troy fairweather
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The bullet is out of the barrel before the rifle starts moving, could be your getting some movement in the gun from the hammer falling like flintlock shooters.
Help me diagnose these grouping issues
- Thread starter JimGnitecki
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You definitely are consistent in POI in the first 2 photos. So second photo with 2 fliers seems like you or a bullet casting issue or bullet weight. The 3rd photo is basically vertical stringing which I think is most likely related to where you place the barrel and your holding technique. Of all my grouping issues, I have dealt with and resolved a lot of vertical stringing problems. Adjusting stock and barrel, determining best resting placement, cheek weld and stock to shoulder weld. All those need to be correct to avoid vertical stringing.
JimGnitecki
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Yes, the "right" place to rest the front end of the rifle is, like, "the best powder out there", subject to ongoing debate. I tried multiple different points under the barrel, and the rifle seemed insensitive to it. Then my best froend's other buddy, who shoots a lot of BPCR, said no, the rest should be under the wood forend! So, I tried that and got good results.
The baby powder and mallet tests did not provide any enlightment on my specific rifle. I am unable to sprinkle baby powder onto the barrel because of the full length telescopic sight. I tried, but the powder did not change at all when I fired the rifle, and it made a horrible mess that took a long time to clean off. The mallet test was also non-definitive: the sound was identical no matter where I struck the barrel.
Determining the best point at which to support the front end of the rifle is evidently a black art requiring special insights I lack.
Jim G
JimGnitecki
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I read your post with great interest. The only 2 cents I can pitch in are tips for the RCBS scale.
Warm up as you are doing, wipe down with a dryer sheet.
Check under the platen where the pressure measuring cell is and be sure there is no powder granule in there.
I block off the HVAC vent to stop any drafts.
I level the scale.
I check it against a beam scale for accuracy.
Blow out the measure before changing powders.
Explanations on request.
But you knew all that, right?
Yes, your list is omprehensive and I have done all I can there!
Jim G
Interesting, then I have one more suggestion and that is have you slugged the barrel to see what the real diameter is ? If yes, then it is shooter error or you have not found the right powder primer combination. I know Pedersoli rifles are normally .458 diameter but on occasion I have seen a couple that were .457 or .459. Since you are shooting cast bullets you should have better results with bullets at least .001 to .002 from the bore chamber to engage the rifling a lot better. Also check the diameter of the bullets from your molds.The twist rate is 1:18. I also do not want to drop the velocity, as I am trying to keep the bullet supersonic to avoid transonic effects as long as possible on longer range shots. Also, I HAVE during ladder testing tried velocities encompassing about 1060 fps through 1400 fps, and the lower velocities did not improve accuracy with my specific rifle even at short ranges, let alone at longer ranges. The rifle seems to prefer higher velocities. In fact, the really low velocities tried gave pretty disappointing results. Unfortunately, this makes the recoil issues with a 500g bullet even more significant, but I am finding that if I hold the rifle properly, the shoulder bruising goes away.
Jim G
JimGnitecki
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The rifle was slugged by a pro gunsmith as being .4563”. The bullets are being sized to .4595", so .0032" of interference fit, which is perfect. And the local BPCR experts say that Accurate 5744 is THE go-to powder. And my SDs when I properly cull the bullets are mid single digit. I currently believe that the outlier shots are being caused by one, or a combination of, of the following:
- Improper shooter hold or position with a new rifle still being adapted to
- Inappropriate engagement of the rSchnabel forend's slope and flare with the front rest assembly
- My inexperience with casting good quality bullets from a brand new mold
- Inadequate bullet quality culling
Jim G
AJC1
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Slip on recoil pads are amazing. They do add to lop which only helps me. Here's one of mine...The twist rate is 1:18. I also do not want to drop the velocity, as I am trying to keep the bullet supersonic to avoid transonic effects as long as possible on longer range shots. Also, I HAVE during ladder testing tried velocities encompassing about 1060 fps through 1400 fps, and the lower velocities did not improve accuracy with my specific rifle even at short ranges, let alone at longer ranges. The rifle seems to prefer higher velocities. In fact, the really low velocities tried gave pretty disappointing results. Unfortunately, this makes the recoil issues with a 500g bullet even more significant, but I am finding that if I hold the rifle properly, the shoulder bruising goes away.
Jim G
As an added benifit they help me by not slipping on my shoulder while shooting offhand. It makes a huge difference
JimGnitecki
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AJC1
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I'd put a piece of tape on your stock and use it to reference your rest position for a while. Some rests have stock stops to aid in repotition. If it doesn't help tape peels right off and move on. I'm keen on blue painters tape for these exercises
JimGnitecki
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I use 5744 on my Sharps too. My last recommendation would be to use .458 diameter cast bullets then. The .4563 is basically .457 and if .458 does not shoot to your satisfaction than the .459 will do. Please keep us posted and good luck.
JimGnitecki
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WHY do you think a smaller diameter bullet then the current one will shoot better?
What features in the 3 posted targets make you believe that the .4595" bullet diameter is too large for the rifle? Certainly the velocity is not suffering, being at close to 1400 fps with just 27.5g of 5744.
Jim G
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troy fairweather
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What size is your bullet sizer, your powder coating I like to size then pc then size them again. Think you get a little more uniform bullet, seem to get a little spring back with pc. What pc are you using to.
My mistake, for some reason I thought you were shooting .457's and you are not.
JimGnitecki
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I powder coat first and then size. The Lee sizer insert is .460". The actual size comes out just a bit under .460". I use Eastwood Black Gloss.
Jim G
JimGnitecki
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Jim Watson: You got me thinking and might have helped me realize WHY BPCR shooters support the front end of the rifle via the barrel itself, not the forend:
Look at this side profile of my Pedersoli Sharps replica:
See how LONG the combination of Schnabel flare and Schnabel downward taper actually is in total?
I did some straightedge analysis on that lower surface of the forend. See the tiny factory Pedersoli dovetail in the upper surface of the barrel, just behind the rear telescopic sight mount? I found that in order to have a flat and level surface to slide upon during recoil, the front bag would need to be positioned so that it is centered at least 2.5" rearward of that dovetail. That would make the distance between the front support point and the rear support point very short (rear support point of course is on the stock). That would significantly magnify any hold error and any rifle movement due to shooter heartbeat. It also of course greatly restricts any potential for trying to move the point of co tact bewteen the rest and the rifle to different locations on the forend, since the flat level portion of the forend is so short to begin with.
On the other hand, putting the front rest support point under the barrel, automatically insures a consistently level surface AND the ability to try many different points of contact. It also greatly diminishes any rifle movement off POA due to shooter hold error or heartbeat. And, a longer distance between front and rear rest points also gives the rifle a signficiantly longer moment arm to resist any sideways movement due to recoil effects.
So, I think I am going to again experiment with placing the rest at different points under the barrel, and see what kind of results I get by doing so.
Thanks for re-drawing my attention to this.
Jim G
459 bullets can be too large to work best based on your bore measurement. Sometimes .001 or .002 work better. You definitely need to rest the barrel in the correct spot. And even though 5744 is the go to powder, I have never been able to make it shoot as good as BP. You definitely have vertical stringing issues which is most likely barrel placement and shooter error.
JimGnitecki
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I am not seeing why .4595" bullets might be TOO large a diameter. The rifle was slugged by a pro gunsmith as being .4563”. The bullets are being sized to .4595", so .0032" of interference fit with the rifling. I have seen multiple references to similar bullet fits in some calibers. For example, a .308 caliber bullet apparently has a diameter of .312" or higher, since the GROOVE diameter is .312"! And Pedersoli shooters seem to most often say that a .460" diamter bullet is needed, presumably because Pedersoli grooves are deep enough to merit that. They specifically warn against using too small a bullet diameter. And, when I look at the 164 yard groups, particularly at the 3 shots that are so close together in even the poorer groups, I don't see a good reason to think a smaller diameter bullet would be better.
Jim G
Jim Watson
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My .40-65 Browning with .408" Badger barrel does best with .411" bullets, I suspect because that is the throat diameter.
But that is not the case. A standard .308 Winchester - and most other .30 calibers - bullet is .308" or not much more for a .308" groove diameter. You can shoot a .311" cast bullet in most .30 rifles.
A .312" bullet is meant for .303 British, 7.65mm Mauser, and 7.7mm Arisaka, maybe 7.62 Russian.
But that is not the case. A standard .308 Winchester - and most other .30 calibers - bullet is .308" or not much more for a .308" groove diameter. You can shoot a .311" cast bullet in most .30 rifles.
A .312" bullet is meant for .303 British, 7.65mm Mauser, and 7.7mm Arisaka, maybe 7.62 Russian.
JimGnitecki
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Your comment on the throat diameter is a good one. A larger bullet limits the amount that the bullet can "rattle around" in the throat before engaging the rifling.
Jim G
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It is possible .457 or .458 is better. The general consensus is .001 -.003 over groove diameter is best for cast bullets. But just like every variable, bullet size makes a difference. My Pedersoli Sharps likes .460 and .459 and .461 are very poor performers. Mine slugged at .458. Your grouping in the first photo is solid, so the I doubt diameter size is the issue. However, don't get hung up on .4595. .30 cal bullets are .308 inches for jacketed bullets and .310 for cast most commonly. .310 cast in my 30 WCF do not perform that well but .309 does. And yes, make sure your bullet kisses the rifling.
JimGnitecki
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I am happy to report today a degree of success:
At today's range session, no more wild shots well outside the group! I am now getting 1.5" to 2" 5-shot groups at 150 meters = 164 yards. at that distance, these are 0.87 to 1.16 MOA groups. And on most of the targets, the closest 3 of the 5 shots were often a 0.75" to 1" group within the group.
The difference was changing the point where the Rempel bipod / small bag assembly contacts the front end of the rifle. Before, it was contacting on the wood forend, which introduced the problems described in post 41 above. Now, it contacts the barrel directly, at a point just behind the rear of the Brass sleeve on the front of the telescopic sight, where its slding movement on recoil does not move the rifle vertically.
Also, I noticed that the LOCATION of each group relative to the POA is now CONSISTENT. Which means my hold is more consistent.
The other difference is my simply getting more used to the rifle and developing more consistency.
The biggest remaining problem is simply ME. I knwo this now because a pattern has now become obvious: the first 3 shots of a 5-shot group are nice and tight - often a cloverleaf, but the last 2 shots tend to be the ones that enlarge the group. So, I think it is simply fatigue: either my eyes are tiring, or my muscles are tiring. I guess at age 72 thta might be expected. But, hopefully, lots more practice should help alleviate that!
And now that I have a good cast bullet that costs me only about $.18 per bullet, I can easily afford the cost of the practice!
Here's one of today's targets that shows a promising 4-round group ruined by the 5th shot:
Lots of good potential evident here!
Jim G
At today's range session, no more wild shots well outside the group! I am now getting 1.5" to 2" 5-shot groups at 150 meters = 164 yards. at that distance, these are 0.87 to 1.16 MOA groups. And on most of the targets, the closest 3 of the 5 shots were often a 0.75" to 1" group within the group.
The difference was changing the point where the Rempel bipod / small bag assembly contacts the front end of the rifle. Before, it was contacting on the wood forend, which introduced the problems described in post 41 above. Now, it contacts the barrel directly, at a point just behind the rear of the Brass sleeve on the front of the telescopic sight, where its slding movement on recoil does not move the rifle vertically.
Also, I noticed that the LOCATION of each group relative to the POA is now CONSISTENT. Which means my hold is more consistent.
The other difference is my simply getting more used to the rifle and developing more consistency.
The biggest remaining problem is simply ME. I knwo this now because a pattern has now become obvious: the first 3 shots of a 5-shot group are nice and tight - often a cloverleaf, but the last 2 shots tend to be the ones that enlarge the group. So, I think it is simply fatigue: either my eyes are tiring, or my muscles are tiring. I guess at age 72 thta might be expected. But, hopefully, lots more practice should help alleviate that!
And now that I have a good cast bullet that costs me only about $.18 per bullet, I can easily afford the cost of the practice!
Here's one of today's targets that shows a promising 4-round group ruined by the 5th shot:
Lots of good potential evident here!
Jim G
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JimGnitecki
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Yes, I know it looks like 3+1, but there are actually 4 shots in that tight part of the overall group. If you look very carefully at the "top" hole, you can see that it is larger vertically than horizontally. 2 of the shots were by coincidence almost on top of each other. My first reaction to seeing the group in the spotting scope after 4 shots was "where id that 4th shot go??" Then the 5th shot went a bit left and low.
Now if I could CONSISTENTLY shoot 5- shots like those first 4 shots, THAT would be awesome. The Pedersoli, the 45-70 caliber, and this latest bullet mold I am using (the Lee .459 500 3R mold) are an amazing combination that motivate me to improve the SHOOTER!
Jim G
