New Starline brass stretch.

[65newloader]

Hope everyone is having a good morning. Got some new Starline brass in for the Grendel. I know, after testing and measurements, neither of my Grendels will not chamber a round with the shoulder at 1.2135". The Hornady comparator modified shell is at 1.211" and other rounds bumped to this measurement chamber fine. The new Starline brass is at 1.204". So, I loaded 20 with what I think was a light load of 25.5gr of XBR. After firing in the Sander Armory 13" barrel, the same Starline brass measured at 1.216". Checked it multiple times. So, I took one and bumped it back .002" and no go. Bumped back another .001" and no go. Bumped it back to the original Hornady modified case specs of 1.211" and good to go. Question now is how much can you bump back at one time? I think() maybe 2 bumps at least to get it back to where it should be and annealing before the first and second bump? I might take a new case and put an even less charge in just to see if it does not stretch so far. What ya'll think? It looks like my 20"BCA(I know, I know, but shooting sub-moa) and the Sanders will use the same shoulder measurement at 1.211". But, the free-bore area is shorter on the Sanders and I can't load as long. DRAT! Glad this is fun.

[riuma]

You're over thinking it. Size til it fits. Anneal when it needs it.~Riuma

[65newloader]

Just thinking .005" might be a little much at one time. Hmmm.

[centerfire]

Just thinking .005" might be a little much at one time. Hmmm.

Are you sure it's the shoulder preventing the sized case from chambering?

[NugginFutz]

Have you checked COL? I've not used new Starline before, but I have seen new Lake City exceed Max COL on the first firing.

[Mad Charlie]

My new Starline cases measure 1.510 in length, and 1.209 base to .350 datum. After they are fired in my chamber, before sizing, they are 1.220 +/- a thousandth or so. I size the shoulder back .003-.005 and roll with it. No issues.

[A5BLASTER]

Hope everyone is having a good morning. Got some new Starline brass in for the Grendel. I know, after testing and measurements, neither of my Grendels will not chamber a round with the shoulder at 1.2135". The Hornady comparator modified shell is at 1.211" and other rounds bumped to this measurement chamber fine. The new Starline brass is at 1.204". So, I loaded 20 with what I think was a light load of 25.5gr of XBR. After firing in the Sander Armory 13" barrel, the same Starline brass measured at 1.216". Checked it multiple times. So, I took one and bumped it back .002" and no go. Bumped back another .001" and no go. Bumped it back to the original Hornady modified case specs of 1.211" and good to go. Question now is how much can you bump back at one time? I think() maybe 2 bumps at least to get it back to where it should be and annealing before the first and second bump? I might take a new case and put an even less charge in just to see if it does not stretch so far. What ya'll think? It looks like my 20"BCA(I know, I know, but shooting sub-moa) and the Sanders will use the same shoulder measurement at 1.211". But, the free-bore area is shorter on the Sanders and I can't load as long. DRAT! Glad this is fun.

First off the measurement of the modified case. Throw that measurement away, it has zero influence on your measurements of your reloads.

Second if your cases won't fit your chamber with 3 to 4 thousands set back from the fired brass length. Your having issues getting correct measurements. 3 to 5 thousands is the range of set back you should look for and 3 thousands is more then enough in every barrel with every grendel brass I have tried. Your getting poor measurements are your getting inconsistent shoulder bumps from your die.

[65newloader]

New Starline measuring at 1.508" length and 1.204" to datum. I even measured a few at 1.201" to the datum. Just did a shot test will a low pressure round and got one to go out to 1.208" from 1.204" and another to 1.206". Hmmm.

[65newloader]

Went by the measurement of what did not fit the chamber of 1.2135. Bump it back to 1.211" and it all cycled. Every one without a problem. I am going to remove ejector pin on the bolts tomorrow and test to see what chambers and what does not. I checked every round on the shoulders when I made them and they fall, according to what I was getting, within .001" of 1.211". If I am looking at .003" to .005" set back from the fired brass, this would put me right near the 1.211", especially at .005". But, when is it too much? I will keep on investigating the specs I am getting. If I have to make a new modified case to go by, I can do that. Thanks for the suggestions.

[A5BLASTER]

Went by the measurement of what did not fit the chamber of 1.2315. Bump it back to 1.211" and it all cycled. Every one without a problem. I am going to remove ejector pin on the bolts tomorrow and test to see what chambers and what does not. I checked every round on the shoulders when I made them and they fall, according to what I was getting, within .001" of 1.211". If I am looking at .003" to .005" set back from the fired brass, this would put me right near the 1.211", especially at .005". But, when is it too much? I will keep on investigating the specs I am getting. If I have to make a new modified case to go by, I can do that. Thanks for the suggestions.

Again your modified cases length is of no importance to the issue and task at hand.

You only need 3 to 5 thousands bump on a fired case. So if your fired case is 1.2315 you need to be in the 1.228 to 1.226 range for proper shoulder bump.

3 thousands is min you should bump and 5 thousands is max you should bump. Anymore then 5 thousands and your over working your brass and shorting its lifespan. Any less then 3 thousands and you run the risk of not being bumped enough too fit the chamber and have easy extraction.

If your fired case us coming out at 1.231 and your bumping back too 1.211 your bumping it 20 thousands. That's way over working the brass. And that's a lot and I mean a lot of stretch.

Are you sure you have the correct bolt for your barrel? I haven't seen any of my barrels ever have that much stretch.

What tools are you useing to measure?

What die?
What press?

You dont need to remove the ejector pin, drop a empty sized case into the chamber and let the bcg run home, then try to extract it.

If it doesn't close, you need to bump the shoulder back, if it is ruff/hard to extract, bump the shoulder back.

Use the case with the longest measurement. Unlock your die and back it way out, then adjust it in slowly between each trybin the chamber till you find it chambers and extracts easily.

If your cases are at 1.231 to start you should find good clambering and extraction at 1.228 to 1.227. That's 3 to 4 thousands shoulder bump.

[tdbru]

NF,
you said "....I have seen new Lake City exceed Max COL on the first firing" is LC now making 6.5 Grendel ammo?
-tdbru

[65newloader]

I am going to check over everything tomorrow. I understand what you are saying. I have two mics. One digital and one manual. I got a fairly good Husky, but it screwed up. I will usually check my measurements 3 to 4 time to make sure they are right before bumping and after bumping. As stated, I did continue to bump back one until in chambered. Then, the readings were as stated, from what I got at that time. I have a RCBS Rock Crusher which still performs well. I have a set of Hornady Custom I just got in, so going to use those tomorrow. Before, it was a set of Lee, and got consistent reading for all the loads I mentioned(20 rnds and all within .001 at the shoulders and all cycled). I understand what fire form is suppose to do. My mistake above the brass was coming back, on one barrel, at 1.2135" not 1.231"(surprised you didn't catch that and ask and it has been edited). A few people are stating their Starline brass is coming in at around 1.510. If my measurements are correct, the lot I got in are around 1.504" with some near 1.5" so it makes since the datum is shorter, also.
I checked the bolts out today and both are type II spec. Will check back in tomorrow after I confirm everything.

[65newloader]

Good thing I am not in habit of beating my head against a brick wall. Bad mic and operator. Thanks for the tip AB! Got another one and checked through over half of the new Starline consistent on new brass at 1.509" average. That is consistent with the specs Starline has on their site. I tend to believe this one now. I will get another for a backup today and still confirm. So, .007" on the first firing to form to the 13" Sanders to 1.216". 1.216" will cycle still, so the .003" set back will be good. For the other barrel, though, I had to force the brass out. The 1.210" will chamber reliably. I will keep the brass from each barrel separate as the rounds for the 13" will not cycle in the 20" if I set them back .003". Maybe just say the hell with it and upgrade to the 24" Sanders as I really wanted to do since it will have the same reamer(probably)? Thanks for all the help and sorry for the confusion.

[NugginFutz]

NF,
you said "....I have seen new Lake City exceed Max COL on the first firing" is LC now making 6.5 Grendel ammo?
-tdbru

If only that were true! No, this was with 5.56 brass.

[65newloader]

Finally got the new calipers with dial. Starline is good to go. Got all measurements after first firing yesterday in both rifles. Shoulders after firing are 13" Sanders was 1.219" (stretched .010" +- .001)after firing and 20" BCA was 1.214"(stretched .003" +- .001"). So, will be bumping back each to chamber accordingly. Thanks again for all the help.