Home Forums Hunting & Shooting Ask The Gunwriters Gas venting and modern bolt actions

I believe so too. Reputable modern cars are designed to crumple and absorb the energy, sacrificial to protect the occupants.

Pierced primers are bad. While not a bolt action, I've been on the firing line next to an M14 that blew out and dissassembled the magazine due to a pierced primer. The bullet left the barrel okay but the gas system didn't eject the case. Funnily enough the magazine spring , follower and floor plate were undamaged and were able to be reassembled seemingly good as new.

I have a customer who shot a full box (20 rounds) of 308 Win in a 270 Win I had built for him. Never popped a primer. He said it grouped well, just kicked really hard and sounded weird. And the bolt closed hard. Point of impact didnt change more than a couple of inches from regular 270 ammo. I guess there really is a god.
Charlie

Charlie and I were fooling with a .308 in the Winchester Classic Action a number of years ago. If I recall correctly, we were trying to see how many firings it took of a stout handload in a single case it took for the primer pocket to open up. Charlie was on the Pressure Trace, and I was doing the shooting. After every shot we'd load the case with the same primer, powder charge and bullet, and shoot.

Everything was going along fine, until about the 12th firing. Again, this is what I recall. May even have it in my loading notes, but it doesn't matter. Everything was normal until that shot--which blew the primer--and a bunch of gas back in my face, along with what felt like brass particles. (I was very glad to be wearing shooting glass, in addition to my everyday glasses.) Couldn't open the bolt by hand; instead Charlie tapped the bolt handle several times until it came loose, probably with a rubber mallet.

We couldn't figure out why it blew. We checked case-length every time we loaded the round, and double checked the powder charge. Might have had something to do with the neck getting brittle, since we didn't anneal the case, but still don't see why everything went from normal to blown with one additional firing.

Anyway, my major point is that the only gas-handling improvement I know between the pre-'64 and Classic Model 70 was a "gas block" added to the left side of the bolt, just behind the left locking lug. Maybe it helped, but I sure got a blast in the face.

My secondary point is that the pre-'64 Model 70 has basically zero gas-deflection or containment. As a somewhat smart-ass gun writer once point out, reliable cartridge cases are what made the pre-'64 possible.

JB, and Charlie, have there been any improvements to the latest M70s from South Carolina and now Portugal in gas handling? Also how about the Tikka and the lowly Ruger American?

I have a CZ 527 in 204 that has pierced 3 primers. Never felt a thing and only noticed the pierced primers upon extraction. I switched from federal 205 GM to 205 AR GM that allegedly have thicker cups and never had the issue again. Not sure if it is an issue with the gun or the primers

Some of the latter NH guns and the current production guns have a small flange on the bolt shroud. I am not sure if this flange or the has block actually do much. In the case of the gas block I would bet its just another piece of shrapnel in the event of a major gas release.

Thanks for posting that, good reminder that pressure signs don't necessarily creep up on you a little nibble at a time.

BWalker,

Yeah, they have a very small "flange," if you can call it that, on the left side of the bolt shroud--but it isn't anything like the bolt shroud on a 98 Mauser. The 70's is not only very small, but there's plenty of space between the shroud and the bridge of the action. In the same place, the 98 shroud extends all the way to the side of the bridge, and fits closely--not in attempt to block gas, but to deflect gas sideways.

I once shot an FN 98 sporter .270 that belonged to someone else, with rather old factory loads. Apparently they had corroded just enough to blow crack in the case, just in front of the head--which happened to be on left-hand side of the case. All I felt was a faint puff of gas on my left cheek.

Did the guy say how this happened? I'm having a hard time comprehending how someone can do this. You have to REALLY not be paying attention to almost anything to do something like this.

I had split case in two instances. On a Ruger 77 in 284 winchester and on a 7X57 Mauser. I felt nothing behind the Mauser, and wind in my face with the Ruger.

I have a hard time believing the box of 308 in a 270 story...

I had a buddy put a .308 round through a 25-06 Remington 700.

Case head was welded to bolt face. We had to open the bolt with a mallet.

Rest of brass was spread across the chamber. But no copper/lead to be found. I know he tried to send it back to Remington. I need to call him and find out what happened to that rifle.

I had two Hornady 9.3x62 cases let go in a Classic Stainless Model 70. The load was 65 grains of Big Game with a 286 grain Nosler. The cases were on their third loading. I was doing some rapid-fire practice and these cases were loaded together. With the first case that let go I noticed it only in retrospect. Thinking about it after the fact I realized there was just a slight puff on my face and no issues with the rifle. Had I been shooting a group it likely would've been enough for me to realize there was an issue to check out. As it was, I was in the midst of rapid-fire and fixated on my next target. The next round caused a rather dramatic gush of air to my face and blew the floorplate open, dumping the remaining two rounds. The rifle was undamaged. Based on this hopefully never again to be experienced issue I'd say the gas handling abilities of the Winchester Classic Model 70 are less than awesome. Thankfully I was wearing safety glasses, as the lenses were etched and the bare part of my face had some stippling.

Lots of investigation later, I determined Hornady brass and RCBS dies are a bad idea for the 9.3x62 loaded to modern pressures. Without going to my notes for all the numerical specifics, there are two problems. First, Hornady makes their 9.3 brass from '06 blanks, likely to decrease costs and ease manufacturing. This is bad because '06 brass is of a smaller diameter ahead of the casehead than 9.3x62 brass is, resulting in a slightly undersized fit in the chamber. This is exacerbated by RCBS dies, which are made to size brass formed from .30-06 brass. This came from long ago, when the 9.3x62 was much less common and RCBS sold forming dies to make 9.3 brass from '06 cases. The brass was undersized to begin with. At first firing it expanded to fit the chamber, then the dies sized them back to '06 size. A couple cycles of this worked these cases beyond what they could bear apparently. Interestingly, prior to this I'd fired a bunch these loads with nary a problem. But it scared the heck out of me! Investigation revealed Norma, Privi, and Lapua cases are properly dimensioned. Lee and Redding dies size cases appropriately. I ended up switching to Lapua brass and a Lee sizing die with the RCBS seater die, which I like better than the Lee seater.

No expert I spoke with had ever seen, or heard of a case failing with a split through the casehead. Has anyone else ever seen this?

They are safe, but they didn't put as much thought, money and time into engineering them nowadays, it's just something for people to shoot a deer, it's no longer being built for the nation's defense. Despite that, probably they are in fact safer with modern metallurgy and cartridges. And the concern today is mostly theoretical, even more since shooters now often wear eye pro. I wonder how some of these budget guns with full diameter bolts will do, since there's no raceways, might be interesting. Most of the gas talk is about older designs, or copies of older designs, because people don't even consider this these days.

Years ago when Dave Gentry was still alive we spent some time talking about this subject at the shop. Hands-down he said the Savage 110 was the strongest, safest action he’d seen. He tested wildcats in them and said he struggled to blow up the action. He didn’t think much of the M70 or M700. Of course he liked the 98, but IIRC thought the Wby action was good too.

The cross sectional area of the bolt lugs in shear stress is almost the same in:
1) 98 Mauser
2) M70 Win.
3) Rem 700
5) Mosin Nagant 91/30
6) sav 110.

I have re barrelled and I have overloaded all (6) actions.
I have killed things with all (6) Actions.

(+) The Sav 110 does have ~~ 5% more bolt lug cross sectional area than the other.
(-) I am done building Sav 110 rifles, but still building the others for my own use.
a) stock availability is poor
b) too many feeding systems
c) too many action lengths
d) too many crazy bolt mods.
e) weak extractors




I did this in 2002 with Turkish Mauser I rebarreled to 243.
I cannot do this in a Sav110, or the extractor falls out.... not even in 223, I tried.

Not relevant but curiosity about the velocities - although not intent, did you chrono any of those Turk loads?

Is anyone currently producing a rifle or just action with the Mauser 98 design?

The older Savage 110's are stronger in shear than the newer ones because the right hand lug is not hollow. GD

Ive looked into this in the past and ive found Mauser makes a magnum 98 action, Granite Mountain Arms has three sizes as does Mayfair Engineering. I believe these are 98 pattern recievers of modern materials and execution. Theres also one by American Rifle Co i think thats the name. Anyway its not a real Mauser per se but a hybrid between a Mauser and 03' Springfield and its called the Mausingfield. That company has some innovative designs and neat looking things. Good news is these small outfits cater even to lefties like myself so we arent left out. Trouble is some of these recievers are north of 4k in cost. Ouch.

This issue of action strength, safety and gas venting has always been on my mind. As a lefty and fan of controlled feed and classic hunting rifles i have tried aquiring such in left jand versions and have several Hawkeyes and a lefty model 70. I know from experiance that the Rugers perform well in frozen crapola and freezing rain type conditions, dust, grit, and muck. They flat work and ive been so happy with my Ruger scout rifle as a staple user. I just dont get encouragement from hearing they arent great at deflecting gas, but then again im not pushing them hard and shooting loads to extract every FPS oit of it, im realistic and cautious. Still its on my mind. I have access to a leftt German Weatherby locally with a crap barrel in 300 wea. Maybe it would be a good canadate to rebarrel to 338 win and have a bit safer reciever. Maybe, but i am not a big pushfeed person nor a Weatherby fan. Still i think of it from time to time.