Apples to Apples....025" vs. .040"

[Richard]

OK, so here goes! Today I shot the EXACT same seven loads/bullets that I shot last week. And, in the same order. In fact, I have included last weeks sheet along with this weeks for comparison.
.45 cal. Rem/PN SML with fat 27 1/2" barrel and Leupold 16X Mk IV with mil dots.
As a note, last week out of 23 shots I 16 sticky primers. This week there were 15 out of 26 shots.
Weather conditions were similar both days with a little more sun last week. Temperatures were about the same with high humidity. Two foulers again fired prior to the actual testing. Again, Clays and H-4198 used on all seven comparison loads. An additional 3031 was shot as a single and with a booster. I will comment on load #8 first. The load was 85 gr. of IMR 3031 with a 300 gr. Sierra FN bullet. First shot................flames about 4' long came out the muzzle with a thundering BOOM and a velocity of 1667 fps! Shot #2 the same but at 1440 fps. As I had loaded only three vials, I decided to kick the last one with 5 gr. of Clays! The flames disappeared and the velocity went up to 2652 fps. You can see how they impacted on the target!
The seven targets and the loads are pretty self explanatory so I will not go into details about each.
So here is what I found but which did not surprise me since I had shot vent openings as large as .040 and larger. In fact, none of the first five loads showed any significant difference in velocity or accuracy from the previous .025" bushing opening and the present .040" opening with the flame channel opened to 7/32". When I shot the .025" bushing, the flame channel was 1/8". As you can see, the 300 gr. bullets both this and last week tightened up and extremely so with the 250 Parker BE and 250 Hornady SST.
What is obvious is that all the loads tested clocked lower velocities with the .040" bushing and 7/32" flame channel than with the .025" bushing with the 1/8" flame channel...............Which would lead one to conclude that the bigger opening in the bushing along with more space in the flame channel drained off some of the pressure ?
While I would have liked to shoot five shot groups to gain more data, I think the 3 vs. 3 gives a pretty good glimpse of the difference in the two sizes of bushings and flame channel. It did not seem to make much of a difference in the "stickness" of the primers. Some of the higher pressure loads did lessen the stickness to a degree. In any event, these primers showed no signs of BULGING AT THE SIDES...........Just the primer protruding rearward from the cup making it not want to slip off the bolt nose. In every case but one, only a single re-strike was necessary for free removal.
Richard

[jims]

I was awaiting this report as are others. I just wish you would get some "cold" weather down there. I would like to see what happens then. I am not wishing you bad weather, just would like to know what bone chilling cold would do in comparisons.
So do you have a preference or too early to tell?

[Deleted]

Thanks for testing Richard....

[rambler]

Thanks Richard!!!

[longbowshtr]

Thanks Richard!

[Alabama]

Richard thanks for the testing. In your opinion is there an advantage, disadvantage, or no difference in bushing size? I get the feeling from your post, your were expecting not to have sticky primers with the enlarged plug.

Is one apple better than the other?

[lwh723]

Good information.

I think group #8 is a testimonial for full-form sizing, considering the results Earnhardt has had with unboosted loaded of 3031.

[Richard]

Your right Luke! If you are shooting those large amounts of slow powder, you need resistance to build pressure and that is what you will get by full forming. On the other hand, if you like shooting land riders, you could shoot most any diameter bushing/vent hole without opening the flame channel. You can also use a lot less (faster) powder and get the same speed. I will wait for Earnhardt to chime in and see how he would like me to proceed. And no, I have not made a decision as to which is better. But here again, the sticky primer issue might just be related to the humidity? One week with cooler temperatures and low humidity and only one out of 21 sticky primers? Next two weeks high humidity and 75% sticky primers?
As I had indicated in previous posts, I had started out on many occasions with a new vent.......031" and ended up anywhere from .035 to .045" and never seemed to see any significant difference in velocities and accuracy and was having no sticky primers??.........Maybe the humidity was low those days? Still many unanswered questions. One thing it didn't hurt was those two 250 gr. groups:)
Hopefully, it will put to rest some fears that the big open hole would cause their primers and guns to blow up!
Richard

[Deleted]

Not to hijack your thread Richard but I shot my Sav-Pac yesterday with the .040 bushing plug drilled out to 7/32... Ran about 20 rounds of 78gns H4198 / 275gn MH through it. Avg 2810 fps.with a 24" barrel... No bulged primers. The extreme spread in velocity was 20fps which I think is good.I didn't experience any gain in accuracy over the stock plug with ventliners. The plug was clean at the end of the 20 rounds which is good thing... I think this load was at the max that I want to shoot and will probably drop it down to about 2700fps... The one that I did notice is when you shoot a primer it shoots twice as much fire out the end of your barrel than a stock plug and ventliner....What do I think?... For a guy who shoots like I do and doesn't want to break any speed records I'm not sure if it's a big deal. The big benefit is that I'll never have to clean the plug or have to change a ventliner again. Also I it's going to be a plus in shooting single powder loads.... Simple unscientific observations by a simple guy...
Zen

[Deleted]

Great comparison Richard!
I'm a little surprised that the velocity dropped like it did with the loads.
But what is very surprising is the low velocity of the IMR3031.
I've shot loads with IMR3031, with a drop down the barrel loose MH bullet and no booster and saw very little loss in velocity.
To me, that just shows how easy the thin jacketed bullets are to swell up (obturate) and fill the bore, and therefore build up pressure for the powder to work efficiently.
I've got nothing against the solid bullets, but it's just easier to get the MHs to work well with straight loads of slower powders.

I wonder if the velocity loss has to do with the booster powders in some way?
Maybe your gaining so much velocity with the .025" bushing with booster loads because it is more sensitive to the bigger powder chamber.
Whereas a straight powder load isn't effected that much.
Just curious

Can you try shooting next week without booster loads? Replace the booster with the same amount of straight powder (H4198) and see how it reacts. If the loads start to misfire or the velocities drop significantly, start shooting with the boosters again so it's not a wasted trip to the range.

Next time I shoot, Ill try some IMR4831 loads with a 327 MH and compare the .025" or .030" to a .040" in the plug.
To see how it effects ignition, velocity as ES.

Thanks again!

[edge]

Could the overcast/sunny conditions have an effect on the chrono readings?

edge.

[rangeball]

Sept 9, 2014 23:24:04 GMT -5 @panhandle said:

Not to hijack your thread Richard but I shot my Sav-Pac yesterday with the .040 bushing plug drilled out to 7/32... Ran about 20 rounds of 78gns H4198 / 275gn MH through it. Avg 2810 fps.with a 24" barrel... No bulged primers. The extreme spread in velocity was 20fps which I think is good.I didn't experience any gain in accuracy over the stock plug with ventliners. The plug was clean at the end of the 20 rounds which is good thing... I think this load was at the max that I want to shoot and will probably drop it down to about 2700fps... The one that I did notice is when you shoot a primer it shoots twice as much fire out the end of your barrel than a stock plug and ventliner....What do I think?... For a guy who shoots like I do and doesn't want to break any speed records I'm not sure if it's a big deal. The big benefit is that I'll never have to clean the plug or have to change a ventliner again. Also I it's going to be a plus in shooting single powder loads.... Simple unscientific observations by a simple guy...
Zen

Thanks Zen. This post made up my mind on what to do with my plug. I think the low ES shows you're achieving good consistent ignition and not having to clean the flame channel should also help consistency.

Sold!

[jims]

I am convinced to get the tungsten bushing but still not decided on the size.

[Richard]

Edge............when I shoot in the morning, whether sunny or cloudy, we always have shade in the area in front of our range so I am never (at that time) getting any glint or hint of sun in the photo cells. I just kind of doubt that is problem?

Earnhardt: Now the delima...............Do I shoot those straight H-4198 in amounts like 70 gr. and up with those same 200 gr. bullets or should I go up in weight?..........It might upset the APPLE CART? I kind of don't think the light bullets appreciate straight powders when riding the lands?
Richard

[Deleted]

Something I was thinking about, would not using a wad change accuracy with this new plug? If we are getting better ignition then it would also mean that the use of a wad isn't necessary, or is it. Maybe this could be part of the testing?

[Deleted]

You could try comparing some of those loads with a .025" or .030" bushing vs. a .040" bushing, without boosters in any of the loads.
But using the smooth formed solid coppers might make it difficult for some of the loads to ignite.

[Jon]

Good info. Thank you for all the work time and money spent. So many variables to try to find answers to.

[Richard]

I am getting some of those 290 TEZ's from Luke to play with bu t think I will definitely need a booster to get them grabbing the rifling. I am going to try 78 gr. of H-4198 and will shoot them with a variety of weight bullets and see what happens?
Richard

[Deleted]

Sept 11, 2014 16:00:14 GMT -5 Richard said:

I am getting some of those 290 TEZ's from Luke to play with bu t think I will definitely need a booster to get them grabbing the rifling. I am going to try 78 gr. of H-4198 and will shoot them with a variety of weight bullets and see what happens?
Richard

That's going to be very interesting.....that's where the ignition system  should shine.....good luck

[Jon]

Very interesting indeed

[longrange]

Looking forward to the results of 78 grains h4198