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I have an early 80's M77 in 25-06. I bought the gun, customized the stock, floated the barrel and put in a 2lb trigger. It has been my favorite rifle ever since. I had some reloads special loaded for it in 100 gr and have owned 25 boxes of these shells and shot this gun with these shells for 40 years until recently ran out. I bought some factory shells last year and am having trouble closing the bolt with factory shells. I literally have to force the bolt closed and I scar the shell in the chamber. Anyone else have a problem like this? I have tried Federal and Hornady factory loads in 100 gr. I bought 20 boxes so I need to know if it is the shell or the gun? Never happened with my original reloads. Thoughts?
 

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The first thing I’d look at is the case it’s self. If a previous fired case, (old stock) chambers I’d start pulling numbers from that case, specifically the datum line and compare it to a new cartridge. Just because it’s factory ammo doesn’t mean it’s right, I’ve seen a difference of 7 thousandths before. It’s also possible you have crud in the chamber, give it good cleaning. And yes, I’m just guessing based on what you’ve said.

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Take a black magic marker and paint the shell case on the shoulder & neck and also the bullet. load the shell and then remove from chamber and inspect the case-bullet to see if any of the black has been rubbed off. It may give you indication if the shoulder is hitting the chamber shoulder wall, or if the bullet ogive is hitting the lands in the barrel. If the shoulder of the case is hitting, you may have a chamber that was reamed to minimum spects.
 

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I would be concerned with the bullets contacting the lands of the rifling , this can boost pressure .
A snug fit of the brass case is not a problem unless it hinders chambering .
I have a 30-06 that has a tight chamber , I reload and the cases last a long time ... full length resizing works the case very little ... I like this .
Take it to a gunsmith shop , bring the ammo and have the smith check headspace (go & no-go gauges) and ask his opinion . I would think long and hard about having the chamber reamed larger ... not good ...I say find or make smaller ammo . The chamber might need a good cleaning and polishing ...look at the marks on the case / bullet ...
Find out what's causing the problem .
Gary
 

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I would be concerned with the bullets contacting the lands of the rifling , this can boost pressure .
It sure can……..upwards of a 7000psi increase.
 

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Your M77 should easily chamber any factory round. I would scrub out the chamber really good because you very likely have carbon buildup causing your problem. I would use a bronze brush that is slightly larger than you case body and attach it to a drill first and then use your .25 caliber brush on a drill to clean out the case mouth contact area. That should fix your issues.
 

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Your M77 should easily chamber any factory round. I would scrub out the chamber really good because you very likely have carbon buildup causing your problem. I would use a bronze brush that is slightly larger than you case body and attach it to a drill first and then use your .25 caliber brush on a drill to clean out the case mouth contact area. That should fix your issues.
Agree ....A good cleaning and a good polishing with J-B Bore Cleaning Compound , wrap that brass brush with 0000 steel wool and smear with J-B bore cleaner and use elbow grease or slow drill to clean polish any carbon out .
This may be all you need to do .
Gary
 

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Agree ....A good cleaning and a good polishing with J-B Bore Cleaning Compound , wrap that brass brush with 0000 steel wool and smear with J-B bore cleaner and use elbow grease or slow drill to clean polish any carbon out .
The JB products are good, (I use them) but I think Iosso, (I use it too) may be more effective in this situation. Gary do really think that steel wool is the best route, steel wool “sheds” a boatload of fine particles, which would probably be a bear to completely remove.

Iosso, a shotgun patch and a larger than caliber bore brush has worked in the past for me.

 

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The JB products are good, (I use them) but I think Iosso, (I use it too) may be more effective in this situation. Gary do really think that steel wool is the best route, steel wool “sheds” a boatload of fine particles, which would probably be a bear to completely remove.

Iosso, a shotgun patch and a larger than caliber bore brush has worked in the past for me.

I've used a brass brush wrapped tightly with #0000 steel wool and smeared with J-B Bore Cleaner to rescue several military suplus rifles , the bores looked like the inside of a sewer pipe with corrosive priming and rust , over the last 50 years ... that was our method "back in the stone age" but I'm sure the new improved products do a better job .
Gary
 

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@gwpercle, going back to the J B Gary, I posted something on the forum a few years back……I usually use Butch’s Bore Shine and C4 on the bore etc, this time it was straight Hoppe’s. I scrubbed and patched until the patch were still basically white. Then I went back and hit it with some J B, those patches were so black it looked like it hadn’t been cleaned in years. Hoppe’s is good to an extent, I love the smell, (probably because I associate it with hunting) but sometimes one needed a cleaner that’s a little more aggressive like J B or Iosso.
 
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