jostein jensen Posted November 6, 2007 Share Posted November 6, 2007 I just testfired my new used SV IMM 9mm open gun. My load was 7.3gr 3N38, 30,5mm and 125gr MG JHP. My aim was around 7,5gr after advice from a shooter who loads major 9 for a 5" open gun. The load was very soft and flat, a little sparks out the comp but hey, it was dark out... Due to darkness the chrono didn't work. This was a bummer cos I had three different loads (7,3 7,6 and 7,8 gr) with me and wanted to see if any one made it to 160 PF. Due to no chrono I didn't fire the 7,8 gr load. All primers had this weird looking ring around the firing pin. Is this normal, or a pressure sign? See pictures of a case. All the fired ones (10 with 7,3 and 10 with 7,6) look the same. Thanks for any advice from you experienced guys. I ask cos I know I don't know DVC from cold northern Norway, above the arctic circle! Jostein. Link to comment Share on other sites More sharing options...
yoshidaex Posted November 6, 2007 Share Posted November 6, 2007 pressure sign but the primer isn't flattened around the edges so i wouldn't worry. go ahead and chrono those loads to see what sort of velocities you're getting. Link to comment Share on other sites More sharing options...
jostein jensen Posted November 6, 2007 Author Share Posted November 6, 2007 OK will do! This is a Federal Small Pistol. Will a Small Rifle take more pressure, and be as soft to fire? THe gun in picky on primers... Link to comment Share on other sites More sharing options...
yoshidaex Posted November 6, 2007 Share Posted November 6, 2007 the pressure will always be there. federal small rifle primers won't exhibit the same signs. HSMITH suggested while doing load developement to use federal small pistol primers since they will show signs of pressure before any other brand of primers. winchester primers are a bit harder also and won't exhibit pressure signs. Link to comment Share on other sites More sharing options...
Brazos Custom Posted November 6, 2007 Share Posted November 6, 2007 (edited) That is classic primer flow and will cause all sorts of problems in the long run. I would not shoot the higher loads until you can chrono the others. You would be better off with small rifle primers and a slower powder like 3n38 if you like VV (being from Norway). Edited November 6, 2007 by Brazos Custom Link to comment Share on other sites More sharing options...
jostein jensen Posted November 7, 2007 Author Share Posted November 7, 2007 So the ring around the pin mark is called primer flow, or is it something else you see that I don't see or know? I can get my SP's swapped for SR's so I'm going to do that now. As for powders, I'll keep using 3n38 cos VV is all we've got in Norway Link to comment Share on other sites More sharing options...
XRe Posted November 7, 2007 Share Posted November 7, 2007 The only other thing you might consider is a longer firing pin. With the hammer cocked (ie, not in contact w/ the FP), is the nose of the FP flush with the breechface? It may be that there's room in the firing pin tunnel for the primer to flow into - and that can happen even without excessive pressure. Link to comment Share on other sites More sharing options...
jostein jensen Posted November 7, 2007 Author Share Posted November 7, 2007 with the slide locked back, the pin is FAR from flush with the breechface/hole. When I push the pin in with my finger so the hammer end of the pin is flush with the back of the pin stop, it is perfectly flush. So with hammer down, it will be flush. Link to comment Share on other sites More sharing options...
GentlemanJim Posted November 7, 2007 Share Posted November 7, 2007 Measure the diameter of the firing pin ...and the firing pin hole The pic looks like they dont match correctly It may be possible that the pin hole is too large. Jim Link to comment Share on other sites More sharing options...
jostein jensen Posted November 7, 2007 Author Share Posted November 7, 2007 what should the clearance be? They look quite tight, but I can check again.. Link to comment Share on other sites More sharing options...
XRe Posted November 7, 2007 Share Posted November 7, 2007 So with hammer down, it will be flush. W/ hammer down, mine protrudes slightly from the breechface. To me, it just looks like the firing pin face is rounded off, so that its not flush all the way across the hole - rather, just the center is flush. That gives the primer room to flow back into the hole around the front of the firing pin. The pin probably fits fine in the hole. A longer firing pin will not fix any pressure problems - however, it may prevent flow into the firing pin tunnel. Harder primers (per Bob's and yoshidaex's suggestion) will help with the flow, as well. I use WSRs, myself... Link to comment Share on other sites More sharing options...
yoshidaex Posted November 7, 2007 Share Posted November 7, 2007 So with hammer down, it will be flush. W/ hammer down, mine protrudes slightly from the breechface. +1 mine protrudes slightly with the hammer down. Jostein, How about a picture of your breech face with the pin installed. Hopefully the FP hole isn't out of spec. Do you happen to know how many rounds this slide has seen? Link to comment Share on other sites More sharing options...
jostein jensen Posted November 7, 2007 Author Share Posted November 7, 2007 (edited) the slide has 6-700 rounds since install. old one cracked and SVI replaced it under warrenty. Here is the firing pin, used the pin stop to pin it in so it protrudes through the hole. Its exactly like XRe said.. its not flat faced! p.s: thank canon for good photos! finally the EOS 400D comes in REALLY handy even with the crappy lens that came with the cam! Edited November 7, 2007 by jostein jensen Link to comment Share on other sites More sharing options...
jostein jensen Posted November 7, 2007 Author Share Posted November 7, 2007 To me, it just looks like the firing pin face is rounded off, so that its not flush all the way across the hole - rather, just the center is flush. That gives the primer room to flow back into the hole around the front of the firing pin. The pin probably fits fine in the hole. so the primer flow may actually be caused by the shape of the pin allowing the primer to squeeze into the hole a bit? A flat faced firing pin would cure this, and its actually not caused by the case pressure being dangerously high? Link to comment Share on other sites More sharing options...
XRe Posted November 7, 2007 Share Posted November 7, 2007 so the primer flow may actually be caused by the shape of the pin allowing the primer to squeeze into the hole a bit? A flat faced firing pin would cure this, A pin that protrudes slightly out of the hole w/ the hammer down will help with this - and yes, part of the problem may be that there's room for the primer to flow back into the firing pin hole. Flat faced or not doesn't really seem to matter - mine is slightly rounded off. The key is that the FP tunnel hole is plugged up completely by the FP, and that requires that the FP is fully blocking it while the hammer is down - and usually we do that by making sure the FP is long enough to protrude slightly while the hammer is down. and its actually not caused by the case pressure being dangerously high? I can't say that either way. Primer signs are really a bad way to guess at the pressure of the loads. Most of us have standardized on a small rifle primer in the Open guns, because it helps avoid some of the flow issues, especially at old major. By the time the shoulders of the primer start to flatten out bad, you're really running high pressure, but until you get there, you just don't know. Loads that have nice looking primers can still be in the 50K PSI range, which is rather high. The problem you may have with this sort of flow is that the flowed out part can be trimmed off by the firing pin tunnel as the case is extracted and ejected, which can eventually cause the firing pin tunnel to get plugged - and you get light hits on the primers... Link to comment Share on other sites More sharing options...
jostein jensen Posted November 7, 2007 Author Share Posted November 7, 2007 OK I'll get my gun set up with a new FP then. Will update with chrono numbers when I get a chance to shoot daytime for the light. Link to comment Share on other sites More sharing options...
yoshidaex Posted November 7, 2007 Share Posted November 7, 2007 is that a interchangeable breechface? Link to comment Share on other sites More sharing options...
Brazos Custom Posted November 7, 2007 Share Posted November 7, 2007 the slide has 6-700 rounds since install. old one cracked and SVI replaced it under warrenty. A cracked slide is a pretty good sign of high pressure (assuming everything is put together right). If the load you are testing is the one that was being used when the slide cracked I would look for something with less pressure. A long firing pin, and small rifle primers will cover up signs of pressure but the pressure is still there and can cause damage in the long run - such as cracked slides, eroded breechface, etc. You need to correct the root cause. If you can make major with 3n38 it will be at less pressure than the 3n37 and would be a better choice for the longevity of your gun. All things being equal a gun run at lower pressure will on average have less breakages than one running at a higher pressure. Link to comment Share on other sites More sharing options...
jostein jensen Posted November 7, 2007 Author Share Posted November 7, 2007 is that a interchangeable breechface? Yes I belive so. You can see on the photo a round edge of the breechface at the very top of the slide in the opening. the slide has 6-700 rounds since install. old one cracked and SVI replaced it under warrenty. A cracked slide is a pretty good sign of high pressure (assuming everything is put together right). If the load you are testing is the one that was being used when the slide cracked I would look for something with less pressure. A long firing pin, and small rifle primers will cover up signs of pressure but the pressure is still there and can cause damage in the long run - such as cracked slides, eroded breechface, etc. You need to correct the root cause. If you can make major with 3n38 it will be at less pressure than the 3n37 and would be a better choice for the longevity of your gun. All things being equal a gun run at lower pressure will on average have less breakages than one running at a higher pressure. Slide cracked with the previous owner after 40k rounds. I bought it with new installed slide. It supposedly was a production error that caused it, but since it was before my time of ownership, I really don't know. It could have been 40k of too high pressure rounds. The previous owner used N350. Link to comment Share on other sites More sharing options...
lcs Posted November 7, 2007 Share Posted November 7, 2007 (edited) Does this gun have barrel ports like the IMM shown on SV website? If no barrel porting and this gun is a 5 inch barrel, IMHO and experience you should be making 160PF without ever seeing high pressure signs with other powders. I can not speak to 3n38 as I have not tested that powder. What is your OAL and crimp? My bad, your OAL is 1.200 yes? Edited November 7, 2007 by FullRace Link to comment Share on other sites More sharing options...
jostein jensen Posted November 7, 2007 Author Share Posted November 7, 2007 yes its 1,200. no crimp. just take away the belling from the powder die. the gun is a 4,5" with these extra holes in it. Link to comment Share on other sites More sharing options...
Bear23 Posted November 7, 2007 Share Posted November 7, 2007 Quite a few guys are running HS-6 in their major 9's. I have the older version of the SV IMM, with the 6 holes. Those have a history of cracking the barrel-comp interface. I run HS-6 in mine with no pressure signs. Link to comment Share on other sites More sharing options...
jostein jensen Posted November 7, 2007 Author Share Posted November 7, 2007 we don't have anything else than VV powders in Norway... Link to comment Share on other sites More sharing options...
dstroyed Posted November 8, 2007 Share Posted November 8, 2007 I’m a little confused. Your first post said 5" then another said 4.5” Regardless, you know that you need to get your load over a chrono before going any further. My ported shorty needs a lot more 3n38 than 7.8, mine is not an SVI. When I started loading 3n38 I was concerned I may not make major with it, but I did. My point being I would be surprised if that load major. I hope your close it sure would save the mess on the loader and save a few bucks with a lighter load. Good Luck with it all. Link to comment Share on other sites More sharing options...
al503 Posted November 8, 2007 Share Posted November 8, 2007 My ported shorty needs a lot more 3n38 than 7.8, mine is not an SVI. Same here. I'm well over 9 grains of 3n38 before making it to major. Link to comment Share on other sites More sharing options...
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