308 Win - Lg vs Sm Primers and Flash Holes

alright folks welcome back it's time for another 308 video and we're going to look at the differences between large primer brass and small primer brass and in the small primer brass we're going to look at the difference between a large flash hole and a small flash hole now we're shooting 308 but I think the results will apply to other cartridges and this video is really a continuation of some videos I made like a year and a half ago in 6.5 Creedmoor we were having some problems with hangfire's we were shooting small primer brass and we ran into some hangfire's I did four videos kind of investigating that situation and looking into different primers and looking into different powders and trying to understand what was causing poor powder ignition in those circumstances and this is really a continuation of that and hopefully this will build on what we learned in that little video series I've got a playlist with those four videos in it this will be added to that playlist because it's really the same subject so here in 308 I picked up some Lapua palma brass this brass uses small rifle primers and it has a small flash hole now I screwed up in a previous video and I accidentally used a resizing die with a decapping pin that was too big for the flash holes so I kind of screwed up the brass by punching out the flash holes and making them larger than they came and since then what I've done is I went ahead and drilled them out what I found was that a 5/64 drill bit fit through the flash hole of the large rifle primer brass just about perfect so I've taken some of this palma brass and i drilled out the flash hole with this here drill bit and then I used a flash hole deburring tool to make sure that the old the birds were removed so that leaves us with palma brass with small primers small flash holes i've got the ones i drilled out which are small primer large flash holes and I've also got some standard Lapua 308 brass that that uses large primers so those are the three things I want to test against one another so in the in the previous four videos on this subject we learned that it really comes down to most importantly primer selection in in the Creedmoor what we found was the seat number 41 primers did a really good job and another good choice was the remington seven-and-a-half those two seem to be our best performers as far as avoiding hangfire's and misfires when using small primers we also found that the S&B small rifle primer was clearly the worst and this is what we used for kind of the worst case scenario and this is what we're going to use today to try and induce some hangfire's in 308 with the small rifle primer brass now I'm not saying these are bad primers like we've we've used them in other applications and they've been okay but they're just they're not as hot like I think this seven and a half and the CCI 41 these are just hotter primers these aren't quite so hot so when you get into certain situations these can cause some problems and that's what we're hoping to do today is cause some problems the other thing we learned in the previous four videos is the most important thing beyond primer selection was case film if you got a nice full case of powder you're generally gonna get good ignition and if you've got a whole bunch of excess case capacity ignition is going to be a problem so those are the two things we want to try and do today we want to use the SMB primer and we want to use a powder with a minimum charge that's not gonna fill up a bunch of the case so here's the test I've got plan we're gonna shoot 168 grain sierra matchking this is what we shot in the last video the groups were great everything was great good bullet the first powder I want to test with is IMR 4895 this is what we shot in the last video we shot up to 40 3.0 grains I want to shoot 43.0 grains again that is a nice full case of powder like just about a hundred percent case fill so with 43 grains of IMR 4895 we're going to see if this SMB primer gives us reliable ignition I think it will now the problem is I do I don't have any SMB large rifle primers so for the large rifle primer brass I'm going to use CCI number two hundreds just a standard large rifle primer to be honest my selection of large rifle primers isn't that extensive I've got the CCI 200s I've got some Winchester WL ours and that's about it so I just figured we'd go with the CCI I think even with the smv primer and large rifle I don't know maybe it's a hot primer I have no idea I haven't tested it I haven't used it but even if let's say it's a weak primer I think you would still get good ignition I don't know the large rifle primer test is really just kind of there as our standard we want to get velocity standard deviation and accuracy information from a large rifle primer test just as kind of a baseline what we're really after is finding out the performance of those small rifle primer brass and seeing how they compare to the large rifle stuff the second powder is going to be a ch3 35 and we're going to be shooting a minimum charge right at the starting charge which is thirty nine point zero grams I looked on the hodgson website which has data with 168 green sierra matchking I also looked on the Sierra load data and that 39.0 grain is just above what they show for starting charges both both sources so this load this 39.0 grain load it doesn't fill a lot of the case well I mean it fills a lot of the case it's probably 60% or something but there's a whole lot of excess capacity left in the case another thing is that h3 35 is a ball powder of spherical powder while IMR 4895 is a single base extruded powder so just by their nature IMR 4895 is easier to ignite than h3 35 we observe that in some of the previous videos on this subject but honestly the differences between single base extruded double base extruded and spherical powders wasn't as big of a difference as we saw with primer selection and case filled but still I wanted to go ahead and use a ball powder as our worst case scenario sort of powder now h3 35 is a great powder for crying out loud I'm not trying to crap on h3 35 or even the SMB primer I'm just saying that we're trying to create a scenario where these components as a combination can result in ignition issues and I'm not even sure whether we're gonna be able to see anything today I don't know we'll see so that's pretty much it did I cover everything I think I did did I show you the load data hopefully I did it's pretty straightforward I want to shoot ten shot groups with each powder and each type of brass so total of 60 shots and the reason I want to do 10 shot groups is that should give us you know better information as far as accuracy and especially like standard deviation numbers so we're going with 10 shot groups today now I've always heard like with this Lapua brass and the small flash holes the thought behind it is that the smaller flash hole concentrates that flame that flare that whatever coming out of the primer into a smaller more intense spot on the powder so I think the whole point of the small flash hole is to get better ignition with small primers so I'm really interested to see whether we see any difference between the small flash hole and large flash hole with the SMB primers so that's it like it we're not even gonna cover any reloading today we're just going to go ahead and hit the range all 60 of our test loads I tried my very best to make them exact clones of one another all of the brass was sized with the exact same fooling through sizing die at the exact same time same exact lot number of bullets and powder and primers everything is exactly the same i seeded all of the bullets with the exact same bullet seeding dye setting at the exact same time like they were all loaded at the same time so any variation between them should have to do with those primers and those flash holes so that's it let's get all in range okay so it's time to get started I've got a target at 100 yards the dots down there are one inch in diameter the gun is an arrow precision m5e one set up with a 20 inch Krieger barrel with a one at 11 twist I'm using a silencer code Omega suppressor and a 6 to 24 by 50 vortex Viper PST now this is a different scope than I had on this gun in the last video the last video I was shooting the vortex strike Eagle it was giving me some focusing problems and come to find out that focusing knob seems to become and loose on me so I swapped in the the PST hopefully that'll work a little bit better today another thing I changed about this gun since the last video was I pulled out the the trigger I was using which was a pretty heavy trigger and swapped in a LaRue MBT trigger so hopefully I don't have any bump fire problems today with this lighter trigger we'll see how it goes the heavy trigger was getting on my nerves so just wanted something a little bit lighter velocity is coming from our lab radar chronograph so let's get started we're gonna start out with the boring stuff or at least I hope it's boring this is the IMR 4895 loads with plenty of case Phil and I really don't expect to have any problems at all with these it's just kind of our baseline test so I'm going to load up all ten in my Magpul pee bag and let's see if they group the gun is warm like I shot seven rounds through it to get this scope zeroed so the guns warm so we shouldn't have any cold barrel conditions affecting our test first up large rifle primers the standard Lapua brass okay next up is the exact same load in the small primer palma brass with the large flash holes [Music] all right so so far so good we lost almost 30 feet per second there in the switch from the large CCI primer to the small SMB primer our standard deviation tightened up a good bit down to 7.7 so our last test with IMR 4895 is the SMB small primers with the small flash holes let's see how these guys do okay so that's our baseline we lost about 30 feet per second switching from the large CCI to the small SMB primers and the large flash hole and the small flash hole were within three feet per second of one another and the large flash hole had the better standard deviation interesting so I'm gonna let the gun cool down a few minutes and then we'll move on to the real test which is a ch3 35 alright so now it's time for things to get interesting or at least I expect them to get interesting we're switching over to our minimum charge of a ch3 35 we're gonna start with a large rifle primer so this these first ten shots I don't expect to have any problems I didn't mention the weather today - it's extremely hot this is the middle of the summer then air temperature is in the upper 80s and in the previous videos with 6.5 Creedmoor on this subject we did a little bit of playing around with temperature but it was extremely cold at that time but even trying to shoot warm rounds and see if we could notice some difference between warm and hot there didn't seem to be a ton of change so temperature might be a factor here but we're just not really accounting for it today so let's get started all right now we're moving on to the small primers this is where things should get interesting the S&B small primer with the large flash hole we're watching for hang fires and misfires so let's see what happens [Music] okay the round did not go off just give it a minute to cook here yep it's been like 30 seconds nothing's happened so I grabbed that round and looked at the primer really quick and it looks like the primer strike was good but yeah I didn't feel like holding it in my hand you never know what could happen so let's move on to the next one all right distinct hangfire that time same thing that time hang fire another hang fire okay so we had one misfire and nine very distinct hang fires our standard deviation went to garbage 37.0 our extreme spread was 129 just awful so this is exactly what we were expecting this is exactly what we designed into this test was to see this sort of result now the final question is whether these small flash holes in the Lapua brass will help with this situation so that's the last group small primers SMB primers with the small flash holes let's see what happens hang fire all right so ten shots and we had ten hangfire's so this turned out exactly as we expected let's get back to the bench talk it all out so at this point we generally have a look at the brass four pressure signs but there there's nothing to see all the brass look great today but what I did do is I tore apart the one misfire to be 100% sure that the primer went off and it did this is exactly what we saw in the previous videos with 6.5 Creedmoor the primer went off and if you look at the powder the powder down at the bottom of the case near the flash hole gets this yellowish color and it all clumps together and this one had a particularly huge clump so the primer went off the flash made it to the powder we just didn't get ignition so let's have another look at the groups here on the top row with our IMR 4895 load where all of them went off no problem I'm not sure what to think about this difference in accuracy like our groups got significantly better with the small primer brass one thing I'll say the large primer will pull a brass I was using has got some miles on it like I've had it for years it's got I don't know 10 or 15 firings on it I'm not sure the last time I had nailed it so maybe I don't know that there are some other factors that may be contributed to the accuracy difference like I would feel a whole lot better saying that yep small primers are more accurate if that was brand new large primer brass and it just wasn't another thing is the velocity difference right it was 30 or 40 feet per second faster in velocity so if we drop that charge down a little bit and got two velocities matching up maybe that would tighten up the groups maybe we just landed in a really bad node or whatever I don't know now the large flash hole versus small flash hold similar size group the velocity was the same you know where they were within three feet per second of one another and the small flash hole had a little bit higher standard deviation now the funny thing is they both had the exact same extreme spread so extreme spread was 28 feet per second and then the standard deviations were seven point seven and ten point four so with a 10 shot sample size I'm not sure if that difference in standard deviation is I think what we probably need is a load where we've got really amazing standard deviations and then compare them with that load and at that point this barrel still pretty new we're still just kind of getting started playing around with this 308 I don't really have a good go-to load that I know will have extremely small standard deviation numbers so we might have to revisit that later on now with age 335 on the bottom row things got a little more interesting the large primer no problem whatsoever good ignition on all 10 shots and then with the small primer all 20 shots were bad we had one misfire and 19 hang fires so no surprise that standard deviations went to garbage the group's got bigger and it was all bad so where do we go from here I've been kind of trying to think this over here for the last few days since I shot these rounds and I think we need one more video because I really haven't determined much of anything on the small flash hole versus large flash hole debate so I think in the next video we need to take this h3 35 load we know that the minimum charge is terrible so I need to just start working up maybe we shoot half grain increments all the way up to max charge and find out about where it starts reliably igniting the powder and compare that point with the large flash holes versus the small flash holes that's probably going to be a lot of work and a lot of a lot of rounds to figure out that point with both types of brass but I think it's worth it because at this point we just you know I have nothing to really say on the subject of small flash hole versus large flash hole it's good that so far we've seen similar accuracy you know our IMR 4895 loads the group sizes were pretty close to one another so it's not like I've destroyed this brass by screwing up the flash holes it's still good brass so that makes me feel a little bit better I think that's pretty much it like did we cover everything I think we did kind of a little bit boring today like it turned out exactly like we planned exactly like we predicted and it's a little bit more fun when you know something unexpected happens but it's a good validation of what we learned in 6.5 Creedmoor and now we know that it translates to 308 so that's where we'll leave it folks I'll see you guys next time

Channel: Johnny's Reloading Bench

Views: 51,175

Rating: 4.9478149 out of 5

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Id: bil4iiSqGXU

Length: 20min 31sec (1231 seconds)

Published: Tue Jul 16 2019