Bad day at the range

[solvability]

I had accuracy problems with 4350 in a 30-06 but figured it out when I shot near dusk - carbine length barrel - too short for full combustion - switched to a faster powder and now get better results.

I like Varget or 4895 now.

I think you have a primer problem too or a case prep problem.

 

[Andrew Leigh]

Hi,

the pattern a group throws is of an indicator of what is going on;

Your first two groups, vertical stringing would indicate either a breathing problem or a dirty or weak spring in the firing pin, or the firing pin itself. On group 1 & 2 you could have been huffin' and puffin' after setting up the target at 100yds? If you were not then a firing pin problem may also explain the misfires.

On the second two groups. Horizontal string could be two things. The first is that the forearm of the rifle was slipping laterally on the front rest when firing. The second thing could be a loose fitting stock, when you get two sub groups within the main it is indicative of the rifle moving in the stock after two or three shots and then it will print laterally in a different place.

You are essentially using the OCW method for load development. This requires more rounds to be loaded starting lower down on the powder charge. I use the OCW method and it is not uncommon to have odd patterns fro vertical to lateral stringing with some real scattered groups inbetween. The groups start loose and get tighter then get loose gain but you will be left in no doubt as to where the sweet spot is. The third option to the above is that I think you may also be at the one end of the OCW method which means you never will know.

In summary I think there could be more than one problem, The easiest by elimination is to check out the hardware first, check the firing pin assembly and then check the tightness of the action screws. If a new rifle these could have loosened after a couple of shots.

Google Dan Newberry's OCW method. I think if you just extended what you are doing that you would get the results you want. It normally takes me 30 shot and I have the load I need without any doubts.

 

[essayons21]

I'm with rcmodel, you need to double and triple check your primer seating depth. What priming system are you using? What brass are you using? Are you cleaning or uniforming the primer pocket? In the tens of thousands of CCI primers I have used, the only issues I have ever had traced back to improperly seating the primer. As mentioned before, the first strike on an improperly seated primer may deform or damage the primer so that it will not ignite on a second strike even if properly seated by the firing pin.

As for IMR4350, I have never had good experiences with that powder in my guns, especially at higher velocities. Maybe try finding a node at a lower velocity, or give 4064 a shot. Every gun is a different animal, and no matter how hard you try some just don't like particular powders or bullets. (My precision 30-06 also didn't like Hornady bullets....)

 

[Trent]

I don't know about Mossburgs, but on my Savage 110 I had to strip the bolt at the range once and adjust the firing pin striking depth. After about 100 shots, on the factory new action, it started light-striking and only setting off about 50% of the ammo. Post-adjustment, it has never failed me.

I can't fathom a bad batch of CCI primers. Never heard of such a thing. I've got some from the early 70's that still go bang just fine.

Assuming that your primers are seated properly.... and you aren't somehow shoving the shoulder back (nigh-impossible if you're using new, unmodified factory dies)...

Get the rifle checked. Make sure headspace is good, AND your firing pin is striking deep enough.

EDIT:

Headspace can be "sort of" checked on fired casings. Measure from the base to the shoulder of unfired vs. fired casings, and note how much, if any, the cases have stretched. If they've grown substantially, you've got generous headspacing. In that event, your firing pin might not be able to reach a primer with sufficient force to set it off. It only takes a couple thou.

 

[rsnell]

Your load exceeds the maximun listed by Hodgdon, Lyman and Hornady. The Hodgdon data lists 52.0 to 56.6 grs of IMR 4350 for a 165 gr bullet. You were probably looking at the H4350 data or the data for a 155 gr bullet.

In 40 years of loading my only primer failures were traced back to oil.

 

[sage5907]

travisd, nobody ever talks about washing cases but after I size, trim an camfer the case mouths, and clean the primer pockets I soak the cases in a bucket of warm dishwater to remove all of the residue from firing and lubricant from the sizing operation. I then rense the cases in clean water, drain the water from each case, and set them out to dry for a couple of days. These steps don't take much time and they insure that if the primer is properly seated it will fire every time.

 

[travisd]

Andrew - I'd never read that but its pretty neat. I'll have to give it a try that way.

Like I said I'm pretty sure I seated the primers fine, I feel every case after I prime them, and I've never had a problem before. Might try and take the bolt apart and see if I can't get it to strike a little harder. It is a fairly new rifle.

As for the load data this is what I'm getting from hodgdon, its for a sierra bullet but same weight and style. I'll try taking it down a bit though.

165 GR. SIE SPBT* IMR 4350* .308"* 3.300"* 56.0* 2746* 48,100 PSI* 60.0C* 2934* 57,600 PSI

 

[Captaingyro]

As you have seen, Andrew Leigh gave you some pretty good advice. If you really understand the OCW method and follow it rigorously, it will yield amazing results.

If you want to see an example of what OCW can tell you, look at your two targets for 57 and 57.5 grains (the two on the right in your post.) If you plot the centers of those two groups, you'll find that they're almost identical...about 1.75" right of the bullseye and about .5" high. You're probably looking at a minor node there. Ideally, using OCW you'll see three or four charge weights in a row giving you the same center like that, and the middle of those charges is your "sweet spot". At that charge weight, small deviations from your intended charge will have little or no effect. (I think you're high in the charge range, and need to explore charges from 52 to 56 grains).

Once you find that sweet spot in charge weight, tighten up the groups with adjustments in seating depth.

Anyway, good luck and have fun.

 

[Utryme]

I had that exact rifle. It wouldn't group much better no matter what I did. Sold it fast!

 

[Andrew Leigh]

My mate has a .300 Win mag in the Mossberg ATR. I was hitting 4" gongs at 300m (not yards) with monotony. I think the rifle is fine.

 

[Wylie1]

Have you tried dialing a square with your scope or checking to see if it takes adjustment? 8 clicks up, 8 clicks right, 8clicks down and 8clicks left. I have had problems with the Prostaff scopes, 3 in 2 years.

 

[Ky Larry]

RC, I kike CCI primers,too. However, I got a pack of 100 CCI SR primers a few years ago that had about a 50% failure rate. Sent the remainder back to CCI and they replaced them. Nothing made by the hand of man is perfect.

 

[travisd]

Just looked at the round that failed to fire. This is after 3 strikes. What's everyone think? Getting light strikes? Doesn't look real deep to me personally but I don't know for sure.

 

[Andrew Leigh]

Very light strikes.

As I said, vertical stringing is indicative of this problem. Did you check your firing pin assembly like I suggested? Looks to me as if you have found your problem regarding the misfires.

Still think you have another problem as indicated by your second two groups. The action screws are not tight enough causing the two groups within a group scenario.

Good luck.

 

[ArchAngelCD]

Wow, that would be a light strike if it were only hit once but 3 strikes??? I agree, check the firing pin, firing pin spring and everything else involved. The good news is, it's probably an easy and inexpensive fix... Please keep us updated.

 

[Wylie1]

I said the same thing those two up there did as soon as I seen it.

 

[Trent]

Yup, those are light strikes, you need to clean/fix your firing pin.

Are those firing pins adjustable to length, like they are on the Savage/stevens actions?

 

[Trent]

I just looked at the exploded diagram of those, doesn't appear the striker is adjustable whatsoever.

If cleaning that bugger out don't work to allow more force to transfer to the primer, it appears that you're gonna need a new striker, and have it fitted properly.

 

[Trent]

Disregard I had the wrong manual.

Look at page 13 of the owners manual, on the exploded diagram, notice the firing pin assembly, how the shaft is cylindrical?

Get that bad boy out of there, and see if the firing pin shaft is threaded in to the housing.

If it IS, mark the location it's currently at (sharpie or scribe), disassemble it. Get some medium strength loc-tite, put a single drop on, and thread it back in not quite as far as it was previously.

(If there's a set screw, pin, or other retention mechanism you might need to stop and think about how to go about this).

Obviously if the firing pin shaft isn't threaded, you'll need to have a new part fitted.

This is assuming it's not just "gunked up". Based on the light strike pic you posted, that firing pin is maybe .002 to short. Should only be maybe a 1/16 or 1/8 turn adjustment if that shaft is threaded, depends on the thread pitch.

Be careful, make it too long and you'll pierce right through primers.

 

[Andrew Leigh]

To the OP

Google "setting a mossberg 30-06 firing pin" you will be surprised by the amount of firing pin problems the Mossbergs have. Is the rifle still in warantee? If so don't fiddle send her in.

Cheers

 

[travisd]

Well I took the stock off and put some lock tite on the screws and snugged them down good. As for the bolt I took it apart and can't really find any way to adjust the firing pin. Traded for the rifle so I'm guessing it's not under warranty.

 

[Trent]

If it's not adjustable you'll need a new firing pin assembly, more than likely.

Is this the manual for your rifle?

http://www.vintagegunleather.com/gun-manuals/pdf_M/mossberg_100atr_centerfire.pdf

It states it has a 1 year limited warranty, so unless it was recently bought and then traded for, it won't be under warranty.

Can you post pictures of the firing pin assembly?

I'm curious how they're put together.

 

[travisd]

Had it about 5 months no idea when it was bought. Guessing the warranty isn't good anymore. I'm guessing I'll just have to call Mossberg and see what it'll cost to get it fixed? A gunsmith probably cant do much can they?
Here's a few pics. This is as far as I got it taken apart. Can't figure out how to go any farther.

 

[Andrew Leigh]

There have been one or two horror stories regarding Mossberg ATR bolts. They may be lies but worst case scenario assume them to be true. Therefore I would send it in and would not tamper with it.

 

[ArchAngelCD]

Well I took the stock off and put some lock tite on the screws and snugged them down good. As for the bolt I took it apart and can't really find any way to adjust the firing pin. Traded for the rifle so I'm guessing it's not under warranty.

Many times a good company, which Mossberg is will fix a faulty product for free or for a very small charge just to keep the customer happy. I would write to them and ask them what to do?