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Airbob10

Airbob10

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I just got my Arisaka Type 99 rifle that I bought through the US. Since the 7.7 x 58 is hard to get, I decided I would load my own. I found a few hundred Norma unprimed cases, as well as a few hundred PRVI unprimed cases. These are brand new cases. The projectile is just .312 (303).
I grabbed the PRVI cases, the bag was the closest and loaded 50 rounds. I have been reloading for years, so I loaded to 75% of maximum, as well made sure the OAL was in spec.
Took the rifle out and started shooting. Everything was going great until one round went off and a lot of blow-back came out of the vent hole in the receiver. I checked the case, and it was black on part of the case, as well it was a little hard to pull out of the chamber. At first I thought I had over loaded the charge, so I weighed them. I bring my small electronic scale with me to the range when I am try out new ammo. They were all in range of what I had loaded.
I started to shoot again, and about 5 rounds later, it happened again. I put the rifle away and decided I had better figure out what was going on once I got home. I took a look at the fired cases and discovered a few had more than average black on them. I then measured the cases and discovered that they were a lot longer than they should have been. I then took the PRVI bag with 50 unprimed cases in it and measured them, guess what, about 30% of them were over length. I took out the Norma bag and all 100 were in spec.
I assumed that the PRVI cases were in spec, but I learned they are not. I am glad that I didn't damage myself or the rifle. I will never make that mistake again. I will always measure all new cases from now on.
Has anybody else had this issue with PRVI cases, or any other manufacturer?
 
How much extra length did they have? With a longer case your bullet was seated deeper.. but I don't really understand what was happening because of the deeper seating.
 
All bullets will be seated the same length, but if a case is too long it will be jamming into the rifling and wont let the bullet go easily thus raising pressure.
 
Sorry, the new cases were too long. I guess that the case wasn't seating properly in the camber or that I forced the case in and it caused more pressure. I had never fired a type 99 before, so I was really hard on the bolt to see how the action really worked. All of the fired cases that had no real powder black on them were within the proper case length measurement. The length should be at 2.270, but I was getting 2.290, 2.302 etc.
 
Duster has it right.
This reminds me of a short while ago there was a thread on different brands of brass. While some were praising Prive, my response was, "I hate Privi!"
 
Good reminder. I have checked my new, or new to me, brass for length before I load it the first time, so far. I thought maybe it was a bit over anal, but your experience makes me feel better about being picky.
 
All brand new cases require checking for length, trimming(chamfering and deburring) as required and FL resizing. They are not ready to load out of the factory. Regardless of the brand name.
 
Every piece of brass I use gets measured, trimmed if neccessary..... No ifs ands or buts, this is neccessary to ensure that everything is on the same playing field. Call it OCD, I call it CDO since that is the proper alphabetic order...... LOL
 
I'm curious if you had other signs of high pressure such has flattened primers and/or bolt face marks on case head. You did mentioned harder than normal extraction. Something which I have observed when working up cast loads in center fire rifles including a 99 Arisaka is light loads can cause blackened cases and gas blowback or blowby which ever you want to call it. Cases look really "sooty" and gas will leak back out of the rear around the bolt. A little scary the first time it happens. In my case increasing the loads a half grain at a time and the problem went away. The other "interesting" thing I've had happen is hang fires with loads that were too light. All this occurred with typical fast burning rifle cast bullet powders eg 4198 and 2400
I'm wondering whether your 75% loads are generating enough pressure to seal the brass case to chamber.

Just some thoughts.

Old Ranger
 
KellyP said:
Every piece of brass I use gets measured, trimmed if neccessary..... No ifs ands or buts, this is neccessary to ensure that everything is on the same playing field. Call it OCD, I call it CDO since that is the proper alphabetic order...... LOL
Click to expand...

:agree:
I process every piece of brass the same way whether it's new, 1F or 5F.
Same as I weight every powder charge...just my way...
 
I looked at the sooty cases. Primers were fine, no marks from the bolts, or any physical damage. The worst one was right at 2.270. Maybe it is too light of a load. It is quite a shock when you get the blow back at the top of your forehead. It is almost like getting a new part in your hair. I didn't have the dust cover on it at the time. I guess that I will try different loads and see how it works. I will always check all cases from now on. I appreciate everybody's help.
 
If the case being jammed into the rifling as many have speculated, would it not cause much higher pressures that would cause an even better gas seal? If excessive pressure causes blow back isn't it usually from a ruptured case or primer? I can't see an entire case being covered in soot with no damage from excessive pressure happening to the case if there was exceptionally high pressure. It sounds to me like a low-pressure situation where the pressure was so low the case didn't obturate to seal the chamber and gasses blew back on the outside of the case.

You say you were using 75% loads? That seems very odd to me. Normally if there is only a max listed one will go 10% below the published load. Are you 25% below starting loads? With which powder? As far as I am aware the only powder that works well with reduced loads in rifles is H4895 with the 60% rule from Hodgdon.

Why it only happened with the longer cases, I don't know. I have had blow back and really sooty cases when using bullets that are too small but if .312" were used that seems correct unless the rifle has a terribly worn out throat and bore.

Prvi cases are also known for being on the harder side. They'll sometimes split a neck on me after the first firing if I don't anneal them. An overly hard case could also prevent a gas seal. Perhaps the long cases weren't annealed properly at the factory?

I have a Martini Enfield with a terribly lose bore at around .316" and also a hugely oversized throat and neck portion of the chamber. This rifle also experienced about 1 in 5 blow backs to the extent that it would blow my hair back and the cases came out nearly solid back with soot. My guess is the oversized chamber neck was preventing a gas seal and only freshly annealed cases would seal properly. Since I started annealing brass for that rifle more frequently the problem no longer occurs. Is this Arisaka a "last ditch" production rifle? If so, or if it's just old and worn, it could also have an oversized neck/throat that causes difficult gas seals. Combine that with overly hard Prvi brass and a very light load and it's a perfect storm.

If the neck of the case was jammed into the throat, the bullet would either take it off or really mess it up when it fired. If they are that oversized and not damaged looking on the very edge, I'd say the case is not yet long enough to be in the throat. I'm not saying Prvi brass is great or that being oversized isn't bad, I'm just looking at the data and trying to figure out why you are getting low pressure symptoms every few shots.
 
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I had the same problem with an old 86 in 45-90, I was being too cautious and didn't load it to enough pressure to seal the case to the chamber. It smoked nearly 20 cases before I gave up and decided to pull the rest and add a few more grains of 4198 IIRC. I suspect you have the same problem happening and you are not producing enough pressure to seal the chamber with the brass. If it were excess pressure due to the case mouth being jammed into the bullet because it was longer than the chamber neck, you would not be experiencing sooted cases as there would be enough pressure to seal the chamber and the soot would be around the primer pocket as the primer fell out before the case is extracted.
 
I read somewhere another way to check for fired brass that is too long is to try and fit a bullet into the neck of the fired case before resizing. The theory being that if the case was jammed into the throat the case couldn't expand completely to release the bullet without raising pressure Therefore because the neck couldn't expand fully a bullet wont enter freely. I suppose a really tight neck like some bench guns have may not fit this theory but I doubt your Arisaka is one of those.
Doesn't cost anything to check it out
 
Lot of assumption about case length. Unless you have cast your chamber there is no way of knowing whether case length is an issue or not

I will side with the guys saying that the case is not sealing the chamber from under pressure
 
You cocked up. I hate to say it, but Sunray nailed it. You should have sized, trimmed, chambered and deburred first. No piece of brass comes out of the box ready to be loaded. NONE. Laziness could have badly hurt you.
 
I knew I cocked up. I am glad my gun didn't get damaged or me. I could have kept it a secret, but there is a lot of knowledge on this site, so I wanted some feedback. I used PRVI cases, PRVI 303 (.311) 150 gr FMJBT and BL-C (2) powder. OAL was 3.130. Load load 41.0 gr to max was 44.0 gr. I was using around 42.8 gr + or - .3 of a gr. I was using my Lee anniversary loader, with a Lee powder loader. I have a Dillon 550 but I am waiting for the caliber conversion kits. By the way, I also have a type 38 that I load as well. PRVI cases and Hornady projectiles. Never had an issue with the type 38.
So my conclusion would be: Always prep your cases properly. Properly measure my powder. Experiment with different loads to come up with the best one that works with that particular rifle. And the best for last... Don't #### up....
 
Airbob10 said:
I knew I cocked up. I am glad my gun didn't get damaged or me. I could have kept it a secret, but there is a lot of knowledge on this site, so I wanted some feedback. I used PRVI cases, PRVI 303 (.311) 150 gr FMJBT and BL-C (2) powder. OAL was 3.130. Load load 41.0 gr to max was 44.0 gr. I was using around 42.8 gr + or - .3 of a gr. I was using my Lee anniversary loader, with a Lee powder loader. I have a Dillon 550 but I am waiting for the caliber conversion kits. By the way, I also have a type 38 that I load as well. PRVI cases and Hornady projectiles. Never had an issue with the type 38.
So my conclusion would be: Always prep your cases properly. Properly measure my powder. Experiment with different loads to come up with the best one that works with that particular rifle. And the best for last... Don't #### up....
Click to expand...

42.8 gr is in no way a "75%" load. It certainly should be sealing the brass to the chamber when you are only 1.2 gr below max. Can you post some pictures of the brass with the soot and hard extraction issues? If the neck was jammed into the rifling, there will be marks on it. I think there is something else going on here. I'm not sure what, but maybe some pictures will help. I would also do a pound cast of the chamber, or at the very least, a cerrosafe chamber cast. I don't like cerrosafe as it shrinks over time.
 
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