June 7 at the range..............

[Richard]

Well, I was all set to start shooting 300 yard bug holes with my new bore guide set up...................... ::)NOT!
It does work just fine. With the guide on the barrel, the push rod which is .434" in diameter goes thru the .438" hole in the guide and enters the bore of the barrel with out touching the crown. The bore of course is .450" . The rod only goes into the bore about 3/8" It seats a SST with the nose just flush with the crown. That means the .434' rod inside the .450 bore leaves just .008" of free play on either side. While not perfect, it keeps things pretty well lined up............I think?
I started the morning off with a slightly tweaked duplex I have been playing with the past two weeks. This week its 10 gr. of 4759 under 61 gr. of 322. I shot it at 100 yards using the Nosler HP's and was pretty well pleased with the 1.1" five shot group. I immediately went out to 300 yards and substituted the SST. Not really great Yes, three in a row went into 3" but five doubled that. By the way, I forgot to use the stadia lines and shot the straight cross hairs. So, you can see from the 100 yard group exactly the drop at 300 aiming dead on at both distances. Next I tried the same load again but this time used the second stadia line aiming at the same bull............it hit high.........similar group size
The next three groups were all with different duplex's of unknown accuracy potential
Based on the potential of the first load at 100 yards, this bullet/bore alignment thing did not prove to be the Holy Grail
Richard

[Dave W]

It is only a couple groups but I am not surprised. It is impossible to tell what happens when the fire hits the sabot, unfortunately SS deleted the pics in the link I provided in the other thread with the stretched sabot petals. If the sabot is not uniform and respond consistently and the bullet does not obturate the same every time it is hard to repeat results every time.
At one time Edge posted that the Parkers are out of round and possibly the .452 250 SST, if the 40 cal fodder is no different, you are shooting an out of round bullet from the start.

I know you are not a believer in knurling, but every all copper bullet I have ever shot(A LOT) shoots significantly better when knurled with less sabot failure. My gun is also one of the guns that shot the 195 BX better than the SST's and XTP's.

FWIW one of my best saboted loads averaged 1.9?? at 200yds. Averaged for an entire fall and winter and I only shot 3 shot groups, my .50 cal does that! I was severely depressed after sinking that much coin in a conversion and my groups were not what I expected. I'm sure there are other shooters and rigs that do better, but mine wouldn't and that is why I went sabotless.

[wilmsmeyer]

I'm of the opinion that a sabot with consistent petatl to petal thickness, centered on its base, and bullet with a "normal-for-us"bearing surface self centers itself. Not sure what any gadget can do to help this. Once the combination is 3-4 inches down the barrel, it is almost impossible to impart seating pressure that would tend to crush one petal to one side. That's my opinion and I've never seen anyone show a test that shows otherwise. And in the 1st 3 or 4 inches you would almost have to try and mess up the seating function to impart enough lateral pressure on one side or the other to adversely damage one petal while leaving an opposing petal "un-squeezed"

If the petals are all the same and the bullet is consistent....what possibly could off center things? If the bullet is somehow deformed or the sabot is not consistent petal to petal, what could possibly fix that???!

If I remember correctly, RB shared the same opinion.

I will watch the results of bore guides but I am not convinced they will help much. Only one way to find out.

[Deleted]

See what the noslers will do when you get a chance, they were acting nicely at 100 yds.
I'm sure this has been brought up before, Do you pre pack your powder before you load your bullet? If not I guess the assumption is that the cup of the sabot will do it during seating.
With your duplexs do you tap the barrel or another method of leveling powder before you add your main powder ? I am going to try some 4759/4198 duplexs next time I shoot and wanted to see if you had any loading technique tips to share .
Thanks ,
Greenhorn

[Richard]

I always tap the barrel several times. Particularly with the starter charge since I want it to settle into the recessed BP (which hold about 11 gr. of N-110) I shyed away from the noslers and XTP's at 300 yards since they usually do not fare very well. The SST's have always shot better. There just does not seem to be any rhyme or reason? Three good one here.........two good ones there? I try to stay objective but I am convinced my trigger pulling is not the problem. My set up to too rock solid and I can feel the trigger break with the cross hairs dead still and centered. All my loading procedures are very methodical and as consistent as possible. My lead sled recoils about an inch and with the grease on the rubber feet (which are sliding on aluminum plates) it is a very smooth rearward push. The 100 yard group was very round which indicates no vertical or horizontal forces. Just frustrating that these things can't be made to shoot bug holes at those longer distances on a more regular basis. As bad as the 8.5" group was, if centered, it would be a dead deer but just not win any shootin' contest
Richard

[deadeye]

richard-those are good mz groups for you-you need to 'practice what you preach" & disclose the bad groups also! ;D

[deadeye]

all kidding aside-think about this. your temps there are probably higher lately. so you have your cool-rod in & you load. your barrel is warming the second you remove the cooler. i doubt your routine is exact on time to the second the trigger is pulled. one time your barrel might return to say 65 degrees,the next loading takes you a little longer it might be 75degrees. unless you have a external barrel cooler also to keep it exact ? i got to the point here i would not even shoot sabots unless it was 50degrees or colder,the colder within reason the better the groups & consistency.

[fishhawk]

Again, here's my point about tight groups at long range with the low BC bullets. The columns don't line up but with only 5mph come and go wind not changing directions equals 9.1" diference in impact point.

Input Variables Firearm type Rifle Sight Height 1.5
Bullet Weight (grains) 200 Ballistic Coefficient .200
Muzzle Velocity (fps) 2800 Temperature 59
Barometric Pressure (hg) 29.53 Relative Humidity 78%
Zero Range (yards) 100 Wind Speed (mph) 5



Ballistics Table in Yards 200 gr., .200 B.C. www.hornady.com

Range (yards) Muzzle 50 100 200 300 400 500
Velocity (fps) 2800 2574 2359 1960 1607 1315 1109
Energy (ft.-lb.) 3482 2943 2472 1707 1147 768 546
Trajectory (100 yd. zero) -1.5 -0.1 0.0 -4.8 -18.8 -46.5 -94.6
Wind Drift (inches) 0.0 0.2 0.8 3.7 9.1 17.9 30.5
Come Up in MOA -1.5 0.2 0.0 2.3 6.0 11.1 18.1
Wind Drift (moa) 0.00 0.18 0.39 0.88 1.45 2.14 2.91

[edge]

IMO, if you get a good group at 100 why switch components when going longer?
Even if I wanted to use the SST I think that either my first 300 yd group would be the Nosler OR at least when the SST did not meet my expectations I would then shoot the Nosler.....but that is just me

edge.

[Richard]

I'm with you Edge................I was thinking about that but the XTP's and Noslers have never been that good at 300. Last week the SST's produced good results so that was the reason Oh well, it gives me something to try next week ;D I have to keep dreaming up new things to try
Richard

[Deleted]

Richard ,
What fishhawk is saying is you did everything right the low bs i mean BC of the bullets gave you the dispersion or has to be recognized as some of the reason for it.
Rossman get us some lazer beam mls and we wont have no issues to deal with,lol.
I think he has a point,
Greenhorn