How to Blow Up Your Rifle ( not mine)

[truck driver]

There is a fellow over on Long range hunting forum that did just that with what he thought was a safe load of Retumbo. Here's a link if you care to read about it.
https://www.longrangehunting.com/thread ... le.196142/
He was testing 190gr ABs and 230gr Bergers in his 300Rum in -30*F temps.

 

[DON]

I read this thread. Not sure exactly what caused the problem he experienced and I'm not referring that his powder was the problem. But working with Retumbo in my 300 RUM and the 200 AB I did notice it would pressure spike. That's one of the reasons I elected to go with RL-25. I'm glad he wasn't injured. I must add here that Retumbo produced really good velocity too.

Don

 

[gbflyer]

Scary. Too bad some gun savage wasted the action. Most likely unnecessary.

 

[TackDriver284]

Wow. Retumbo is what I use in the 7 Mag with 160 AB and it shoots great. Just got me thinking if 3,140 fps is a tad too fast. I just never had any heavy bolt lift or seen pressure signs with the brass. My load developments was in the hot dog days of summer. Hard to imagine that a very slow powder like Retumbo can pressure spike especially like faster powders do.

Could it have been any other factors besides the powder?

 

[gerry]

I saw that on another site and will make the same comment here. Something other than a pressure spike is very likely to be the problem. Maybe a wrong bullet in the box or much more likely he put a charge meant for a 190 under a 230 gr bullet. Plain and simple the guy screwed up. On related note if someone is getting bad pressure spikes he is already loading too hot and is "tickling the dragon" as our good friend DrMike is fond of saying.

 

[truck driver]

I've never used Retumbo but did experience a heavy bolt lift when shooting Swift Sirrocco II bulets in my 338Wm after shooting Nosler PTs with what I thought was a safe load well below max.
What does shooting two different brands of bullets have to do with it my guess is metallurgy.
Different jacket materials cause different amounts of fouling causing higher pressure.
The post doesn't say if the rifle was kept in a warm place prior to shooting but the ammo was. Wondering if condensation had froze in the barrel between shots semi plugging the barrel.
I have seen my rifles sweat in cold weather between strings so I try to let them cool between shots and not let the barrel warm to the point that it will sweat.

 

[Polaris]

I have noted a cold-weather phenomenon in a much more sedate caliber. Was loading 46 gr BL-C2 in 30-06 under 168 bthps. Load was tested and used extensively in warmer weather. I placed well in an OTC match with it. When I fired it near the zero mark, I got a barely perceptible delayed ignition, and bent an oprod. Flashover. Powder is heated to the combustion point, but lags a bit to overcome the thermal inertia, when it does, it does so very rapidly and spikes pressure. In my case, it bent an op-rod in my M1 Garand. I suspect a similar phenomenon here with the very large charge of very slow burning powder in extreme cold.

I was able to replicate the effect in an old bolt action secured in a vice and triggered remotely. Showed moderate pressure signs... somewhat flattened primer and slight sticky extraction with a load that should have been in the 45K psi range or lower. Pulled down remainder of loads and powder charge was within spec, BL-c was the only possible ball powder in my inventory at the time. Sent the powder back to hodgedon, and they confirmed it was within specs and not contaminated or deteriorated. They were unable to replicate the condition in their lab with the same lot of powder.

After this occurred, and while searching for a new op-rod, I read up on the phenomenon. It is not well understood, as it is difficult to replicate under lab conditions. Contamination with lubricants and tumbler media lodged in flash hole were other suspected causes. My procedure eliminates these possibilities. I do not tumble after sizing, use an alcohol soluble lube and an alcohol wash with thorough dry time under mild heat prior to priming and charging.

 

[TackDriver284]

TD, I used to drag my rifles out of the house and head to the range in hot /humid weather early mornings and once I set up at the range, my rifles condensates due to the hot / humid temps when I pull them out of the cases because the rifles were inside the house 30 minutes prior and the rifles are cold before pulling them out. I dislike cleaning my rifles due to that reason.

I always clean my barrels if changing to a different bullet before shooting.

 

[truck driver]

TD, I used to drag my rifles out of the house and head to the range in hot /humid weather early mornings and once I set up at the range, my rifles condensates due to the hot / humid temps when I pull them out of the cases because the rifles were inside the house 30 minutes prior and the rifles are cold before pulling them out. I dislike cleaning my rifles due to that reason.

I always clean my barrels if changing to a different bullet before shooting.

Yeah I have seen this happen also and found that storing the rifles over night in the basement at lower temps help solve that problem when going hunting or to the range.
It takes me 1&1/2hrs to get to my range and then a 1/2hr to set up with the rifles laid out so they reach air temps before I shoot them. I also alternate rifles between shoots to give them more time to cool down now that I have seen them sweat in cold temps while shooting caused from barrels heating up when shot multiple times in a row.
Talk about cleaning this discussion has made me think I need to clean the 338Wm before I shoot the swift bullets so I don't have any foreign fouling in the barrel since I last shot it with PTs.

 

[SJB358]

I’m with Gerry. This is a shooter/loader induced problem.

I thought at one time Retumbo was spikey but it turned out it was a brass problem in my 264.

TD, 3140 is slightly faster than I’d expect but I’ve done 3075-3100 with 24” 7 Mags for years with 25, Retumbo and Magpro and never had a snicker of an issue.

 

[35 Whelen]

Ditto what Gerry said
And you gotta love Dr Mikes sayin " ticklin the dragon" lol

 

[preacher]

TD-That Swift bullet is softer/more ductile jacket material and core. The Partition of the Nosler PT does not obturate easily. PTs go fast for less pressure than the 'sticky" softer makes that "bump up" (obturate easily). They usually foul more, yes, but the fouling isn't the culprit. Hawks are the same way. The first Barnes X were softer than the XBT later model. The Swift A-Frames are about halfway between the Scirocco and the Partition, in my experience. Hornady's are hard jacketed, slow to bump up and can usually go fast w/o the pressure of, say Speer or Sierra. Interesting though, aint' it?

 

[longrangehunter]

I read that post a week ago over at LRH.com. I worried about that back in 2010-'11 w/RETUMBO in my 6.5/300 WSM, and come to think of it why I only run the 140's at 3,000-3,050 fps. Seems like a wise choice now, and why I don't like heavy on the powder loads even in a custom action way over built then his Remington 700.

 

[FOTIS]

You walk on the edge of the cliff you might fall off!

3129 in a 300 rum with a 230 gr is ridiculous! 2900 is more like it

 

[bowfishn]

Man some of you guys, and you know which ones, are like a pack of Wolves.
If you read the OP's post you would see guy was using loads with both bullets a few grains under book loads. 91.6 gr Retumbo with 190 ABLR Fed 215 primer Coal of 3.600" look in Nosler loading data 95 gr Max, the load that caused problem was 86.8 gr Retumbo behind 230 gr Berger Fed 215 primer Coal of 3.600" Look in Berger loading data 88.2 gr Max.
The speed recorded at 3129 with the 86.8 grains of Retumbo Behind the 230 Berger was the first shot after shooting with the 190's, it was the fluke overload most likely upwards of 95K to 100K pressure.

A charge of 91.6 Retumbo would not have caused that much pressure, the wrong powder loaded by mistake yes that could have, but he would have already found that out when pulling some of the round he had loaded. Also the reloaded ammo he has he is sending in to be checked. Before making unfounded accusations about what you think he might have done get your facts straight.

 

[Ehgbyf]

I blew up a short action Remington 700 a few years ago. Chambered in 300 whisper and I had a double load of aa#5 with a 220 grain bullet. It blew the bottom metal open and cut my arm pretty bad. I can’t believe it did not blow the suppressor off the barrel. It is the loudest gunshot I have ever heard. It rang my ears for days. I was shooting off the hip through a chrono. This is the only thing that saved my eyes. I still have a bone fragment in my right hand that pokes the skin when I move my left thumb. Scared the hell out of me.

I had to buy a new ptg bolt and have the barrel set back and rechambered.

 

[FOTIS]

OK then I will re-phrase...carelessness has its consequences. Is that better?



The reason I was a wolf above (should have read the whole post) is that people with RUMS have a tendency to load to the max and above due to the super tough brass.

3500 fps with 180's and 3200 plus with the 200 grainers is undoable safely. I get those #s from my 30-378 and that is almost max in my gun.

 

[FOTIS]

Cartridge          : .300 Rem Ultra Mag
Bullet             : .308, 230, Berger Hybr G7 #30430
Useable Case Capaci: 96.163 grain H2O = 6.244 cm³
Cartridge O.A.L. L6: 3.598 inch = 91.39 mm
Barrel Length      : 26.0 inch = 660.4 mm
Powder             : Hodgdon Retumbo

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-20.0   85    76.00   2450    3065   38182  11117    100.0    1.753
-18.0   87    77.90   2507    3210   41091  11253    100.0    1.693
-16.0   90    79.80   2563    3355   44231  11384    100.0    1.638
-14.0   92    81.70   2618    3501   47624  11512    100.0    1.584
-12.0   94    83.60   2673    3648   51292  11637    100.0    1.532
-10.0   96    85.50   2726    3796   55252  11757    100.0    1.482  ! Near Maximum !
-08.0   98    87.40   2780    3946   59483  11873    100.0    1.435  ! Near Maximum !
-06.0  100    89.30   2832    4097   64020  11986    100.0    1.389  ! Near Maximum !
-04.0  102    91.20   2884    4249   68891  12093    100.0    1.346  !DANGEROUS LOAD-DO NOT USE!
-02.0  104    93.10   2936    4403   74126  12197    100.0    1.305  !DANGEROUS LOAD-DO NOT USE!
+00.0  107    95.00   2988    4559   79758  12295    100.0    1.265  !DANGEROUS LOAD-DO NOT USE!
+02.0  109    96.90   3039    4717   85822  12389    100.0    1.226  !DANGEROUS LOAD-DO NOT USE!
+04.0  111    98.80   3090    4877   92361  12477    100.0    1.189  !DANGEROUS LOAD-DO NOT USE!
+06.0  113   100.70   3141    5039   99422  12561    100.0    1.154  !DANGEROUS LOAD-DO NOT USE!
+08.0  115   102.60   3192    5203  107060  12638    100.0    1.120  !DANGEROUS LOAD-DO NOT USE!
+10.0  117   104.50   3243    5370  115336  12710    100.0    1.087  !DANGEROUS LOAD-DO NOT USE!

 

[longrangehunter]

You walk on the edge of the cliff you might fall off!

3129 in a 300 rum with a 230 gr is ridiculous! 2900 is more like it

Yep! That's as fast as I run that same bullet in my 300 NM in the TRG...... I just figured why bother going any further since it was a bug hole, and said "good enough for the chicks I run with"!!! lol