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1911man
09-02-2012, 8:52 PM
I am looking for a local gunsmith to talk about backboring or lengthening the forcing cone of my 870 20ga. To see if it will help on patterning. I have seen on the Internet that it should help. I want to know if it will help and also reduce recoil at little. How much do you think it will cost. I am located in the southbay area of SF.

ysr_racer
09-02-2012, 8:55 PM
Save your money, buy ammo and take a class.

You'll get much more out of it.

BigDogatPlay
09-02-2012, 9:06 PM
+1

While you might get some benefit in perceived recoil from back boring the barrel, and you get some added velocity and a shorter shot string, it might be beneficial to understand what is going on with how your gun patterns now. Is this for a defensive gun or a sporting gun? And what is your expectation of pattern and at what distance?

Bear in mind that if your intent is to shoot rifled slugs at some point through a defensive gun, back boring the barrel will negatively impact accuracy.

G-forceJunkie
09-02-2012, 11:01 PM
Give Hans Vang a call, that is his speciality: https://vangcomp.com/

Thefeeder
09-02-2012, 11:36 PM
Try a different brand, shot size or load weight of shells.

What is your goal ? Are you looking for better density, equal spread, ect?

kentactic
09-03-2012, 6:16 AM
Shotguns are suppose to have wide patterns thats why we use them, if you want a tight group put a slug in.

prc77
09-03-2012, 7:06 AM
Shotguns are suppose to have wide patterns thats why we use them, if you want a tight group put a slug in.

so untrue.

.300 Weatherby Mag
09-03-2012, 9:31 AM
Save your money, buy ammo and take a class.

You'll get much more out of it.

+1

In a pump shotgun... The difference wouldn't be worth the $$$ invested... If we were talking about modifying a high quality target shotgun, then it might be a worthy investment... But in reality, you should find a barrel in whatever length you like and be sure it accepts screw in chokes and shoot it..

I love my pump shotguns but don't modify them other than having them threaded to accept screw in chokes..

kentactic
09-03-2012, 12:37 PM
so untrue.

Reading the OP again perhaps your right being its a 20GA. Forgive me as i tend to think of all firearms in the sense of being weapons. I forget people shoot at birds and circular clay disks simulating birds. Also isnt SB249 dead for now? I read they dropped it....

prc77
09-03-2012, 3:05 PM
Reading the OP again perhaps your right being its a 20GA. Forgive me as i tend to think of all firearms in the sense of being weapons. I forget people shoot at birds and circular clay disks simulating birds. Also isnt SB249 dead for now? I read they dropped it....

Huh?

223556
09-03-2012, 3:10 PM
Huh?

Think he was refering to your signature.
Tagged, Im gonna be working on my 870 soon, interested to see the comments on back boring.

kentactic
09-03-2012, 5:46 PM
Huh?

I see your vague Huh and raise you a What?

TacticalTrainingAssoc.
09-03-2012, 6:01 PM
Don Lazzarini in Santa Clara does serious shotgun work... DLG Enterprises (408) 492-1013. He's done work on my duty 870, AR, and all my Glocks. If it's a defensive gun, you are responsible for every pellet that comes out of it, you NEED to know the pattern with your chosen load.

prc77
09-03-2012, 7:45 PM
Don Lazzarini in Santa Clara does serious shotgun work... DLG Enterprises (408) 492-1013. He's done work on my duty 870, AR, and all my Glocks. If it's a defensive gun, you are responsible for every pellet that comes out of it, you NEED to know the pattern with your chosen load.

DLG lengthened the forcing cone on my Moss 500 and beveled the loading port on the same 500 and SLP. Very fair price, and turn around was fast. I patterned 8 different brands of 00 buck before the forcing cone work. The FC work that Don perfomed, tightened up the pattern with most of the buck. The tighter the pattern the better.
Like TTA ^^ said. "You are responsible for every pellet". Know how YOUR shotgun patterns.

1911man
09-04-2012, 7:20 PM
My goal for doing the forcing cone lengthening is to tighten up the groups evenly and I want it to pattern as dense as a 12 ga. with the same amount of shot at 40 yards. It will be for turkey hunting. I have heard that the forcing cone on a nova is about 3 1/2 inches! I have also heard that the benelli M1 and M2 autos, the forcing cones are already lengthened. I don't know if that is true though. Also part of the reason why I am investigating this is that I saw a tactical shotgun show that these two guys were comparing a 20ga. With a 12ga. They said they used the same loads and started shooting big poppers at 5 yards, then at 7 yards, and at 10 yards. The results were about the same, when they stepped back to 15 yards the 20 could not do what the 12ga. did. Then I googled 12 vs 20ga. During the search I found a guy that tested a 20ga. Before and after back boring and he almost doubled the shots that hit the patterned turkey head at 40 yards. My theory is that in the show I was watching 12 vs 20 ga. If the guy that was shooting the 20 ga. Had a back bored 20 would the results would have been closer or more evenly matched?

Thefeeder
09-04-2012, 7:28 PM
Won't a tighter choke have the same result as all the smith work?

lewdogg21
09-04-2012, 7:41 PM
Won't a tighter choke have the same result as all the smith work?

2x.

deckhandmike
09-04-2012, 8:23 PM
Just change the choke for 20$. Waste of money unless your doing competition skeet/trap shooting and even there it's debated if it's even worth it.

ysr_racer
09-04-2012, 8:28 PM
Who was it that said this again.

Save your money, buy ammo and take a class.

You'll get much more out of it.

hermosabeach
09-04-2012, 9:39 PM
I removed / smoothed the forcing cone in my mossberg 500 around 10 years ago

I did not notice any change in recoil

With OO buck, it reduced the pattern by 2 1/2 inches at ten yards

I never did a before and after compairason with bird shot

I picked up a reamer from Brownells and went to work with a vice and a tapping handle
The reamer was under $100

For the 870, i would spend the $100 towards a barrel with removable chokes

For non chrome lined barrels it is probably a 1 hour job from a gunsmith
If they have the reamer, then it should be a $50-$100 job

For the unknown on the final result, buy another 870 or a used barrel with removable chokes. You can then select the appropriate chooe for the job

The pattern on 12 and 20 gauges is similar. It is pellet density that is impacted with heavier or lighter shot loads

The 20 gauge is great for closer in upland birds

With geese you tend to go to higher velocity and heavier loads to have a dense pattern at distance or for tough birds like turkeys

1911man
09-05-2012, 6:09 PM
From what I have been told and have read is that a short forcing cone and or a tight choke will retard the pellets. When exiting the barrel the pellets produce a inconstant pattern, that is why when you shoot a denser pattern shot will tend to float around the shot pattern. Either more pellet holes, when parenting a shotgun, will group to the right, left, up or down.

The barrel that I might have worked on does have tubes.

Why would the 12ga. In the show that I watched knocked down a popper at 15 yards and the 20ga. Could not. If what they said was true that the loads were the same?

kentactic
09-05-2012, 6:39 PM
Keep in mind guys a choke can have the opposite affect. Some times a bunch of pellets being jammed into a smaller area so quickly causes a rebound affect making the pellets spread out more then with no choke. Not to mention making them out of round like 1911 said.

1911man
09-06-2012, 9:07 PM
That is exactly what message I was trying to convey. Thanks.