I had guess that was the case but the typo didn’t help. However, honestly we still don’t know what the new brass headspace is. OP said 1.1552, I guessed 1.552, but Shaggy357 guess 1.559 but I don’t know how he came up with that number.

 

['Freak]

OK, thanks! I had guess that was the case but the typo didn’t help. However, honestly we still don’t know what the new brass headspace is. OP said 1.1552, I guessed 1.552, but Shaggy357 guess 1.559 but I don’t know how he came up with that number.

They’re to me simply reference measurements for the comparison of case head to shoulder lengths. The number I get measuring a case using my combination of instruments and gadgets isn’t likely to be exactly the same number you’ll get using your stuff to measure that very same case. I don’t bother to even look up the SAAMI spec head to shoulder datum length; don’t really matter for anything other than satisfying a curiosity.

What to me does matter is finding at what particular case head to shoulder length reference number obtained using my case measuring thingamajigs, it is when that case has been manipulated enough that it’s reached the point of completely filling the bolt face to shoulder length of the chamber, not any longer and not any shorter.

Once I have that number, and write everything down, and especially if I mark it on and save that case, I don’t have to be bothered with pulling the firing pin and ejector and trying to find that chamber’s length again.

Once I have that particular “this chamber’s full up” case length reference number, I can compare it to the number I get when measuring any other case in the same manner with the same stuff and I’ll know how much that case is any shorter or longer than the rifle’s bolt face to chamber shoulder length.

Screw SAAMI lengths. I can bump a case shoulder to make it a thousandth or two shorter than the chamber’s length, and not just bumped a thousandth or two shorter than some once or twice fired case but still dunno exactly how much space that shoulder bump is gonna end up leaving betwixt bolt face and case head in that chamber.

 

[jlow]

They’re to me simply reference measurements for the comparison of case head to shoulder lengths. The number I get measuring a case using my combination of instruments and gadgets isn’t likely to be exactly the same number you’ll get using your stuff to measure that very same case. I don’t bother to even look up the SAAMI spec head to shoulder datum length; don’t really matter for anything other than satisfying a curiosity.

What to me does matter is finding at what particular case head to shoulder length reference number obtained using my case measuring thingamajigs, it is when that case has been manipulated enough that it’s reached the point of completely filling the bolt face to shoulder length of the chamber, not any longer and not any shorter.

Once I have that number, and write everything down, and especially if I mark it on and save that case, I don’t have to be bothered with pulling the firing pin and ejector and trying to find that chamber’s length again.

Once I have that particular “this chamber’s full up” case length reference number, I can compare it to the number I get when measuring any other case in the same manner with the same stuff and I’ll know how much that case is any shorter or longer than the rifle’s bolt face to chamber shoulder length.

Screw SAAMI lengths. I can bump a case shoulder to make it a thousandth or two shorter than the chamber’s length, and not just bumped a thousandth or two shorter than some once or twice fired case but still dunno exactly how much space that shoulder bump is gonna end up leaving betwixt bolt face and case head in that chamber.

I don’t have any problem with the numbers being different, I mentioned in my original post “The Sinclair could sit slightly different on the brass's shoulder but no possible way 1/2" different.” My problem is with the ACTUAL numbers like “New 1.1552” and people guessing that it is “1.559”. Regardless of what you say, there clearly IS a problem or there would not be any case head separation.

The OP was using the wrong tool, giving us numbers that does not make sense, people somehow coming up with new numbers. This to me has the making of one big “Cluster Fu**”. Why then in addition go on a rant about SAMMI….

I can understand why mistakes can be made - we all make them, but somewhere along the line, we have to be more careful. In the end, reloading IS DANGEROUS and without care bad things can happen.