TxBowHunter409
Gold $$ Contributor
To give a back story. The gun is a Bergara B-14 6.5 Creedmoor. I ran several boxes of ammo through the gun to break in the barrel, get some fired brass to check headspace, and just to see overall how it shot with different factory ammo. I then loaded up a ladder test using some of the once fired Hornady brass just in testing. Found a couple of charge weights I wanted to explore more, so I loaded up some additional rounds using the same, now twice fired Hornady brass to test these charge weights. Shoulder measurements were pretty consistent on the once fired Hornady brass, as well as some of the other brass I tested including Sig and Federal with the majority falling in at 1.4850. There were a few that 1.4855 and even a 1.4860.
With that being said, I close to bump my brass to 1.4835. I figured if the headspace was actually 1.4850, it would give still give 0.0015's clearance. And in the chance that most of the brass just didn't have enough pressure to fully fire form with the exception of a small handful. And that the 1.4860 was closer to the actual headspace. It would still only put me out like 0.0025. All was fine and dandy through the next couple of loadings on the Hornady brass I had picked to use for testing because I had more of it.
Where the questions appear was when I decided to test VV N555 in the gun. I had always planned on using my normal Lapua brass anyways, so I figured I'd go ahead and get new Lapua brass to test this powder. Loaded up a ladder test on it in 0.3 increments like I normally do from maybe a half grain over the books starting charge to 0.6 over the maximum charge weight so I could get an idea of where pressure was starting. Yes I know new Lapua brass can camouflage pressure signs pretty good, so yes I was checking everything closely. Brass looked good on the two max loads. No ejector marks, primers looked good, no heavy bolt lift, etc. All good.
Found a charge that looked promising, so I was going to load up a couple dozen at this charge weight to do more testing. Specifically at 300 and 500 yards. But before I loaded these I decided to check the shoulders on the once fired Lapua brass. The first one I tested came in at 1.4875. So I started testing all the Lapua brass that I had shot and ended up with a variety of results. The vast majority came in at 1.4860, but there were several as you can see in the photo that came in at 1.4865 all the way thru 1.4875.
I know this is long, so bear with me. My question is, do you think the 1.4875 is likely closer to my actual headspace? Like these are likely those rounds that were at max load or above? It's obvious I need to adjust my initial headspace I was using, but how far? I'm thinking that if the 1.4875 is the actual headspace, then make a dummy round at 1.4855 and verify that it chambers well. What are y'all's thoughts?
And y'all don't beat me up too bad in the comments. I normally use the cheap brass to get my headspace on other guns because it seemed to just expand easier than Lapua after a firing. This is the first time that I've had once fired Lapua actually stretch more than the cheap stuff. And sorry for the long post.
With that being said, I close to bump my brass to 1.4835. I figured if the headspace was actually 1.4850, it would give still give 0.0015's clearance. And in the chance that most of the brass just didn't have enough pressure to fully fire form with the exception of a small handful. And that the 1.4860 was closer to the actual headspace. It would still only put me out like 0.0025. All was fine and dandy through the next couple of loadings on the Hornady brass I had picked to use for testing because I had more of it.
Where the questions appear was when I decided to test VV N555 in the gun. I had always planned on using my normal Lapua brass anyways, so I figured I'd go ahead and get new Lapua brass to test this powder. Loaded up a ladder test on it in 0.3 increments like I normally do from maybe a half grain over the books starting charge to 0.6 over the maximum charge weight so I could get an idea of where pressure was starting. Yes I know new Lapua brass can camouflage pressure signs pretty good, so yes I was checking everything closely. Brass looked good on the two max loads. No ejector marks, primers looked good, no heavy bolt lift, etc. All good.
Found a charge that looked promising, so I was going to load up a couple dozen at this charge weight to do more testing. Specifically at 300 and 500 yards. But before I loaded these I decided to check the shoulders on the once fired Lapua brass. The first one I tested came in at 1.4875. So I started testing all the Lapua brass that I had shot and ended up with a variety of results. The vast majority came in at 1.4860, but there were several as you can see in the photo that came in at 1.4865 all the way thru 1.4875.
I know this is long, so bear with me. My question is, do you think the 1.4875 is likely closer to my actual headspace? Like these are likely those rounds that were at max load or above? It's obvious I need to adjust my initial headspace I was using, but how far? I'm thinking that if the 1.4875 is the actual headspace, then make a dummy round at 1.4855 and verify that it chambers well. What are y'all's thoughts?
And y'all don't beat me up too bad in the comments. I normally use the cheap brass to get my headspace on other guns because it seemed to just expand easier than Lapua after a firing. This is the first time that I've had once fired Lapua actually stretch more than the cheap stuff. And sorry for the long post.
