Load development issues for a Cooper 223 with Lapua brass

[barrowsr]

HI,

I am working up loads for a new Cooper M21 in 223 using Lapua match brass and have found velocities to be 150-200 fps higher in my gun that in the Sierra manual for a given powder charge/bullet combo. I’m also getting primer cratering about 2 grains below published maximum. Anyone think the WW small rifle primers are too soft or is the firing pin fit too sloppy? I’m using H4895 and H335 both of which seem to fill the case well before I get to published maximum loads – which I have not yet. Any suggestions or comments would be most welcome.

Thanks,

Robin

 

[jonbearman]

I would think the chamber in the cooper is tighter than say a savage or whatever. The tighter the chamber leaves less room for expansion.Dial your loads down a bit and start over to find a node that delivers lower pressure with acceptable accuracy.

 

[hedditch]

Check your scale. I just put 27.6 grs of H335 in a Lapua 223 case and I didn't even get to the bottom of neck with the powder. That was the max load for a 52 grain bullet. You didn't mention what bullet you were using.
Dave

 

[barrowsr]

Hey thanks for the replies: I'm using 50 gr Sierra Blitz King and also 53 gr Sierra Match king. I'm maxing out on capacity with 26 grains of H4895. I can get about the same amount of H335 in the case - using a drop tube gets it just into the neck but velocity was very erratic with the H335.

 

[Keith Glasscock]

Definitely check the scale. I can get 27+ grains of H4895 in my cases and still easily seat a 50 grainer.

BTW, I don't use the win small rifle primers with full-house 223 rem loads. They tend to crater early. Try the CCI 450, it has a thicker cup and seems to "read" a little closer to what one would expect for a given load. The Federal 205M also does well for me at SAAMI 223 pressures (55k psi), but I haven't pushed them up to the CIP numbers (closer to 60k psi).

 

[Ohio1]

Try Wolf primers also, they have a tough one that won't crater easily!

Steve

 

[BradY]

Lapua cases are thicker than others and have slightly lower volume- I have found so its easier to get to a certain velocity than other cases but on the other hand, pressure can build up quicker. Try CCI BR4's or CCI 450's for a primer with a thicker cup. I run 26gr of benchmark in lapua cases with a 50gr nosler ballistic tip and CCI 450's in a long throat chamber and dont have any pressure problems. But work up loads to your own safe point.

 

[SmokinJoe]

Just to add a bit. I agree that the WSR primers are a bit on the soft side & CCI450, Fed205 or Wolf would be better choices. In the Wolf primers use either Small Rifle Magnum (a standard SR primer with thick cup) or the 223 Small Rifle (a true SR magnum primer). The Wolf nomenclature can be very confusing. If you want an education on Wolf primers, contact Widener's. I have several Coopers & have sent the bolts of all of them to Gre-Tan Rifles to have them bushed. This gives you the smaller .062" firing pin diameter used in BR actions & a much improved fit. Try it, I think you'll like it. Another powder to try in 223 with the bullets you are using would be H322, and give the new CFE223 a try, too.

 

[DOGCAPPER]

If you are jamming in the lands it will give you a pressure spike at or near max load...The book is a guide...Do what your rifle tells you...LT

 

[barrowsr]

Thanks for all the suggestions. My Redding balance beam scale checks out fine. The bullets are not touching the lands – I spent a lot of time making sure that didn’t happen. I’m definitely going to switch primers – probably CCI benchrest. I’m been prepping the rifle for a SD prairie dog shoot so that will be an opportunity to fire-form all the cases. Neck sizing some fired cases tightened up the groups. I’m using Redding Benchrest bushing dies and am really happy with them so far. If another brand of primer still gives me the cratering I’m definitely having the firing pin hole bushed. My standard deviation for 10 shot groups is ranging between 25 and 35 which I think is still too high – any thoughts?

Robin

 

[KevinThomas]

Don't think I've ever seen a single thread with more good advice on it than this one. All issues from the newer, softer, thin cupped WW primers to the case capacity question dealt with nicely and correctly. And most especially, the fact that reloading books are little more than guide lines, or reports on what they published expereinced with certain combinations. Remember, your mileage may vary!

Carry on, gents!

 

[ReedG]

My .223 load data shows loads from 24.0 to 26.0 of H335 with Sierra 53-gr. MHP. Hodgdon book shows 26.0 as "max" for that bullet. None of my loads show any pressure signs. Best groups in Tikka M595 Master Sporter are with 24.6 gr.

I have never used H4895.

I have a Cooper M21 in 6 PPC and it will not tolerate anything anywhere near a hot load. My BAT SV thrives on 30.4 gr. of 8208XBR with 65-gr. Bergers, but the Cooper at 29.4 has extremely hard extraction and bolt opening with "flat" primer. The Cooper does, however, shoot one-hole groups with 28.4 gr. of 8208XBR.

Not sure what you have done for load work-up, but I would start at the bottom of the Hodgdon recommendation and work up in 0.4-gr. increments and find what the little Cooper likes.

Hundreds of BR shooters use W-W primers. I use Fed. 205M's and I don't think the W-W's are any softer than them. In my world, ANY primer that is showing pressure signs is trying to tell you something.

I haven't tried 8208XBR in my .223 yet, but in over 8,000 rounds of .223 reloads I've yet to find anything that will outshoot Varget. Only problem is that most loads are compressed and take slow trickling to get them into Lapua cases. My factory rifles (Ruger M77 MkII, Savage M12, Tikka M595) have shot groups at 200-yds less than 1/2-in. with Varget and 40-gr. Vmax's and/or 52-gr. Bergers. That's all I expect from box-stock factory rigs.

Enjoy your Cooper, they are excellent rifles.

ReedG

 

[Glenn Powell]

My. 223 sako l461 seems to like 25g h335, lapua brass, 53g SMK, CCI BR, just have an issue with flyers! I did try some 55g blitz kings and they were 150 to 200 over listed velocity, called the manufacturer and the Guy said if I was not getting pressure signs with a load under Max I had a fast barrel. I don't know what my velocity's are with the SMK, my crono won't read them.

 

[SmokinJoe]

If you go to saubier.com , there is a sticky to Cooper's factory test loads for various calibers. You might get some interesting info there.

 

[FroggyOne2]

Try the Tula (Wolf) SRM primers, I believe you will see better numbeers with them over the CCI BR's.

 

[barrowsr]

"If you go to saubier.com , there is a sticky to Cooper's factory test loads for various calibers. You might get some interesting info there."

Smokin Joe;

I couldn't find the link you mentioned - but it sounds like good information.

Robin

 

[ReedG]

Here's the link ...

http://www.saubier.com/forum.html