Browning XBolt Factory Bedding

[choprzrul]

This is not the first time I've seen this on an XBolt. Hornady CX, Barnes TTSX and LRX, along with Absolute Hammers. 168gr TTSX, 175gr LRX, 208gr LRX, 190gr CX, and 162gr AH. All over top of RL26 and Fed 215M using Lapua cases fire formed and annealed. Gun shoots 1.5" to 2.25" groups no matter what I did.....up and down the powder ladders, MCarbo trigger spring, thoroughly cleaning barrel, not cleaning the barrel, hot, cold barrel, 30 & 25 in lbs actions screws, 40 & 35 in lbs, 50 & 40 in lbs. Dang thing is a PITA....but it's my son's rifle and he really likes it :-(

Anyway, today I decided to check and see if the action really was bedded.....so I got out the Plastigage and reassembled to 40 & 35 in lbs, took it apart, and found there is a gap of 0.003" to 0.006"+ between the receiver and the bedding. The bedding in front of the recoil lug just barely touched the plastigage.

Makes me question the factory's choice of bedding material/process. Either the material shrunk as it cured over time, or they used a generic receiver to bed it and then assembled the stock and this receiver later?

Just thought I'd share in case someone else is getting a similar headache :-(



Yeah....my work space is a mess....

 

[David_h]

Composite stock? Will be interested to hear what you end up doing. Skim bed? I have two x-bolt pros which have the carbon stock. They may have used the same factory blob for bedding. So far shooting good but won't rule out a redo on skim bedding in the future. I put in MCarbo spring but can't remember factory bedding.

 

[choprzrul]

Yep...skim coat. Gonna drop it off at my gunsmith's place today.

 

[David_h]

Please ask him to take pictures before reassembly. Curious to see the job. Thanks

 

[ShtrRdy]

Can you tell where the barreled action was touching?

 

[choprzrul]

Can you tell where the barreled action was touching?

I'm not for certain as I used only four little pieces of the plastigage. 1 in the rear, 1 in front of the lug, and 1 on each side of the front bolt. I suspect, but don't know for sure, that the thinnest measured gap might actually be contact points had the plastigage not been present. I'll ask my gunsmith if he can do a prebedding evaluation. He has some blue stuff he uses to check how the action and stock are mating up after bedding.

What surprised me was the bedding material they had in front of the lug was doing absolutely nothing.

 

[cohunt]

Never thought of using plasti-gauge to check-- good idea--- make sure it's new plastigauge though as over time it will harden and not give a true measurement (learned that at race engine building school over 30 years ago)

I think the factory blob bedding is hit or miss--- my 7mag x-bolt shoots excellent with my handloads-- factory loads weren't near as good though.

 

[just_jon]

How much of a gap would be considered acceptable? My HC Max LR has a .003" gap on both ends of the action.

 

[choprzrul]

Post skim coat bedding load developement. The gun seems to shoot much better now. This group was measured with a caliper and plotted on PointBlank:

 

[David_h]

Any pics of the bedding, particularly at the rear bolt? Good shooting.

 

[choprzrul]

Any pics of the bedding, particularly at the rear bolt? Good shooting.

I'm not sure if this picture from my smith is while it was in process, or when finished. I can tell you for certain that the gun shoots much better now

 

[HSmithTX]

That sure looks like after, I have two X bolts and neither look like that from the factory.

 

[V35BTC]

Factory bed jobs are usually poorly done. Weatherby uses some sort of hot glue looking stuff under the lug. I have an Accumark that was never better than 1.5 MOA. I did a test on it, when the front screw was loosened, the action separated over .050" from the stock. A little mill work and some Pro Bed got it to .0015" and a skim bed on top of that got it less than .001". Results- 5/8" MOA with three different loads.

 

[sable tireur]

I have always enjoyed working with the Browning X-Bolt rifles/receivers. Great rifles can be built from those receivers.

Back when both Winchester and Browning started getting grief for the poor performance of their factory rifles, they thought they could get away with that 'hot glue' treatment. No go.

We tested then properly bedded a pallet full of new factory rifles then re-shot them at 100 yards. Always a significant improvement.

Your stock is also one of the problems. There is some flexing which occurs even when properly bedded. These are bean counter approved inexpensive stocks. I suggest starting a search for another stock which fits your son and one he likes so you can plan on replacing it in the future.

Enjoy your new found accuracy!