Case expansion in .284- Lapua v Peterson?

[ChrisNZ]

I have traditionally used (converted) 6.5-284 Lapua brass in my straight .284. The load I settled on was doing 2845 with 180 Hybrids/H4350 and all was fine.

I was recently forced to get some Peterson .284 brass as there was no Lapua available here in NZ. First discovery was they're much heavier brass and I needed to back off the load quite a bit, no problem. Tests with virgin brass felt a bit stiffer (on bolt lift) at 2830 but it was shooting fine. I've just shot that load in a regional comp using the same once-fired brass and while the gun was great on paper with seven successive Xs at 900, I had some serious extraction issues.

What experiences have others had in this regard?

thanks
ChrisNZ

 

[Loudenboomer]

Published loads of near max have been lifting and extracting good with Peterson brass with both H4831SC and IMR 4955. 180gr JLK Temps into the 80's.
What's your case head expansion?

 

[Willow]

I have traditionally used (converted) 6.5-284 Lapua brass in my straight .284. The load I settled on was doing 2845 with 180 Hybrids/H4350 and all was fine.

I was recently forced to get some Peterson .284 brass as there was no Lapua available here in NZ. First discovery was they're much heavier brass and I needed to back off the load quite a bit, no problem. Tests with virgin brass felt a bit stiffer (on bolt lift) at 2830 but it was shooting fine. I've just shot that load in a regional comp using the same once-fired brass and while the gun was great on paper with seven successive Xs at 900, I had some serious extraction issues.

What experiences have others had in this regard?

thanks
ChrisNZ

I use Peterson brass in a 284 Shehane in Aust. I run a mild load of ADI2213SC - 54.70gr - this yields 2815fps with Berger 184s - accuracy is excellent. What I have noticed with the brass, aside from primer pockets staying bloody tight (no complaints about that), is that I had to trim the Peterson brass after 3 firings despite the mild load and 35 degree shoulder. There seems to be some brass flow early on as I did have some heavier bolt lifts and after making sure I was happy with my shoulder bump (didn't want to overdo it as I lost an initial batch of cases after 13 firings due to oversizing causing case head separation). I checked the case length and found they had grown around 12-15 thou, so I trimmed, chamfered and deburred, threw one back in the rifle to check for bolt close - smooth as butter and no problems since.

I have not had issues after 1 firing though so maybe double check your shoulder bump. The other thing to consider is what brass your chamber was reamed for as Peterson runs considerably thicker in the neck than 6.5-284 Lapua - a loaded round for me measures .3165...I ordered a custom reamer knowing this. Most necked up 6.5 lap brass measures considerably thinner so you might have some tight fitting brass depending on the neck diameter...

 

[v63800]

I have traditionally used (converted) 6.5-284 Lapua brass in my straight .284. The load I settled on was doing 2845 with 180 Hybrids/H4350 and all was fine.

I was recently forced to get some Peterson .284 brass as there was no Lapua available here in NZ. First discovery was they're much heavier brass and I needed to back off the load quite a bit, no problem. Tests with virgin brass felt a bit stiffer (on bolt lift) at 2830 but it was shooting fine. I've just shot that load in a regional comp using the same once-fired brass and while the gun was great on paper with seven successive Xs at 900, I had some serious extraction issues.

What experiences have others had in this regard?

thanks
ChrisNZ

hi chris
how much did you back the load off

thanks phil

 

[One Eye Pete]

I run a 284 Shehane using both Lapua and Peterson 284 brass.
I normally run 184 Bergers and 180 Sierras using H4831SC or AA4350 (you have to use whatever you an get). My velocities are in the 2780 to 2850 range depending on the combination I'm using.
The Peterson brass normally seems to give me better SD and ES numbers however, after a few firings I have encountered "clickers" with the Peterson brass. This has not happened with the Lapua brass.
My JGS reamer print shows 0.5 in. at the 0.2 line. At the time I was using a Whidden bushing die.
I have since switched to a Shehane die from F Class Products (Blake Barrels in Phoenix AZ). So far on my second set of Peterson Brass using this die I have not experienced "clickers" but time will tell.
I spoke to a friend of mine who runs a straight 284 and he also mentioned encountering "clickers" with the Peterson brass. He solved his problem with a Redding small base die.
It seems to be that with the chamber I have, the Peterson brass either needs to be squeezed down more with the sizing die or the chamber needs to be opened up more at the 0.2 line. Since I do not know of anyone making a small base die for the Shehane I'm presently going to try modifying a Redding 284 small base tie to only squeeze the bottom of the Peterson Shehane cases. I really don't want to make a modification to my chamber as long as the Lapua brass is working OK.

 

[LCazador]

I run a 284 Shehane using both Lapua and Peterson 284 brass.
I normally run 184 Bergers and 180 Sierras using H4831SC or AA4350 (you have to use whatever you an get). My velocities are in the 2780 to 2850 range depending on the combination I'm using.
The Peterson brass normally seems to give me better SD and ES numbers however, after a few firings I have encountered "clickers" with the Peterson brass. This has not happened with the Lapua brass.
My JGS reamer print shows 0.5 in. at the 0.2 line. At the time I was using a Whidden bushing die.
I have since switched to a Shehane die from F Class Products (Blake Barrels in Phoenix AZ). So far on my second set of Peterson Brass using this die I have not experienced "clickers" but time will tell.
I spoke to a friend of mine who runs a straight 284 and he also mentioned encountering "clickers" with the Peterson brass. He solved his problem with a Redding small base die.
It seems to be that with the chamber I have, the Peterson brass either needs to be squeezed down more with the sizing die or the chamber needs to be opened up more at the 0.2 line. Since I do not know of anyone making a small base die for the Shehane I'm presently going to try modifying a Redding 284 small base tie to only squeeze the bottom of the Peterson Shehane cases. I really don't want to make a modification to my chamber as long as the Lapua brass is working OK.

I run the 284 Shehane and also started with 6.5/284 Lapua brass. I had Neil Jones make me a full length bushing die with bump bushings and a micrometer adjustment. Expensive but well worth it. I've never had an issue with the Peterson brass but I did have to make some adjustments to the die and also to my fireform load, too hot for new brass. After backing off on my fireform load and after adjusting the die everything works perfect. Neil can make a die to fit with a small base.

 

[ChrisNZ]

I appreciate all those comments.

To answer a few queries, I backed the load off 1.3gr from what the Lapua liked. My brass treatment is a Wilson FL bushing set to give 2 thou of shoulder movement and the cases are then neck mandreled using Imperial graphite. Seating is dead smooth and consistent, gun was holding 1/4min of elevation at 900 on the weekend at a comp. Resized brass goes into the chamber nicely.

I'm going round to my gunsmith buddy this afternoon and he's going to make me a custom shortened small base die. The FL die was moving the web area close to one thou which slightly more than the amount of base case expansion on firing.