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N310/SVI, New to Reloading


IVC
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My SVI Limited with 5.4 barrel has finally arrived and after having some issues with the factory ammo I decided it was time to start reloading, both to get the feeding reliability and to get the slight edge in recoil. While I'm waiting for my pre-ordered Dillon 1100, I got a Forster Co-Ax as a future backup and as a ways to develop initial loads. I have all the measuring tools, including a chrono. So far, so good.

 

I talked to Casey over at SVI and he gave me a recipe that uses N310 and 1.200 COAL. I double checked with him that he didn't mean N320 (he didn't), so I wrote it all down, but felt a bit uneasy because N310 is one of the fastest powders out there and it's not listed in any manuals for .40. The long COAL is what made me feel a bit more at ease with respect to pressure, so I started at 0.5 gn less powder than the final recipe and put together rows of 10 rounds, each row with 0.1 gn more. I am loading Montana Gold 180 FMJ, using Federal primers #100. For the initial batch I measured each powder charge, partly to be careful, but most importantly because I didn't have a powder measure (only the trickler that came with the scale). So, now that I have been able to measure everything and collect some data, I have several questions.

 

(1) Is there any reason to use a very fast powder for .40 Limited? I understand why one needs slow powders for, say, 38SC in an open gun, but is there any reason to prefer one over another for Limited? Any idea why such a well established manufacturer suggests N310 when it seems almost everyone else uses N320 or slower powders? 

 

(2) My primers are not getting flat, but they do get somewhat less rounded then before firing. Is this because Federals are soft, or is this a sign of building pressure? There is no cratering and the speed/PF are all within range, but I understand that this doesn't mean the pressure doesn't spike during firing (which is why I'm worried about fast powders when I cannot measure the chamber pressure directly). 

 

(3) My final load, after getting Redding x10 powder measure, has the following velocity/PF distribution: 963 ft/s +- 7 ft/s (extreme spread 24), which is 173 PF (171 - 175). However, I've had a batch that had standard deviation of 17 ft/s (about the same PF). Are these numbers reasonable to be considered "consistent," or should I work on my process? Also, as a practical matter, should I drop the PF a bit and still be reasonably safe on a chrono stage?

 

(4) To me it seems that I should get better consistency if I use a powder measure than if I measure each load. The reason is that the scale has it's own inner inaccuracies and it only measures up to 0.1 gn. A good powder measure, on the other hand, can be calibrated once and then the inaccuracies only come from the small inconsistencies in the mechanical system that drops powder. I can measure 10 or 20 loads, divide the weight by 10 or 20, and get a very good value for the average charge weight. Is this correct thinking? 

 

As a final disclosure, I spent a lot of time in physics labs, so I am very familiar with measuring, setting up precision equipment, data collection and error analysis. 

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56 minutes ago, IVC said:

My SVI Limited with 5.4 barrel has finally arrived and after having some issues with the factory ammo I decided it was time to start reloading, both to get the feeding reliability and to get the slight edge in recoil. While I'm waiting for my pre-ordered Dillon 1100, I got a Forster Co-Ax as a future backup and as a ways to develop initial loads. I have all the measuring tools, including a chrono. So far, so good.

 

I talked to Casey over at SVI and he gave me a recipe that uses N310 and 1.200 COAL. I double checked with him that he didn't mean N320 (he didn't), so I wrote it all down, but felt a bit uneasy because N310 is one of the fastest powders out there and it's not listed in any manuals for .40. The long COAL is what made me feel a bit more at ease with respect to pressure, so I started at 0.5 gn less powder than the final recipe and put together rows of 10 rounds, each row with 0.1 gn more. I am loading Montana Gold 180 FMJ, using Federal primers #100. For the initial batch I measured each powder charge, partly to be careful, but most importantly because I didn't have a powder measure (only the trickler that came with the scale). So, now that I have been able to measure everything and collect some data, I have several questions.

 

(1) Is there any reason to use a very fast powder for .40 Limited? I understand why one needs slow powders for, say, 38SC in an open gun, but is there any reason to prefer one over another for Limited? Any idea why such a well established manufacturer suggests N310 when it seems almost everyone else uses N320 or slower powders? 

 

(2) My primers are not getting flat, but they do get somewhat less rounded then before firing. Is this because Federals are soft, or is this a sign of building pressure? There is no cratering and the speed/PF are all within range, but I understand that this doesn't mean the pressure doesn't spike during firing (which is why I'm worried about fast powders when I cannot measure the chamber pressure directly). 

 

(3) My final load, after getting Redding x10 powder measure, has the following velocity/PF distribution: 963 ft/s +- 7 ft/s (extreme spread 24), which is 173 PF (171 - 175). However, I've had a batch that had standard deviation of 17 ft/s (about the same PF). Are these numbers reasonable to be considered "consistent," or should I work on my process? Also, as a practical matter, should I drop the PF a bit and still be reasonably safe on a chrono stage?

 

(4) To me it seems that I should get better consistency if I use a powder measure than if I measure each load. The reason is that the scale has it's own inner inaccuracies and it only measures up to 0.1 gn. A good powder measure, on the other hand, can be calibrated once and then the inaccuracies only come from the small inconsistencies in the mechanical system that drops powder. I can measure 10 or 20 loads, divide the weight by 10 or 20, and get a very good value for the average charge weight. Is this correct thinking? 

 

As a final disclosure, I spent a lot of time in physics labs, so I am very familiar with measuring, setting up precision equipment, data collection and error analysis. 

 

N310 is good for the heavier bullets for the caliber -- especially when loaded long like that. For example, a classic bullseye load is N310 with 200 and 230 grain .45's.

I'm using 4.2g N310 for 180gr Ibejiheads RNFP coated, .401 diameter at 1.21 OAL out of a 5.4" SV AET barrel for 172pf (as per a calibrated set of LabRadar's).

I did a bunch of tests with my competition gun with N320 and N310 and various bullets and diameters and the N310 & .401 Ibejiheads was more consistent over the chrono and in a blind taste test shooting freestyle.

 

That SD & ES spread sound about right. For e.g. USPSA, you're never going to notice any difference in accuracy of that spread..

 

In terms of primers, I use CCI spp and don't have any problems.

 

With a dillon powder measure, I get very consistent 10 drop weights.

 

If you're new to reloading and paranoid, switch to N320 and go up about 0.5gr.

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Oh yeah... Note that MG's take more powder to achieve the same velocity. Both because they are .400 diameter and between their jacket alloy is very hard.  I didn't see any primer problem signs with MGs and CCI primers.

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In terms of the chrono rules, the idea is to make sure that you're at least 1.5 standard deviations above the goal velocity (and you're using a temperature stable powder) or 2x, if you're more conservative.  There have been some write ups of the math about that.

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50 minutes ago, candiru said:

Oh yeah... Note that MG's take more powder to achieve the same velocity. Both because they are .400 diameter and between their jacket alloy is very hard.  I didn't see any primer problem signs with MGs and CCI primers.

 

Great info - thanks. 

 

My target load is 4.8 gn of N310 and it's right on the money based on the velocity I was told it would achieve out of my gun (no surprise there, the guys who built the gun would know what they are talking about). You mentioned that MG are harder and need more powder (you use a good 0.5 gn less) - how do bullet type and the extra powder affect recoil? Is it about the same, or something noticeable?

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50 minutes ago, candiru said:

In terms of the chrono rules, the idea is to make sure that you're at least 1.5 standard deviations above the goal velocity (and you're using a temperature stable powder) or 2x, if you're more conservative.  There have been some write ups of the math about that.

 

That's a good rule of thumb. I'll stick to that and adjust the average of my load based on the standard deviation I'm getting out of my equipment and process. I'll wait until the progressive press arrives before finalizing the adjustments, though, as my SD is likely to change with the different press. 

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Great info - thanks. 
 
My target load is 4.8 gn of N310 and it's right on the money based on the velocity I was told it would achieve out of my gun (no surprise there, the guys who built the gun would know what they are talking about). You mentioned that MG are harder and need more powder (you use a good 0.5 gn less) - how do bullet type and the extra powder affect recoil? Is it about the same, or something noticeable?


The load I quoted was for Ibejiheads which are coated lead. The lead is soft compared to the hard jackets and so will seal up more in the barrel which means that it takes less powder to get the same velocity.

As for the perceived recoil, it’s effectively the same.
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I also have an svi 5.4 sight tracker.. I load 4.7-4 8 gr N310, fmj bullets out to 1.200 oal..mix brass, federal primers.. Për Casey suggestions.. This load is money for my sight tracker.. 

You are GTG!! 

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Bear in mind N310 is an extremely temp sensitive powder.  If your Level II/III matches occur in late summer, you are fine.  If in the Spring or fall, maybe not.

 

My goal for any load is single Digit SDs and strings of ten or twenty where no round dropped to minor.  I shoot for 172PF anyway, just because chronos are calibrated differently, and the setups are not always identical.  One shooter I know loads to 165PF.  That's just stupid.  He got dropped to minor at a major match and was livid.  He still loads to 165.

 

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6 hours ago, zzt said:

Bear in mind N310 is an extremely temp sensitive powder.  If your Level II/III matches occur in late summer, you are fine.  If in the Spring or fall, maybe not.

 

My goal for any load is single Digit SDs and strings of ten or twenty where no round dropped to minor.  I shoot for 172PF anyway, just because chronos are calibrated differently, and the setups are not always identical.  One shooter I know loads to 165PF.  That's just stupid.  He got dropped to minor at a major match and was livid.  He still loads to 165.

 

Ugh. No. VV powders are very much on the temperature stable side of reloading powders.  In other threads on this very forum, people have discussed this, such as the following https://forums.brianenos.com/topic/191646-temp-sensitivity-n320/ where it's mentioned that "The VV manual states their powders have a 1% velocity increase and 3% case pressure increase with each 18 degree (f) temperature increase."  So, you'll need to qualify your statement with more data as many of us have experience with it over reasonably wide temperature spreads and have seen (very) good stability. I have chrono results from the low 40's to 100 and the numbers are within the SD variability from batch to batch (.40S&W major loads).

 

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On the question of why use fast powders for limited guns, the general consensus has long been that fast powder + heavy bullet = less felt recoil.  If I recall correctly, the SAAMI formula backs that up.  

 

recoil-energy-calculated-2.png.21f6bb6c0de9d0fe8b79690b9a6bb654.png 

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Load:  RP case, WLP, 3.7ge N310, 200gr LSWC.  85 deg = 754fps.  41 deg = 705 fps.  30 deg = slide would not cycle.

 

That is a lot more than the 1% variance VV claims.

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On 5/24/2019 at 7:04 PM, ltdmstr said:

On the question of why use fast powders for limited guns, the general consensus has long been that fast powder + heavy bullet = less felt recoil.  If I recall correctly, the SAAMI formula backs that up.  

 

Thanks for this information - I hoped there would be a meaningful explanation beyond just basic preference. 

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UPDATE: I shot my first match with the SVI and my N310 4.7 gn, 180 MG FMJ, 1.200 coal reloads. No problems in feeding and no problems with ammo. It was pretty soft shooting so I'll consider this load to be GTG as Furrly suggested above. Just need to get used to the new gun. 

 

The only issue I had was feeding out of my Barney magazine - I used an MBX 10-round magazine as a dedicated Barney and the gun wouldn't go back into battery without a light tap on the back of the slide (no, I didn't ride the slide). My guess is that it has to do with the very long coal. The 4 other SVI mags fed without any problems. Anyone had similar issue with MBX vs. SVI? 

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MBX mags need to have the spring conditioned before use.  New springs are long and strong.  Load the mag fully and let it sit for two weeks.  That will cure the problem.  If there is a lot of angle to the follower, bend it so it sits flatter.

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18 hours ago, IVC said:

UPDATE: I shot my first match with the SVI and my N310 4.7 gn, 180 MG FMJ, 1.200 coal reloads. No problems in feeding and no problems with ammo. It was pretty soft shooting so I'll consider this load to be GTG as Furrly suggested above. Just need to get used to the new gun. 

 

The only issue I had was feeding out of my Barney magazine - I used an MBX 10-round magazine as a dedicated Barney and the gun wouldn't go back into battery without a light tap on the back of the slide (no, I didn't ride the slide). My guess is that it has to do with the very long coal. The 4 other SVI mags fed without any problems. Anyone had similar issue with MBX vs. SVI? 

I have found that svi pistols are finicky with any mag other the svi mags.. I run mbx on my other limited blasters but have found that svi mags run without a hitch on my svi sight tracker..svi pistol grips have a unique mag dimension.. From day one I ran with Brandon and Casey recommended.. It's been spot on.. 

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A somewhat unrelated question (don't want to start a new thread). I have a small(er) batch of Montana Gold 200's - I ordered them at the same time as the 180's thinking that it would be nice to experiment. While it seems that the consensus is to use 180's for matches, I would like to play with the 200's in practice since I already have them. 

 

What's a good starting point when switching to 200's? I assume coal should stay the same for feeding purposes, yet that will result in smaller internal volume after (longer) bullets are seated. Any good rules of thumb? 

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