Pressure issues, need some help

[DLT]

Weird thing is, unless I misread the thread, it worked fine in another rifle/cartridge.
So, I'm thinking he either messed up and dumped some different powder in this container between now and then, or he's got some primers that aren't all the same. Or he's got mixed brass. And the velocity wasn't off much between fine and a blown primer/stuck bolt?
There's only so many possibilities.

I went back and looked at my messages with another member here working on the 22creedmoor and it was hot to the charge weight. I had forgot till I went back and looked and exactly what I tested. I can assure you the powder that’s in there came in there from vv, all my large primers came out of a 1500 fiocchi pack and my small 450s came out of a 1000 pack I do not mix primers. Nor do I mix brass.

 

[DShortt]

I went back and looked at my messages with another member here working on the 22creedmoor and it was hot to the charge weight. I had forgot till I went back and looked and exactly what I tested. I can assure you the powder that’s in there came in there from vv, all my large primers came out of a 1500 fiocchi pack and my small 450s came out of a 1000 pack I do not mix primers. Nor do I mix brass.

Huh. This is weird.
Unless you just got into this brick of primers, I have no further suggestions.
I will ask that if you determine the cause, please post it. Something is getting overlooked somewhere. But I don't know what it is. I'm very curious to know what.

 

[DLT]

Huh. This is weird.

It’s weird and not explainable to me yet. I came here like I do with all my problems because this group has ages more time and experience

 

[243winxb]

They used Lapua small rifle primer brass

What brass was used with the N160, over pressue rounds? Your Primer used?
i may have missed it.

Tests of H4831 have shown,, some powder lots are different by +/- 5% This can be a total of 10%. slowest to fastest.
N160 may have issues?

Common reasons for over pressure are.
1.Less Brass volume.
2. Bullet bearing surface extra long.
3. Difference in powder lots.
4. 2nd pressure spike from poor ignition of powder. (Small primer usage, when data requires LR primers.(guessing on this one).

 

[DLT]

What brass was used with the N160, over pressue rounds?
i may have missed it.

Tests of H4831 have shown,, some powder lots are different by +/- 5% This can be a total of 10%. slowest to fastest.
N160 may have issues?

Common reasons for over pressure are.
1.Less Brass volume.
2. Bullet bearing surface extra long.
3. Difference in powder lots.
4. 2nd pressure spike from poor ignition of powder. (Small primer usage, when data requires LR primers.

I was using sig sauer large rifle primer to begin with. Then went with Lapua small rifle brass

 

[SKWERLZ]

No idea as they don’t list what primer or case. Only gives small primer and 26” barrel. I can’t be the only fool who has tried n160 in a 6creedmoor

Exactly, so you assume it’s different components and work up accordingly.
Honestly that’s pretty fast powder for 6manbun.
Fast powders In cases that like slower powders hit pressure suddenly.

N165 is a better option as is N565.

 

[DLT]

Exactly, so you assume it’s different components and work up accordingly.
Honestly that’s pretty fast powder for 6manbun.
Fast powders In cases that like slower powders hit pressure suddenly.

N165 is a better option as is N565.

I know this. I just wanted to try it ! N160 is “supposed” to be slower than H4350. Seems like we’re all learning that’s not the case or I have powder problem of some kind. Don’t put me in some class with the manbun crowd please

 

[243winxb]

Looking at N160 load data, with bullets close to rhe same weight ,shows a wide spread of powder used.

This is a direct result of bullet construction & bearing surface. Sierrs uses 4 different lead core hardness for their bullets.

But Sierra load data used less powder then a 44.1 gr, Berger 105 gr VLD Target.

The mystery remains unsolved.

 

[DLT]

Looking at N160 load data, with bullets close to rhe same weight ,shows a wide spread of powder used.

This is a direct result of bullet construction & bearing surface. Sierrs uses 4 different lead core hardness for their bullets.

But Sierra load data used less powder then a 44.1 gr, Berger 105 gr VLD Target.

The mystery remains unsolved.

It does vary wildly their data , I noticed it. Still assumed I was plenty low enough.

 

[SKWERLZ]

I know this. I just wanted to try it ! N160 is “supposed” to be slower than H4350. Seems like we’re all learning that’s not the case or I have powder problem of some kind

I consider h4350 too fast for 6manbun as well.
H4831 is a great starting place unless you’re running really light bullets then h4350 can work.
N165 is famous for being easy on barrels and friendly.

 

[DLT]

I consider h4350 too fast for 6manbun as well.
H4831 is a great starting place unless you’re running really light bullets then h4350 can work.
N165 is famous for being easy on barrels and friendly.

The way 160 acted im uneasy about 165. Different powder is different powder but damn

 

[243winxb]

https://www.adiworldclass.com.au/powder-equivalents/

Burn rates compared

The chart shows N160 & N560 being within 5% of each other. NO WAY when looking at data.

Note N540 powder charge difference.

 

[SKWERLZ]

The way 160 acted im uneasy about 165. Different powder is different powder but damn

165 is considerably slower and common in 7mm short mags with 180’s.
160 is more appropriate for 7-08 and 260’s.

 

[DLT]

165 is considerably slower and common in 7mm short mags with 180’s.
160 is more appropriate for 7-08 and 260’s.

It might be, I know this barrel is in the short rows so much so I probably won’t even be buying anything new for it

 

[LCazador]

I was using sig sauer large rifle primer to begin with. Then went with Lapua small rifle brass

I don't think it's a primer, powder, or brass issue. Something is amiss with your chamber vs. brass dimension. When you have expansion of .030" on the case head something is drastically wrong. You confirmed that dimension. Excessive headspace is the culprit I think. Fireform some new brass and make a note of case head dimension, case length, and shoulder diameter. Fireform using a load that starts at least 10 percent below the starting load not the maximum load. Once your new brass is fireformed take note of the same dimensions that you started with. Use new brass only to find your chamber dimension.

 

[DLT]

I don't think it's a primer, powder, or brass issue. Something is amiss with your chamber vs. brass dimension. When you have expansion of .030" on the case head something is drastically wrong. You confirmed that dimension. Excessive headspace is the culprit I think. Fireform some new brass and make a note of case head dimension, case length, and shoulder diameter. Fireform using a load that starts at least 10 percent below the starting load not the maximum load. Once your new brass is fireformed take note of the same dimensions that you started with. Use new brass only to find your chamber dimension.

If or when I mess with it again I will do this. Thank you

 

[Doom]

The issues here aren't explained by differences in case volume or primer size or selection. Blowing a primer and 0.030" expansion is extremely high pressures, probably pushing proof pressures. Either the bore/bullet diameters are at play or the powder is not acting like N160. I would doubt bullet/bore diameter is an issue so it is likely powder. I would question where the powder came from, how old the powder is (VV is dated on the container), and would discuss this issue with Capstone (VV distributer).

Under no circumstances would I use that powder in any more reloads.

The case is Lapua and the bullet was 107 SMK. See the 2020 Reloading manual below.

https://d7rh5s3nxmpy4.cloudfront.net/CMP755/files/Vihtavuori_Reloading_Guide_2020_ENG_www.pdf

 

[DLT]

The issues here aren't explained by differences in case volume or primer size or selection. Blowing a primer and 0.030" expansion is extremely high pressures, probably pushing proof pressures. Either the bore/bullet diameters are at play or the powder is not acting like N160. I would doubt bullet/bore diameter is an issue so it is likely powder. I would question where the powder came from, how old the powder is (VV is dated on the container), and would discuss this issue with Capstone (VV distributer).

Under no circumstances would I use that powder in any more reloads.

The case is Lapua and the bullet was 107 SMK. See the 2020 Reloading manual below.

https://d7rh5s3nxmpy4.cloudfront.net/CMP755/files/Vihtavuori_Reloading_Guide_2020_ENG_www.pdf

I will look this evening for the date code. the powder was purchased late May from a pretty big gun shop in Charlotte. No doubt it has the new vv label on it. Don’t really know how long it’s been since they changed it though. Thanks for that compilation of their data. No chance the bullet or bore diameter is possibly off.

 

[dellet]

Yes. It’s just hard for me to believe the tiny things that I had off, caused that much destruction.

Ultimately I think the powder might be a big part of the issue, plenty of similar complaints from the Internet. Plenty of success also.
You can’t trust published data to notify you of a compressed load, or a COAL that’s not a jam. That’s just a simple fact. Just like you can’t trust a burn rate chart to keep you from blowing things up. N160 is listed as much slower that H4350, yet it takes the same basic charge weight.

One factor that is huge and hasn’t been answered is loaded length, and if you’re 100% sure the bullet is not jamming into the lands.

When you look at the VV load data, the SMK is loaded almost .200” shorter. Even tho bullet length is comparable to the Berger bullets listed. Either the bullet has a very short bearing surface, or it hits the lands very early.

 

[DLT]

Ultimately I think the powder might be a big part of the issue, plenty of similar complaints from the Internet. Plenty of success also.
You can’t trust published data to notify you of a compressed load, or a COAL that’s not a jam. That’s just a simple fact. Just like you can’t trust a burn rate chart to keep you from blowing things up. N160 is listed as much slower that H4350, yet it takes the same basic charge weight.

One factor that is huge and hasn’t been answered is loaded length, and if you’re 100% sure the bullet is not jamming into the lands.

When you look at the VV load data, the SMK is loaded almost .200” shorter. Even tho bullet length is comparable to the Berger bullets listed. Either the bullet has a very short bearing surface, or it hits the lands very early.

I will measure when I get back into the reloading room. The throat is past gone in this rifle. I know the 107 smk is seated maybe 2/3 into the neck and doesn’t touch the lands