Heavy bullet AR

[4xforfun]

Two years ago I did a little testing with a friends Rock River Arms 223. 1 - 8 twist The goal was to try some heavy bullets to try negate some of the windage. I had some 85.5 Bergers and H4895 and tested 20.5 to 22.5. It shot under 1/2 inch 3 shot groups with everything!! I was shooting with ANOTHER buddy who also had a 1-8 twist RRA and it also shot very small with the same loads.
Last fall i bought one for myself. 24 inch heavy stainless bbl 1 -8 twist and tried the same recipy....85.5 Berger, Lapua brass, 205 match primers, and started at 20.5 H4895. It shot a 12 - 14 inch group at 100 with the starting load. WTF!! I jumped to a near book max load with the same result. I figured something went south with....something, so I grabbed my box of factory Hornady 53 V-Max and it shot under 1/2 inch as it normally does. I double checked the stamping on the tube.....1-8 twist. All the 85.5 holes looked perfectly round. All loads were loaded to MAG LENGTH....same as before. in fact, I didn't even change the seating die from 2 years ago. CONFUSED!!

Any Ideas? My buddy is going to try the left over loads in his RR as the last go around with this load was very successful.

Thanks,
Tod

 

[ELR LVR]

1. Differently cut chambers is my first thought (very different freebore from the initial test barrel?)
compare how far away bullet is to lands between both barrels
2. Your new 8 twist may not actually be an 8 twist, they can vary slightly
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I conducted a similar test recently just for fun using 88 ELD-m's but in a 7 twist upper
Although I seated bullet close to lands so had to single feed (OAL was like 2.340")
Gave 1 inch groups at 50 yds open sights,
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My guess is, Omitting the SMH culprits such as loose sights
your new barrel has too long of a throat (but I dont see 12-14" groups due to this??? so???
or is not twisted quite fast enough.
Run a cleaning rod through it with a bore brush and measure twist per distance
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another thought............I have heard of FUBAR's such as Remmy putting out a rifle with no rifling in the barrel
got overlooked in the QC Dept.
It's possible
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Maybe see if you can send the barrel back explaining that it wont shoot

 

[karrarararararar]

The 85.5 is not a mag length bullet. Stick to 77's if you want to shoot from the mag

 

[gdbleb]

Time for the borescope I think. In addition to checking the twist. And single load as Karr.... stated above.

 

[searcher]

If your twist "checks out" and nothing loose on the gun (check the barrel nut or handguard nut for tightness), I'd give it a quick go with a few other powders and see what changes. You may find that barrel won't shoot that bullet no matter what you throw at it. A few powder changes will tell you pretty quick. I'd also be inclined to install a Wolff "extra power" mainspring before calling the barrel bad, given that bullet you are using. I've had many horrendous groups shooting certain bullets in A/R's (and bolt guns...) trying different things out. Your situation reminds me of when I tried 87 V-Maxes in my 1-8" tw 6BR. My groups weren't that big - but not too far from it. The 75 V-Max shot incredibly well.

 

[Herzo]

I would check the twist on your barrel. In my experience, the 85.5 can be finicky at the margin.

 

[ELR LVR]

Here:
Read Post # 8

Keyholing with a new barrel

25 creedmoor 1 in 7 twist. 26 inch. A round 30 shots , all keyholed. 133 berger , 117 sst,and 117 round nose bullets. All keyholing. Brass looks normal But the crowd looks rough. I'm no machinist. And it's a McGowen barrel. Any suggestion?

forum.accurateshooter.com

 

[Old Navy]

Too slow twist rate. Mine loves the 80.5 Bergers.

 

[SKWERLZ]

Button rifled barrels can vary considerably in twist rate.

 

[4xforfun]

If the twist was that far off to give 12 MOA plus groups, wouldn't the bullet tumble as well? Also, I need it to be able to feed out of the mag....comp rules. The only gun I have ever seen shoot even 6 MOA had the bullets hitting the muzzle brake.... On the other hand I have seen a FEW 12 moa SHOOTERS!!

Also, what am I looking for with my borescope? I have shot 7 different kinds of factory ammo through it up to 69 grains, and the WORST it shot was 1.5 MOA.

 

[William Vogel]

If the twist was that far off to give 12 MOA plus groups, wouldn't the bullet tumble as well? Also, I need it to be able to feed out of the mag....comp rules. The only gun I have ever seen shoot even 6 MOA had the bullets hitting the muzzle brake.... On the other hand I have seen a FEW 12 moa SHOOTERS!!

Also, what am I looking for with my borescope? I have shot 7 different kinds of factory ammo through it up to 69 grains, and the WORST it shot was 1.5 MOA.

Half of a 85.5 Berger is seated in the brass and I’ll bet some of the ogive. That’s a really long bullet to load to 2.26. I load them for my 223AI at least 2.560.

 

[SSchnd]

I would As KARARARARAR stated not try them at mag length, those are a single load long kind of projectile. Start at Touch and Jump test. Some have success while others have not. The 80.5 may serve you better.

 

[jelenko]

I also would not recommend the 85.5's at mag length.
I tried some 63 eld vt's at a long AR mag length [i.e., 2.340]. They shot something over 10" groups.
When loaded to 20 thou off the lands, the first [and only] group was just under 3/4".

I was hoping the 62 eld vt's could be used in a windowed mag but no go.

 

[4xforfun]

Well, I ordered some Berger 70 VLD, 73 BT, 75 VLD and some Hornady 75 BTHP. I will just need to find a home for 9 boxes of 88.5's.....unless I chamber up anther 22 BR in 8 (ish) twist.

Thanks,
Tod

 

[4xforfun]

Well, I ordered some Berger 70 VLD, 73 BT, 75 VLD and some Hornady 75 BTHP. I will just need to find a home for 9 boxes of 88.5's.....unless I chamber up anther 22 BR in 8 (ish) twist.

I will report on how my buddy does with my 85.5's in his RR.

Thanks,
Tod

 

[DHD]

I have used/tried the 70 VLD's in my 223 AR's. Yes I have had them shoot decent but they are finicky to find that load. They will be too long to jam, so you will have to find the right jump. Possible, for sure, but you decide if the juice is worth the squeeze. I have some modified PRI magazines so I have loaded them to + .010" jam and they shot very accurately there, but they laugh at a standard magazine so I keep some for those occasions I need to be different.

The 75 VLD is even longer so MORE of the same. The 73 BT may be one of the easiest heavier bullets to find a good load for, I have ever used. Multiple powders and multiple seating depths and this bullet just is not picky. Better than a 77 SMK? Maybe so, at least for me.

While it is still a secant profile, I have shot a few thousand Hornady 75 BTHP's and can find a good load at magazine length with them. I keep a BIG box of them around because they are inexpensive and shoot pretty decent. Not as consistently accurate as the 73 BTHP or the 77SMK though.

 

[ELR LVR]

I would try the Sierra 69 TMK's and forget all the others. They work well.
I tried the 77 TMK's but didnt have much advantage considering they were slower.
(The TMK 69's are great For Mag Length Loads and have higher BC than standard 69 BTHP's)
Keep it simple

 

[SKWERLZ]

I would try the Sierra 69 TMK's and forget all the others. They work well.
I tried the 77 TMK's but didnt have much advantage considering they were slower.
(The TMK 69's are great For Mag Length Loads and have higher BC than standard 69 BTHP's)
Keep it simple

The 69 smk is one of my favorite bullets for 223.

Looking forward to slinging a few with my 22ARC
I have to try the 69TMK.

 

[4xforfun]

I added some Tipped 69 gr SMK to my order.

Thanks for the help,
Tod

 

[Rock Knocker]

The only time Ive seen a rifle shoot that bad was my AR with 16" Black Hole Weaponry barrel, CFE223 and 53gr Vmax, 14 inch groups and no keyholes. I had never seen anything like it, every thing else works fine, its just that combo.