16" 5.56 1:7 twist with 40 gr bullets

swampratt

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I was heading out yesterday to shoot and do a little hunting and wanted to try some N133 in my AR15.
I need a squirrel round.
I thought I grabbed the 55 gr box of Nosler bullets but pulled the lid on some 40 gr boat tailed ones.
My load is not a max load even with 55 gr according to some load data books.

I did notice they looked quite short and seated very easy compared to my normal 55gr V-max load.
After I made a round i stopped and double checked the box of bullets.
Ouch 40gr.

EEEHHHH ....Go for it is what my head said.
I looked at load data and i was below max by quite a bit 24.7gr N133 CCI 450 in FC cases.

I also took some old loads of 55v-mag and 26gr of H4895 I had built for my Bolt bun that were seated 2.278" and seated them to 2.253" same as the 40 gr load.

That is a severely crushed amount of powder at 26gr and for my AR load I use 25-25.5 gr.

First shot out of the gun was high and right. I do not know when the last time I shot it was and it was put away dirty. I usually drag a bore snake through my dirty shot rifles a few times before shooting for a group but did not do that this time.

The 55gr did not do so well and I expected that as I have tried that 26gr short seated deal in it and it was not great.
I pulled one shot way left and high and knew it when i touched off the trigger.
Yea I screwed that shot.

I shot the 40gr loads first and numbered the holes after the loads were shot.
Now this was only 85 yards but it does show promise with that 40gr and 1:7 twist barrel.
Shots number 2 3 and 4 are under 1/2" center to center which are the 40gr bullets.
https://www.midwayusa.com/product/1758562732.

I will be making more and testing again.
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Jcann

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I don't know how well the jacket on those bullets will hold up at a given MV but you can check the rpm with this formula. Hopefully they won't come apart if you push them hard.

Example, Muzzle velocity of 3,000fps x (12" in a foot/7" twist) x 60 sec. in one minute
MV = 3000 FPS, 1:7 Twist

3000 x (12/7) x 60 = 308,571.43 RPM
 

swampratt

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I'd skip the 40gners with a 7 twist.

When I was doing load development for my 22" barrel .223 with 1:9 twist I shot H4895 powder as it was most accurate for all bullets I had used.

I tried 75gr 69 gr 60 gr and 55 gr.
I shot them all with the best accuracy load in the upper accuracy node range.

The heavy bullets were way down at 300 yards vs the 55gr and the 55 gr had even less drop than the 60 gr V-max.

I stuck with the 55gr V-max as the velocity allowed less drop and less wind drift.
Maybe H4895 was not a fast enough powder.. OR a powder that did not have enough velocity in that case.

I did get some velocity readings in my 16" ar with the 55gr V-max load and H4895.
2789 FPS in my 1:7 twist 5.56.

Now today I shot the 40 gr. Nosler with 25.3gr N133 and got 3204 and 3194 FPS for 2 shots recorded.
Chrono' was 15 feet from the Muzzle.

Next up was 24.7 gr. N133 55 Nosler flat base.
3024 and 3010 FPS for 2 shots fired.

I did not shoot for groups with the AR today.

I will only use the 40 gr on tree rats or other vermin.
55 gr. V-max or the 55 Nosler will be for the Deer.

My testing on heavier bullets consisted of a 5+ foot tall cardboard box that a refrigerator came in.
I set it up with an X 6" below the top of the box.
At 100 yards I shot at the X.
Then moved to 200 then 300.
I shot all the different weight bullets at that X and that was an eye opener.
Heavy bullets actually drifted much more than the V-max 55gr.
Not to mention the drop with the heavies was much greater.
I got rid of almost all of the heavier ones after that testing.

Yes you can work it up on a trajectory calculator with bullet BC and velocity.
But in my eyes nothing beats real shooting for your testing.

Today I am pretty happy with the velocity increase with N133.
Just need to test hot and cold weather shooting with it and see if the group stays tight. Once I find a good load.
 

StitchJones

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When I was doing load development for my 22" barrel .223 with 1:9 twist I shot H4895 powder as it was most accurate for all bullets I had used.

I tried 75gr 69 gr 60 gr and 55 gr.
I shot them all with the best accuracy load in the upper accuracy node range.

The heavy bullets were way down at 300 yards vs the 55gr and the 55 gr had even less drop than the 60 gr V-max.

I stuck with the 55gr V-max as the velocity allowed less drop and less wind drift.
Maybe H4895 was not a fast enough powder.. OR a powder that did not have enough velocity in that case.

I did get some velocity readings in my 16" ar with the 55gr V-max load and H4895.
2789 FPS in my 1:7 twist 5.56.

Now today I shot the 40 gr. Nosler with 25.3gr N133 and got 3204 and 3194 FPS for 2 shots recorded.
Chrono' was 15 feet from the Muzzle.

Next up was 24.7 gr. N133 55 Nosler flat base.
3024 and 3010 FPS for 2 shots fired.

I did not shoot for groups with the AR today.

I will only use the 40 gr on tree rats or other vermin.
55 gr. V-max or the 55 Nosler will be for the Deer.

My testing on heavier bullets consisted of a 5+ foot tall cardboard box that a refrigerator came in.
I set it up with an X 6" below the top of the box.
At 100 yards I shot at the X.
Then moved to 200 then 300.
I shot all the different weight bullets at that X and that was an eye opener.
Heavy bullets actually drifted much more than the V-max 55gr.
Not to mention the drop with the heavies was much greater.
I got rid of almost all of the heavier ones after that testing.

Yes you can work it up on a trajectory calculator with bullet BC and velocity.
But in my eyes nothing beats real shooting for your testing.

Today I am pretty happy with the velocity increase with N133.
Just need to test hot and cold weather shooting with it and see if the group stays tight. Once I find a good load.

Man, I don't bust out the chronograph until my load development is done (but I don't really load with a velocity goal in mind either). Even then I only look at the velocity to get a SD and to get a rough guess for my come ups until I can actually verify them.

I start with a ladder test to find my powder charge (usually move in .2 gn intervals) . Then make adjustments to seating depths and neck tension. I use three round groups during that process until I have a couple good combinations, then step to five round groups.

If I try a different bullet, brass manufacturer, or power. the process starts all over so I have a true apples to apples comparison.

To me, if you're seeing drift on a 300 yard target that's an indication of an issue with your load, rig or technique. Unless you're shooting in some serious wind.
 

swampratt

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I was curious as to if there would be any significant velocity change with the new N133 and 55 gr bullets so the chrony was
used.
I also wanted to know if I was sub sonic with the 12 gauge slugs and if the wad different seating forces I was feeling
would actually make a difference in velocity and it did.

Just something else I must watch for in the shotgun loading arena.
I just began loading shotgun shells so all this is new to me.
Muzzleloader reloading is much easier and more accurate.

Could be I need to get a roll crimper.
I also need to back down the #5 loads.

When i am working up loads i do not use the chrony either.
 

StitchJones

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Man, those shotgun slugs you're working with are really awesome!

Lol, it's like throwing a kitchen sink at the hogs.
 

swampratt

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Man, those shotgun slugs you're working with are really awesome!

Lol, it's like throwing a kitchen sink at the hogs.

I thought the same thing.
Now I just need to make them accurate and if that does not happen i will drill the mold cavity deper and make them even longer and heavier and I may even make them bore size and powder coat them if i can't get the accuracy.
Should be really heavy by then.
 
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