XCB- bullet in the .308 win

[Ian]

Sounds like your alloy was good for 34 grains. To push it more it may need a heat treat or a jacket (polymer, paper, or epoxy).

I've run 10.4 bhn low-antimony/trace tin alloy to 37.5 grains with nearly MOA groups out of an M1A, fed from the magazine....but the bullets were powder-coated. One of those things that shouldn't work but does.

 

[fiver]

just as a learning experience push the 4064 a little more.
I know it started opening the group size up,,,, but just so you have something to really fall back on go ahead and go up some more,,,, see what happens.
once you have a point of controlled horribleness your gonna start learning, by making it [the groups] not so horrible.
don't be afraid to fail.

look what happened when you went up this last time.
what made the groups better?
the faster speed?
more gas volume?
pressure timing?

a slower powder making the bullets go faster shot better groups, what would happen with a little more of an even slower powder?
your still hitting the base of the bullet with the same amount of pressure you were with the N-110 [shrug] soo?

 

[Spindrift]

Ian; I have assembled the necessary stuff for powder coating, and have coated a few bullets- just haven’t gotten around to load development yet. So, it is on my list.... I just want to work more with conventional lube first (lot to learn).

Fiver; I will try to push the 4064 harder, see what happens. Will also try slower powders.

Thank you for your help!

 

[Spindrift]

I have a couple of new bullets to try, they are quite similar to the xcb- bullets. Arsenal molds 311-170, aka HVTH, or «Sliver». HVTH stands for «high velocity, target, hunting»; which covers most bases. And the Lee 312-160. I shot the HVTH for the first time yesterday, 5 shots/1,2 MOA/100m with 19grs n110.
All the bullets are conical nose designs weighing 165-172 grs. Next time, I will try some comparative testing.

 

[Gary]

Interesting; I like the design of the one on the right. No need for lube grooves with PC.

 

[Spindrift]

My thoughts, exactly. It seemed to work well with conventional lube (at conventional speeds), I plan to test it with pc later.

 

[Brad]

I am in the camp that believe that grooves aren’t all bad with PC. Give the displaced metal a place to go.

 

[Will]

I am in the camp that believe that grooves aren’t all bad with PC. Give the displaced metal a place to go.

I agree. After removing lots of bullets shot at higher velocity I truly believe having grooves that allow the lead to flow evenly is a advantage.

I’d like to see some pics of the slick bullets after being fired.

 

[Spindrift]

I understand the logic behond «metal displacement grooves», you might very well be correct. Sadly, I have no practical means of capturing the shot bullets (maybe come the spring, when some other ranges open). So for now, I’ll just shoot and see.

 

[fiver]

too bad you can't access those ranges now.
snow is the best bullet capture system there is.

 

[Spindrift]

Tried some powder coated XCB- bullets in my Howa .308 today. BHN 14, 1 layer of epoxy. Bullets sorted by visual inspection only. Sages alu GC. Sized .309. Norma cases, WLRP. Neck expanded/flared to one thou bullet grip. Shot from prone at 100m with support on a bag. It seemed to like imr 4064, 37 grs- this 5 shot group is 37mm (about 1,25 MOA)

 

[fiver]

nice.
I'm running them naked with 40grs.
you might find another node up there too.
but 37 is no slouch in the speed area either, your touching jacketed speeds easy enough right there.

 

[wquiles]

Really nice shooting - plus I love that electronic scoring system

 

[Spindrift]

Thank you!
Yes, it is very practical. I usually bring 4 rifles and 200 rounds, and shoot them in 1,5-2 hours. I would have been able to shoot far less in my limited range time without the electronic target.
But some info is lost, like the shape of the holdes.