Old primer effects on accuracy

I just recently received my new 38 Super. My friend who built it for me had some very impressive ransom rest results. The load was given to him from Bob Marvel. 110gr Hornady XTP, Starline brass. 4.5gr Bullseye, and small rifle primer. In retrospect the only SR primers I have are about 7-8 years old. I used this load at this past weekend's Bullseye match. To get all 30 rounds of slow fire off I had 6 duds. Solid hits but duds. Most were not even close to call. I assume the primers were the cause. The second question I have is the Hornady 110gr XTP is .357 in diameter. I'm thinking this could cause premature barrel wear. After a little research this bullet is used in 38 specials. All the jacketed bullets listed for the super are .356. I have been using the Dardus 125gr LSWC on the short line and it is deadly accurate and is .357 in diameter. The rule of thumb I have always gone by is jacketed .001" less than the lead counterpart. Any advise or comments will be appreciated.

Bill

Try it with your existing ammo. But there are 115 grain bullets in 355 that might be as accurate. I’d also try the S Pistol primers.

what barrel is in it.

for the Dardus bullet we have been running .356 in both Kart and KKM barrels as well as Colt.  All group around 1.6" or less at 50 yds.  Try the Dardus with 3.6-3.8 of BE.. the karts and KKM slugged at .354

For my 38 super EIC pistol I run 115 XTPs with 3.8 - 4.1 of BE. That is a .355 bullet

jglenn21 wrote:what barrel is in it.

It has a kart barrel in it. I have no idea what the twist is.

Bill

jglenn21 wrote:for the Dardus bullet we have been running .356 in both Kart and KKM barrels as well as Colt.  All group around 1.6" or less at 50 yds.  Try the Dardus with 3.6-3.8 of BE.. the karts and KKM slugged at .354

For my 38 super EIC pistol I run 115 XTPs with 3.8 - 4.1 of BE. That is a .355 bullet

I haven't slugged the barrel but I do have some Dardus .356 that I have been shooting in my 9mm.

Bill

My Supers like the 125gr Zero .356 bullet. Neither one groups well with .355 in 115 or 124gr. As far as old primers it depends on how they were handled. I still have Norma primers from the 70's that function perfectly. They are getting old enough now I may donate the rest to a museum. 

Len

How about some S&W Alcan primer Len.. Still have some of those that work well.

Standard Kart in Super is a 1-16 twist..

I shot a bunch of those Alcan primers. I was still shooting them as late as ‘07 or ‘08.

Hell, I’m still using Winchester 452AA. 

8-year-old primers are not old, unless they’ve been stored in salt water. Sounds like you have something else going on.

LenV wrote:My Supers like the 125gr Zero .356 bullet. Neither one groups well with .355 in 115 or 124gr. As far as old primers it depends on how they were handled. I still have Norma primers from the 70's that function perfectly. They are getting old enough now I may donate the rest to a museum. 

Len

My loading room is inside my house so there isn't a moisture or humidity problem. What load are you using with your 125 Zeros?

Bill

messenger wrote:

LenV wrote:My Supers like the 125gr Zero .356 bullet. Neither one groups well with .355 in 115 or 124gr. As far as old primers it depends on how they were handled. I still have Norma primers from the 70's that function perfectly. They are getting old enough now I may donate the rest to a museum. 

Len

My loading room is inside my house so there isn't a moisture or humidity problem. What load are you using with your 125 Zeros?

Bill

I use 4.6 gr of Bullseye. I have some test results that show 4.2 gr slightly more accurate but with my dot on the slide they didn't cycle 100% of the time. The picture is using a Lee rest at 50 yds.

One difference between the small pistol and small rifle primers is the hardness.  If the pistol is not set up properly, usually stronger mainspring (hammer) you can get some ignition issues.  Used to be a real balancing act back in the early 38 Super major power factor days of IPSC to get really low trigger weight and 100 percent ignition with the rifle primers.  Then again, I didn't blow out as many primers either.  Just something to think about when using SR primers in pistol loads.  CR