Bolt vs Auto Loading

G

gnfiter3

Sergeant
Full Member
Minuteman
May 28, 2007
301
7
Florida
#1
Looking though many reloading sites lately; I found a couple that caveate, max for bolt gun. While I have no need to push the pressure envelope, yet, I do have these questions:
1. max loads from manuals: Do they apply to both bolt and gas guns.
2. Would it be safe to assume that a load listed by brothers on the Hide, that does not exceed max from a manual, are safe to try in both bolt and gas guns?
3. Will pressures signs be different in a gas gun vs. a bolt; as in extractor marks or something that may not occur as fast in a bolt rifle?


Does someone have a load for their bolt .308, they would not shoot in their AR-10?

I think it may just come down to how hard can you push a bolt vs. an auto??
 
#2
Re: Bolt vs Auto Loading

I load .308 for my bolt gun and AR10. Yes, the pressure signs are a bit different. With bolt guns ejector wipe is a serious pressure sign that usually comes after flattened primers. I've yet to push a load that hot in a bolt gun. However, in an AR10 (and ARs in general) "ejector swipe" is commonly present because of the camming action of the bolt. Armalite released a tech note about it, I've posted it in this forum before. The loads I shoot through my bolt gun are impossible to shoot through my AR10 because I use the 208gr A-max in my Savage seated to 2.98"
 
#3
Re: Bolt vs Auto Loading

As I said, I have no reason, yet to push any limits, seeking more speed. I generally load AR ammo to max mag length, but that may not aid in accuracy over published OAL.

So far the best load for my AR-10 has been 41.5 of IMR 4064, while my 40X likes 43.0. Both loads are well within published data. Which is why I asked the question on max recommended loads in manuals, bolt vs. gas guns. It may be that continuing up for better accuracy for my AR: as the 40X groups are tighter than the AR, I hit those pressure signs. I know flat primers are a sign, but if there are other signs in the AR that manifest before the flat primers; I want to be sure of all of them. You know the Armalite wasn't cheap, so I certainly don't want to break anything. Also, I think it will shoot tighter, assuming I do my part.

I've seen a few post that warn that the load is over published max, but that seems to be in bolt guns.
 
#4
Re: Bolt vs Auto Loading

AR15BlueDot18Gr33VmaxDSCF0027.jpg


I fired this load of 18 gr Blue Dot 33 gr Vmax in an AR15 chronographs between 4100 and 4200 fps in a 26" barrel.

You can see the AR15 bolt head pattern embossed on the case head.

The bullet leaves the rifle so fast and the charge is so small, there is not enough gas pressure long enough to cycle the action.
 
#6
Re: Bolt vs Auto Loading

Yes, and it is damn dangerous too.
I gave some mixed brass [ that I got ~ 7 gallons for $63] to a friend, who shot it in him Rem700. There was almost no pressure sign at the primer, but the head separated and he got gas in his eye. He had to drive two hours to find a doctor.

The consensus was that that piece of brass had been stretched by being fired in a machine gun.

I have never had a case head separate on me in regular shooting, and I hope I never do.
I have had lots of case heads separate in experimental work, and all that was harmed were guns, not people.
 
#7
Re: Bolt vs Auto Loading

I found a thread on pressures signs, way back on page 135 or 136 of the Reloading Section here. It has been several years since the topic was posted to.

In any case, my questions were sparked by the possibilty of driving 4 hrs to shoot 1K. It also seems that most shooters use bolt guns for that distance, and I wanted to try my AR-10 at that distance too. Seems the more speed I can get, the more likely to get a 168 or 175 Berger VLD out there. So as I thought of working up to push the VLD's out there, I thought about the pressure issue and was looking for the true signs with a gas gun. I have somewhat of a feel for tight bolt, and flat primers; which this thread made me question if those were the best indicators.

Experience from the guys here seemed, a simple solution to my inquiring mind. I never exceed published data, as a rule; and generally stop .50 grains below any published max. There are guys who seem to push past the published, for whatever reason, get what they're looking for.
 
#8
Re: Bolt vs Auto Loading

Update, there's another pressure sign thread, but again, it's a bolt gun. Again, flat primers seem not to be the best way to read the signs. Seems as if I could destrory an AR using bolt gun indicators.
 
#10
Re: Bolt vs Auto Loading

Well, other than poor loading techniques, old brass, and zero attention to detail, it seems you have to be over the max by quite a bit to be dangerous. Good case prep and inspection should keep most of us out of the danger zone, and the hospital.

Subsonic rifle loads with pistol powders seem to be another way to build up explosive pressures.

Is there anything to the rumor the manauls have a built in safety margin in the max load listed?
 
#11
Re: Bolt vs Auto Loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gnfiter3</div><div class="ubbcode-body">
Is there anything to the rumor the manauls have a built in safety margin in the max load listed? </div></div>
Well, yes and no. It's not the LOADS that have the pressure margin built in, it's the firearms. The weak link is the CASE!!!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sumbuddy else</div><div class="ubbcode-body">2. Would it be safe to assume that a load listed by brothers on the Hide, that does not exceed max from a manual, are safe to try in both bolt and gas guns?</div></div>
That is a great place to start. However, based on the Uniform Gas Theory and the TANSTAAFLL principle, I would add the results from YOUR rifle with YOUR loads including especially the length of YOUR barrel. If you are getting 25 fps "more" than the books say you should be for a max load, regardless of how far "under max" your actual load is, you are probably okay. 50-plus fps and you're pushing it. 100 fps and your load in YOUR rifle is probably using up your brass/rifle safety margin, and you could burn your throat out a bit early.

Specs is specs, and there's more than "energetic disassembly" to be a concern. An interne-famous barrel breach of an M1A a few years ago, shooting quality factory surplus, was traced to a barrel made out of steel that was BADLY heat treated. You can look it up at www.thegunzone.com. <span style="text-decoration: line-through">Two</span> <span style="font-weight: bold">Three</span> things of note: the barrel had successfully fired thousands of rounds before failing. Second, micro-cracks in the bore had started to rust, further weakening the steel. Finally, the original threads on the gun boards discussing this before the scientific post-mortem came in were full of wild, mis-informed, and often plain silly and wrong speculations.

One thing I took away from that is that repeating a dangerous situation a thousand times still does not remove the unacceptable danger from number 1,001. Latent defects in your steel can cause enough problems with known-safe factory loads. I see little sense or utility in pushing it.

A LOT of loads I see posted here boast of velocities that I wouldn't touch with a bolt gun or a gas gun.
 
#13
Re: Bolt vs Auto Loading

Slow-burning powder loads safe in a bolt gun may damage an M1 or M14/M1A operating rod.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Just remember -- a cast Springfield Armory M1A receiver is technically not as strong as an M14 forging, and an M14 is a piston-driven action.

A steady diet of very high pressure loads can contribute to something like this (courtesy the Wisconsin Rifle Team):

28vdhc9.jpg

</div></div>
 
#14
Re: Bolt vs Auto Loading

Grump, I hear you on some of these loads. I also see that on several of the current threads, the how much is to much keeps coming up. The bolt vs. gas gun thing too.

Just seems if you have a load that shoots to your liking at 2650 fps, looking for a self distruct point at 2850+ isn't about much. Not a 1k shooter so maybe it's can I get a nother 100 fps? Thing.

Some of the test I have read hear make me wonder what credentials the author has to exceed the limits as they seem to do.

I still just want bughole ammo at 100 and the chance to shoot 600 somewhere. The definitive this is what you look for is still hanging out there. If my moderate 43 grs of 4064 shoots as well in my AR as in my 40X, I'll be satisfied, for now.
 
#15
Re: Bolt vs Auto Loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gnfiter3</div><div class="ubbcode-body">Looking though many reloading sites lately; I found a couple that caveate, max for bolt gun. While I have no need to push the pressure envelope, yet, I do have these questions:
1. max loads from manuals: Do they apply to both bolt and gas guns.
2. Would it be safe to assume that a load listed by brothers on the Hide, that does not exceed max from a manual, are safe to try in both bolt and gas guns?
3. Will pressures signs be different in a gas gun vs. a bolt; as in extractor marks or something that may not occur as fast in a bolt rifle?


Does someone have a load for their bolt .308, they would not shoot in their AR-10?

I think it may just come down to how hard can you push a bolt vs. an auto??

</div></div>

I can't speak to loads for an AR-10 but I definitely have loads for my 308 bolt gun that I would not shoot in my M1A - anything over 175-gr, anything loaded with any powder slower than about IMR-4064, and any load in soft commercial brass.

I recommend you google Zediker's article on reloading for gas guns and read what he has to say. Maybe not all is applicable to your AR-10 but some would be.

The AR rifles do not handle case head separations, blown primers, M-splits in the brass, etc. as well as some bolt guns or the M1/M1A series of rifles do. I speak from firsthand experience.
 
#16
Re: Bolt vs Auto Loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Clark</div><div class="ubbcode-body">Yes, and it is damn dangerous too.
I gave some mixed brass [ that I got ~ 7 gallons for $63] to a friend, who shot it in him Rem700. There was almost no pressure sign at the primer, but the head separated and he got gas in his eye. He had to drive two hours to find a doctor.

The consensus was that that piece of brass had been stretched by being fired in a machine gun.

I have never had a case head separate on me in regular shooting, and I hope I never do.
I have had lots of case heads separate in experimental work, and all that was harmed were guns, not people. </div></div>

Was your friend wearing safety glasses? Did he have a complete head separation or a partial?

I have a left-handed friend that hunts with a right-hand 700 in .270 Winchester, and he had a blown primer with a factory load. The lens on his safety glasses was gas cut, and so was his forehead and face above and below where his glasses were, but his eyes escaped injury. I guess nothing works as well to protect the shooter as the old K98 Mauser.
 
#17
Re: Bolt vs Auto Loading

Fortunately, I'm not thinking of going over published max charges anyway. Just looking for a few points on making sure I have some indications of where my loads are pressure wise.

It's still interesteing to note, a few loaders asking about pressure signs, and the bolt vs. AR still has not been definitively defined; though I have seen somethings that make sense.

A good inspection of the cases before loading is essential. Constantly going max load should warrant closer inspections, and a point where you retire the brass early. Any common sense thing that reduces the likelihood of having a case come apart. Brass is certainly cheaper than the price of an AR-10, esp. one from Armalite.

4064 is my .243, .308, choice, even tried 25 grs. in a few 223 loads. One manual said that load was 1 grain over, but it shot well and the brass resized with no more effort than with Varget or BLC. May try it agin, if a more suitable powder is not available, Varget, RL15 or the like.
 
#18
Re: Bolt vs Auto Loading

My favorite bolt gun load for deer (out of a 700V) is 43.5 of 4064 pushing a 165 Ballistic Tip. I'd be more than confident shooting that through an AR-10.

44 of Varget or Reloader 15 is considered by many as the go-to charge for 168s and 175s, bolt or gas gun.
 
#19
Re: Bolt vs Auto Loading

Sinister: I was working up to 43.5 of 4064 in my 40X. when it shot ragged five shot group at 43.0 I quit, with a smile. Will be working the same .5 increments for the AR to see if it likes anything above 41.5, which is a starting load for me.

The fact that I weigh every 308 round makes having two loads, no big deal, but I sure would like to load all my rifle loads progressively, hense a sense of, where's the Varget?

On the otherhand, RL15 is said to meter better than varget, in a 550, so the progressive loading for the AR may be possible. Just have pounds of 4064
 
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