• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

Bolt clearance effects on accuracy?

I measured a new Defiance action yesterday. The front of the bolt measures .6995", the back of the bolt measures .700", the middle of the bolt measures .699".

A .702" pin is a go and a .7025" pin is a no go on the rear of the receiver. A .703" pin is a go on the front and a .7035" is a no go.
 
Fast14riot said:
Well, how many Stolle brothers actions and later Kelbly made Stolle-Panda actions won stuff before being bushed, bumps added or otherwise tightened up? I'm all for driving development and design further through testing, but I do like to take a step back every now and again at look ar the original design intent.
Click to expand...
That's true. The aluminum is a great insulator from vibrations.

At some point, with any action, you're going to start seeing some vertical from excessive bolt clearance at the rear. The danger in that is....you'll chase your tail thinking it's some sort of tune issue, barrel issue, 'bad' bullets, 'bad' powder, 'bad' primers, 'bad' bedding, 'bad' scope(s), your sports psychologist letting you down, etc, etc. Now, where that point is...I'm not totally sure. But having owned a half dozen Panda and three Kodiaks, the trail is pretty well marked by the bread crumbs. ;)

I bought a used Kodiak last season to build my Hunter gun around. I knew the history of the action and it's owner (a friend) had struggled with vertical. When I checked it, there was .009 bolt-receiver clearance at the back end. How much it had when new...who knows? Mike Bryant bushed the bolt for me to provide .004 total clearance. Mike, Alex Wheeler, Randy Robinett and Mike Bigelow all provided input before I settled on the clearance number. Again, we're talking aluminum receivers. On a steel receiver, that clearance number would be quite different.
WCp9sZtl.jpg


All better, now.
Re3T13Ol.jpg


I'd buy a new Panda in a New York minute. :)

Good shootin' :) -Al
 
LVLAaron said:
What were they competing against at the time?
Click to expand...
Remington, Shilen, Wichita and Hart. With a sprinkling of one or two others. None of which had tight bolt to receiver clearances. It was also rare as hens teeth to shoot an agg in the ones back then. When I started there was still a Mauser action to be seen on the firing line.
 
Last edited:
Years ago a friend was given a SA 700 that he used to build a Hart barreled .22-250. This action's bolt may have been repolished to remove rust, but that is just conjecture. In any case, the bolt seemed a lot looser than any other Remington we had seen. The rifle shot erratically, sometimes looking like it wanted to shoot, but throwing shots. After fiddling with it for a long time, I loaned him a video on sleeving bolts, and he sleeved the bolt. Problems solved. I grant you, it was an unusually loose bolt, but it does prove, at least to my satisfaction, that if you get past a certain amount of clearance, you will have problems. IMO, for benchrest, about .002 to .003 will work just fine.
 
AlNyhus said:
Mike Bryant bushed the bolt for me to provide .004 total clearance. Mike, Alex Wheeler, Randy Robinett and Mike Bigelow all provided input before I settled on the clearance number. Again, we're talking aluminum receivers. On a steel receiver, that clearance number would be quite different.
Click to expand...
Curious as to what you would pick (or what others might have recommended) for the clearance number on a steel BR receiver?
 
AlNyhus said:
This is a one piece bolt sleeve that Stan Ware did on one on my 700's. Receiver I.D. is .705, bolt measures .704.
ZEyt1ull.jpg
Click to expand...
Nice work right there. I'd bet my lunch money it shoots few, if any flyers, set up like that.
 
AlNyhus said:
This is a one piece bolt sleeve that Stan Ware did on one on my 700's. Receiver I.D. is .705, bolt measures .704.
ZEyt1ull.jpg
Click to expand...
I tried .001 clearance on one 700 after reaming receiver to .705, however the bolt had some drag in operation so I just turned the sleeves to .0015+ total clearance.

I suspect if I would have milled the sides of the split sleeves opposite the lugs it may have worked nicely at .001.

Maybe try @Will Henry s method for the bumps next time.
 
Fast14riot said:
Well, how many Stolle brothers actions and later Kelbly made Stolle-Panda actions won stuff before being bushed, bumps added or otherwise tightened up? I'm all for driving development and design further through testing, but I do like to take a step back every now and again at look ar the original design intent.
Click to expand...
No doubt. But the op mentioned Jim so I am sharing some history. I have known Jim for about 10 years and have had many discussions about all things accuracy. I consider him a friend and respect his opinion. Now when he was doing this it was before he made actions, before the tpe even. I don't know how the bolt fits were on those actions he worked back then. But he is a big proponent of snug bolt fit.

I have a slightly different approach. I don't think the bad vibrations come from seating that lug. Its only moving a few ten thou to seat however the back of the bolt body is traveling however much clearance allows and slaps the bottom of the action body. That's what concerns me. How I mitigate that is to be ultra anal about the lug seats so the back of the bolt body has clearance all the way around it when the lugs are seated. A bolt body held hard against the action body when the lugs are seated is a no no in my book. So I don't mind .002 to .003 in a steel action. But thats why we think aluminum can have more room and less vibration. And its why the aluminum nuevo exists. I worked on Jim too for an aluminum action before that.
 
Last edited:
AlNyhus said:
That's true. The aluminum is a great insulator from vibrations.

At some point, with any action, you're going to start seeing some vertical from excessive bolt clearance at the rear. The danger in that is....you'll chase your tail thinking it's some sort of tune issue, barrel issue, 'bad' bullets, 'bad' powder, 'bad' primers, 'bad' bedding, 'bad' scope(s), your sports psychologist letting you down, etc, etc. Now, where that point is...I'm not totally sure. But having owned a half dozen Panda and three Kodiaks, the trail is pretty well marked by the bread crumbs. ;)

I bought a used Kodiak last season to build my Hunter gun around. I knew the history of the action and it's owner (a friend) had struggled with vertical. When I checked it, there was .009 bolt-receiver clearance at the back end. How much it had when new...who knows? Mike Bryant bushed the bolt for me to provide .004 total clearance. Mike, Alex Wheeler, Randy Robinett and Mike Bigelow all provided input before I settled on the clearance number. Again, we're talking aluminum receivers. On a steel receiver, that clearance number would be quite different.
WCp9sZtl.jpg


All better, now.
Re3T13Ol.jpg


I'd buy a new Panda in a New York minute. :)

Good shootin' :) -Al
Click to expand...
Why is the soot pattern on a fired case neck different with a 2 or 3 lug bolt. What's going on.
 
You must log in or register to reply here.

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Classified Ads

Forum statistics

Threads
165,828
Messages
2,203,920
Members
79,144
Latest member
BCB1

Share This Page

Back
Top