Case Filling - does it affect accuracy

Case Filling - does it affect accuracy

Joined: June 19th, 2016, 9:39 pm

December 14th, 2016, 9:16 pm #1

Hi Again

I've just got a ransom rest so will be testing soon but a query for the experts.

I've heard lots of varying opinions on the effects of case filling and the impact on 38 wadcutter load accuracy. Most of the powders I use for 38's are really low volume (titegroup/N310) but in your experience do you think there is an impact?

Thanks in advance
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Joined: November 16th, 2014, 3:55 pm

December 16th, 2016, 5:55 am #2

Hi

Yes!
I have used 3,0grs N310 with 125grs H&N WC for many years, now I use 3,4grs N32C TinStar, nearly 100% filling volume.
Very precise, clean and nearly no speed oscillation

Try it
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Joined: January 22nd, 2012, 7:12 pm

December 17th, 2016, 1:25 am #3

Hi Again

I've just got a ransom rest so will be testing soon but a query for the experts.

I've heard lots of varying opinions on the effects of case filling and the impact on 38 wadcutter load accuracy. Most of the powders I use for 38's are really low volume (titegroup/N310) but in your experience do you think there is an impact?

Thanks in advance
Well, I'm stating no, it will not have a noticeable effect on accuracy in a 1900 era cartridge like the .38 special, especially with capacity filling hbwc's.

the evidence is some of the most substantial on record.

Bullseye, ww231, WST, titegroup, N310

they all have shot record scores.

Jim
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Joined: September 8th, 2014, 8:24 am

December 17th, 2016, 8:07 am #4

I would have to agree with you Jim. Over countless years and even more 1000's of rounds through a 38spl at target velocities, ISSF and PPC I have found no discernible velocity spread with the light quick powders. I would add 452AA to that list also until it was discontinued. Using Bullseye through my mod 14 and 2.1gr loads I can consistently get under a 3fps spread over 12 round test. I have tested the bulk fill powders and find them very pressure spike sensitive when getting to capacity. I'll stick with Bullseye, WST and N310.

cheers
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JB
JB

December 17th, 2016, 7:41 pm #5

Along with the effect of accuracy is on going question about free space in the case. Vihtavuori Manual warns against under load detonation causing pressure spikes possibly when the powder lays flat down in the case away from the primer and towards the front of the bullet base. Some call it flash over. Some claim by holding gun vertical before firing and then horizontal changes velocity and pressure ratios noticeably. Allegedly even recoil will transfer position of the powder in the case in under loaded cases. Their are many opinions and conjectures regarding this. The straight wall .38 special case and .357 cases(shooting .38 special loads) especially vulnerable regarding this phenomenon. Claim is shot to shot deviations in velocity and pressure are normally increased when using loads that leave the case half empty, therefore not recommended for target loads according to them.
Not sure if this is gospel or still conjecture.
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Joined: June 19th, 2016, 9:39 pm

December 17th, 2016, 7:45 pm #6

I would have to agree with you Jim. Over countless years and even more 1000's of rounds through a 38spl at target velocities, ISSF and PPC I have found no discernible velocity spread with the light quick powders. I would add 452AA to that list also until it was discontinued. Using Bullseye through my mod 14 and 2.1gr loads I can consistently get under a 3fps spread over 12 round test. I have tested the bulk fill powders and find them very pressure spike sensitive when getting to capacity. I'll stick with Bullseye, WST and N310.

cheers
Thanks guys, I'm still learning as I'm a fairly new ppc shooter and have found h&n HBWC heads with N310 very accurate, although will need to ransom rest them.

The lead shoot nicely although they are a bit dirty but the 125g copper coated waddcutters seem to be the preference in mainland europe with the australians using swc heads recessed into the case and I just wonder what the benefit of each is.

I'm the only club member bar one shooting lead with the rest using the copper plated.

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Joined: August 21st, 2013, 3:31 pm

December 17th, 2016, 9:15 pm #7

Hi Again

I've just got a ransom rest so will be testing soon but a query for the experts.

I've heard lots of varying opinions on the effects of case filling and the impact on 38 wadcutter load accuracy. Most of the powders I use for 38's are really low volume (titegroup/N310) but in your experience do you think there is an impact?

Thanks in advance
On the question of case filing and unused space. There have been many discussions and opinions about filling unused space in certain cases, the .38 special and .357 case, straight wall cases as such. Vihtavuori Manual warns that "when using a large amount of free space the shooting characteristics can vary widely depending on the location of the powder.In some cases can actually double the pressure. Can effect velocity changes between first and following shots. Recoil can reposition the powder in the case having the same effect. Powder position can be altered just by position of the muzzle direction and movement of the gun. The shot to shot deviation in velocity and pressure are normally increased when using a load that leaves the cases half empty, there fore not recommended for target loads"
The risk of under load detonation becomes a risk, especially when using loads with any of the smokeless powders and can generate a burn of a shock wave to detonate instead of a normal burn of the powder that could cause damage to gun or injury to shooter. T
This theory has been around for some time and there are many arguments pro and con about this. Some call it flash over. If it is true it can definitely effect velocity/pressure and in turn accuracy.

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Joined: September 8th, 2014, 8:24 am

December 17th, 2016, 10:47 pm #8

Have to agree with you Jim, I can remember when people ran away from Bullseye in droves due to reports of detonation with small charge loads and it flashing across the top of the charge therefore not "burning" as such. So 30 years or so on, we're still using Bullseye and still the same charge weights, I haven't heard of a gun blowing up in oooohhh how long?? There definitely is a difference in velocity spread from first shot to subsequent shots, all due to powder placement. I have tested countless rounds fired over a chrono with load loaded in the horizontal position in relation to rounds loaded in the vertical position against first shot vertical to subsequent horizontal shots. Yes, less air space is good for consistent velocities with small powder weights, the bulkier the powder negates the issue. Just a personal powder preference, adapt and overcome....

Irish-PPC, I am one of those australians using the rounds in question. 38spl case with 2.1g of Bullseye and a 100g SWC sunk 3mm down in the case is my fave. I am getting fantastic accuracy out to 50yds with minimal recoil, as with this discussion thread I find that I get no unburnt powder and the velocities are extremely consistent.
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Joined: August 21st, 2013, 3:31 pm

December 17th, 2016, 11:17 pm #9

Tony,
Now you have my attention. You say 2.1 BE. with a 100 grain SWC and getting fantastic accuracy out to 50yards.
1. Is this a cast boolit or swaged?
2. What is the actual oal of loaded round?
3 Roll crimp or taper crimp
4. What kind of groups are you getting, center to center?
5. Getting any tipping?
6. Any idea of velocity?
7. What kind of brass?
8. What primer?
7. Shot from machine rest,bench rest?
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Joined: September 8th, 2014, 8:24 am

December 18th, 2016, 12:44 am #10


JB, details are as...


1. Is this a cast boolit or swaged? - swaged and powder coated

2. What is the actual oal of loaded round? - 1/8th" below case mouth on a 38spl case.

3 Roll crimp or taper crimp - Taper of course, doesn't work harden the case as much. Makes for easier loading during fast runs.

4. What kind of groups are you getting, centre to centre? - If I could load a picture I would. Up and down around the 1 1/2" side to side less than 3/4". we're more interested in the side to side as that is a true capture of the group size. we've both been around long enough to know that there are too many variables to accurately give an up/down group. Try the link below for photo.

5. Getting any tipping? - None

6. Any idea of velocity? - including SD and MAD
662.9
666.7
661.1
660.3
678.3
665.9
665.9

6.6 - SD

5.3 - MAD


7. What kind of brass? - Win is the only brass that will fit in my gun, PMC too thick in the case wall, haven't tried Starline.

8. What primer? - Fed 100's of course

7. Shot from machine rest,bench rest? - ransom rest, takes the idiot factor out of the equation.

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