AR disease strikes again

[stagpanther]

Understood. But my point remains that the 350L chamber over-all best fit that allows the fullest use of the case for powder is with a spire point short base kind of bullet especially if you want to get anywhere close to winchester's somewhat broad-washed claims for the cartridge's performance.

[stagpanther]

Others have been having good luck sizing down 0.357 and 0.358 jacketed bullets. Most are sizing to 0.356 (0.355 is not a standard Lee push through size).

I don't know of any other spire point type bullets that are 357 or 356 (with the possible exception of the ftx, which looks more like an xtp fitted with a rubber nose. ; ) ).

[mehavey]

I've run .357 sizing in cast -- it liked the .358 "a smidge" better
I've run .356 sizing in jacketed, but no difference/improvement over just sizing down a thou from as-bought .358 (and that single thou is very smoothly done in a single step)

RE: the anomalous results when using the LEE 200gr cast and Lil'Gun...

wondering if the bullet was "stoppered" at the mouth/throat and ran up the start pressure

... I've run that LEE 358-200RF at the same freely-fit chamber OAL with about a half-dozen powders/loads and it's all been ho-hum-exactly-as-predicted. That Lil'Gun result, however was so totally off-the-wall/out of any extrapolation of previous baselines that I'm now think something else happened -- a specific "that bottle of powder" issue that I'm beginning to suspect. Will try something to isolate...

Film at Eleven....

[stagpanther]

... I've run that LEE 358-200RF at the same freely-fit chamber OAL with about a half-dozen powders/loads and it's all been ho-hum-exactly-as-predicted. That Lil'Gun result, however was so totally off-the-wall/out of any extrapolation of previous baselines that I'm now think something else happened -- a specific "that bottle of powder" issue that I'm beginning to suspect. Will try something to isolate...

Lil Gun is notorious for it's potential for incomplete powder combustion and can send a column of powder down behind the bullet--it's by far my favorite powder for pyrotechnic special effects out of my 16" lever gun carbine. I know Hodgdon lists it for the 350L--but I would pass on it, I use it in "roomy" pistol cartridges with large primers. Maybe you had a secondary bore pressure spike after the extraction started?

[mehavey]

... the state (Iowa) that specified at least 0.357 minimum diameter (instead of 35 cal), was not paying attention
to the fine print when they wrote their rules. They wanted to allow the 357 magnum, but did not realize that
an ammo maker can ship "in spec" 3[57] magnum ammo as small as 0.355.

I think Winchester used this argument to get them to accept the 350L.

Ahem..... this number look familiar ?

(Aaaahh, eeeerrrr.... That's my 1894 Marlin 357 groove diameter slugged just now.)

[stagpanther]

I guess that means I can go hunting with my LC9?

[P Flados]

9mm does not meet the Iowa rules (see below).

Center-fired straight-walled rimless cartridges chambered for handgun use with bullets from 0.357" to .500" diameter and a case length from 0.850" to 1.800"

Center-fired straight-walled rimmed cartridges chambered for handgun use with bullets from 0.357" to 0.500" diameter with a case length from 1.285" to 1.800"

In addition to the rules, they have a list that includes:

.357 Magnum
.357 Maximum
.38 Super

Note that the bullet / bore of the 350L is not much different than the 38 Super.

Building an AR pistol set up to run hot 38 supers could be interesting for someone expecting close range shots.

[mehavey]

...bullets from 0.357" to .500" diameter....

...irrespective of size what it is when it leaves the muzzle.



I can't explain myself, I'm afraid, Sir
… because I'm not myself, you see...
...we're all mad here. ...
(and I do so love the Red Queen)

[stagpanther]

Building an AR pistol set up to run hot 38 supers could be interesting for someone expecting close range shots.

I converted a Glock 20 to 9 x 25 Dillon with a 8 inch barrel--it is far more interesting than the 38 super IMO (I have a colt commander in 38 super). Getting someone to ream a Dillon chamber in a 9mm blank is far harder than you might think.

[stagpanther]

Thanks to mehavy (sorry if you didn't want me to spill the beans) who was kind enough to lend me a 350L magazine--I went out and tested some loads again today--though it was a bit futile--temperature is in the 20's with winds in the 20 to 30 mph range. Nonetheless, the rifle cycled flawlessly with the magazine with no issue whatsoever, which is good since I've heard some people were having issues with cycling the 350 L in a semi-auto.

[stagpanther]

BTW--the hornady brass appears to be significantly thicker at the mouth than starline's, I'm guessing something around .003 thicker. That might explain the better seal against gas leakage down the side of the case.

[stagpanther]

I think when/if/hopefully someone like Speer maybe comes out with a 160 gr hot core or barnes comes out with a 140 tac TX--then we'll see a real world reliable 250 yd DRT medium game 350 L cartridge. I suspect winchester will "delay" the release of their 150 gr extreme point as long as they can while they remain the only conduit for it in their loaded factory ammo.

[P Flados]

Stag,

You (and quite a few others) seem be more concerned about range limitations than seems to be appropriate in my opinion.

Folks are getting their hands on the Hornady 165 FTX bullets and others are getting good accuracy with the both the 150 and 165 factory deer ammo. The 165 will have a little more drop than the 150, but it seems to be a reasonable choice if you are anticipating longer shots.

Based on good reports out past 200 for these bullets, I am betting they do fine for expansion at any range where there is a good confidence in shot placement.

Wind drift is usually a bigger uncertainty than drop for most long range real world hunting applications.

Now a really good shooter (can read the wind much better than I ever will) with the right tools (range finder, electronic gadget with gun specific drop and drift info) and the right setting (plenty of time, stationary target standing broadside, wind not too strong, gusty or shifty) can use his modern technology to dial in scope adjustments to get within say 2 moa of perfect for drift and drop (this number would be smaller for a 300 Win Mag). The 2 moa value above is the only piece of the puzzle that is cartridge specific.

Now add in the other stuff. With bags and/or a bipod, this hunter with the skill of a sniper can probably hold within 1 moa even in a field setting. Given a 1 moa gun/load (and this includes uncertainty for temperature swings) his total uncertainty is around 2.5 moa using the square root sum of the squares method. This "optimum" condition would allow for ethical shooting out past 300 yards. This "optimum" condition is unlikely to come around for 99.999% percent of all 350L hunters in their entire lifetime.

Now lets swag some numbers for someone who is closer to say the top 1% of real guys that are both hunters and avid rifle shooters. He does his homework and has the tools to make good (within 3 moa) drift and drop adjustments (partially due to only going long when conditions are good). Lets say he is at 1.5 moa for hold but has a much better than average gun at 0.75 moa (again, long shots are only in optimum conditions). Using these numbers, the total SRSS uncertainty of 3.4 moa will stay in a 10" circle out to 290 yards. Using a Hornady 165 in this setting does not really sound any worse than a slightly flatter shooting Winchester 150. Both should still have adequate velocity for expansion. Both need drift and drop adjustments for good confidence at the ranges we are talking about.

If you can use any gun you want, and you expect a reasonable percentage of your potential shots to be over 200 yard, the 350L is not a good choice. You really want flatter shooting and smaller wind drift numbers. This is pretty obvious to almost anybody who knows enough about guns to consider shooting out past 200 yards in the first place.

On the other hand, the vast majority of hunters are good with a 200 yard (or less) effective range.

For the straight wall states, all of the guns with adequate terminal ballistics out past 200 yards have the same concerns for bullet drop and wind drift.

I really do not see a lot of disappointed hunters who pass up long distance shots because the feel they made a bad choice when they chose to use the 350L.

[stagpanther]

Well, I wasn't going to post this til next week--but had a change of heart cause I thought I should for safety reasons. However, I won't jump to any conclusions until i gather more information and try to get some input from industry experts.

Today I kaboomed my 350 L build.

As far as i can tell, i'm the first to achieve this dubious distinction with the 350 L.

The basics are this: I retested the same loads I shot yesterday because conditions were warmer and not nearly as windy. The first load was 28.9 gr of 1680 driving the 180 hot core sized to .357. The same load yesterday was getting me an average velocity around 2,065 fps +/- COL was 2.27. The one thing I did different today was use the starline brass untrimmed at around 1.704 as opposed to what I formerly trimmed to 1.701. While that is the only thing I changed, I don't see how this can account for a catastrophic failure. During loading I doubled checked my RCBS feeder against my balance--so I know that was OK. The dummy rounds made to the specs drop in and out of the chamber freely, and when dropping the bolt on a cartridge it comes right back out with no resistance--nor is there any evidence of the bullet engaging the throat or lands.

Here are the pictures of the failed case which ruptured on the side. Looking at the SAAMI specs--the area of expansion seems to match (.2") the depth of the area from the rim face to top of web. One key thing I never noticed before when looking at the SAAMI chamber specs--it appears that the headspace datum is actually the bolt breech face (in other words the case does not headspace off the mouth, at least as far as I can tell). I'm not sure how that works in the world of AR's, having never encountered that before.







The bullet exited only slightly faster than they did yesterday--around 2100 fps. the magazine was destroyed (sorry about that mehavy) the bolt extractor was (naturally) destroyed as well. The charging handle--which was old and well used/abused, failed the first time I mortared the gun. The bolt was seized in the upper due to the bolt lugs being locked to the case in the chamber and the carrier having back out.

Having kaboomed an AR before, I knew that if I could gradually work the lugs so they moved--and managed to turn the cam pin in the upper receiver slot enough--I could get the bolt and carrier loose eventually. It took me a couple of hours, but it worked. I took the entire upper apart inspected cleaned etc and didn't find any notable damage other than what I already mentioned. I do not believe this was an exceedingly high pressure failure as you might find in a powder pressure spike (which I've done) because there was no evidence of brass vaporizing, it seems to have simply shredded on the side of the head. Within two hours I completely repaired and reassembled everything, and went out and fired some factory hornady American whitetail. No issues. Also, as I had the barrel and components apart, I also replaced the Rex Silentium comp with a JP brake--the reduction of the concussive report sent back to the shooter was noticeable--at the price of only a slight increase in felt recoil--which now feels about the same as that of a 5.56 carbine. So what.

There's the basics.

[stagpanther]

Reincarnated rifle.

[mehavey]

I was going to say fail-as-bolt-was-opening/extracting, but after looking at that Ejector extrusion you're talking some extreme pressure before the case let go/before the bullet exited the barrel. Had the case not failed (when it did)/releasing pressure you would have seen much higher velocity still.

Since you & I are both seeing something that can't be explained even by loading blunder, I'd like UncleNick's opinion on reflected pressure wave thoughts.

[stagpanther]

I was going to say fail-as-bolt-was-opening/extracting, but after looking at that Ejector extrusion you're talking some extreme pressure before the case let go/before the bullet exited the barrel. Had the case not failed (when it did)/releasing pressure you would have seen much higher velocity still.

You can't see it in the pictures--but there's actually a small column of displaced material up the side of the head atop that expanded "plug" pressed into the ejector. Notice how the engraved lettering is intact on the ejector "plug"--as well as on the rim face.

[stagpanther]

Since you & I are both seeing something that can't be explained even by loading blunder,

Everything has an explanation--or at least I sure want to find out what it is. I'm sure if I called winchester and told them I used a bullet resized to .357 chances are they would say I took it out of specs and tuff luck on me (even though the SAAMI specs I see allow for a max of .357).

[9x19]

Glad you are uninjured... best of luck understanding The Incident.

[mehavey]

I'm sure if I called Winchester and told them I used a [handload of any kind ]...

It takes upwards of a 80-90ksi spike to produce that dramatic a depth of brass extrusion (which is what I'm keying on)*
(Experts/metallurgy guys chime in yeah/nay)
* is there any chance of soft brass in the head?. Are rims/web area growing on any of the other cases?

As you note, you are in bullet spec otherwise.


As to headspacing from the breech bolt face, all the rimless gas guns show that (look at the 30 Carbine drawing -- as the 350L ain't nothin' but the 30 Carbine on steroids)

OOC, what is the as-loaded mouth diameter ?






Again, will be very interested in what your engineering contacts have as thoughts/findings

[stagpanther]

OOC, what is the as-loaded mouth diameter ?

If you mean OD of case at mouth--right around .376. I measured hornady's factory stuff and it's about the same. I measured hornady's empty case vs an unfired starline and the starline is definitely thinner in the case wall around the mouth.

[mehavey]

.376" when loaded with the HotCores?
(I do know the factory Federals/Winchester are that. I would think the 357s might be .3775/.378") The chamber is (supposed to be) 0.3789"

But no matter (much) as long as the loaded cases drop in/drop out without interference.
Again, I'll be interested in alternate theories as they arise,

[stagpanther]

I just looked at your photo and then took a second look at my case. Something interesting I noticed. In your photo the area you call "the belt" and measured at .4 compared to a "normal" of .385 (I assume that's roughly at the top of the web) on my blown case it's all the way out to .42 +/- . My guess is that this area is analogous to unsupported area between the chamber face and bolt face rim/wall.

[stagpanther]

.376" when loaded with the HotCores?

Yes, the hot core sized to .357--in one or two cartridges maybe a hair over that. But the wall thickness is noticeably less on the starline wall at the untrimmed case length of 1.704 and probably accounts for "taking up the slack" of the thicker .357 bullet. I used lee's included 350L mouth expander and the tension to the bullet was not remarkable when seating it.

[mehavey]

Yup, that's web transition area, and when it gets blown, you're (we're) up there.

Just went down and sized some HotCores to 0.356 (no big deal) and yeah, the as-loaded mouth diameter/Starline is ~0.3765 - 0.3770.

FWIW: also measure random case lengths to be 1.702 - 1.7025 very consistent.