I recently discovered that my Remington Sendero 300 win mag (which was shooting about 1/3 MOA with handloads) had suffered damage to the rifling at the crown. Needless to say the accuracy went in the dumps. I sent the barreled action away to PGW Defence Technologies in Winnipeg, Manitoba to have it cut and crowned. When I received the rifle back they had cut approximately 3/4" off the end and cut a recessed muzzle crown with no bevel and lapped the bore. I set it back into the stock and tried it out. I wasn't expecting the handloads to group the same as they did but I didn't think that they would be shooting about 1 MOA [img]images/icons/frown.gif[/img]. I tried a couple different loads a half grain up and down of the old load the only one that showed promise was the half grain up load. Should I keep trying to tweek the loads or should I try something else, I'm worried that if I keep going up in powder charge I'm going to get overpressure. I guaged the wear on the barrel to be about .003". The load I was using was 68.0 gr IMR 4350, 200 gr sierra BTSP seated .02" off the lands, winchester cases, 215M primers. Hunting season is here and I don't have a load that I can confidently shoot into the vitals of an animal over 400 yards.
When you have your barrel shortened, it vibrates differently and usually requires you to re-tune your loads. I think that you're headed in the right direction with the IMR-4350 but you will approach the high pressure level before you get it tuned.
Personally, I would switch to either IMR-4831 and work up to 70.6 grains per the Sierra manual or try Re-22 and work your way up to the top load listed in the link below.
This is a tough one, When I do all of my recrowning, I generally take off about 0.050" off the muzzle or enough to clean up any old crown contour there is.
I much prefer an 11 degree crown which a add a couple things of my own.
Did PGW give any explanation for the excessive barrel amputation?
I have had to do this on factory barrels that were belled out but with your rifle shooting in the 1/3 moa range this was certainly not the case. Sounds like someone made a mistake and had to cut off more barre to fix it. Pretty hard to screw up a recrowning job though.
If you came to my shop with this problem I would tell you to develope the load until you get the velocity to where it was before the problem, save 15-20 fps for the shorter barrel.
THis will give you nearly the same pressure as before which your rifle obviously liked.
Then I would start with your bullets seated where they are now and then test the load seated 0.005" less, then 0.005" less and 0.005" shorter still.
BAsically, you want to keep the same pressure and velocity but you may have to find a new sweet spot for your load length as shortening your barrel by 3/4" seems to have effected the harmonics of your barrel.
It may suprise you hwo your rifle will shoot with shorter lengths.
If this does not work, I would be a little concerned about them lapping the bore. If done correctly, this really does not take any real amount of metal off the bore, just polishes what is there.
IF done incorrectly, you can get buldges in your bore or actually over sized bores which will destroy your accuracy, especially if your bore is tighter at the throat then the muzzle end.
This can be a real pain to figure out unless you make a muzzle case and measure your muzzle diameter.
You can also take a lead bullet, pure lead is best that is close to .308 and drive it down your barrel from the chamber end.
You will actually be able to feel any variations in bore diameter as you push the bullet down the length of the barrel. In the loose spots it will be much easier to move the slug.
This is really to bad. A recrowning job should be one of the easiest accuracy enhancing proceedures to do. I only charge $15 to do it in my shop even with using live piloted bushings to match the crown to 0.0002" or less of the axis of the bore.
There is just no reason to screw it up like this.
This is a place to start, after that, may need a rebarrel job if the lapping washed your bore out to much.
Not good news but its better to know then wonder!!
Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.
Your rifle will shoot just fine. As I stated above, you just need to re-tune the load because the harmonics have changed. Nothing done to your rifle can be construed in any way as damage. Ross and Stephen know what to do to fix a rifle, there’s no doubt about that at all. If you need more information about what was done and for what reasons, please call Ross and get the best information straight from the gunsmith that did the work.
Work on the new loads and if you need assistance, give a holler.
I want to get this over with now rather than wait for this to bother me more.
Ross and Stephen of PGWDTI are friends of mine, personally and professionally. More than that, they are recognized for the quality of their work around the world. The language that you use to disparage their name and condemn their work is unacceptable. You know nothing about the rifle that got sent to them and you know nothing about the conversation that they had with their customer and you assume nothing but the absolute worst about their work.
Quote: “This is really to bad.”
Quote: “There is just no reason to screw it up like this.”
Other gunsmiths that post on public forums have the good sense, good manners and common courtesy not to condemn a fellow gunsmith out of respect and professionalism. You, on the other hand, go out of your way to make the above statements with no validation whatsoever, but work off of assumptions, when the answer can be as simple and probable as re-tuning the load. Adjusting a load for a change in a barrel has been done hundreds of thousands of times in the past and will need to happen in the future. It’s not unusual at all.
There is no reason to build a case against the gunsmith such as you have done except for unadulterated self-aggrandizement. You have taken advantage of this forum to use thinly veiled “answers” as a massive self-promotion campaign for your business. Len doesn’t seem to be bothered by it but I am. You need to get a new theme that isn’t so intensely self-centered. The rest of us have plenty of work simply because we strive to deliver the highest quality projects that we are capable of, consistently, one job at a time. We certainly don’t spend endless hours blowing our own horns trying to drag work in. All I can say is that I hope you outgrow this.
I know, Len, you don't have to tell me. But it was making me nuts. If you have to pull this, so be it. Regards to you and I hope that your toast turns out O.K.!
Crispin, I apologize if I came across the wrong way. I am in no way dis-satisfied with the work they did. In fact I am truly impressed with the amount of time it took them to finish the work. They had the work complete including the lapping of the bore which they did not charge me for within one day and believe me the job was truly professional. I assure you I will not be using any other gunsmiths in the future and would recommend them to anybody looking to have quality work done. I was merely looking for advice on the development of my load.
If anybody might know how much wear is allowable on a barrel before it is time to replace it. And as the bore opens up slightly won't the pressure drop and more powder be required to maintain that "sweet spot"?
The removal of 3/4" of barrel was required because there was ptting and damage inside the bore for almost a half inch at the muzzle. This I could see with a weak magnifying glass. As for changing powders I am going to see if I can add another half grain of powder and mess with the seating depth a little. I have had really good results with the 4350 in the past amd am reluctant to change until I've exhausted all my options first. Thanks for the input thus far guys I appreciate it.