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Discussion Starter · #1 ·
Hello all,

I'm sure this has been discussed before, but I'm not finding any answers clearly describing the differences between standard and magnum primers and when it is best to use either.

For many of my bolt gun reloads I have had no issues deciding on a primer as different load manuals usually have a general consensus on what to use for a particular cartridge (i.e. 300 win mag uses a mag primer). I've had loading frustrations on both my AR-15 and M1A service rifles. I know they will never be as accurate as my bolt guns, but I feel there is better grouping for both of these rifles.

I am fairly new to reloading for gas cycling weapons. I've done my homework and experimentation on brass (with proper sizing and head spacing), bullets (different mfg. and weights), and powder (different mfg. and charges). So far, I have had marginal grouping results with several different combinations. The only constant in my loads are primers (CCI SR for AR, and CCI LR for M1A). I'm looking to change, but I'm unsure on whether I need to start with a brand change and/or switch from standard to mag primers.

I'm looking for a good starting place to save me time and money to achieve my goal. Any suggestions?

Thanks in advance!
 

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For 308Win cartridge, MAG primers are not needed nor recommended - the powder weight and cartridge size are fine for standard LR primers. Typical primers that work well are Winchester WLR, Wolf, CCI200, CCI34.

For 223Rem, a magnum primer is sometimes used for better ignition of the somewhat large (for a small rifle primer) powder charge.

If the cartridges fire ok without any 'hang-fires', delays, or other oddities, then I doubt that changing primers would make a noticeable accuracy difference unless you are shooting beyond 500 yards. Even farily large differences in MV don't make much poi difference at closer distances.

Jay Kosta
Endwell NY USA
 

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as has been well-articulated above, accuracy in your case will not likely be improved by mag primers.

in your M1A and AR rifles here is what WILL help (more or less in this order).

1. Better BULLET selection.
2. match BEDDING (or Free-Float handguard/rail system on your AR)
3. TRIGGER job (or match trigger on your AR)
4. Better BARREL (a heaver/match barrel on EITHER is a no-brainer).
5. LOAD DEVELOPMENT (easiest tweak besides adjusting load data is bullet seating depth--controlling/limiting bullet "run-out" also can help a good bit).
 

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I read somewhere sometime ago that a good rule of thumb was, with a rifle cartridge over 60 grains of powder, use a mag primer. Ive done it for years and haevnt found it wanting. I really dont use ball powders, so it works for me.
 

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Discussion Starter · #6 ·
6. Practice
7. Practice
8. Practice
Really? This isn't my first rodeo.

I've heard ignition of ball powders can be better with mag primers. I was actually looking for some validation to this claim. For example, shooting any charge of TAC out of my AR yields inaccurate results. Furthermore, it leaves my rifle filthy. Would mag primers help with at least the cleanliness, and if it cleaned things up, would that be a sign ALL the powder is burning where I could get consistent results?
 

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So what rifle are you reloading for? M1A or AR? What barrel length?

What's your load? What brand for the case, bullet, powder? How much powder and what COAL?

What kind of groups are you getting? What shooting conditions? Bench on a rest? Iron sights or scope?
 

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Discussion Starter · #8 ·
So what rifle are you reloading for? M1A or AR? What barrel length?

What's your load? What brand for the case, bullet, powder? How much powder and what COAL?

What kind of groups are you getting? What shooting conditions? Bench on a rest? Iron sights or scope?

Whew, I have to answer some of the load data from memory as I'm out of town for the holidays and do not have my load data sitting in front of me. That being said, I am loading for both rifles and having unacceptable results from both (compared to my bolts).

Both rifles were shot off a bench with bags, about 40-60 deg. minimal wind (no more than 1-3 mph any direction). Elev. 4800'. Fairly level (1-5deg.) Always shot in same location.

AR is a BM varmitter...24'' 1-9" barrel. I have installed a 3 lb, single stage timney trigger, burris PEAR scope mount, and a 10X super sniper on this rifle.
LC brass and CCI SR primers have been constants in all loads. I've tried 52 gr. MK, 55 gr. blitzK, 69 gr. MK, and Hornady 68 gr. BTHP (other bullets tried didn't go very far with testing). Powders tested were worked from mins (from sierra manual) and worked up. As of now, IMR 4895 and H335 have produced about the same (and best) results. Groups are roughly 1"-3" 5 shot groups. Usually, 1-2 outliers (outliers being the 3" range). And before you ask the powder charge question, I'm measuring every test charge on a digital scale exactly (very time consuming...).

M1A is a SAI loaded...stock, irons. This rifle has been more forgiving, 1"-2" @ 100 yds, open sights. i'm not too pissed, but I want more (I know it's capable). REM .308 brass, IMR-4895 (by far the best improvement), sierra 165 HP. This is a hunting load, not a match load.

I hope this gives you enough. Charge weights can be given when I'm back to Reno. I've been reloading a long time and frankly, snuffed. I've seen results on this site with gas cycling rifles, and know results can be better....
 

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mags

I've personally not seen any change in accuracy comparing primers. What has been the single most important piece of the accuracy puzzle is the seating depth of the bullet. I always laod my 308 to 2.80 OAL and 223 to 2.26 OAL. Iuse BLC-2 powder for 223 and H4895 for 308.

Maybe this is not new info for you however.

Chiro
 

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I can't be of much help with the AR but I can suggest a few things for the M1A.

In regards to the M1A, you are getting in to the area where a lot of people will tell you that you are asking for the improbable, not impossible but not easy either. The closer you get to 1" groups the harder it is to improve the groups, especially if you are shooting irons. I use a scope and don't do much better than you are seeing.

Have you had anything done to improve the rifle? The stock fit is the first thing that can always be improved on Springfield M1A rifles. The easiest fix with the greatest potential for improvement is the fit of the hand guard.

You don't want the hand guard to touch the stock along the sides and you want it to move freely from front to rear (just a little, maybe 1/8").

The stock ferrule (the metal cap on the end of the stock) should be tight and it shouldn't touch the front band except at the bottom lip of the band. There should be a slight space between the two except where that bottom lip is, and there it should come in to solid contact with the ferrule with several pounds of pressure. Make a witness mark with a pencil across the ferrule and the bottom lip of the front band. Squeeze the two together with your hand and release the two quickly. The idea is that you should see the witness marks line up after releasing the two. If they don't then something needs to be done so that they do. This gives you an indication as to whether the stock and the barrel are returning to the same rest position after each shot. If they don't then your groups will suffer.

Make sure that the operating rod guide (the round hoop that is pinned to the barrel that the op rod goes through) does not touch the stock on the bottom or the sides.

Make sure that the back of the receiver does not move from side to side.

Those are some of the easiest things to look for and fix.

As for the load, I like using either IMR 3031 or 4895 for my 168 grain loads but I prefer Hornady Amax bullets. I've had better luck with getting tight groups using them out to medium ranges (no more than 600 yards). I usually stick to velocities of about 2550 fps and that should be somewhere around 42.0gr of IMR 4895 in a medium volume case (Winchester or Remington) with a COAL of 2.83" using the 168gr Sierra bullet. I also prefer Federal 210M primers. I know people will tell you that they aren't safe but I've used them for many years and I've never had a problem. The military also uses them for their long range cartridges so I'm not the only one that thinks they work well.
 
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swagbrdr,

To answer one of your questions, I personally have had better luck with ball powders using magnum primers. In particular, I use Win 748 for 30-30 - when I started developing the load I would find that the barrel was dirty. I read more from my manuals and found the rule of thumb is mag primers with ball powders, so I switched to a mag primer and re-worked the load. I found the barrel to be much cleaner and have been using mag primers with ball powders ever since.

Since Win 748 is one of the powders listed for 5.56, that is what I used to develope loads for that along with mag primers. Never had a problem with a dirty barrel on the 5.56 either. My conclusion is that mag primers do help with ignition of ball powders, especially if the case is not 100% full.
 

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swagbrdr

My previous post about practice, practice, practice, was not meant to be snide or condescending. If you look at the other replies, you'll see a pattern. That is, do not expect any miracles as a result of swapping primers. I'll go one further and say, do not expect any improvement at all. Except for big cases with slow-burning powder, primers are the least important of the expendable components.

JMHO

Ray
 

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I use the CCI #34 nato primers in all my military calibers. There a tad hotter over the standard lr primer about 1.5 times. As were the magnum primers are about 2 times hotter. Plus the #34 primers have a thicker wall for floating firinng pins so slamfires can't happen.
 

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I'll reference my concurrent post about magnum primers and H335 in the AR...

http://m14forum.com/ammunition/127041-magnum-primer-h335.html

I actually found the standard CCI primers more consistent with H335 in two different AR's, my 20" H-Bar and a 16" RRA carbine. The results surprised me, quite honestly.
 

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Discussion Starter · #16 ·
Hey all,

Have an update on the AR. I ditched the 24" barrel and went with a 18'' Daniel Defense barrel 1/7 twist. This greatly improved accuracy right off the bat when I shot a 3/16'' group from 100 yds using XM193 ammo. I'm super stoked! Next, I'll be developing a hand load for this thing. I came into some Wolf Mag and Rem 7 1/2 primer I'll be using rather than the CCI SR. Luckily, I placed the barrel order 2 days before Newtown...

RAMMAC: Thanks for the info on the M1A! I'll look and try some of your suggestions. I am looking at purchasing a Sadlak spring guide as I have read on other posts that it's a must buy.
 

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I use the CCI #34 nato primers in all my military calibers. There a tad hotter over the standard lr primer about 1.5 times. As were the magnum primers are about 2 times hotter. Plus the #34 primers have a thicker wall for floating firinng pins so slamfires can't happen.
no, they are NOT thicker. They MAY be a (tiny) bit HARDER. Virtually all LR primers are .027" inch cup thickness, although there is some variation in SR, SP, etc. primers.

All CCI-34's do to be "Mil-Spec" is to ensure the primer CUP HARDNESS factor that exceeds a specified firing pin indent standard (via a copper crusher inserted into dummy case.fixture with a size "C" .225x.400 annealed copper cylinder made by WRA for the DOD. Hardness (in this case) comes from the ANNEALMENT process, not thickness.

Besides the fact that "slam fires" are ALMOST a MYTH, that all you need to do to avoid them is ensure you seat primers below flush, AND (finally) that both the M1 and M1A/M14 are designed to PREVENT them anyway, if one does happen (once per lifetime MAYBE), who CARES (unless you are a grossly unsafe shooter and not minding where your muzzle is pointed)??

SEE THIS RECEIVER BRIDGE? Even if the bolt is allowed to "slam" forward, the firing pin has been HELD SECURELY BACK until the bolt is virtually fully seated.

There isn't sufficient kinetic energy left in the firing pin to "do" much of anything to the primer even if it moves forward at this point!

Use whatever primer you like, seat em fully, obey the 4 Rules of Gun Safety, and quit worrying about this silliness.

 

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Magnum primers simply burn longer than a standard primer to help ignite all the powder in cases that contain large amounts of powder. I don't load magnum rifle rounds but a guru wiser than I told me a good rule of thumb is about 70 grains or more for rifle = magnum primer. It's not necessary in a .308 and can raise pressure. If you're looking for conistency a match primer may help, but you most likely won't see the difference from the primer alone.

Back to your bullet selection for either rifle - normally a "match" type bullet will have a better ballistic coefficient. To go along with this the longer the bullet, usually the better for the BC. A longer/heavier bullet will normally work better with a faster twist rate barrel. The Sierra 168 grain HPBT match bullet is a good baseline for the .308 cartridge. It may not shoot the best out of your rifle, but it tends to shoot very good out of most any rifle. If you can get 2600 - 2700 fps with that bullet you should have good results.

There have been some good tips in this thread, try some and see what works.
 

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CCI told me that the number 34 primers have a different angle on the anvil legs to make them less sensitive. I believe the different angle is the result of the anvil legs being shorter but CCI didn't describe it that way. The #34 primer cups do seem to be the same thickness as the other large rifle primers. The #41 primer cups seem to be thicker than any other rifle primers, large or small. Magnum small rifle primers do have thicker cups than non-magnum small rifle primers. Standard force and magnum large rifle all have the same primer cup thickness. The large rifle primer cups are thicker than the magnum small rifle primer cups. The exception seems to be the small rifle #41 primers which may be the thickest of all. I'll have take another check of the cup thicknesses to be sure though.
 
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