Cci 450 vs 7.5 toughness of cup

[Majday]

I know many have done extensive shooting with varying makes of primers. I have seen the chart about cup thickness.

The 450 is .025 as well as the 7.5 and BR4

My question, is the 450 "tougher" than the 7.5 or BR4? Does the 450 take more pressure to show than the 7.5 or BR4?

I have a ruger mk2 20p and cratering is similar in the 7.5 and BR4. I dont have hard bolt lift or swipes on case head I know just try the 450 to see how the gun shoots them, but I thought I'd ask first.

Edit: also I tried to find info on the fed205mar but wasn't finding much for thickness. I would assume they are the same at .025?

Thanks for any information.

Jameson

 

[GLShooter]

I really don't see any changes from one to the other other than group size and the variation in velocities. The later issue is not hard and fast. Various powders yield some faster and some slower result's.

 

[Bill Norris]

I know many have done extensive shooting with varying makes of primers. I have seen the chart about cup thickness.

The 450 is .025 as well as the 7.5 and BR4

My question, is the 450 "tougher" than the 7.5 or BR4? Does the 450 take more pressure to show than the 7.5 or BR4?

I have a ruger mk2 20p and cratering is similar in the 7.5 and BR4. I dont have hard bolt lift or swipes on case head I know just try the 450 to see how the gun shoots them, but I thought I'd ask first.

Edit: also I tried to find info on the fed205mar but wasn't finding much for thickness. I would assume they are the same at .025?

Thanks for any information.

J

Normally Fed primers have softer cups than other primers but not really sure about the 205MAR.

 

[Coyotefurharvester]

I've been running the 205MAR in my 20p AR because I didn't want to use my Rem 7.5 and I run a bit more headspace in the AR brass during the winter(load, unload unfired rounds easily). The 205's have worked very well, no backing out or flattening, repeatable accuracy.

 

[Mike Samer]

Prior to having the firing pin bushed on my Model 70 .308, I found 450s and BR4s were more resistant to blanking than the Rem 7 1/2s.

 

[SmokinJoe]

FYI, the Fed 205 is .021" thick.

 

[perazziguy]

Prior to having the firing pin bushed on my Model 70 .308, I found 450s and BR4s were more resistant to blanking than the Rem 7 1/2s.

+1 for having the firing pin bushed.

 

[HTSmith]

I have found the Rem 7.5's a little more resistant to "puckering" in my factory action. I've never tried the Federal 205's in my factory action, but they hold up to crazy loads in my 6PPC. Never tried the BR4's. Maybe the cup thickness isn't the whole story?

 

[searcher]

The BR4's and the Federal 205's can both handle a lot of pressure. The 7 1/2's are tough enough that, if you are piercing them, I'd be inclined to back off the load as the cure, as opposed to a "fix" with another primer. I hate bolt face damage.

 

[shoot4fun]

Here is a chart that I have found to be closest to valid. As in many things produced in bulk there may be differences lo to lot.
As far as the difference in hardness between the 450 and 7.5 I would want the one that produces the most consistent chronograph numbers and best on-target accuracy.
When I have tested Federal GM Math, CCI400 and 450 and RP7 1/2 in different calibers one has always been best (just not always the same one). Not sure if you've given any thought to the difference in pressure produced by different brands of primers in same load. Maybe that is causing your cratering issue?

 

[Majday]

This is all good information. Thank you. I haven't "tested" one brand vs another as I don't always have much time. I've been lucky to find a load with my 20p that is acceptable for me with whatever bullet I've tried.

I have had the thought of maybe needing to look into getting the pin bushed. I've had no piercing on any but cratering when I'm pushing it a little bit (as far as I can tell) trying for the most velo. No head swipes or hard extraction. This makes me think I can get a little more with the pin being the limiting factor.

 

[SmokinJoe]

Here is a chart that I have found to be closest to valid. As in many things produced in bulk there may be differences lo to lot.
As far as the difference in hardness between the 450 and 7.5 I would want the one that produces the most consistent chronograph numbers and best on-target accuracy.
When I have tested Federal GM Math, CCI400 and 450 and RP7 1/2 in different calibers one has always been best (just not always the same one). Not sure if you've given any thought to the difference in pressure produced by different brands of primers in same load. Maybe that is causing your cratering issue?

This chart is a little different from the ones I have seen previously. In my own experience the 7 1/2 seems a little softer than CCI 450/BR4. Agree that the Fed 205/205M seem to handle high pressures well.

 

[fkimble@charter.net]

Recently was working up a load in 6Br with 107 Sierra & VV140. Started with CCI 400s. When they started getting flat, I switched to 450's. nice and round so continued upward.

Frank

 

[Bill Norris]

Recently was working up a load in 6Br with 107 Sierra & VV140. Started with CCI 400s. When they started getting flat, I switched to 450's. nice and round so continued upward.

Frank

I use the 450's in my 260AI Peterson brass with 140 & 142 gr. bullets to accomplish safe loads up to 3000 FPS and beyond with no signs of pressure. Have noticed lower E S & S D #'s using the small primer brass.

 

[varget204]

I do not have a hardness tester; but when shooting CCI 450 VS Rem 7 1/2's I always get bigger firing pin strikes on the 7 1/2 's

 

[L.Sherm]

If your not over pressure shoot the 7.5, 205, or 450 whichever is the most accurate.
If your load won't handle those you need to back it down.

 

[Mike Samer]

It's not always a pressure issue. Firing pin diameter definitely comes into play with SRPs. My .308 model 70 Palma rifle had the standard large diameter pin for .473 and up case head cartridges, .082 diameter IIRC. Their .223 etc. actions used a much smaller pin diameter. After bushing, I get a case life of over 18 firings (so far) in both the bushed model 70 and an un-bushed 40x action. That is with the same loads that blanked primers in the un-bushed M70.

 

[LCazador]

The chart above shows some differences shown on my chart. I have 450, 7 1/2, and BR4 with a cup thickness of .025" with cup height of .113" for 450, .110" for 7 1/2, and .109" for BR4. If you seated all three to the same depth you'd actually have a softer hit on the shorter cup primers. Assuming the firing pin force will drive the shorter primers in and result in a softer firing pin strike. This can also result in inconsistent firing pin strikes. Fed 205M are .0225" cup thickness with a cup height of .1075". Federal 200 and Rem 6 1/2 are .020" cup thickness and .109" cup height. In my opinion judging pressure by primer obturation is not best practice. Measure cartridge head diameter and don't exceed more than .001" expansion. Or if you want to play nice with your brass don't exceed more than a half a thousandths.

 

[goodi]

I have been using cci 450, cci br4, federal 205m, 1990 vintage rws srp, new issue rws srp, 1980's vintage rem 7 1/2 (2 anvil) and newer rem 7 1/2 (3 anvil) primers in 6mm BR, .17 rem, 6x47 lap, 222, 223 etc.

Easy chambering and extraction of cases, satisfactory visual inspection of fired primers, continuing firm primer seating and removal etc all indicate pressures are not excessive in these calibres.

However, I no longer use the new 3 anvil rem 7 1/2 's due to the occasional pin hole leaks on the primer edges.

cheers

goodi

 

[Majday]

This is where I'm at on the fired cases with xbr and 7.5s. They shoot well just wondering if maybe the 450 or even the 205MAR would be better.