Low load density 110 sub loads

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martin_impact
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Low load density 110 sub loads

Post by martin_impact »

I got a couple of bullets left (.308 110 FMJ RN for .30 carbine) that didn't work out so well for cheap supersonic practice ammo. Feeding was fine despite the short lenght (~1.8"ish) however it seems the bullets really didn't like that fast 1 in 7 twist. They even keyholed.

Now since I'm also loading for other calibers, I usually got plenty of VV N320 and also some N310 and N340 at hand. Gordons reloading tool suggests load densities around 40% at theoretical velocities at the sound barrier.

I'm wondering If load densities this low should concern me, or should be fine for that type of powders.
They are on the lower side of some suggested .45ACP loads so they might be fine. Still I'm probably going to experience quite a bit of pressure and V0 variation depending on powder location, right?

What do you think? Worth to give those bullets a second shot for light (manual) plinking loads or not a good idea?
Any powder I should possibly favour?

I'm leaning towards the N310. It's the fastest with lowest load density (by a very small margin) but I heard it to be the easiest to ignite, so probably favourable in low load density applications. It will also produce the highest and fastest pressure spike, which might help to seal the case better and keep chamber and brass (outside) cleaner.
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bangbangping
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Re: Low load density 110 sub loads

Post by bangbangping »

Check out this thread...lots of low density loads including N320 on the first page. I've used N340 and 125 grain bullets with decent results.

In my opinion, the two biggest issues are the opportunity to double charge a round and the possibility of sticking a bullet in the barrel. Start high and work down, pay attention while charging cases. Light subs with fast powders are lots of fun.

Edit to add:
martin_impact wrote: Tue Jan 11, 2022 6:21 am Most likely. FWIW I just tested a 125 SMK sub load with N340. Six rounds each either raising or lowering the muzzle before firing. The raised (powder back) set averaged 1043 FPS while the powder forward set averaged 968. Also, the ES of the powder forward group was about twice that of the group with the powder against the primer.
martin_impact
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Re: Low load density 110 sub loads

Post by martin_impact »

bangbangping wrote: Thu Jan 13, 2022 10:59 am Check out this thread...lots of low density loads including N320 on the first page. I've used N340 and 125 grain bullets with decent results.

In my opinion, the two biggest issues are the opportunity to double charge a round and the possibility of sticking a bullet in the barrel. Start high and work down, pay attention while charging cases. Light subs with fast powders are lots of fun.

Edit to add:
martin_impact wrote: Tue Jan 11, 2022 6:21 am Most likely. FWIW I just tested a 125 SMK sub load with N340. Six rounds each either raising or lowering the muzzle before firing. The raised (powder back) set averaged 1043 FPS while the powder forward set averaged 968. Also, the ES of the powder forward group was about twice that of the group with the powder against the primer.
thanks. yeah, I saw that but it was with a bit heavier 150gn bullets I think, so I wondered how things might change going even lower in bullet weight, and with a faster powder (N310).

I'll definitely will watch out for double charges. Confirming holes on paper is a wise thing too for sure, however I guess that with the 8" barrel I got it shouldn't be a serious issue.

Loaded some since I got some advice in other forums too, will also have them pressure tested at a ballistics/firearms proof facility before firing them in my gun. Looking forward to testfiring. I really enjoy that stuff. Will keep you updated!
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Re: Low load density 110 sub loads

Post by Blowout »

I did a ladder using Evergreen 110gr M1 carbine copper coated bullets. Started with 12gr W296 and went up to 20gr. I was trying to to determine at what velocity the bullets might stay together and actually group.

Did an earlier workup at 17gr - 20gr and they wouldn't group and the copper coat was shedding from the bullet while coming out of the barrel. The linear comp was filled with copper shavings.

None of the 12g - 20g loads provided anything resembling a group at 25yds so I shelved the bullets. I guessed at around 17-18gr the copper coating was coming off the bullets. I wasn't checking during the shooting session as I should have been.

The 12gr - 14gr the loads I assume were subs because of the reduced sound level (didn't chrono them). I was using a 8.5" KAK barreled pistol.
300Blk 8.0" pistol with 80% lower
martin_impact
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Re: Low load density 110 sub loads

Post by martin_impact »

Thanks for the info! I dind't try any other than pretty much full power N110 loads but yeah... I felt like dumping a couple of those bullets in a 12 gauge shell would have been more precise...


After reading some more stuff on the topic and picking some brains of handloades with experience on reduced loads, I decided to jump the gun and shoot my loads before having samples of them pressure tested, since I felt pretty confident about them. At least pressure wise.

I did some simulation with gordons reloading tool and tried to modify all parameters as reasonable as possible to what I measured (case capacity, bullet lenght, etc...). I had some pretty good accuracy with it before, but mainly use it to get into the ballpark or to analyze tendencies. Also by viewing the pressure level vs. the barrel lenght graph and knowing where the gasport is I think you can compare loads and guesstimate if it will cycle the gun based on other loads characteristics. Which in this case, wasn't the case. Obviously.

So what I did was I just put powder in my Dillon powder measure/dispenser on my 650 and checked which powder charge a pre-set slider (for a N320 9x19 PCC load) it would produce and it put me right at 4.07grain (10 charge average, it of course won't dispense to this level of accuracy, even though N310 meters pretty well). Checking with gordon it predicted a V0 of almost exactly the sound barrier at 340m/s (1115f/sec) so I thought it would be a nice first load to try and compare to GRT predictions. I honestly was too lazy to fill up, calibrate and again clean my Charge master of powder for the 13 testrounds I made. So my plan was to chrono them and check them for basic function and accuracy, compare results to simulations and then work from there.

So data was:
PPU 110 FMJ RN bullets
Converted & neckturned(!) 223 cases (RUAG "T" stamped)
4.07grain of N310
COAL of 44mm (1.732")
S&B small pistol magnum primers

I first made 3 shots to check for POI, function, pressure signs, stability, Chronograph setup etc and then shot the remaining 10 rounds with alternating between two targets and also alternating between pointing the muzzle downwards and skywards before slowly bringing back to level to influence powder charge orientation within the case. Velocities were:
318 m/s - 1043fps
317 m/s - 1040fps
310 m/s - 1017fps

Accuracy wise, it really wasn't specatucal, however I also was struggling a bit to precisely line up my sights since the target was a bit in a darker area and the holosun with ACSS chevron reticle is really nice with using a magnifier but really not that enjoyable to use at 1x. I prefer simple 2MOA dots and dim them down for "precision" work, but couldn't really find a comfortable setting with the ACSS reddot in this situation.
But the good thing was, all impacts were nice and round. So no traces of keyholing, instability or jacket seperation.

Gun obvously didn't cycle (8" pistol with A5 H2 buffer setup on a law folding stock with 7075 spacer) but cases came out pretty clean. Even on the necks.

Velocities for the alternating target/powder orientation were:
in chronological order:
f - 315 - 1033
r - 320 - 1050
f - 308 - 1011
r - 316 - 1037
f - 310 - 1017
r - 320 - 1050
f - 312 - 1024
r - 316 - 1037
f - 311 - 1020
r - 320 - 1050
(shot 4 to 13, f: powder forward towards bullet, r: powder rearward towards primer)

The groups printed about 1" at 25m (~27yards) with one 2" flyer on the forward group which I suspect was caused by poor sight alignment.
There was a slight offset between the two about 45 degrees and 1/2". Since I alternated between the two I wouldn't suspect it to be a NPA issue, however with only 5 shots and stuggling with precise aiming it might just be the way statistics played out, and the whole accuracy potential with this setup is more like 1.5" at 27 yards. Next time I'll check at another range at 55yards with a different optic now I know they should fly table and somewhat straight.
It's also interesting to see that actually velocity seems to be influenced by powder charge orientation, but not that much.
Averages were:
Charge forward: 311,2 m/s - 1021fps
Charge rearwards: 318,4 m/s - 1045fps
Also the rearward charge orientation numbers printed suspiciously with alternating between 320/1050 and 316/1037. I doublechecked the numbers since It happened before I wrote down numbers from the wrong row of my magnetospeeds display. I don't know. Maybe the charge is super accurate and what I withnessed was the difference between three and two kernels of N310 inside the flashhole :lol:

So yeah, here it is. Results so far. Wasn't able to try them with a can on, since I'd first need a license to own one where I live and that might take a little while, but I can imagine how quiet those loads have to be. I also wasn't able to feel any "bolt bounce" trying to open with simply too little energy, but I might check with a slomo cam next time to see if there was any noticable movement at all without closing the gasblock. Might have been with a suppressor, but pressure drops pretty rapidly with N310 and there's also not much gas volume to work with...

I'll keep you updated on further testing.
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dellet
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Re: Low load density 110 sub loads

Post by dellet »

Port pressure has no meaning, muzzle pressure is what you need to look at.

The bolt won’t release until the bullet exits the barrel, and that will be the pressure at the port available to cycle the action.

If you are trying to get a 110 grain bullet to cycle in an AR, you need to heavily modify the rifle or move to a much slower powder. LT-30, CFE BLK, R-10 will all do it until the action gets so clogged up with unburned powder that it quits cycling.

Powders faster than 4227, 296 have a hard time cycling heavy bullets suppressed, never mind without one and a sub 150 grain bullet.

Always interested in new ideas and data, looking forward to more test results.
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martin_impact
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Re: Low load density 110 sub loads

Post by martin_impact »

Thanks for tuning in.
No, I didn't really intended to make those lightweight loads cycle the action. If I did, I probably would have looked for the lightest carrier out there (JP aluminium?) and run it with a SCS System with a custom spring, all weights removed or even a Custom "buffer" made from delrin. With a suppressor that creates much backpressure or a "booster" (Noveske KX3 or some stuff of that sort). And probably a slower powder thats not too messy as you mentioned.

But what I was basically trying to do is find a use for that 450 and something left .30 carbine bullets. And creating a super quiet manual load using VV Pistol powder seemed like an interesting way. Both to create a quiet load and to get some experience with reduced rifle loads.

Regarding the port pressure I was basically interested in the pressure courve from port to muzzle and see if I can draw some conclusions there.

With a 220gn ELDX VVN110 load I was at the very edge of reliable boltlock with a "H0" buffer and slightly lightened carbine spring (8" 1in7 Wilson Combat barrel). I didn't made any further measures to increase gaspressure/amount into the carrier or reduce moving mass, since a suppresser would very likely take care of that. Besides some load development and accuracy testing I feel theres no real point to shoot much of those subs until I got a suppressor anyways. So currently I'm more about finding a economical but straight shooting supersonic load. Those 110s failed miserably @ around 600m/s / 2000fps so next I'm gonna try some 124FMJs and also see if I find a subsonic load that groups those 110 FMJ RN well.

It might not be the best thread to ask this, but regarding subsonic loads, whats your considerations when choosing the velocity you want your load to be at? I understand that the sound barrier is not really a "fixed wall" but rather a zone where certain areas on the bullets tip might actuall start experiencing supersonic airflow before something like the main mach cone forms. So I guess it's a mix of making sure the bullet will experience no supersonic airflow because of both sound level and stability reasons. If the Load had perfect velocity consistency (ES =0) where would you want the V0 to be and considering reality with some incosnistencys and V0 variation I guess you would want the typical highest reading V0s to be below that so your average V0 will be even lower, right? Makes sense?
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dellet
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Re: Low load density 110 sub loads

Post by dellet »

You’ve clearly done a lot of research on the technical part of shooting, so will not answer you directly concerning velocity, other than right ES/SD numbers when compared to a bullet drop calculator can be very enlightening concern vertical spreads on target.

Some things to think about.

Long range shooters look for a load that will not drop below 1350 fps before hitting the target.
Palma shooters use very specific bullets knowing that their bullets will drop below 1350.
Precision air rifle shooters stay around 950 fps.

Sub sonic or reduced load rifle shooters can’t figure out why for the most part their groups suck.

4227 is a very versatile powder and does very well with reduced low density loads.
300 Blackout, not just for sub-sonics.
martin_impact
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Re: Low load density 110 sub loads

Post by martin_impact »

Thanks, that's both helpful and interesting.
I've done a few of those V0 spread calculations to see how things would print on further targets, I think Brian Litz advised it in one of his books. I'm aware I might not get the best results with N310 however after doing some research it seemed like a pretty interesting powder. I used it (and mostly N320) in some PCC loads for USPSA/IPSC type competitions and usually got plenty of it at hand and it's readily avaliable where I live.
I'll check out 4227 too, but I'm not sure I'll use it in the long run since I'd probably only buy it for an application that's not too high on my priority list (reduced loads), but still interesting.

950ish is interesting. I guess most handloaders like the idea of staying as close to sonic speed as possible to not give up more energy than what is necessary while keeping sound levels low. I think I'll try a few more loads with the 110s and see if I find some more accuracy "down there", once I mounted a more suited optic to test group sizes with. Might also do the same with the heavier sub loads. Also got some 220 Berrys to try out.

Also funny you mentioned palma shooters. I'm not a long range shooter (because unfortunately I'm lacking the time/capacity to shoot all the disciplines that are interesting) but for my "short" barreled 308 (20") I felt like a 155 scenar would be one of the bullets that would make sense when trying to reach out a bit further, because of not really having the capacity to accelerate heavier VLD bullets to adequate velocities. The 155 scenar seemed like a good idea because it's got a pretty high BC for it's weight and should reach somewhat acceptable velocities out of the short 20" barrel. Now that you mentioned that those palma bullets are designed to do well in the transsonic zone, I'm wondering how well 155 scenars do there, since they are pretty long for their weight. Hadn'd had the chance yet to test them further out than 300, because IPSC consumes me :lol:
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Re: Low load density 110 sub loads

Post by martin_impact »

I'm back with a couple more results. I loaded 20 more with the same specs and took them out to a 50m / ~55yard range with a 4x scope.
It was on the cold side and I struggled a bit with beeing comfortable off a bench (I prefer prone) so I likely caused more flyers than the load itself, but it seems there's some potential here.

Raw numbers were:

Min 304 / 997 Max 323 / 1060
Avg 312 / 1024 S-D 4.8 / 15.7
ES 19 / 62

Series Shot Speed
1 1 304 m/s 997 fps
1 2 313 m/s 1027 fps
1 3 319 m/s 1047 fps
1 4 307 m/s 1007 fps
1 5 306 m/s 1004 fps
1 6 313 m/s 1027 fps

1 7 313 m/s 1027 fps
1 8 316 m/s 1037 fps
1 9 309 m/s 1014 fps
1 10 304 m/s 997 fps
1 11 313 m/s 1027 fps
1 12 315 m/s 1033 fps
1 13 314 m/s 1030 fps

1 14 313 m/s 1027 fps
1 15 323 m/s 1060 fps
1 16 316 m/s 1037 fps
1 17 315 m/s 1033 fps
1 18 316 m/s 1037 fps
1 19 315 m/s 1033 fps
1 20 310 m/s 1017 fps

I made no effort to influence charge orientation other than letting the bolt go home the same during manual cycling and not shaking the carbine after loading the next round. Shot off a bench, rear unsupported only with my left hand, front (BCM foregrip) on a sandbag.
Made 6 shots to check chrono, get somewhat comfortable and do a rough zero, followed by a 7 shot group where I struggled a bit with NPA and trew them sideways a bit, 6 shots were within a ~0.65" vertical though, with one 1.1" high flyer that however was very close to average V0, so probably my fault too.
Second group (shot 14 to 20) looked like this:
Image
(x-ring dia just shy of 1")
left cluser: 313, 323, 316, 315
high single: 316
right double: 315, 310

So I don't really see a correlation of V0 and shot placement. It was probably all me and the loads potential after some more dialing in of my marksmanship fundamentals would have probably been in the 0.4" range at 55 yards. Probably.
Ask me again in one year or so, since I started working on those fundamentals again. Currently I can only exclude obvious called flyers (like those I just mentioned briefly in shot 7 to 13) and try to intrepret the patterns and data I get.
Also the pattern of having two groups within a group (like the 4 clsuter and double) usually means either having a mechanical issue, or beeing good at repeating a marksamship fundamental mistake. I bet on the latter. Another reason why I suspect the load to have quite a better potential then the first glance at this group might make one suppose.

At least the V0 data seems mostly uncompromised, so maybe trying other primers, uniforming neck tension or throwing charges more consistently than a dillon or so will show some better results. Any other ideas? Weighting bullets or brass? ...not really a fan of that :lol:

Coarsly running some numbers, the POI spread just by V0 spread within 304 and 323 m/s is about 14mm / 0.55" at 50m/55y when shot parallel to the ground. Which isn't exactly what happens when having it zeroed at 50m, but the program (JBM online) wouldn't let me input a constant launch angle and see how hits print at a certain distance with varying V0, or does it?
At least it seems to be in a reasonable range very close to what the "good shots" on my targets printed.
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