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AR Twist and long bullets

R

Ride2Live

Alpha
Hello,
Early last year (maybe a year earlier) I bought a new Springfield Armory Saint AR-15.
I made some changes to it, but all in all, it seems like a pretty nice gun, never having owned an AR before.
I encountered a problem with bullets.

This gun has a 16" barrel with a 1:8" twist.

Before all the hoarding started, I bought a bunch of loaded Hornady 75 gr ammo, and because I reload, I recently bought a bunch of Hornady 70 gr GMX bullets. I even bought, by accident (yeah, I know...it's old age) 2000 Speer 55 gr HP bullets, when I was supposed to click on 70 gr. I am tempted to sell this 2000 and buy more 70-75 gr bullets. I want to shoot longer distances.
Anyhow...

So then I see this Hornady disclaimer in fine print somewhere. It said "70 gr and above will not stabilize correctly in a barrel of 1:8" twist or higher. Terrific...
I looked at other 16" barrels, and they were 1:8 also, is this a standard or something?

So what can I do?

Any help is gratefully appreciated.

Regards,
Robert
 
1:8 should stabilize 70-77gr most bullets just fine...but since the GMX is copper, it's considerably longer than a lead cored 77gr...

So, yeah, performance may not be optimal.

Try shooting them and see how they perform; you may be pleasantly surprised.

The good news is those 55gr bullets will work just fine in your 1:8; I’d definitely keep them.

And, military standard is 1:7.
 
Another note, If loading at top of pressure you could have higher pressure with a faster twist? I usually run hot loads(1/8 twist) with 556, but will need to check having only a single 1/7 twist barrel. The load manual will have what twist was used so that helps.
 
If military standard is 1:7, should I seek out a 1:7 barrel to swap into this gun?
How much and who would I use in your opinion?
The reason for not wanting the 55 gr is that I want to shoot longer distances with a scope. I don't use it for home defense or hunting. (I could, but I'm much better with a pistol, being a competitor for years) I watched a two gun competition, where the AR portion could be up to 500 yds, and the RO would call out the target range after the competitor had run up two flights of stairs and pulled their AR out of a barrel at the top. That's cool, at least for an old bugger like me.
 
Ride2Live said:
If military standard is 1:7, should I seek out a 1:7 barrel to swap into this gun?
How much and who would I use in your opinion?
The reason for not wanting the 55 gr is that I want to shoot longer distances with a scope. I don't use it for home defense or hunting. (I could, but I'm much better with a pistol, being a competitor for years) I watched a two gun competition, where the AR portion could be up to 500 yds, and the RO would call out the target range after the competitor had run up two flights of stairs and pulled their AR out of a barrel at the top. That's cool, at least for an old bugger like me.
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How much do you want to spend on a barrel? What barrel length and weight also? 55gr will still get past 500 yards and kill pigs with a 55fmj.
 
TEXASforLIFE said:
How much do you want to spend on a barrel? What barrel length and weight also? 55gr will still get past 500 yards and kill pigs with a 55fmj.
Click to expand...
I guess I'll have to find out what they cost and the quality levels. I'll stick to 16" but have a 1:7" twist. I don't want to kill any pigs (we don't have them here anyhow), but have a heavier (not 85 gr) HPBT shape for increased accuracy at the longer ranges and less deviation due to wind. So I figure 70 - 75 gr would be perfect.
I'll have to find someone at the 3 gun matches who compete nationally and find out what they use I guess. I realize an AR is not a sniper weapon, but I think it could be used at longer distances if it was set up correctly and used the right combination of powder and bullets.
TEXASforLIFE said:
A 75gr lead/copper will still work fine in a 8 twist, but an all copper is questionable! The job calculator could help find answers?
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If you have a BTHP 75 bullet, what difference does it make if it's partially lead or all copper? Same shape, same weight.
Also, what's a "Job Calculator".
 
Knowing you have a given twist rate on the barrel from Springfield, Why would you seek ammo or bullets that dont line up? Then seek to switch a barrel rather than ammo that suits the twist. Like buying a diesel truck and upset it does not run 87 octane.
If you want to snipe, then why not build a dedicated sniper MSR platform to suit your needs?
 
Ride2Live said:
If military standard is 1:7, should I seek out a 1:7 barrel to swap into this gun?
How much and who would I use in your opinion?
The reason for not wanting the 55 gr is that I want to shoot longer distances with a scope. I don't use it for home defense or hunting. (I could, but I'm much better with a pistol, being a competitor for years) I watched a two gun competition, where the AR portion could be up to 500 yds, and the RO would call out the target range after the competitor had run up two flights of stairs and pulled their AR out of a barrel at the top. That's cool, at least for an old bugger like me.
Click to expand...

I think you're overthinking this.

Trade those GMX’s for some 69 or 77gr Sierra Match Kings; they'll run fine in that 1:8 twist.

One question, though—have you even shot this rifle yet, using those bullets?
 
Also the reason competition shooters run higher grain bullets is to make sure they hit the target with enough energy to register the hit.

I always ran 55 grain ammo and never had any issue putting the bullet on target.

I didn’t want to pay the higher cost for the higher grain bullets.
 
All copper needs more area for weight as lead heavier so it can be shorter given the same weight. Most bullets up to 77 and some up to 85 that have lead will stabilize with 8 twist. It was supposed to be JB calculator, my bad! The calculator will let you know if you have enough velocity and/or twist for the bullet. It's an improvement over the greenhill formula for stability. At 70-75gr an 8 twist will be fine for a copper/lead bullet.
 
Ride2Live said:
If military standard is 1:7, should I seek out a 1:7 barrel to swap into this gun?
How much and who would I use in your opinion?
The reason for not wanting the 55 gr is that I want to shoot longer distances with a scope. I don't use it for home defense or hunting. (I could, but I'm much better with a pistol, being a competitor for years) I watched a two gun competition, where the AR portion could be up to 500 yds, and the RO would call out the target range after the competitor had run up two flights of stairs and pulled their AR out of a barrel at the top. That's cool, at least for an old bugger like me.
Click to expand...

Don’t swap out barrels. Don’t put a lot of stock in military standard. Don’t get me wrong, there is some stuff I’d like to have taken back home with me but you have to understand that a lot of what goes on is money and politics and that is behind closed doors. Having said that, 1:8 out of 1:7-1:9 is going to be, middle of the road and will be just fine. My 1:8 shoots lights out with 99% everything. Like Hans said, try them out. I know ammo is hard to come by but there is a lot of quality, heavy bullets out there for the .223/5.56.
 
BangBang said:
Don’t swap out barrels. Don’t put a lot of stock in military standard. Don’t get me wrong, there is some stuff I’d like to have taken back home with me but you have to understand that a lot of what goes on is money and politics and that is behind closed doors. Having said that, 1:8 out of 1:7-1:9 is going to be, middle of the road and will be just fine. My 1:8 shoots lights out with 99% everything. Like Hans said, try them out. I know ammo is hard to come by but there is a lot of quality, heavy bullets out there for the .223/5.56.
Click to expand...
My 1:9’s have no difficulty stabilizing 69gr SMK's...which, if you listen to the internet “experts” (who have never tried it, because the internet told them the bullet will be traveling sideways as soon as it leaves the barrel...:rolleyes:) simply isn’t possible. In fact, my 1:9, 16” HBAR got its best group with them at 300yds...about a 2.5”, 5-shot group.

I think a lot of hand wringing about having too slow a twist for a certain weight (or too fast...which means the person talking doesn’t really understand how it works; you can’t overstabilize a bullet and hurt accuracy) is seriously overblown. People need to stop believing what the read on the internet and go out and press the trigger for themselves, and get results that are applicable to them...not some anonymous interwebs guru.

(Yes, I am not unaware of the irony, there)
 
HansGruber said:
My 1:9’s have no difficulty stabilizing 69gr SMK's...which, if you listen to the internet “experts” (who have never tried it, because the internet told them the bullet will be traveling sideways as soon as it leaves the barrel...:rolleyes:) simply isn’t possible. In fact, my 1:9, 16” HBAR got its best group with them at 300yds...about a 2.5”, 5-shot group.

I think a lot of hand wringing about having too slow a twist for a certain weight (or too fast...which means the person talking doesn’t really understand how it works; you can’t overstabilize a bullet and hurt accuracy) is seriously overblown. People need to stop believing what the read on the internet and go out and press the trigger for themselves, and get results that are applicable to them...not some anonymous interwebs guru.

(Yes, I am not unaware of the irony, there)
Click to expand...

That’s so true. So many folks jump to google to see what it says and like you posted above, many would be surprised at what would happen in terms of twist rate and bullet weight. I’m not saying that to be the case every single time but I have a Bushmaster 1:9 that shoots heavier grain bullets better than the lighter grain bullets. I have another 1:9 that just drills with 55-62 but won’t perform so well with anything over 62gr. I’m ok with that.
 
Mine is 1:7 and shoots great with 55 and 62. I haven’t shot any of the heavy bullets but I assume it will do it with no problems.
 
HansGruber said:
I think you're overthinking this.

Trade those GMX’s for some 69 or 77gr Sierra Match Kings; they'll run fine in that 1:8 twist.

One question, though—have you even shot this rifle yet, using those bullets?
Click to expand...
My humble apologies for taking so long to get back to all you fine gentlemen who took the time to answer my question. So here's the rest of the story.

Overall, my ignorance and inexperience with reloading rifle cartridges has produced a lot of mistakes, too much misspent money buying the wrong things and an unfamiliarity with what the AR needs. It's compounded by our current situation of having to buy a compromise instead of what I need or want, and getting wrong advice occasionally. So to answer your question directly, I have shot the AR with only factory Hornady and Federal Ammo with 55 gr HP ammo. I plan on buying a 1-8 or 1-6 decent quality rifle scope instead of my current EOTech 552 Red Dot rifle scope. It's a thing of beauty, but I want to be able to reach out to 400 yds with a scope with windage and elevation reticle, lighted if possible.

I bought two sets of dies, both wrong and unused based on advice, a Hornady Match Grade 2 Die Set #544207, and a Redding Match Die Set # 36111. Both I will resell, neither has been used.
Now, according to the pro at Redding, I bought the #39111 3 Die Match Grade Die Set, and that I will keep.

I'd love to trade those GMX's for Sierra 69gr MatchKings, because I finally was able to buy a box of 500. In all my research, 69 gr will or should be fine out to 400 yds. But how do you advertise a trade?
And according to the newest Lyman Reloading Handbook, Varget powder produced the most accurate groups in Sierra 55 Gr, 69 Gr and 75 Gr bullets, but I simply can't find any. I'm just going to wait until I find some I guess.

In jacketed bullets, I have 55 gr SPT, 69 Gr HPBT and 70Gr GMX. At the time I bought the GMX, I couldn't find what I wanted anywhere, and these popped up, so I grabbed 300 of them. Better than nothing. These I want to trade for 300 of the 69 gr HPBT.

I have not reloaded any 223 cartridges yet, because of the Die issue (resolved) and no powder. I can't find the primers I want either Remington, Federal or CCI, so I bought 4K Tul-Ammo, primers, I hope they are OK.

While I have always wanted to own an AR, this entire experience has soured me of the whole project. While I know that SpringField Arms is not a $3000 premium line gun, the name told me it wasn't bottom of the barrel either.
But I sure didn't expect to have to go through all this to have some fun at some targets. A long time ago in a Galaxy far, far, away when I was 15, I was 23rd (better than 24th) in the nation for NRA small bore rifle 4 position competition using my Anshutz .22 rifle. I like the challenge of long distance, but I'm too old to take it seriously anymore.

Oh, I almost forgot...I bought 2K supposedly "Once Fired" brass cases (My wallet does have limits), and I wrote the owner of the company online and pointed out to him examples and photo's that half of them were not "Once fired". Not surprisingly, I never got a reply. I hope to get 1K of these "reloadable", but I'll have to check each one carefully, and because a lot of the primers were crimped in, it broke the pin in the first die, which I replaced. So that meant that I had to deprime all the brass in a separate operation with my Lee (Lyman) Depriming tool, which is really built heavy duty and was able to push those primers out. I use a Hornady Lock & Load Progressive press with an automatic case feeder. Made this much faster.

I'd love to have a Trijicon Rifle sight, but those are about 1/2 the price of the entire rifle. So I'll probably have to settle for a Vortex 1:6 or 1:8 after doing a lot of research.

It's been fun...

Thanks,
Robert
 
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