To duplex or not?

[Richard]

To duplex or not?
Weather yesterday morning at 6:30 a.m. was 70* with little to no wind; humidity was somewhat less than the past few weeks but the mirage picked up considerably by mid morning. Again, Clays and H-4198 powders used on all loads including singles; .060” veggie wads used on all bullets; full Formed bullets were all of the .451” variety and knurled up in and around .454” before being run thru Airborneike’s FF die. The cool rod used on and off after about every 3 shots to keep the barrel from getting hot vs. warm!

To foul the barrel is used the 225 FTX FF with a 5/65 duplex. The first shot printed out of the five shot group although velocity wise it was right with shots 2 & 3? In any event it left the last four shots in a .867” 100 yard group.
At this point I was attempting to showcase three progressive duplex loads and try to come up with which might be better suited to the Kentucky Challenge? They would be 8/60, 9/60 and 10/60 along with the 290 gr. Barnes TEZ FF.

Starting with the 8/65 I got an average of 2688 fps (10’ from muzzle-Pact chronograph) with a 19 fps ES and a 3 shot .867 cloverleaf.

9/60 yielded 2707 av. With 17 fps ES and a somewhat vertical 1.1” three shot group.

10/60 gave 2719 fps with 32 fps ES but a Five shot .711” group slightly horizontal. Edge had noted in some of my past groups with 10/60 that they had very little vertical although some horizontal………..which is evident here.

Moving on to a 250 gr. TEZ FF with the same 10/60 duplex I got an average velocity of 2779 with a whopping 70 fps ES? But a nice little .499” three shot group? A contention of mine has been that you can still get small groups with large ES’s at close range.
Don’t feel that because I put some of my opinions on paper that they are carved in stone because many times they come back an bite me! I just look at “stuff” over a long period of firing many shots, some “trends!”

For the benefit of Riverrat who questioned why I don’t test single powders? I loaded up Five vials of 72 gr. H-4198.

The first group ( or start of a group?) was with this 290 TEZ. Velocities wee 62 fps apart and the two bullets printed 2.1” apart and I scrapped the remainder of the group.

With only three vial left I went to the 300 gr. BE FF and here go much better results posting .742” group at 2767 fps with 17 fps ES (chorono only captured two shots- sun getting into photo cells likely). Noticeable with both groups was a more distinct/heavy recoil than occurs with the duplex loads.
So much for 100 yard testing. The next two are shot at 300 yards!

290 TEZ FF with the 10/60 duplex. Started out hitting the steel target to check on POI; then five shots at the target. Vel. for all six shots was 2729 with a 51 fps ES (the first shot at the steel was the slowest and opened the ES from 40 to 51? The first three shot did well at 1.822” with shots 4 & 5 opening the group to 3.1”

The final group with the 250 TEZ (chrono only captured the first shop) and 10/60 duplex gave a nice three shot .719” group! I was tempted to shoot five but was instructed NOT to!

So, a little more testing/tweaking next week before the Challenge; with the likes of quite a few good trigger pullers being in attendance, it will be interesting to see how things shake out.
Richard

upload an image

how do i print screen

[Dave W]

Duplex.
We must be the only ones those 70 ish gr charges of 4198 does not shoot for.

Nice shooting and good luck/skill in a couple weeks.

[Mid_Tn_Plowboy]

If I can figure out how to get rid of my vertical stinging that occurs in my N110/H322 loads.... Duplex for sure. I have little to no horizontal.

[Dave W]

Aug 5, 2015 12:44:43 GMT -5 Mid_Tn_Plowboy said:

If I can figure out how to get rid of my vertical stinging that occurs in my N110/H322 loads.... Duplex for sure. I have little to no horizontal.

Load, bullet, etc.?

[Deleted]

Thanks Richard, what this tells me is that with "harder" bullets you'll for sure need a duplex to get good obturation. The softer bullets like BE's you can get away with duplex however, why, maybe simplicity. I don't plan on single loads but it's neat to see the difference. Today's range report might be different than tomorrow's range report with same loads but still a great report! Very informative.

[Richard]

Thanks Dave but there is a lot of good shooters coming!
Chad........I think you nailed it. The softer the format, the easier to get fattened up with single powder loads. I saw that after those first two shots.
I am hoping Edge can come up with some advice for me to reduce that vertical on the last group!

[Deleted]

It seems as if I have vertical stringing also so I'm curious as to what his fix would be.

Seems as if I read some where that the bedding job could have something to do with however that's me reading it somewhere so I could be wrong.

[Richard]

I know for 100 % that bedding is not the issue with my rifle. Many of my loads have absolutely no vertical and if it was bedding, they probably all would show signs of it. If that was a 100 yard group there might be some concern.......Particularly if it was with my match rifle. However when your looking at one of our ML'ers, how many people would be concerned with a 3/4" vertical group, even at 100 yards? Heck I see guys come to the range to sight in their hunting rifles and are happy as a pig in dung with any kind of a 1 to 2" three shot group at 100 yards. To them, its "meat on the table!"
I was really just messing with Edge as he is a person who really looks at my groups and actually reads the text and deciphers what is what. He picked up on that 10/60 load with the 290 as having virtually no vertical, just horizontal. And, you can see some of that horizontal in group #4. While it was only 3/4" at 100, it could have been 2 1/4 at 300 with probably little to no vertical. I have to believe it is a combination of the bullet and load in this case.
Now, when you look at group #5 the 10/60 with the 250 TEZ, it is virtually round at 100. If you then look at the same combination at 300 and project that sub 3/4" group back to 100 you would be looking at a .239" group and could probably not even see any vertical? That 10/60 load has shot round groups with various other bullets at 100 and even 300 that could not be considered vertical......So to me, it just the particular load, not bedding. A rest set up or variable shoulder pressure will cause vertical.

[Dave W]

Was the same POA used on groups 4&5 and 8&9?

[Mid_Tn_Plowboy]

Aug 5, 2015 13:46:02 GMT -5 Dave W said:

Aug 5, 2015 12:44:43 GMT -5 Mid_Tn_Plowboy said:

If I can figure out how to get rid of my vertical stinging that occurs in my N110/H322 loads.... Duplex for sure. I have little to no horizontal.

Load, bullet, etc.?

10/60 N110/H322 300hp ff, it did the same with 200sst/ N110/H322 10/50. Great horizontal but they pattern vertically. I haven't tried any N110/H4198 duplexes.

[edge]

I am certainly no expert at shooting...not by a long shot

Here is something that I read a long time ago on load developement, yes of course it is from the Houston Warehouse 

"Virgil said his practice was to seat the bullets so the engraving was half as long as the width of the lands. He noticed an interesting phenomenon with rifles that could really shoot: if the bullets were seated a little short and the powder charge was a bit on the light side, the groups formed vertically. As he seated the bullets farther out and increased the powder charge, the groups finally became horizontal. If he went still farther, the groups formed big globs. He said the trick is to find the midway point between vertical and horizontal. That point should be a small hole."

My take away is that you probably just need to tweak.
Personally I would leave the booster alone and add/subtract 1 and 2 grains from the 4198 with the bullet combos to see what combo gave the barrel harmonics to produce a bughole, you might prefer to adjust the booster instead. I chose the 4198 since it is 6 times the mass changing it will move it incrementally and still give the "bump up" that your bullets seem to like.
IMO, changing both at the same time would be wrong as with changing any two components  would be.

The groups look good to me, and my only preference for a horizontal group is that at least some of the dispersion is the wind so it is not load related, also since my target of choice is Whitetail deer the boiler room is slightly wider than it is tall leaving more margin for error horizontally

edge.

FYI, if anyone is interested in reading Secrets of the Houston Warehouse it is now available in pdf here:

precisionrifleblog.com/2013/10/18/secrets-of-the-houston-warehouse-lessons-in-extreme-rifle-accuracy/

OR directly here:

2poqx8tjzgi65olp24je4x4n.wpengine.netdna-cdn.com/wp-content/uploads/2013/10/secrets-of-the-houston-warehouse-by-dave-scott-precision-shooting-magazine-special-edition-1-1993.pdf

[Deleted]

Edge, did you say tweak it or did you say you like to twerk it like Millie Cyrus? Lol

Seriously though thanks for the info. Next time I make it to the range I'll have several loads to try.

[Richard]

Dave: Actually the POA for the 290 was dead on the bull using the second BDC @ 20X (group #8) For #9 I used the same (2 nd) BDC @20 X but held at 6:00 (5" under) on the bull below. I came up with that POA based on a shot I put on the adjacent steel target and where it hit.

Unfortunately we do not have the option of seating the bullet closer or further away from the land as Virgil did. ( I read that article when it first was published in PS magazine. Great article)
I was looking back thru my note book on loads and found others with the 10/60 that produced some horizontal with the 290 TEZ yet, I found some 300 gr. SST's with that combination that produced very round bug holes. Then there was that .063" three shot bug hole with the 10/60 load but the 290 TEZ was smooth sized rather than FF'ed? It has got to be some "harmonic" thing! So, that is what I will play with?--------------------10 and 59 on Tuesday

[Deleted]

Knurling the bullet up and full forming might be the vertical stringing also??? Are you indexing your full form bullets? @ 100 yards I didn't see a difference in my group when I was knurling up the SST then full forming however at 200 yards it was huge! Maybe a 5" group at best. I felt if I indexed I might see a difference in group size but never tested it. To me smooth form is a hunting man's tool to greatness. Less to worry about and easier in the field. So I never went back just don't see the advantage over smooth.

Their are some that have full form figured out and that's great I just can't quite get a handle on it. So smooth it is!

[rambler]

Aug 6, 2015 12:27:04 GMT -5 @78riverrat said:

Knurling the bullet up and full forming might be the vertical stringing also??? Are you indexing your full form bullets? @ 100 yards I didn't see a difference in my group when I was knurling up the SST then full forming however at 200 yards it was huge! Maybe a 5" group at best. I felt if I indexed I might see a difference in group size but never tested it. To me smooth form is a hunting man's tool to greatness. Less to worry about and easier in the field. So I never went back just don't see the advantage over smooth.

Their are some that have full form figured out and that's great I just can't quite get a handle on it. So smooth it is!

Do you guys use course files or medium when you knurl?

[Dave W]

Aug 6, 2015 12:07:10 GMT -5 Richard said:

Dave: Yes, same POA!
Unfortunately we do not have the option of seating the bullet closer or further away from the land as Virgil did. ( I read that article when it first was published in PS magazine. Great article)
I was looking back thru my note book on loads and found others with the 10/60 that produced some horizontal with the 290 TEZ yet, I found some 300 gr. SST's with that combination that produced very round bug holes. Then there was that .063" three shot bug hole with the 10/60 load but the 290 TEZ was smooth sized rather than FF'ed? It has got to be some "harmonic" thing! So, that is what I will play with?--------------------10 and 59 on Tuesday

Looks like the additional speed the 250 gets from the same load nearly canceled out the BC advantage the 290 has. Virtually identical POI's at 100yds and a negative inch or so at 300yds for the 250.

[Dave W]

Now you threw me a curve, you were editing while I was typing.
Be interesting to see the same POA for both bullets.

Plowboy, I would try altering the ratio to see if that cures the stringing.

[edge]

Aug 6, 2015 12:07:10 GMT -5 Richard said:

SNIP.
that produced some horizontal with the 290 TEZ yet, I found some 300 gr. SST's with that combination that produced very round bug holes. Then there was that .063" three shot bug hole with the 10/60 load but the 290 TEZ was smooth sized rather than FF'ed? It has got to be some "harmonic" thing! So, that is what I will play with?--------------------10 and 59 on Tuesday

I would not be surprised at all if you found that the 290 TEZ shot best with load X and the 300 XTP liked load Y and that the 300 SST liked load Z since they rarely show the same size shape groups with the same loads.It is pretty certain that it is not your shooting ability or the consistency of your lead sled.

While knurling could certainly contribute to bullet concentricity issues I would rule that out at 90% since you have some groups that barely deviate from a straight line and the odds of that happening seem very small indeed.

IMO, the bullet construction, jacket material/thickness/mono metal, at the moment of ignition determine the exact harmonics since everything else in the loads has been identical...the base of the bullet is in the exact same position no mater the bullet weight or construction.

edge.

[rangeball]

I agree with edge. Harmonics at play. You can tweak loads to find the sweet spot, but ultimately I wonder if something like this would be much easier-

www.amazon.com/LimbSaver-Sharpshooter-X-Ring-Barrel-Dampener/dp/B00Z6K10HQ

Reviews are certainly favorable, and its cheap enough.

Richard, it would be a neat test to see if you can use the same load and bullet and manipulate the location of this thing to show horizontal, vertical, then like baby bear just right.

[Richard]

Range...............I have had one of those things around here for a number of years. I played with it on my bench gun but never got anywhere? When they first came out, I would see them on a few guns but little by little they seemed to disappear? Even the screw on tuners? On the LR rifles I almost never see them. .22 bench rest rim fire?.......definitely and some short range CF BR. I have to look and see if I can find it? But like a lot of that Limb Saver stuff from a few years back, they often got "sticky!" If I locate it and it has not turned to mush, I would be willing to give it a try. It might be that because these barrels are pretty thick that it may have little effect if any? We will see! The problem with tuners is they need to be adjusted for the load. The mechanical type have graduations on them much like our scope turrets where you can get back to a previous setting....not quite so with the Limb Saver. I kind of have a feeling they come under the heading of "snake oil!" or another gadget to get tossed in the drawer. If they worked that well, everybody and their brother would have one on their rifle? Just saying?

Edge.........what I was doing this afternoon was going over my notes and reviewing which load and which bullets gave me round bug hole groups since I started shooting this barrel some 13 weeks ago. It is invaluable to keep good clear notes as a reference. Every one of those sheets I post here go into a loose leaf folder and I can just page back and look for good groups and what load was used.

Dave........the reason I changed POA was I wanted to try to keep the shots in the intended bullseye. When I shot the Gong, I saw I was about for or six inched high and hence the change in POA.

[edge]

Aug 6, 2015 12:07:10 GMT -5 Richard said:

SNIP--------------------10 and 59 on Tuesday

IF Virgil was right that a weaker load tends to be vertical and a hotter load tends to be more horizontal (edit) then your 10/59 SHOULD be less horizontal and that will be interesting to see. Will it be that way, who knows but it will be a great experiment, thanks for trying it

edge.

[Richard]

Got them already loaded up!

[Deleted]

It's crazy how little variations in powder mixes can change everything, I've found in my Macgowen, with 275 Match Hunters that 12/58 is the most accurate load for it in cool weather, while 10/60 and 11/59 still both shoot MOA or better, sometimes the smallest of changes in loads can make a world of difference in group size, as well as the conditions outside.
Same gun, 69gr of H4198 with a 275BE didn't look all that impressive and I almost didn't even test any further, bumped it up to 70gr, instant bug hole, ya just never know unless ya test and test alot.. much of the painstaking process is taken out by members of this board, thank you all.... cause there are so many good base line loads to start out with, it saves time, money and our shoulders..

[Richard]

I guess that is what makes this game interesting? All the various combinations that can be played with. Probably for the majority of hunters, if they get a load that shoots well enough to take deer (or whatever?) at the distances they hunt, then they are satisfied and do little testing. On the other hand, since I don't do the hunting I used to and am more interested in punching paper, this playing with different loads allows one to gather a lot of useful information plus a lot of fun bench time.
Tomorrow I will trade the ML'er for the bench gun (6mmBRX) and fire around 65 shots at 600 yards. If the weather cooperates I will be hoping to average in the low 2" or high 1" range for 8 five shot targets!

[rangeball]

Richard, if you can find it, it would be interesting to see if it works for you.

[Richard]

Its been quite a few years since I last saw it but think I actually tossed it! I will check?

[schunter]

Aug 7, 2015 13:49:14 GMT -5 Richard said:

I guess that is what makes this game interesting? All the various combinations that can be played with. Probably for the majority of hunters, if they get a load that shoots well enough to take deer (or whatever?) at the distances they hunt, then they are satisfied and do little testing. On the other hand, since I don't do the hunting I used to and am more interested in punching paper, this playing with different loads allows one to gather a lot of useful information plus a lot of fun bench time.
Tomorrow I will trade the ML'er for the bench gun (6mmBRX) and fire around 65 shots at 600 yards. If the weather cooperates I will be hoping to average in the low 2" or high 1" range for 8 five shot targets!

Good luck tomorrow! Not that you need it.

Scott

[miketodd58]

I googled one of Mr Hankins old posts about duplexing and he had this to say.

SNIP.

Richard is mainly a Duplex shooter so that comment by a Singles shooter is off topic...thanks, edge.

[Richard]

SChunter..............Glad we got together today!

[schunter]

Richard, I enjoyed meeting you as well.