A Problem for the experts

[wv109323]

This will be a long post so the problem up front is : I have a Mi-hec mold that I can not get to shoot with any accuracy .
My goal is to develop a load to be used for the NRA Distinguished revolver competition with slow fire targets at 50 yards. My anticipation is accuracy of 2 1/2" at fifty yards or better.
Here are the things in common to the problem:
Firearm is a S&W model 14-6 with a 6" full lug barrel with probably less than 3000 rounds.
All primers used were Winchester Small pistol.
Brass was misc. mixed and not trimmed.
Loading was done on a Star Progressive and RCBS single stage for some of the small test lots.
All boolits were sized in a Star lube-sizer with Red Carnuba or 2500 from Whites. The nominal size was .358 and the boolits came out at .3577. The forcing cones of the cylinder are very consistent at .3572.
All testing was done with a Ransom rest at 52 yards.
I slugged the bore and could not measure diameter due to the odd number of rifling in a S&W barrel but the boolits showed good engraving in the rifling.
There was very,very little leading of the barrel observed with any of the loads.
Bullet alloy was wheel weights(clip-on) mixed with range scrap from a Bulleye pistol range.
All cast boolits were from a Lyman 20 lb. bottom pour pot with PID controls.
All boolits were rolled crimped in the crimping groove.
Casting temps were 700 to 730 degrees. Molds were preheated on a hot plate.
Here are the variables:
Powders- Bullseye- WST- WW231
Molds as follows
RCBS 2 cavity 358 158 round nose flat base-steel
NEI- 2 cavity 358 158 SWC with a radius base- Aluminum
Mi-Hec- 4 cavity 360 158 SWC flat base- Brass
The RCBS boolits as cast were .3577 to .3583 and weighed 156 to 154.5 gns.
The Mi-hec boolits as cast were .3603 to .3608 and the latest bullets weighed 155 to 154 gns. The earlier cast boolits were less uniform but still 155 to 151 gns. I had a learning curve( lead and mold temp.) with the Mi-hec brass mold.
Here are the group sizes fired by mold:
Factory rounds:

Magtech 158 gn LRN 5 rounds in 2 1/2"
Remington 158Gn. LRN 6 rounds in 3 5/8" with 4 rounds in 1 1/4"
NEI mold:
3.2 gn. BE 10 rounds 5 1/2"
4.5 gn. of WW231 9 rounds 2 1/4" with 8 rounds in 1 5/8"
4.5 gn. of WW231 10 rounds 2 1/2" (retested to confirm results)
RCBS-RN mold
4.1 gn. of BE 10 rounds 4 1/4"
3.2 gn. of BE 10 rounds in 4" with 9 rounds in 3"
3.5 gn. of WST 10 rounds in 1 15/16"
Mi-Hec mold
4.5 gn. of WW231 10 rounds in 16"
3.5 gn. of WST 10 rounds fired, 8 rounds in 13 1/8" and 2 rounds off the paper(?)
3.5 GR. of WST 9 rounds fired, 7 rounds in 12" and 2 rounds off the paper
4.2 gn. of BE 10 rounds fired only 4 rounds on the paper
Does anybody have any idea of my problem with this mold? I thought at first it was the quality of my cast boolits but the last boolits were as good as I have ever cast. Bases were very flat, weights were consistent. There was no resemblance of a "group" with many of these loads. There may be 4" between any two shots. The 3.5 gn. of WST had 5 rounds within 2 3/4" but that was it. The other two molds had good results with the proper powder charge.
The only thing I can come up with is the .360 diameter is allowing the rifling to "smear" lead down the side of the boolit and the base of the bullet has a small fin that corresponds to each rifling in the barrel.
I appreciate any comments. I hate to have a mold that I can not use, especially since I bought a 4 cavity to reduce my casting times.

[Hickory]

The first thing on the menu would be to buy new brass weigh and trim them and sort them in three lots, light, medium and heavy. Use the lot that is most consistent and retest. Then the experts here can give a better evaluation.

[9.3X62AL]

Do you have a baseline of accuracy fired with known accurate factory ammunition? I suggest finding however many Winchester Super-X 38 Special wadcutter you can manage to locate, and get an idea of the revolver's mechanical accuracy using this acknowledged standard in the caliber. The brass this ammunition uses is first-rate.......if you are serious, snag about 5K of this product and use it for your first couple seasons. After that, I suggest the use of Hornady 148 grain HBWCs atop 2.7 grains of Bullseye or 3.0 grains of WW-231, very lightly roll-crimped after flush seating into the accumulated W-W target wadcutter cases. I have seen both the factory loads and the reloads I'm describing meet or beat a 1" standard at 50 yards. My sister is a 1475-class PPC shooter, she and her much-modded Model 10 can perform this stunt at will from the 50 yard barricade.

If rules require a SWC or RN bullet, I would select something like the Lyman #358311 RN that lacks a shoulder. The shoulderless designs tend to self-center in forcing cones better than shouldered SWC designs do. IIRC, your underlugged Model 14-6 has a crush-fit barrel as opposed to a pinned barrel like older-series pre-1981 S&W revolvers. Be cognizant that you may have some thread constriction that will need addressing for the revolver to do its best work. Such a constriction will need a lap-out if present.

Don't make the bullets uber-hard, if you resort to castings for your competition loads. BHn of 8-9 is plenty hard for bullets running 800 FPS, and 50/50 beeswax/Alox is very adequate lube. You are kind of "gilding the lily" with the Carnauba Red, though I doubt it does any accuracy harm.

[Old School Big Bore]

+1 on sort the brass, that's fundamental. Do you have any tin to add to your alloy? A small amount can make your boolit quality more consistent. IDK about the WST but your Bullseye & W231 loads sound on the warm side. I have the MP 358 HBWC mold; PM me if you wish.
Ed

[wv109323]

I am satisfied with the NEI and RCBS molds and loads results. With the same parameters the Mi-hec boolit stinks. With the factory Mag-Tech and Remington ammo results were good. The Remington ammo was six misc. rounds and may not have been from the same box. Still 4 were in 1 1/4".

[williamwaco]

The only thing I can come up with is the .360 diameter is allowing the rifling to "smear" lead down the side of the boolit and the base of the bullet has a small fin that corresponds to each rifling in the barrel.

All boolits were sized in a Star lube-sizer with Red Carnuba or 2500 from Whites. The nominal size was .358 and the boolits came out at .3577. The forcing cones of the cylinder are very consistent at .3572.




Which is it? were they .360" or .3577"

I have never attempted .360 bullets. In most cases when I attempted to load them "as cast" they expanded the cartridge cases so much they would not chamber in my revolvers.

I would not be surprised if .360 bullets were problematic. .3577 should work fine.

After loading one of these bullets, pull it and measure it at the base.
Your groups sound like what I get when the case is swaging the base of the bullet during the seating procedure.

I usually find these bullets have been swaged down to .354 or .355. Those bullets splatter all over.

[44man]

Throats of .3572" and using boolits larger????? For those throats, you should be using .357" boolits.
You need to get a good groove measurement to see what you have, they could be less then .357" but if larger, the throats need lapped.
You are using the cylinder for a size die. Even if the brass is sizing, I bet they are still too large.

[wv109323]

William,
The Ml-hec boolits are .3603 to .3608 (as cast) and they are sized to .3577. I was trying to say the .3603 bullets would have a larger "body" assuming that the lube groove and crimp groove are the same depth. ( a .3603 boolit versus a theoretical .3580 would have a "body" that is .0023 larger). The sizing affects just the outside diameter making the grooves shallower. The rifling lands are engaged into the body of the bullet from the shoulder to the base.
It appears from the slugged boolit that the rifling land is "smearing" the lead down the side of the boolit and leaving 5 fins (where the 5 lands are) on the bullet base.
I seated and pulled a bullet. The diameter was .3576 instead of .3577 or .0001 difference. I felt like that could from pulling it from the crimp. The neck sizing stem on the Star and the RCBS dies were .3560 which means I had .0017" tension.
I may not have been clear in my original post. The worst group I got from the RCBS and NEI molds was 5 and 1/2 inches center to center. The best was 8 of nine rounds in a group of 1 and 5/8 inches
center to center. The best loads were producing groups under 2 inches.
With the Mihec mold I can not find all the rounds to measure the group size. I am shooting at a 24 inch by 24 inch cardboard target. The group sizes listed are from the boolits that struck the target backer.
The problem is the boolits from the Mihec mold. I am just trying to get the Mihec mold to shoot groups around 2 and 1/2 inches to speed up my casting times with the 4 cavity mold.
9.3X62AL mentioned a Model 10 that shot 1" groups. I bet that Model 10 did not have a factory S&W barrel. I am using a stock S&W Model 14-6 , not a modified firearm. The 158 SWC or RN is mandated by the rules.
All three molds have a sharp, square shoulder to engage the rifling.

[9.3X62AL]

You are correct, WV--the Model 10's barrel is a truck-axle Davis behemoth, with 4-position front Patridge adjustable and a very smooth action job--but OEM springs. It lights CCI SP primers easily and reliably.

[MtGun44]

The 4.2 BE load seems WAY hot for this load. Try something more like 2.7 or 3.0 gr BE.
Same thing with the W231 load - seems WAY hot. I'd be using about a grain less for
starters for target ammo in a M14.

Also - what is that design? Do you have a pic? I would be using a full wadcutter design
like a H&G 50 or one of the many Lyman designs in the 148-160 gr range with only one
lube groove filled.

OH- just read the requirement for a SWC or RN. Still, I would lower the charge
significantly and I wonder if you are getting some sizing damage on those MH .360s.
Is it possible that they are being pushed out of round?

What are you measuring with?

Frankly, I have never seen those kind of "groups" with anything other than massively
undersized boolits in revolvers, like .451 in a S&W 1937 .45 ACP that needs . 454 or larger
to group well.

Bill

[wv109323]

MtGun44
I sent you a PM.
I tried lighter loads with the RN and NEI mold about a year ago. ( I did not have the Mi-hec mold at that time). The results were not that impressive. I have discarded all the info but groups ran in the 4-6" range with 3.0 and 3.5 gn. of BE and similar loads of WW231. The group of local Bullseye shooters that I run with told me that with CAST 158 gn. bullets the velocity needed to be around 840 FPS. My results confirmed what they said. I recently spoke with a shooter that was using a swagged bullet (Zero brand) and he was using 3.2 gn. of BE with success. I never tried under 3.0 of BE with my cast boolits. I could not get the accuracy I wanted until I warmed the loads up. I found a target with 4.0 gn. of BE produced a group of 2 1/8" with the NEI boolit.
As a side note the Distinguished Revolver competition started out with factory ammo only.( 158 lead SWC or RN) When ammo become scarce the rules were relaxed so that reloads could be used.
The Mi-Hec is a SWC, single grease groove, with two crimping grooves. The metplate is larger than the typical 158 SWC but nothing strange at all.
Measuring is done with a Fowler 0-1" mic.
Bullets are consistently round, when measured and then the bullet is rotated 90 degrees. All the boolits are sized in a Star nose first with a flat punch.
I concur that I have not seen results like this. Usually this performance is due to undersize boolits not stabilizing. In those instances you get keyholing. I have no evidence that the Mihec bullets are keyholing. Like I said in my title, this one is for the experts.