Spindrift
Well-Known Member
Most of the time, when we powder coat our bullets, we use bullets designed for the use of conventional lubes. The dimensions of the nose is designed with the intention of being used without the added (about) 0,002in of the coat.
And the big picture is, we’re doing fine.
However, there are some issues that might arise from the fact we’re using bullet designs in this «off-label» fashion
1) Chambering issues. This is a particular problem with bore-riders that are well-fitting in the first place. However, it also presents a method to ameliorate the situation with an under-sized bore-rider.
2) Crimping. The shorter COL enforced by the fattened-up nose might render the crimp groove unusable (sometimes remedied by trimming cases to sub-standard length).
3) Base distortion. Particularily with PB bullets of generous as-cast size, you might get skirting at the base if all sizing is done in the nose- first fashion. Sizing base-first before coating might be necessary before coating to avoid this.
4) Loss of sophistication. Sometimes, adding 0,002in and the sizing down can render small tapers or stepped bands cylindrical.
The NOE 309-177 caught my attention, and I tried to find some info on the mould. A Google search yielded nothing. All varieties were in stock. These two observations combined, lead me to the conclusion this mould is probably incredible unpopular. Which might be undeserved?
Let’s take a look at the technical drawing
On the face of it, this looks like a disaster. But if you add 0,002in to all diameters, it looks a lot better! In fact, it looks like it’s .311 big brother. I don’t know if the .309-177 was designed with PC in mind, or if it is intended for the tight K-31. But it looks quite well-designed for a coat-only bullet.
With such a wide-meplat bullet, I consider it non-productive to pursue velocities above 2000- 2100fps. And I’ve found coated PB bullets to be capable of good accuracy at these velocities. I got a 2-cav PB mould. I’d rather have a 4-cav, but that was not an available option.
Casting, coating and sizing (post- coat, .310) was unproblematic. The alloy is my nuclear medicine lead with some tin (eye-balled, about 1%?). BHN around 15 after one month of maturation.
I’ve started load development in my Howa .308. This is a well-used rifle, factory standard reciever and chamber. The barrel is shortened to 18,5in, and threaded for supressor. It is bedded into a GRS Berserk adjustable stock, and has a Timney trigger and nice scope.
(Photo taken before winter set in)
I have previously shot some groups with Norma 200. Groups were OK, despite the fact I got some hang- fires (Norma 200 does not seem to like reduced loads in cold weather). This time, I tried Vectan Tu-3000 which is a single-base extruded powder with a listed burning rate in the «4895»- ballpark.
Ambient temp was 20F, making shooting slightly challenging due to cold fingers. First, I tried 31 grs. The «flier» on the right, is the cold bore shot. Including the flier, 1,1 MOA. I’ll chrony it later.
32 grs resulted in a slightly larger, almost perfect horizontal string
This should be fun! I’ll keep you posted on further developments.
And the big picture is, we’re doing fine.
However, there are some issues that might arise from the fact we’re using bullet designs in this «off-label» fashion
1) Chambering issues. This is a particular problem with bore-riders that are well-fitting in the first place. However, it also presents a method to ameliorate the situation with an under-sized bore-rider.
2) Crimping. The shorter COL enforced by the fattened-up nose might render the crimp groove unusable (sometimes remedied by trimming cases to sub-standard length).
3) Base distortion. Particularily with PB bullets of generous as-cast size, you might get skirting at the base if all sizing is done in the nose- first fashion. Sizing base-first before coating might be necessary before coating to avoid this.
4) Loss of sophistication. Sometimes, adding 0,002in and the sizing down can render small tapers or stepped bands cylindrical.
The NOE 309-177 caught my attention, and I tried to find some info on the mould. A Google search yielded nothing. All varieties were in stock. These two observations combined, lead me to the conclusion this mould is probably incredible unpopular. Which might be undeserved?
Let’s take a look at the technical drawing
On the face of it, this looks like a disaster. But if you add 0,002in to all diameters, it looks a lot better! In fact, it looks like it’s .311 big brother. I don’t know if the .309-177 was designed with PC in mind, or if it is intended for the tight K-31. But it looks quite well-designed for a coat-only bullet.
With such a wide-meplat bullet, I consider it non-productive to pursue velocities above 2000- 2100fps. And I’ve found coated PB bullets to be capable of good accuracy at these velocities. I got a 2-cav PB mould. I’d rather have a 4-cav, but that was not an available option.
Casting, coating and sizing (post- coat, .310) was unproblematic. The alloy is my nuclear medicine lead with some tin (eye-balled, about 1%?). BHN around 15 after one month of maturation.
I’ve started load development in my Howa .308. This is a well-used rifle, factory standard reciever and chamber. The barrel is shortened to 18,5in, and threaded for supressor. It is bedded into a GRS Berserk adjustable stock, and has a Timney trigger and nice scope.
(Photo taken before winter set in)
I have previously shot some groups with Norma 200. Groups were OK, despite the fact I got some hang- fires (Norma 200 does not seem to like reduced loads in cold weather). This time, I tried Vectan Tu-3000 which is a single-base extruded powder with a listed burning rate in the «4895»- ballpark.
Ambient temp was 20F, making shooting slightly challenging due to cold fingers. First, I tried 31 grs. The «flier» on the right, is the cold bore shot. Including the flier, 1,1 MOA. I’ll chrony it later.
32 grs resulted in a slightly larger, almost perfect horizontal string
This should be fun! I’ll keep you posted on further developments.
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